UPPSALA UNIVERSITET

Institutionen fö r arkeologi och antik historia

Västergarn Boat Rivets in Context Case study : The Missing Boatyard

Richard Koehler

MA thesis 30 credits in Archaeology Spring term 2020 Supervisor: Christoph Kilger Campus Gotland

1 Abstract

Koehler, Richard (2020). Västergarn Boat Rivets in Context, Case study: The Missing Boatyard Koehler, Richard (2020). Skeppsnitar och båtvarv i Västergarn. En kontextuell fallstudie Gotland has a rich material cultural heritage from the Stone Age to the Middle Ages thanks to the island's strategic location in the middle of the Baltic Sea; especially true for the Viking Age when Gotlanders had extensive trade contacts with the east dating from the mid 12th century and Gotland’s economy was dominated by such contacts. This essay deals with Gotland's maritime infrastructure and its development between about 1100 and 1400 based on a case study of boat rivets from the medieval settlement of Västergarn. The study focus is on Västergarn’s emergence as a maritime community on Gotland's west coast, and if Västergarn had the opportunity to decide its own economy, i.e., to control its’ external contacts and internal trade with the rest of Gotland? What role did maritime traffic play in Västergarn economy? Is it possible to draw conclusions about site maritime organization and infrastructure based on the extensive rivet material? What supply chains with the surrounding area may have existed that made such activity possible? What professional skills and knowledge were in place? In the analytical part of the dissertation a classification system for Västergarn's rivet material is established and discussed in comparison with other literature on boat building technology from the rest of Scandinavia, in particular the Baltic Sea area. Results of the study indicate the existence of a boatyard mainly for the repair of clinker-built vessels. Further conclusions about how shipping, especially after clinker-built vessels were replaced by cogs, affected Västergarn's economy and its’ further existence as a port, however, is not established.

Gotland har ett rikt materiellt kulturarv från stenåldern till medeltiden tack vare öns strategiska läge i mitten av Östersjön. Särskild är detta tydlig för vikingatiden då gotlänningarna hade handelskontakter österut. Sedan mitten av 1100-talet dominerades den gotländska ekonomin av kontakterna med tyska handelsförbund vilket också får nedslag i de materiella källorna. Denna uppsats behandlar Gotlands maritima infrastruktur och dess utveckling mellan ca. 1100 och 1400 utifrån en fallstudie av båtnitar från den medeltida bosättningen Västergarn. Syftet är att studera framväxten av Västergarn som ett maritimt samhälle vid Gotlands västkust och hur Västergarn utvecklades som en hamn. Hade Västergarn möjlighet att bestämma

2 över sin egen ekonomi, dvs att kontrollera de externa kontakterna och interna handeln mot övriga Gotland? Vilken roll spelade skeppstrafiken och användningen av skepp för Västergarn´s ekonomi? Går det att dra slutsatser utifrån det omfattande nitmaterial om platsens maritima organisation och infrastruktur? Vilka försörjningskedjor med omlandet kan ha existerat som möjliggjorde en sådan verksamhet? Vilka professionella färdigheter och kunskaper fanns på plats? I avhandlingens analytiska del etableras och diskuteras ett klassifikationssystem för Västergarn´s nitmaterial och jämförs med annan litteratur om båtbyggningsteknik från övriga Skandinavien, i synnerhet Östersjöområdet. Resultat av studien tyder på existensen av ett båtvarv huvudsakligen för reparation av klinkbyggda skepp. Vidaregående slutsatser om hur sjöfarten särskild efter att klinkbyggda skepp ersattes av koggar påverkade Västergarns ekonomi och vidare existens som hamn går däremot inte att dra.

Key words: marine craft, boatyard, WBS, supply-chain, Knärr, Cog, boat, ship, maritime community, interdisciplinary

3 Acknowledgments

I am indebted to many people for their generous support with this thesis, but especially my supervisor Christoph Kilger with special thanks for his professional guidance and endless patience with my attempt to transition from an engineering/construction background to academic writing. It is truly a project in progress

To Paul Wallin, his guidance and support with my special problem courses allowing me time and space to accomplish extra research on boat rivet artifacts.

Thanks to academic colleague Dan Carlsson and excerpts from his book, Vikingatidens Västergarn, to my better understanding of the Kronholmen landscape and cog wreckage there.

Also to Johan Rönnby for his paper, ”Kuggmaren 1: The first cog find in the Stockholm archipelago”, offering me great insight on cog construction and thoughts on profiling cog reality at Västergarn.

Rube Edberg’s, The Wrecks under our Feet, is a truly inspirational document with clear landscape connection to Västergarn, and it is with my sincere appreciation for his generous gift, one well absorbed.

To Erika Sandström and her 2016 summer class on Medieval Rural and Urban Gotland, the foundations material still very much in use.

The Vikingeskibsmuseet in Denmark for generous material backing on the Gokstad boat, with special thanks to Tríona Sørensen and Allan Kristoffersen for personal support and interest.

With cross-Baltic appreciation to Edvards Puciriuss in Estonia for his open-access sharing details of the Haapsalu boat design and creation.

My colleague, Anton Uvelius, and our lab discussions on artifact analysis during dark December days and nights.

But mostly and primarily it is with deep thanks to my wife, Inga-Märit, without whose love and total support this thesis would have never materialized.

Dedicated to Inga-Märit

4 Content

1. Introduction 1.1. Introduction and Research Overview …………………………7 1.2. Research Aim……………………. …………………..………...... 8 1.3 Research Questions…………...……………………………….....9 1.4 Research Method and Theory….……………………… ……….10 1.5 Source Material and Criticism…... …………………………….11 1.6 Terminology……………………………..…………………………12 1.7 Thesis Layout…………………………………………. …………..13 1.8 Gotland and Västergarn………………………………………….13 2. Ships, Boats and Vessel Services 2.1 Västergarn’s Maritime Landscape ……………… ….………..16 2.1.2 Introduction and Overview……………………………..……..16 2.1.3 The Knärr Classification…………………..…….……… ..… 17 2.1.4 Gokstad Small Boat Classification……………………..……20 2.1.5 The Haapsalu Boat…..…………………………………………21 2.1.6 The Cog……………………………………………………23 2.1.7 The Boatyards…………………….……………………….…… 25 2.1.8 WBS…………..………………………………………………..…25 2.1.9 Adjacent Shipyards……………………………………….…….27 2.3 Chapter Summary…………………………………………………32 3. Maritime Artefact Classification…………………….….33 3.1 Iron Boat Rivets in Context………………..………………….…33 3.2 Rivet and Rove Design……………………………………………34

5

. 3.3 Tracking Mass Material……………………………………………37 3.3.1 Iron Artefacts - Classification Across Context…..……………37 3.3.2 Deformed and Incomplete Rivet Profiles…..………………… 37 3.4 Cross-Sectional Shaft Profiles…………………………………….39 3.6 The Classification Dilemma…………………………………….....42 3.8 Discussion of Source Material……………………………….…....45 3.9 Artefact Inventory & Distribution……………………………..….46 3.10 Chapter Summary………………………….………………...48 4.0 Landing Places and Harbours……………………………49 4.1 Landscape Overview…………………….………………………….49 4.1.2 Västergarn as Special Economic Zone……………………..….50 4.2 Discussion: Landing Place and Harbour………………… …….51 4.2.1 Landing Place.…………………………………………….…..…..52 4.2.2 Harbour……………………………………………………….……53 4.3 Chapter Summary………………………………………………..….55 5.0 Summary and Conclusions………………………..….…57 6.0 Discussion and Recommendations……………………..….59

Bibliography…………………………………………………..……..…62

Appendix A Västergarn Artefacts……………………………. ……69 Appendix B Scandinavian Cargo Boats…………………… ……...70 Appendix C Rivet Inventory A………………………….……… ……..71 Appendix D Rivet Inventory B.…………………………… ….……..72 Appendix E WBS…………………………….……………. …….73 Appendix F Small Boat Specifications……………………… .…74 Appendix G Shoreline Elevation Chart……………………… ….…75 Appendix H Peace Zone & Boat Building..…….…………….. ..….76

6 1 Introduction

1.1 Introduction and Research Overview

The mixed Scandinavian economies over the Viking and Middle Ages were greatly sustained by seaborne trade, as was true for the economy of Gotland over this time period. The realisation of this external trading and exchange process was thoroughly dependent on a very defined, if informal, supporting logistical system of ports, harbours and landing sites; an array of maritime facilities that were often more of a concept in principle than functional reality. Evidence supporting a Gotland maritime network is mixed. While there is ample archeological evidence of trade goods as exports and imports in an exchange process around the Baltic Sea area and eastward into Russia, consensus is lacking on Gotlandic trade zone composition or of boat building facilities that supplied the marine craft. The perhaps unintentional result of such generalization is that trade, as a subject, is thought of purely in terms as a “physical product exchange” process that largely took place in a vacuum with minimal outward or inward influence on natural and human environments. To illustrate further, the terms “trade” and/or “trading” in a Viking Age context are frequently characterized in popular literature by a seemingly singular focus on the physical objects of trade such as hack-silver, foreign coins and jewellery, to name a few common examples, while allowing little attention to the process of trade beyond the trade goods. Important collateral effects of trade modus operandi on urbanization matters of social, cultural, economic development and security are simultaneously undervalued as is obvious by its limited reference, discussion, or total exception. In other words, trade has been positioned as a mechanical process of limited cultural, social, or economic exchange. In fact, the opposite is true. In the strictest sense trade is the process of barter premised on certain mutually acceptable provisions of supply and demand. Trade

7 requires an agreed and secure meeting place, a venue to accomplish negotiations and conclude the exchange; a point at which today can be accomplished electronically but in Västergarn’s Middle Age society the process of trade was a physical catalyst bringing people together for in- kind exchange of ideas, articles, food, and other necessities in a place of safety such as a Peace Zone decree attributed to Gotland (see Chapter 4). The act of trade is represented by the exchange of goods between countries as well as between individuals, a subject that leads to the topic of globalization and a range of new issues on urbanization vs. hinterland, and while outside the scope of this paper the subject cannot be ignored for historical analogy to Västergarn’s trade position. Västergarn, a Middle Age coastal settlement on the island of Gotland, depended on marine craft for survival as a maritime community, but data such as vessel classification, size, ownership, fabrication and repair are mostly silent in both historical sources and the archaeological evidence, or so it has been. With this thesis I argue that the building block sequence to create a working knowledge of a Västergarn marine vessel profile starts with the archaeological evidence, i.e., with the boat rivet artifacts, and that there was a particular classification of boat that was best matched to Västergarn history. I will identify this virtual maritime craft as the Västergarn Class Boat, a vessel category aimed to be synonymous with Västergarn for current and future research.

1.2 Research Aim

In maritime associated excavations boat rivets are too often discarded without proper consideration of their archaeological significance and greater contributions to be made when profiled across their contextual setting. This is especially true when rivets are found in a mass material environment without shipwreck, associated ship debris or other maritime reference material for identification guidance. In such situations the otherwise distinctive shapes of boat rivets and roves can easily become lost in the classification process, often dismissed as scrap metal and inventoried anonymously in uncategorized clusters. All too often they are simply discarded. There are several supporting objectives in my research with aim to test classification of Västergarn boat rivet artefacts against literature and overcome the scrap bias:

(a) Connect rivet profiles with boat categories (b) Demonstrate artefact value in a reconstructive archaeology context (c) Illustrate how rivets can be used to connect to their hinterland (d) Introduce the Work Breakdown Scheme (WBS) to archaeology

8 (e) Bring new knowledge to mass material field classification theory (f) Argue forcefully for classification of rivet material in excavations

Each rivet artefact has a particular history to communicate by unlocking its’ classification and functional role in a shipbuilding/ship repair discourse. This paper aims to bring life to these inanimate objects in a methodological diagnostic approach wherein the rivets are considered as foundation units in the skeletal framework of a Västergarn classification boat.

1.3 Research Questions

This thesis is a journal in maritime discovery arranged in case study format with aim of validating wrought iron boat rivet artefacts as supporting evidence of a presumed boatyard site at Västergarn. The case study method is an appropriate tool here, in a study for qualitative data recovery with limited resources. My discovery process is analytically grounded and arguably diagnostic with conceptual forensic foundations in constructing what I introduce as a “boatyard dialogue” that positions contributions of boat rivet artefacts in a Västergarn site catchment analogy. I present my research arguments that mass-material iron artefacts offer unrealized value and resources of new knowledge for landscape and coastal archaeology in values that are well beyond their more commonplace designation of “scrap-metal”. Three core research questions are examined by discovery and validation in specific chapters:

(a) What were the most credible Middle Age boat classifications that would have visited Västergarn over its’ life-cycle for purposes of trade? (Chapter 2) (b) Do Västergarn rivet artefacts match Middle Age boat classifications and construction details? (Chapter 3) (c) Without man-made improvements would Västergarn’s contemporary coastal profile have harmonised with visiting ship service requirements? (Chapter 4)

The three-chapter research cycle employs the “form follows function” principle attributed first to Louis Sullivan and industrial design wherein the primary form or shape of an object should relate to its’ intended function (Lewis 1896). Using Västergarn rivet artefacts as the reference base, I apply Sullivan’s basic design model to each chapter starting with Middle Age ship and boat designs that were common to Baltic Sea trade (Chapter 2) to first profile vessels by their

9 design classification and how ship classification dictates harbour design (object: form). Chapter 3 in sequence on rivet classification discusses iron rivet morphology and topologies common of Västergarn rivets (object: function) in correlation of rivets with ship profiles. Chapter 4 summarizes in a Landing Place narrative illustrating how Västergarn’s natural landscape form had to follow functions created by ship operational requirements. In summary then, the broader parameters of maritime trade and support systems contemporary to the Västergarn site over its’ greater life-cycle period profile ca 1100-1400 AD are examined in determination of credible Middle Age vessel categories that would have required shipyard services. Iron fastener (rivet) artefacts from Västergarn excavation years 2005-2017 are classified against period vessel designs in a skeletal vessel reconstruction method to quantify rivet taxonomy with ship design.

1.4 Research Method and Theory

The aim of this thesis is to test classification of Västergarn boat rivet artefacts against literature and apply findings across Middle Age ship and boat building technologies common to the Baltic Sea. This is a maritime foundation question for Västergarn, an analytical journey following grounded theory, qualitative data, observation, and argument. I apply topology and morphology methods across the Västergarn archaeological evidence that supports a late Viking Age/Middle Age boat-building or boat-repair activity model at Västergarn ca1100-1400 AD. It follows a conceptual forensic themed scheme of discovery, evaluation, application, and summary of findings essential to understanding the place of boat rivets across Västergarn’s life cycle, a process method that I will call Rivetology. A “missing boatyard” profile is applied by imposing a Västergarn based rivet topology to period profiles of Middle Age deep-water cargo ships and boats that could have called at Västergarn and by extension to shore-based boat support and supply services that would have been obligations of Västergarn in a maritime context. By application of contemporary supply chain theory and methods across the boat yard model we see how the demands of supporting such a facility would affect the resident Västergarn community. Empirical data for this thesis are taken from a research study I conducted at the Archaeology Lab of Uppsala University-Campus Gotland (Visby, Sweden) between November 2018 and January 2019 with objective of separating boat rivet category artefacts from general category iron objects. The resource base was mass material categorized primarily as iron that was collected over Västergarn excavation years

10 2005-2015. Artefact topology and morphology identified and isolated complete rivets, independent rivet components, roves and other maritime fasteners or clenching type items such as clamps, bolts, spikes, and tacks from mass material for stage 1 classification purposes. Classification was further reinforced by literature comparison and analogy with published material. A total of 2,834 boat rivet fastener category items were recorded and 1,208 photos taken. Departmental documentation for Västergarn maritime artefacts was reviewed and guidelines recommended parallel with lab work. Additional information on classification and photographic documentation of laboratory material is contained in Appendix A of this thesis.

1.5 Source Material and Previous Research

My search aim to construct a conceptual model of Västergarn as a transitional Viking Age to Medieval Age boatyard sourced material focused on the Baltic Sea Basin and Danish straits. This is an exceptionally large area of course, but it is also the region most immediately connected to Middle Age Gotland and Västergarn for direct trade and the marine vessel types that serviced that trade. A source critical assessment of Medieval ship or boatyard site literature suitable for Västergarn’s time period found a variety of Northern European based reference materials but seen in a collective basis it primarily treats the more landscape category subjects of deep-water harbours, docks, jetties and port construction, all on scales greater than Västergarn’s setting. There is negligible application for Västergarn from those sources to assist with boatyard design, and I have also discounted theme or period literature focused on Iceland, the North Atlantic and the British Isles. For boat classifications there is considerable literature available from boat burials and shipwrecks across Sweden and over greater Scandinavia but little material specific to rivet morphology for reference. Boat burial rivets tend to be complete (head, shaft and rove), not deformed, and uniform as a general observation if the grave has not been overly disturbed or scattered by cremation, but they offer virtually no useful information for this study more than a generic quantity inventory. Ship burial data however can be allocated to Västergarn artefacts in a rivet quality relation to a measurable boat size if the burial rivets have been quantified. Gunilla Larsson treats this subject very well in Section 2 of her book, Ship and Society, using shipwreck and boat burial material to illustrate boat rivets in ship profiles (Larsson 2007). The vacuum of rivet fastener literature forces contextual classification

11 assumptions on Västergarn rivet artefacts. Photos (by author) of selected Västergarn finds have been superimposed in the thesis text where they can add clarification. For previous research on boat rivets and boatyards, Rune Edberg’s study on Viking age boat building and repair at Sigtuna, Subterranean Maritime Archaeology in Sigtuna, Sweden: excavated evidence of Viking Age Boat building and repair (Edberg 2013) is in considerable depth and the only literature source focused on matching mass material rivet artefacts with period boats. There are striking parallels between Sigtuna and Västergarn in excavation evidence and although the geographic area of Västergarn is tiny in comparison, the similarities of matching artefacts and boats follows similar patterns of discovery. A second paper by Edberg, The Wrecks under our feet. A study based on the findings of clench bolts in Sigtuna’s occupational layers, although unpublished, convincingly addressees the hidden value of archaeological mass material (Edberg 2009: unpublished). Edberg’s research has been a foundation resource, particularly on rivet classification and the challenge of mass material artefacts.

1.6 Terminology This thesis is about Västergarn, a Medieval maritime site in Sweden on the island of Gotland, and the location of a much discussed but not proven landing site or harbour with attached boatyard facility. The evidence supporting either harbour or boatyard is circumstantial to date, even argumentative, but archaeologically the site offers some interesting clues. Modern constructs are applied to build a transformative picture conveying boat rivets from excavation artefact to their place in a Medieval boat and thus by extension to an image of visiting boats at Västergarn. Supply-chain management of the maritime environment, logistics, supportive infrastructure, services demand and service terminology is used in a project picture of Västergarns’ supply chain- consumer matrix. This thesis throughout uses the identifier of “boat rivet” to describe the iron fastener in marine vessel construction while recognizing and accepting other terms such as “clench bolt” and “clench nail” are in common use. Chapter 3 discusses the classification subject in more detail.

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1.7 Thesis Layout

Chapter 2, Ships and Shipyards, surveys Medieval ship and boat classifications as the foundation for tracking Västergarn boat rivets from inception to end. Chapter 3, Maritime Artefact Classification, is the core thesis chapter as it follows interpretative arguments and classification opinions on rivet and fastener morphology and topology. The focus in Chapter 4, Landing Places and Harbours, is on landing sites and harbours in a comparative discussion to match ship and vessel categories (found in Chapter 2) with the physical and supporting infrastructure that would have been required of Västergarn in order for it to function as a fully operational Medieval maritime facility. Chapter 5 summarizes with conclusions, and Chapter 6 is thesis closure with Discussion and Recommendations.

1.8 Gotland and Västergarn

The collective maritime history of Gotland is extensive dating from the Neolithic, but credibly it can be recorded across the Early to Late early Bronze Age, ca1200-100 BC. The symbolic and archaeological evidence of marine craft in Sweden is widely documented in rune and picture stones, but more symbolically in stone ship settings. The early Viking Age from around 750 AD and trading routes east accumulated enormous hoards of precious metals on Gotland over the ninth to eleventh centuries. Peter Sawyer contends that the abundance of silver did not itself stimulate economic activity, but rather that it was accumulated by Gotlanders as a form of collateral (Sawyer 1993: 188) and hoard material did not often change hands (for reasons not elaborated by Sawyer). There is probably some argument for his reasoning, but also ample room for a counter position by Ben Raffield that Gotlands’ self-positioning posture as a key intermediary in the Viking Age long-distance slave trade functioned on a foundation of silver as the recognisable form of payment (Raffield 2019: 691). In a contemporary economics assessment, Medieval Gotland could have matched David Ricardo’s classic economic theory model wherein a country exports those products for which it holds a comparative advantage and imports goods and services where it is deficit (David Ricardo 1817). Gotland was a net importer of critical material goods to meet domestic consumption needs and to service production of export

13 products, especially raw and semi-processed metals such as wrought iron for farm tools, weapons, and boat building. Equally important were imports of non-ferrous base metals and alloys for production of jewellery and other Gotlandic cultural items that were highly valued for export. Other domestic products that held no special competitive advantage in product quality i.e., wool, tar, limestone, baptismal stones, etc., were exported to niche markets but not in quantities to support the overall economy. Despite a generally negative trade balance, or as a consequence of it forcing exports to equalise with imports, Gotlanders managed to establish themselves as stakeholders in international niche markets (Gustafsson 2020: 80) but the process was slow. Even so, we can see how the long established Gotlandic practice of accumulating wealth (for whatever reasons) could have contributed to a “barter” type economy in Västergarn that would have been practiced in the Peace Zone, a distance of “eight arms” or about 14 meters from the beach inland offering merchants’ legal protection along the Gotlandic coast (see Chapter 4). Archaeological evidence to support a range of 50 or more locations situated around the Gotlandic coast indictive of active Viking Age trade (Carlsson 2018). By the beginning of the Middle Age trade on Gotland began to concentrate on more stable locations with predictable trade patterns as opposed to the random Viking Age ventures east. Visby and Västergarn were two of the first on Gotland transiting to Middle Age trade, and both sites began initial construction phases of boundary walls (Gustafsson 2020: 85-87). By the 1200s Sweden is recognized as a state by other countries, principally Christianized, and participating in church orchestrated administrative skills such as accounting, tax enhancements and discovery of the virtues of state bureaucracy. Gotland becomes a node in the growing international trade community with Visby and Västergarn as active participants. In July 1361, Gotland was attacked and conquered by Valdemar IV of Denmark. Around 1470 the Hanseatic League rescinded Visby’s status as a Hanseatic city. After over 300 years of Danish rule Gotland was returned to Sweden by the Treaty of Brömsebro in 1645 and remains Swedish today as a province. Comprising an area of 3,000 sq/km and 800-kilometre coastline, Gotland is the largest island in the Baltic Sea, ringed by smaller satellite islands with their own archaeological interest (Edquist 2015: 39). Although isolated geographically speaking, Gotlandic people and cultures evolved or blended over the centuries into a unique maritime and agricultural society that remained Viking Age into the early Middle Age. Västergarn is in name today both a Gotland parish and a small maritime settlement within the parish, a rural quadrant that was once Medieval Västergarn. Located on Gotland’s west coast approximately

14 25 km southwest of Visby, the contemporary designation of “maritime Västergarn” means mostly recreational boating and fishing although the area has long been a site of marine activity and community, mentioned already in Medieval source material as both landing site and harbour (Zachrisson 1999: 10; cited Floderus 1934: 81). In medieval times the Västergarn community was enclosed within a very rough semicircle wall of earth and stone to the north and east, an enclosed area of about 12.5 hectares (current area) leaving the west side open to the Baltic Sea (See Figures 1 and 24). This area is primarily pastureland today with three medieval structural remnants; i.e., the ruins of a Romanesque church (late 12th century?), a 13th century Gothic style church that remains in service today, and remains of a castle or defence tower (Zachrisson 1999: 13). The wall is actually a sloping embankment, open to the west on the beach front section. (Chapter 4 for orientation map). It is the open area that connects directly with Chapters 3 and 4 of this study. Rivet artefacts classified in Chapter 3 were excavated in a rough profile approximately 25 m on both sides of the blue NE x SW line in Figure 1 below, placing them in settlement contexts of nearby houses. No forge or other strong indications of metal working have been found aside from 60-70 kgs of slag that has not been date or quality tested. The blue excavation line continues south west to the beach area and possible landing site or boatyard zone. Artefact distribution suggests an area of ship destruction or repair where vessels were broken down for recycling or other use. If so, it is not clear why vessels would have been pulled so far from the waterfront for destruction unless the beach area was prioritized for other activities to the community such as maintaining an open access trading area as discussed Chapter 4.

Figure 1 above: Embankment area open to the sea for trading and marine support. See Appendix H for larger map.

15 2. Ships, Boats and Vessel Support Services

2.1. Västergarn’s Maritime Landscape

The Baltic Sea over Västergarn’s history was an active maritime area of pirates, regional conflicts and home to a mixture of marine vessel types ranging from war ships and Cog type large bulk carriers to midsize regional trading boat category vessels. A variety of coastal trading cargo designs particular to needs of regional cultures and customs serviced smaller markets. While there were sufficient design similarities to create general vessel categories there was nothing that could be classified as the standard design for a particular vessel category as would be recognized today. Every country and region facing the Baltic had its’ own particular maritime traditions formed by cultural influence, local environment, and natural resources available for vessel construction, supply, maintenance and crews. Gotland fits this maritime profile, i.e., not one of a country, but that of an established maritime Baltic society that was clearly a combination of both consumer, ,and provider of material goods and human services. Västergarn’s place in this scenario was one of an important node in the Baltic maritime matrix. The maritime thread beginning in Chapter 1 continues here with an overview of ships, boats and vessel fabrication in establishing a foundation profile of Västergarn’s particular maritime history. In a comparative sequence we see how evolving Medieval marine vessel construction technology and increased vessel size affected harbour design and services such as vessel building, maintenance and repair, and general support services to visiting mariners. Marine vessels of any type are complicated system-based machines no matter their time in history or design function and all marine systems are dependent on a stable land- based support organisation for construction, maintenance and resupply.

2.1.2 Introduction and Overview – Middle Age Vessels

In this chapter I present the principal Middle Age cargo ship and boat categories that conceivably could have called at Västergarn over its’ extended active life cycle (ca 1100–1440 AD) for purposes of trade, general commerce, or diplomatic mission. I profile vessel specifications

16 against Västergarn rivet artefact evidence to assess the most probable match of vessel(s) fabrication and repair requirements with a conceptual boat yard. The maritime facilities that both transient and resident Västergarn vessel owners would have expected in terms of community supported maritime supply and services are critically discussed. The Work Breakdown Structure (WBS) is introduced and illustrated with a demand and supply schematic that identifies critical path modules in Västergarn’s capacity to support maritime facilities. The ninth and tenth centuries dominate our impressions of Viking Age ships as iconic expressions of shipbuilding techniques, certainly as seen from today’s perspective (Bill 2008: 175) and well represented in particular by the symbolic Oseberg and Gokstad ships. The history of that early era in shipbuilding is a supporting foundation for this chapter, but not the focus. Innovations in shipbuilding technology and new construction methods over the 12th century created larger ships capable of carrying increased cargo loads reaching 60 tons by 1100 AD and larger capacities up to 120 tons by the 13th century. The larger ships created associated demands on maritime societies to upgrade from landing site categories and provide improved harbour facilities with shipyard capacity and support services that would have been linked across the Baltic Sea trading network. The growth experienced in maritime communities was not equal in all regions however, and not all communities adjusted to increased demands for conversion of their waterfront facilities. Some could not change for intrinsic economic reasons, while others were hindered by the unsuitability of their natural maritime landscapes for expansion, an example being the flat shallow beaches of Västergarn that could not accommodate Medieval Age deep draft cargo vessels. By around 1100 AD the environment for territorial expansion by raid or conquest over Northern Europe and the British Isles had diminished along with need for Snekke war ship type vessels of 40 or more warriors, replaced by more mundane commercial needs best serviced by marine craft with greater cargo capacities (Christiansen 1997: 15f).

2.1.3 The Knärr Classification

Many, if not the majority, of Baltic Sea Medieval Age cargo vessel constructions were influenced by clinker-built designs derived from Scandinavian traditions, with several variations of the Knärr being especially prevalent. Strict definitions of ship building traditions across countries were blurred as designs proved highly adaptable to local and regional design norms and material sources for vessel construction and maintenance. In this section we consider the ubiquitous Knärr.

17 The largest Viking Age merchant class vessel was the Knärr. Recognizing that the expression “Knärr” (High Medieval prose :“Knorr”) can mean different things to different readers it is useful to begin with a brief historical look at uncovering the original root meaning of Knärr; its’ etymology, and see how the term connects with contemporary characterizations of ship types (Heide 2014: 93). Looking back in history the primary purpose of all early Viking Age ships was for raiding and warfare, but the basic hull design was stable and became precursor to the cargo vessel category. The understanding of Knärr as “cargo ship” probably came into common use with alternative meanings sometime over the tenth century before being the dominant meaning (Heide 2014: 107). Even so several other terms, i.e., Bardi, Kuggi, Búza, were shared terms across the 9th – 14th centuries in general historical and mythological categories, but Knörr (Knärr) for seagoing trader was in use over the entire period (Simek 1979: 26-33) .

Figure 2: Chronological distribution of vessel terms. Adapted from Old Norse Ship Names and Ship Terms. Simek: 33.

The Knärr category vessel is an evolutionary product of Viking Age clinker ship building tradition, constructed on a full-length keel with overlapping hull planks (strakes) joined together by iron rivets and roves similar to those found in the artefact material at Västergarn. The construction supply chain of a Knärr classification was very regional in terms of local supply for various wood types in hull fabrication, tar and caulking material, raw materials for sails, rope, and fittings, all being categories accessible to Västergarn. Basic smithing skills for on-site production of rivets were not beyond those of Västergarn’s hinterland supply although the process was labour intensive and may have required more permanent staff. Originating in Norway as a cargo ship apparently to support cross Atlantic explorations in its’ original use, the Knärr profile is perhaps the best recognized vessel in the Viking Age cargo category. Although shorter in overall length in comparison with the better well known and

18 famous Longship the Knärr length/width ratio was much higher in substantiation of a purpose-built design with heavy framing for greater load capacity. The larger vessels in North Atlantic service reached 20 to 30 meters in length and were fully decked at both ends for passenger and general cargo protection while not sharing the open middle deck with animals. Knärr type vessels were powered at sea by a single large square sail and rowed in port for manoeuvring purposes. Marine craft archaeological evidence clearly demonstrate that large Nordic bulk carrier cargo vessels in ship categories such as the Knärr were in North Sea and Baltic Sea service during the 11th and 12th centuries (Crumlin- Pedersen 2000: 244). Jan Bill names at least two probable factors that encouraged development of specialised cargo carriers in Viking Age Scandinavia; one being increasing volumes of trade, and secondly the stratification of society that required lower transportation costs (Bill 2008: 175). Construction specifications were adjusted to meet cargo and operational parameters, ranging from 14 m length and load capacity of 4.6 tons for coastal trading Knärr type vessels, and up to 16.3 m length with cargo capacity of about 15 tons for long distance Baltic sailing. Typical for Viking Age clinker constructed ships, the Knärr category was of shallow draft design of 1.0 to 1.5 meter or less and suitable for landing place beaching for purposes of trade or repair. Being shallow draft was an important specification for visiting Västergarn where the beach profiles were shallow and only beaching type landing site options were available. Knärr category vessels were well suited for Baltic Sea traffic for bulk cargo and live animal transport, and yet requiring a small operational crew size of about four to six.

Figure 3: Knärr (Knörr) cross-sectional elevation view illustrating bulk cargo, animals, and crew areas. No dimensions provided. Simek 1979: 33.

19

Figure 4: Ship remains found in the Roskilde fjord described as a probable Knörr II type cargo ship from 1030-1050 AD. No dimensions provided. (Heide 2012: 107 né Crumlin-Pedersen and Olsen 2002: 124)

The maritime designation of “Knärr” is well entrenched in common marine vocabulary across the Baltic Sea, but it is not always applied in context with actual vessel size or intended vessel use. While there is little doubt that larger class Knärr vessels visited Västergarn, I argue that Västergarn was not dependent on larger class boats or ships for survival; i.e., not the large Knärr or Cogs, but that it was well served by small to mid-size vessels. The prevailing seacoast conditions at Västergarn were not accommodating for large deep draft ships or boats, forcing cargos from larger vessels to be lightered or exchanged ship-to- shore by small craft, a time consuming and weather vulnerable operation.

2.1.4 The Gokstad Small Boat Classification

Two significant factors set my parameters for Västergarn small boat argumentation: the prevailing seacoast and sea bottom conditions, and the rivet artifact classifications. As is discussed in Chapter 4, Västergarn coastal conditions were more suitable for shallow draft beaching type vessels, and the excavated Västergarn rivet inventory more closely matches smaller vessel configurations. To reach a small boat classification profile for this study I have selected the Gokstad Boat (9.77 m), Figure 5, as a vessel type; not a standard, for Baltic shallow draft boat comparison purposes and note its’ distinguishing dimensional differences with the Gokstad Long Ship (23.8 m). While the Gokstad Ship grave is widely recognized and

20 documented, much less is published about the three small boats interred as grave goods in the same burial. It is the larger of the three grave good Gokstad boats as reconstructed by the Vikingeskibsmuseet (Figure 5) that I selected (see also Appendix F for Gokstad boat specifications and Vikingeskibsmuseet link). Visiting boats of this size and cargo capacity would have easily traversed both the Baltic Sea and along the Västergarn coast, placing reasonable supply and service demands on the local community. If in need of repair or other maintenance while visiting Västergarn the boat yard would offer services, and the cargo capacity was large enough for general cargo and animals. Frequency of visits was dependent on established trade relationships and visiting traders would be welcomed under the Gotland-at-large “Peace Zone” proviso (Chapter 4).

Figure 5: Gokstad Boat as reconstructed by Vikingeskibsmuseet, Roskilde, Denmark Photo Werner Karrasch. Copyright: The Viking Ship Museum, Denmark.

2.1.5 The Haapsalu Boat

The Haapsalu Boat is of contemporary construction by a reconstructive archaeology association in Estonia. Design parameters are based partially on open-source Gislinge boat model drawings provided by the Roskilde Viking Ship Museum in Denmark, but the bulk of the final design is essentially an in-house authenticlly detailed and purpose-built contemporary version (9.209 m) of the larger of the three Gokstad burial boats, especially in cross-section amidships. The essentially flat

21 bottom shallow draft design is accredited to central Sweden and west Slavonic boats of the Baltic tradition and well matched to beaching (landing place) activity. All hull rivets are made of hand forged iron with square cross section design of approximately 5x5 mm, a rivet shaft specification that corresponds very well with a cross selection of Västergarn rivet artefacts. The roves are also hand forged iron, and hand forged iron spikes were used on keel ends where riveting was not possible, but no bent (i.e., clench) nails were used anywhere in the construction (Puciriuss 2020). Boat structural sections are of oak across the keel, stems, and frames, with 5 lapstrakes of pine. During installation of the pine strakes the builders observed that rivet heads and rove ends would occasionally sink marginally into the wood as an effect of the riveting process, and that the distance between rivet head and rove does not necessary give the actual thickness of planking as is so often suggested in literature (Puciriuss 2020). The completed boat (Figure 6) specifications are 9.209 m LoA (length overall) with 1.9 m beam, and 1.0 m draft. It is fitted with 6 rowing places and estimated cargo capacity of 3 to 4 tons. The hull is keel pig framed with Keelso for 15 m2 sail configuration.

Figure 6: Haapalsu Boat. Photo Valerji Larionov. Photo Copyright: Larionov Photo Estonia

The significance of the Haapsalu Boat goes far beyond a successful reconstructive maritime project. It is represented here as a working demonstration of how culture and trade systems would have spread

22 around the Baltic Sea as design ideas were exchanged and adjusted to match locally soured materials of construction. The builders are in Estonia and the boat represents a mixture of data and practice sourced from Denmark and Norway, blended with Estonian traditional details. Approximately 600 hand forged rivets from 1.5 cm to 10.5 cm were used in construction of the Haapalsu boat with the majority being in the 1.5 cm to 3.5 cm range, a spread that matches closely with the largest grouping in the Västergarn excavation count. Rivets in these ranges were used primarily to secure the upper most lands and strakes, an area of the boat that receives continuous wear and damage during landing, loading and unloading operations, the most probable wood sections for replacement at a Västergarn boatyard where new lumber, rivets and labour would be offered. As we see in Chapter 3, rivets removed for repair work cannot be reused, and repair work of this nature would account for the large quantities of 1.5 cm to 3.5 cm artefacts and lend credibility to the missing Västergarn boatyard argument.

250

200

150

100 Artifacts

50 Haapsalu

0

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 7.0 8.0 9.0 10.0 Rivet Comparsion Chart - Västergarn Artifacts and Happsalu Boat Construction

Figure 7: Rivet Comparison Chart – Haapsalu (red) to Västergarn artefacts (blue). See also Appendices C and D.

2.1.6 The Cog

Although it is my opinion that Cogs and similar deep draft large cargo ships were infrequent visitors at Västergarn for purposes of trade or resupply, Cogs were a major Middle Age ship classification across the Baltic Sea and should be mentioned here as part of the full Västergarn maritime picture.

23 Cogs appeared in North European records over the 10th century, first in the Netherlands, probably as a basic cargo vessel. The design became widely identified with the Hanseatic League and long-distance maritime trade in Northern Europe (Hocker 2004:72f), and cogs (German: die Kogge or der Koggen) were familiar across German and Dutch fleet networks up into the 15th century (Hodges 1991: 85). The term “cog” or “cog ship-type” developed into a familiar all-purpose Medieval Age merchant ship classification between the 10th and 15th centuries in Northern Europe and Mediterranean countries (Weski 1999: 360, 366).

Figure 8: Cog motif in Sanda Church located about 4.5 km inland east from Västergarn. An exceptionally clear image depicting classic Cog design features; lapstrake hull, full stern rudder, forward and aft castle decks, single mast, and straight stem and stern post. It is interesting to note what appear to be two bow anchors, possibly to counter shallow mooring conditions of Västergarn bay. The parade of fish at water surface level may suggest connection with Gotlandic sea-going farmers. See also 2.1.8 WBS for Sanda supply chain connection. Photo: Christoph Kilger, by permission.

Constructed in a “bottom first” technique with lapstrake sides in appearance to similar vessels of the clinker-built tradition (Hocker 2004: 74) cogs followed a technique characterized by connecting hull planks and caulking methods in a clinker technique. In this method cog hull planks are joined together with clinch nails with the nail ends bent

24 inwards on the inside. Joints are sealed with moss held in place by caulking sintels and covered with wooden laths (Litwin 2003: 151). Cogs and their variants were one of the bulk cargo category ships over much of the Middle Ages, commonly measuring 8 m width by 20 m at the waterline (Cushing 2010: 27) although later ships reached 26 to 28 meters at the waterline. Cogs were configured initially as a flat- bottom construction vessel in order to service North European trading cities located on tidal rivers or tidal harbours where they could be beached. In an operational description cogs would sail as close as possible to the beach and wait for the tide to recede allowing the vessel to settle on the seabed. Cargo loading or un-loading could take place between tides, and with the incoming tide the vessel would be lifted and returned to the navigable sea. This method allowed trade to function without demands for docking wharves, but overall it was an inefficient process that was always subject to sudden weather interruptions disrupting cargo handling operations (Zwick 2016: 112) and the always present danger of hull damage from rocks or other debris on the seabed. In an operational concept Cogs offered very little for Västergarn as the Baltic Sea has no significant tidal range to accommodate the Cog bottom beaching design. As harbour facilities evolved with the growth of maritime trading cities and ship building technologies, tidal based ship operations were replaced by sheltered harbours with dock facilities for loading/unloading, and permanent warehousing facilities. This evolution never took place at Västergarn with negative effect on its’ growth. By the mid-1400s small Medieval merchant class single-masted cogs were rapidly being replaced by a range of larger and faster ships equipped with more sail and greater cargo capacities (Adams 2013: 20). Rapid economic development in Northern European and the Baltic regions over the intervening years had a transforming effect on vessel design. As direct trade volumes expanded across maritime communities the cog class vessels became obsolete. 2.1.7 The Boatyards Historical literature sources credit Västergarn with boat building and repair functions, both being activities that of necessity would be located at the shoreline for ease of vessel recovery during repair and for launch of new construction. The concentrations of Västergarn rivet artefacts are however located inland, away from the Medieval shoreline, and they are more suggestive of shipwrecking or recycling activity than one of new vessel construction. Further evidence supporting boatyard activity is an inventory of over 2,000 boat rivet components and a few iron wood-working tool fragments excavated at Västergarn and classified as

25 supportive of clinker construction (Chapter 3, Figures 20, 21 & 22), but no significant evidence of Cog classification vessel construction.

2.1.8 WBS - Background and Applications for Archaeology

The Work Breakdown Structure (WBS) is a hierarchical direct application model that functions in diagram format to identify and separate individual material supply and labour modules of a project into deliverable (achievable) components. It is widely used internationally in the project management planning (design) phase to identify and allocate time and material resources, and then during project implementation (project execution) to ensure project success. In industry the WBS is both a planning tool and project execution plan, but as illustrated in this thesis the WBS is applied as a discovery schematic. The WBS model offers new techniques in archaeology for postmortem interpretation of artifacts in a landscape reconstruction mode with supporting societal profiles. In the Västergarn model illustrated below in Figure 9 (see also Appendix E for greater detail) the raw material and service demands on the near and extended community become quickly obvious. Virtually every individual block can be expanded with its’ own individual WBS to complete an overall supply and service obligation picture.

Boatt

CCoonnssttrruucctt Huullll AAllllooccaattee CCrreew

RRiivveettss SSmiitthh LLaabboorr CCaallkkiinngg SSlliippwaayy CCoonnssttrruucctioonn SSaaiill

FFoorrggiinngg TToooollss FFoooodd Wooooll aanndd Moossss Maaiinnttaaiinn AAcccceessssoorriieess --OOaarrss Weeaavvee

IImppoorrtt RRaaw IIrroonn BBuuiilldd FFuurrnnaaccee SShheelltteerr HHoorrssee HHaaiirr BBuuiilldd TTrraannssppoorrtt ttoo SSlliippwwaayy FFllaaxx aanndd Wooooll

LLooccaattee Woooodd aanndd BBlloooom CChhaarrccooaall RReessoouurrcceess PPrroodduuccee PPiinnee TTaarr OOppeenn Waatteerr AAcccceessss AAllllooccaattee RReessoouurrcceess CCuutt

SSmeelltt BBeelllloowwss CChhaarrccooaall ffoorr TTaarr

Worrk Brreakkdown Sttrrucctturre ((WBS)) – Viikiingg Age Boatt RRaaw OOrree AAccttiivviittiieess iinn rreeddaarree ffoorreeiiggnn bbaasseedd ((PPrreelliimiinnaarryy))

RRiivveettss 1294

Figure 9: Work Breakdown Structure (WBS). A suggestive model for construction or repair of a Knärr category boat. Service and supply demands on the community are identified (see also Appendix E). WBS concept source: NASA.

26 Each WBS module in Figure 9 represents a labour function or material supply requirement to be filled by imports, by the Västergarn resident community or its’ immediate hinterland networks as represented in Fig 8 with probable Sanda community supply source. Every module must be broken down further into its’ own particular supply chain to reach a full understanding of project time and cost to the community. Figure 9 illustrates a boat construction assessment of time, labour and materials at the construction site (boatyard), but it must also be evaluated from a shoreline view. The event and supply chain under the “Slipway” heading module requires independent evaluation of the waterfront or shoreline to determine suitability for boat beaching and boat launching events to match the fabrication yard. In the absence of an accessible waterfront that was functional in terms of meeting vessel design requirements there is little reality of a boat building or boat repair site of any significance.

2.1.9 Adjacent Shipyard Evidence and Shipwreck Remains

Paviken: A thorough maritime assessment of Västergarn must contain an orientational review of neighbouring Paviken, one of the earliest recognised Viking Age maritime sites on Gotland (Elfwendahl 1989: 5), researched and documented by archaeological excavations intermittently between 1981 to 2016 (Carlsson 2016). Paviken and Västergarn are practically adjoining sites sharing approximately the same general coastline but with decidedly separate life cycles and different timelines. Of the two, Paviken is documented as one of seasonal occupation rather than a continuing community where Viking Age artefacts testify to a semi-permanent trading place from about the first half of the 8th century (Lundström 1981; Callmer 1994: 58) to around 1000 AD as evidenced by coin finds and the dendro-dated jetties in the Västergarn creek (Carlsson 2011), whereas analysis of Baltic ware ceramic artefacts in Västergarn indicate continuous community activity starting ca 1050-1100 AD at the latest (Holmbäck 2017). From archaeological evidence it is clear that the two sites were active participants in their particular maritime cultural landscapes, and both seem to have been dependent on international trade with open access to the sea. Boat building and repair activities are attributed to both, but only at Paviken is sufficient artefact evidence available to support a conceptual working harbour and boatyard activity model. Dock and slipway remnants, ship-working tools, remains of an iron- working forge, and boat rivets are represented in the archaeological record at Paviken, but Västergarn excavations to date yield primarily rivet artefacts only along with a few possible tools that have not been fully identified.

27

Figure 10: Shipyard harbour artefacts from Paviken (After Lindström 1981)

Figure 11: Paviken wharf and jetty type structures supportive of boat building and a working and a working harbour for trade. Dan Carlsson (Paviken Research Project 2013-2016)

The close proximity of Paviken and Västergarn would assume a phased resettlement of maritime activity although Paviken was thought to have been abandoned around 1000 AD, but more current evidence arrived from iron age 10th century 14C dated posthole structures at Västergarn (Carlsson 2019) suggest an active overlapping timeline.

Kronholmen Cog: In 1995 the remains of a cog were discovered at nearby Kronholmen peninsula during construction activities at a golf course. Unfortunately, much of the vessel was destroyed by excavation machines but enough was recovered to identify it as probably of the Frisian-German building tradition, dated to the first half of the 13th

28 century by 14C analysis of associated debris (Rönnby 1996). It is assumed the cog was possibly wrecked in a storm or suffered fire damage that lead to sinking. Kronholmen was an island at the time and the cog may possibly have taken storm shelter in the open channel. There is speculation that the wreck is evidence of emerging ship building or repair activity (Carlsson 2011) but not proven. This find is reviewed here as circumstantial confirmation of what might have been an intended shipyard in the immediate Västergarn area that was planned to take advantage of a protected waterway in use at the time.

Figure 12: Kronholmen Cog (i.e., Koggen in red circle) orientation to Västergarn. Note that the grey shaded area was open water at the time of the cog loss. Map credit: Dan Carlsson.

Stora Karlsö is a small unoccupied island about 6 km southwest of Västergarn, known today mostly as a nature reserve but it is also home of abundant prehistoric remains. Stora Karlsö’s prehistory is long having has passed across archaeological zones from Mesolithic to the Middle Ages Iron Age in terms of habitation and a trading zone. High cliffs situated on the west of the island offered an elevation point 51 m

29 above sea level that probably provided a visible navigation mark for early seafarers.

Figure 13: Two carpentry rivets and three caulking sintels recovered during the 2014 excavation north-east of the Stora Förvar cave mouth. Credit: (Gustafsson 2016: 273)

An archaeological survey conducted in 2014 uncovered a few cog ship type artefacts in the form of calking sintels, rivets and nails. The sintels were given an estimate period date of 1350-1400, in a timeline with Västergarn’s lifecycle, but they seem to be scattered finds possibly from shipwreck debris. The rivets were not dated but appear to be very similar to Västergarn artifacts in the 1.0 cm to 1.5 cm range and more probably boat rivets. On the right side of Figure 13 clench nails are observed but not identified as such by the author (Gustaffsson 2016: 273). No significant evidence of shipyard activity is recorded for Stora Karlsö.

2.2 Nordic Nautical Language

We are often reminded of the seeming complexities of Nordic nautical language in marine research and I wish to conclude this chapter with material from two well-known researchers on Nordic nautical language; expressive, colloquial and terminology rich, and perhaps in no period more so than over the Viking Age and up to about 1400 AD, heavily influenced by North Germanic languages and especially by Old Norse (Simek 1979: 26). Proper names of ship and boat types, vessel construction techniques, and vessel tools and equipment tended to follow colloquial naming progressions, all influenced by local custom and culture. With long timelines and multiple dates and cultures of origin to the present day it is not difficult to appreciate how confusion has influenced modern

30 interpretations of Viking Age and Medieval nautical terms especially in separating the historical, the mythological, the archaeological evidence, and old Norse sagas. In his detailed study of old Norse ship names and terms, Rudolf Simek assessed the application of descriptive words pertaining to the ship as a whole; i.e., the core of a ship as a defined modular identity positioned separate from its’ exterior environments of shipyard construction, auxiliary equipment, human contributions (crew), the sailing routes, navigation instruments or seamanship skills. The findings are distributed across three groups of expressions:

a) Proper names (ca 150) b) Generic terms simply meaning boat or ship (ca 260) c) Poetical circumscription terms; Old Norse poetry (ca 560)

Proper names (a focus point of this chapter) are further distinguished between historical and mythological, with some allowances for fiction especially in Icelandic sagas, beginning with animal names and royal ships; i.e., “Alptr” (the swan), “Fálki (the hawk) or Grágás (the gray goose), etc. By the 12th century onward ships and boats were often called after saints, such as “Pétrsbolli” (St. Peter’s boat) or “Katrínarsúd” (St. Catherine’s ship), but also after the vessel owner, vessel builder or perhaps the resident society that both contributed materially to the ship’s creation and would be supplied by its’ existence. Poetical names contributed also; some clear and meaningful, i.e., “Fífa” (arrow) or “Skjöldr” (shield), and some not so clear such as “Fiardakolla” (cow of the fjord). Of course, as he points out, a number of Old Norse ship names cannot be explained in contemporary terms (Simek 1979: 27 - 29) and their historical influence must be considered contextually. In contrast, Eldar Heide contends that greater interpretative focus on Old Norse saga textual evidence is needed to increase contemporary understanding of Viking age ships in terms of their original working purpose and appropriate supportive designation (i.e., war ship, cargo ship, etc). Heide further cites that most research has focused on material remains with little systematic attempt to match or cross-reference period ship types known from Scandinavian Medieval texts (runic inscription and manuscripts) with artefact evidence, suggesting that shortcomings are not reflections of poor scholarship, but evidence of need for more in-depth research (Heide 2014: 81-82). That there is confusion over Knärr and Knorr and other names attached to Viking and Middle Age cargo boats is not surprising.

31

2.3 Chapter Summary

This chapter has examined Knärr and Cog category vessel topologies relative to Västergarn archaeological evidence of Medieval ship remains in a comparative matrix. Innovations in shipbuilding technology and construction methods placed continuing requirements on maritime communities to provide improved harbour capacities, shipyards and support services. The effects were significant and far reaching across the Baltic trading network with large growth in some maritime communities, but growth was not equal. Not all societies adjusted to increased demands for change in their waterfront facilities, some could not change for economic reasons and others perhaps were hindered by the natural landscape of their harbour not being suitable for expansion. Boat-yard type facilities are required for vessel construction and repair, each operation with its’ own particular demands on hinterland supply, i.e., the resource base that an urban site needs to support itself internally and externally. In a final question, was Paviken-Västergarn trade dependent on foreign vessels or were community owned-operated ships and boats the core suppliers of shipping? Once again, the boat rivet thread is observed: dependency on foreign-owned vessels supports a boat repair model over new construction, whereas community sourced and operated vessels favour greater emphasis on new construction with expanded logistical dependency on hinterland suppliers . The thesis thread continues next in Chapter 3 rivet classification that will place rivet artefacts in orientation with the ship types discussed here.

32 Chapter 3 Maritime Artefact Classification

3.1. Iron Boat Rivets in Context

Rowing and sailing class marine craft were essential components of Viking and Medieval Age trade and communications networks in Sweden and across the Baltic rim, and both vessel categories are associated with Västergarn’s history. Rivet artefacts are commonly connected with both new vessel construction and repair, although not exclusively, and boat rivet artefacts recovered at Västergarn can easily be inferred as visual substantiation of ship building and ship repair activities at that location even in the absence of physical boat building wreckage as source material. The recorded excavation history of Västergarn spans more than 150 years, dating from 1864, although interest at that time was focused primarily on the earthen wall or embankment (see Appendix H for site orientation) that identifies Västergarn (Zachrisson 1999: 9) in the landscape, and the 13th century Romanesque church ruins within the embankment (Cassel 1999: 25). There is no record of boat rivet recovery from the first excavation and rivet artefacts recovered at Västergarn over succeeding excavation years have been recorded although never classified. Västergarn appears in Medieval source material already in the 1300s, described as an unrivalled harbour location, active port, trade and resupply point well into the 1500s suggesting, by extension, that a supporting boatyard of some dimension would have been a necessity (Elfwendahl 1989: 56; Zachrisson 1999: 11 cited Flordeus 1934). Hard evidence of a boatyard at Västergarn remains elusive despite intermittent excavations of the 1970-80s and more recent 2005-2017 excavations of approximately 1100 sqm by the Uppsala University- Campus Gotland archaeology department, corresponding to approximately 0.9 per cent of the surface area within the earthen embankment. Aside from scattered rivet artefacts, some slag and miscellaneous small iron objects suggestive of tools, no clear confirmation of actual boatyard activity in the form of an iron working

33 forge, residuals from vessel construction, repair or demolition exist to date. The maritime iron artefacts recovered at Västergarn can only be classified individually and contextually as they have no identifiable shipwreck or boat burial in the near proximity to cross-check in authenticating their origin, but the rivets alone do provide circumstantial validation of Viking and Middle Age boat building or repair activities at Västergarn. Certain assumptions supporting the reality of a shared harbour and boatyard facility can be made by classifying Västergarn site artefacts in a comparative marine landscape matrix across documented excavations of regional Scandinavian-Baltic shipyards of similar chronological age such as Sigtuna (Edberg 2013), Birka (Johansson 2006), Hedeby (Kalmring 2009). Empirical evidence of the missing shipyard is however found in the rivets, and this chapter will show that correct classification is the key to opening the Västergarn infrastructure puzzle. In this chapter I present my classification assessment of rivet artefacts to validate shipyard activity at Västergarn of a capacity sufficient to have serviced Viking and Medieval era clinker-built vessels while discounting the possibly of cog class shipbuilding or repair. I also call attention to the negative effect on boat rivet research resulting from a lack of consensus agreement in archaeology on Viking and Middle Age boat rivet standards, but I want to leave this section with a question: can classification of iron maritime artefacts help determine vessel design, construction and origin?

3.2 Rivet and Rove Design

The great significance of iron boat rivets in the history of seafaring and the key role rivets played in the evolution of clinker or lap-strake constructed vessels is over-shadowed by their small physical configuration, typically 150–160 mm in length and about 10 grams in weight, although these values are adjustable in proportion to vessel size. This is an important consideration in classification of rivet artefacts to ensure no misinterpretation of their original position in the ship profile. To begin the classification process of an individual rivet artefact is to begin with its’ creation. Pictorially speaking a complete boat rivet consists of two detached parts but with three distinctly unassuming profiles: a single piece shaft with head, and a separate rove. The parts are fabricated individually by an iron smith and then joined together at the boat yard during vessel construction. In the installation process a two-part base rivet assembly becomes a single unit joined by heat and compression and subsequent bonding with wooden boat hull. The rivet thus formed can be removed only by leveraged force or destruction of

34 its’ individual parts, resulting in distortion of the rivet with recognizable profiles in archaeological remains.

Head

Figure 14: Complete Boat Rivet Artefact. Excavation year 2011 (R. Koehler) The riveting process in boat building is a relativity simple procedure of creating a permanently bonded joint; technically a type of lap joint or fused assembly. In an illustrative sequence, the rivet shaft is inserted through a pre-drilled hole in the wood clinker and joined to a plate (the rove) by means of a cold working bonding procedure (hammer forging) that fuses rivet shaft and rove into a single unit. This joining method is a category of forged bonding, or forge welding (Groover 2007: 770), a welding process wherein the components to be combined are heated to hot working temperatures (pliable but not molten) and fused together by compression hammering (Groover 2007: 730; McDonnell 1995: 2), a process made possible in Viking Age iron working contexts due to the malleability of wrought iron. Once bonded the rivet cannot be removed except by destruction, i.e., the act of separating or disconnecting the rivet shaft from the rove (Groover 2007: 770), a process that simultaneously destroys both the integrity of the rivet and that of the surrounding wood joint, i.e., the lap joint in a clinker ship construction. The visual end result is effectively a double-headed rivet fastener consisting of the shaft and rove, a configuration that strongly supported both tension and shear loading forces on the rivet that vessels would experience at sea.

35 Loose rivet finds in the excavation material could have been separated from the hull by destruction of the surrounding area of the hull clinker itself, such as situations when the boat is scraped. In many excavation contexts “clinching category” iron artefacts are the only remaining evidence of wooden objects or structures with their distorted profiles adding to the classification puzzle, but at the end of the vessel lifecycle it is usually the rivets, in part or whole, from which with careful measurement, ideas can be formulated about the original construction of the boat and its’ origin (Larsson 2007: 30). In an archaeological setting boat rivets, nails, bolts, i.e., fastener finds of all description are not attractive enough to be competitive with silver, gold, jewellery, pottery and similar objects of highly perceived value, and that they are not easy to conserve only adds to the rivet devaluation.

Figure 15: Mixed rove examples from Västergarn mass material across excavation years 2005- 2013. A large mix of shapes and designs, leading to questions of origin, function and cultural design influence. (R. Koehler)

Independent roves (Figure 15) on the other hand are far more recognizable by their distinct flat or semi-flat profile, rhombus, square or possibly round shape with hole in the centre. The task of boat rivet identification in the field can be confusing due to both the above- mentioned distortion by forced extraction (Figure 14) and general corrosion across the finds. Small rivets (1.0 to 1.5 cm) consisting of combined shaft and rove could look simply like an unidentifiable clump of rust, and where rivet shaft and rove have been clearly separated in the destruction process there are other potential interpretation problems. For example, individually separated shaft parts of a rivet can easily be

36 mixed with spikes, bolts or nails. In this situation, the length and cross- section configuration of the artefact shaft can be a defining specification (Bill 1991: 55) as discussed in 3.3.2.

3.3 Tracking across Mass Material

Contextually speaking, the preliminary classification phase of rivet artefacts should start on-site in concert with excavation activity where rivets are often found individually or clustered variously with nails, spikes, bolts and other iron items of a general description. Rivets from clinker constructed vessels are registered across hundreds of archaeological sites in Scandinavia, parts of Northern Europe, and the Baltic region, but if rivets are not identified as being especially important to the understanding of a specific site, they may remain anonymous to archaeologists (Bill 1991: 55). The greater majority of rivet finds in Sweden are however sourced from some element of clinker-built boats, i.e., as remnants of their original construction or repair history in boat burials or as wreckage debris.

3.3.1 Iron Artefacts – Classification across Context

The difficulty in establishing a typological model for Västergarn maritime fastener artefacts is well illustrated by the absence of a clear universal definition for boat rivet artefacts. The menu that rivets, nails, bolts, spikes, and similar fastener artefacts share is one of common purpose, i.e., that being to secure closure, but closure with mixed design forms. There are however some other defining parameters for boat rivets starting with original design, functionality and relational contexts which I will present and discuss in this section.

3.3.2 Deformed and Incomplete Rivet Profiles

Despite the difficulty to determine how fasteners and other rivet-like elements were used in boat construction there are physical characteristics in the Västergarn fastener material that will help understand their purpose in a boat building environment. Physical characteristics are viewed in two distinctly different magnitudes: a) deformed and incomplete shapes b) cross-sectional shaft design Visual assessment is the opening step. Physical examination of rivets recovered at Västergarn suggest some as complete units and seemingly

37 undamaged, but yet deformed or misshapen longitudinally in a profile that might be consistent with twisting pressures applied at sea or simply the visual result of forced separation.

Figure: 16. Mixed deformed rivet artefacts from Västergarn excavation year 2008. Rivet heads and roves are predominately square shaped. (R. Koehler)

Other units may consist of complete shaft and rove; as singular shafts or independent roves of which many are misshapen or bent. This implies that these particular components were deformed during separation from their original position in hull framing during destruction of the wood structure surrounding the joint. Rivets of this configuration could also have been deformed when separated from the hull during scrap recovery of wood clinkers for reuse in other applications. Recycling was a common occurrence when vessels reached the useful end of their maritime life but continued to have value in other constructions. In excavations some rivets are found simply as a shaft only with no rove, and roves are found independently, both examples being indicators of a planned removal process, probably with a spiksökare removal tool (Larsson 2007: 110; Edberg 2013: 202). Conversely, a complete rivet of head, shaft and rove, but without apparent damage could be residuals of boat sections that were burned during the scrapping process allowing the rivets to fall free.

38

Figure 17: Spiksökare tool from Sigtuna 1993 Excavation. Photo: Edberg 2013: 202). Photo copyright: Run Edberg.

Damaged rivets, whatever the original cause, had no useful place in new vessels. Such distorted rivets were unsuitable for boat repair or new boat construction, nor any recycling value back to primary metal, and thus a new profile of scrap was added to the accumulation of shipyard debris material. In his Sigtuna study on Viking Age boat building and repair, Edberg interprets rivet scrap as waste from dismantling and repair of boat (Edberg 2013: 197) as is the situation at Västergarn. It is this debris mass however that represents a rich resource to be sifted through carefully and it is a resource too often overlooked in excavations. At the end of the vessel lifecycle it is usually the rivets, in part or complete, that are preserved in matrix remains and from which, with observant measurement, hypotheses can be formulated about original construction of the vessel (Larsson 2007: 30).

3.4 Cross-Sectional Shaft Design Profiles

Deformed rivets offer a shape that clearly speaks to elements of damage in a classification profile, but is there a case for classification by rivet shaft morphology? There is considerable argument for a “yes” answer, and there are at least two broad-based arguments for tracing rivet origins by cross-sectional review of shaft design, although there is not universal agreement on this subject.

3.4.1 Square Shaft or Round Shaft

Of course, surface corrosion over time has modifying effects (see Figures 16 and 19) and what might originally may have been a square shaft would today appear to be round, but it does seem evident that at least two noticeably different boat-building traditions emerged over Viking Age Scandinavia and the greater eastern Baltic region. The western part of Scandinavia identified as Denmark and south Norway is viewed as a source of round shaft rivets (Larsson 2007: 118) whereas the eastern geographic dimension of this sector is designed as square

39 shank in a Baltic/Slavic tradition encompassing eastern Sweden, the Baltic Sea (presumably Gotland, Åland, etc.), Finland, Estonia, Russian river basins, and apparently the other Baltic rim countries (Larsson 2007: 118; Stalsberg 2001: 370; Bill 1994). Circumstantial evidence of Swedish origin distribution is found in Russia where boat rivets have been identified as coming from central Sweden (Larsson 2007: 235), but is it obvious that the rivets represent residue from work performed on site by Scandinavians or by local craftsmen trained in the Scandinavian tradition of clinker boat building? Absent of conditional metal analysis techniques, such as ICP-MS or SEM, to investigate trace elements, can it be confirmed that rivet origins found in Russia are actually from Sweden, or is it possible they are copies of a central Sweden design fabricated on site by locals under Scandinavian direction? The last option, if true, would of course represent a transfer of technology and acknowledgement of exporting cultural influence on design. The 12th century seems to mark some turning point as square shanks replaced the circular style, a technology perhaps in the production process where previously the majority of rivet shank profiles were on average exclusively round (re: Scandinavia) or square (re: Baltic regional area), but usually not mixed, with square shank shafts seemingly characteristic of a Baltic clinker tradition (Bill 1994: 60). Westerdahl is more nuanced, offering first that this field of study would benefit from more research and whereas the “slight” possibility that square rivet shafts were partly an eastern phenomenon across Finland, Russia and the Baltic region is balanced by Nordic rivets round in cross- section (Westerdahl 2003: 11).

A: Round shaft B: Square shaft Figure 18: Excavation year 2011. Both examples from the same trench. (R. Koehler)

40

In continuation of these descriptions and speculations, the implications of rivet shaft design and rivet origin are particularly interesting in evaluating the influence of boat repair and/or original vessel construction activities at Västergarn. For example, a proportionally high number of matrix square shaft rivets suggests repair of boats with an eastern origin (in a broad general context) and consistent with evidence of Gotlandic participation in trade over the eastern Baltic region, Russia and Baltic states. Conversely, a high percentage of artefact round shaft rivets could theoretically offer confirmation of rivet fabrication on Gotland and ship origins looking west to the Swedish mainland and Denmark. These are central considerations but missing from the round vs square debate is strong reference to motivations for the different design traditions. The Swedish-Danish-Russian geographic triangle covers a very wide area ethnically speaking and reasonably it must be assumed that there was cultural influence on design and technology. Knowledge is both imported and indigenous, and there must have been locally derived resource or craft reasons for each method of production. Culture is but one influencing factor, but there are other more practical reasons for different shaft designs. Quality and access to the raw material to be worked into rivets, i.e., malleability of the raw iron and assurance of continuous supply are consumption determines of a production schedule that is balanced ultimately by smithing skills. The physical creation of a square shaft is simpler and faster than round, but all factors must be considered. A simple WBS diagram (see Figure 9) will outline required resources and resource origins in an archaeological site evaluation. Jan Bill addresses the subjects of production organization and material supply in depth, pointing out the rationalization of a square shaped production process over round (Bill 1994: 60). The importance of the question, i.e., that of regionally produced iron opposed to imports, is significant as it influences study of:

a) the Swedish and international supply and logistical chains for import of processed iron bars to Västergarn needed for production of rivets and other iron-based components for new vessel construction and repair (Hyenstrand 1979: 147). The quality and availability of this raw material (currency bars) would vary greatly from supplier to supplier both in Sweden and from other Baltic resources requiring a continuous trading function at Västergarn’s shipyard to ensure uninterrupted supply (Crew 1995: 8). b) the extent foreign origin vessels contributed to shipyard repair

41 activity by requiring new rivets and other iron fittings and by extension the contribution of such work to the local economy.

In his inclusive study of maritime associated iron artefacts found in Sigtuna’s occupational layers, Rune Edberg has come to regard boat rivets (i.e., clench bolts) as fragmentary evidence of boat destruction preserved on dry land (Edberg 2009), an analogy that fits Västergarn.

3.5 Fastener Finds Other Than Maritime

There are a number of options to be considered in classifying rivet finds, understanding that the versatility and simplicity of basic rivet design and function ensured wide utility across many applications well beyond those attached to vessel fabrication or repair. Practically speaking, any wood or metal structural element with a joint construction that required permanent connection or assembly such as found in conventional house framing, wagons and sledges (Johansson 2006: 16-17), shields, boxes, coffins, and boat graves (Klevnäs 2007: 31) are unclassified sources of rivets. As a consequence of their multi-purpose design, rivets and their various configurations and applications, constitute some of the common finds across Viking and Medieval Age archaeological sites. I have discounted from this survey the few rivets found in graves near the Romanesque church at Västergarn as being coffin fasteners and unrelated to maritime activity.

3.6 The Classification Dilemma

Classification has many masters, and Nona-Daniela Palincas brings welcome attention to the cultural influences on classification, critically pointing out that categorizations for the same phenomena differ across different societies (Palincas 2005: 219) while reminding us that perception is filtered through our senses. Classification issues are to be expected as cultures are different and all are influenced by local circumstance, but there is still ample room for cross-cultural dialogue. Culture is a powerful influence, both transcending and incorporating technology while evidence can be fleeting. We see Nordic and Baltic countries, and into areas of Russia all utilizing iron rivet technology for common purpose but without common terms (across translations). In continuation across this subject, it is Edberg’s position that there is not a good clench bolt (rivet) typology and thus with predictable confusion, added cause for continued debate (Edberg 2009). On the “confusion” point there can be no doubt, and that “clench bolt” is but one of the arguable terms used to identify metal fasteners in clinker boat construction.

42 In the introductory dialog of his treatise on classification and typology, William Adams clearly positions his view that artefact classification is arguably the single most straightforward analytical procedure in archaeology (Adams 2001: 136) and that archaeologists are prone to mixing classification with typology. More importantly, he goes on to remind us that contextual materials are not “self-labelling”, and certainly not in mass material contexts. In another assessment view, Dwight Read maintains that classification is, of necessity, the foundation of data analysis in archaeology (Read 1974: 216). Their arguments are collectively well taken and comparative in substance, but the question still remains as to who owns the foundation specification on classification, noting that agreement is based on consensuses. To cite an example, Viking Age boat rivets are unpretentious artefacts, but they represent a distinctively manufactured product that involved multiple layers of society and resources in their life cycle from raw iron ore origin to archaeological artefact. There are no agreed standards of fabrication assessment nor of material quality in a modern-day context for post-excavation appraisal and classification purposes. Of course, moisture is the great classification equalizer. Surface corrosion and distortion over time has modifying effects on all iron artefacts as is true of Västergarn artefacts. What originally may have been a square shaft could today appear to be round, but with time and careful observation there does seem to be some evidence of the two different shaft designs.

Figure 19: Corrosion effects across mixed rivets. Excavation year 2005. (R. Koehler)

Rivet typologies could suggest evidence not only of the spread of different design traditions, but also regional and technical exchanges of vessel design and construction wherein rivet length and shaft thickness is proportionate in relation to the size of vessels (Bill 1994: 60). These are technical parameters where design follows function, but more

43 interesting in a cultural sense for tracking purposes is rove shape and decoration, a subject for special study since the rove area, although small, offers the only space in a rivet configuration for artistic or ethnic expression. Returning to Palincas, we are reminded that the rove section in rivet configuration was probably the only significant option for a craftsman to insert cultural bias (Palincas 2005: 219).

3.7 Discussion: Iron as a Rivet Raw Material

For a complete summary of Västergarn’s capacity as a boat building centre a brief overview of the raw iron supply chain is necessary. Sweden was the most probable source of wrought iron for rivet production and other iron items for maritime use, as well as needs of the Västergarn community at large. Iron supply is a trade topic as discussed in section 1.1 Research Overview.

3.7.1 Wrought Iron as Base Material for Rivet Production

In a Viking Age rivet chronology, wrought iron is the base material for rivet fabrication with many steps in progression from raw iron ore to finished product. To fully appreciate the rivet’s position in the “Ship Building - Ship Repairing” dialog associated with Västergarn a short overview of a rivet’s life-cycle is appropriate. Before rivets can be fabricated, wrought iron must be produced, and in iron age Sweden that activity took place principally on the mainland where raw iron, lake and bog iron, deposits are found in abundance north of Lake Mälaren, Dalarna and Gästrikland regions. Processing iron was labour intensive requiring substantial employment and charcoal resources to support production. Although iron utilization in Viking era Sweden was ostensibly widespread across agricultural and military sectors, consumption was not demanding and iron production in terms of quantity was low over the seventh thru ninth centuries AD. 3.7.2 Gotland as an Iron Consumer

Gotland was a Viking and Middle Age iron importing consumer society although bog iron was worked at least during the centuries around BC/AD transition (Gustafsson 2013: 23; cited Rydén 1979). Additionally, there is some incomplete evidence of continuous direct iron reduction on Gotland (Nihlén 1932) and two examples of excavated pit-type shaft furnaces, one each in Follingbo and Stånga parishes, and associated slag remains indicate iron was produced. Nevertheless, any serious on-island iron smelting of the era must

44 assume dependency on imported raw iron ore, an assumption that opens logistical questions on both raw material sources and supporting trade and transportation system for bulk raw iron cargo to reach Gotland. It is obvious that any large volume of boat rivets produced on Gotland would have originated from smelted iron imported probably in the form of currency bars (Hyenstrand 1979: 147), primarily from Sweden although perhaps not exclusively. Even so, imported smelted iron bars had to be reforged on Gotland before they were suitable for rivet production, a process that is represented in part by slag deposits found today in Paviken and Västergarn excavations.

3.8 Discussion: Source Material

There are multiple descriptive terms in a ship fastener classification dialogue, i.e., clench nail, clench bolt, tree nail, iron nail, spike, rivet, and rove, to mention the more common. Literature is mixed, and in summary all are described as fasteners and all are argued successfully in maritime applications, but conversely some can be similarly validated for dry land applications as well. This creates one problem, but another problem; perhaps greater, circulates around the absence of an agreed vocabulary on fastener classification terms in maritime settings. Boat fastener artefacts, the core issue of this thesis, offer ample evidence of the mixed description dialogues for the basic three nomenclatures, i.e., clench bolt, clench nail, and rivet, but with no agreed classifications. Rune Edberg cites delays in the clinch nail section of his 2013 Sigtuna shipyard study resulting from the absence of a universally agreed terminology (Edberg 2013: 201) but the problem is widespread, distracting to research and it is more than semantics. Iron fittings, i.e., fasteners, that held the boat together, were subject to stresses never considered by the builders and there is a direct correlation between where the fastener was inserted originally and where we today try to classify it from excavation material. In summary, archaeology has no agreement on marine fasteners, neither physical nor technical description. This is an unfortunate barrier to research and there seems to be no immediate path to resolution. Perhaps a neutral solution is the best answer and to that goal as a starting point I suggest engagement of an independent standards organization such as the International Organization for Standardization (ISO) in Geneva. The ISO is recognized globally with worldwide membership including every Baltic Sea rim country. Sweden is represented by the Swedish Institute for Standards, and an inquiry on formation of a Maritime Fastener

45 working committee could be a start to resolution of the cross-sectional shaft dialogue (Section 3.4.1), at least in the Baltic region.

3.9 Artefact Inventory & Classification Distribution

ARTIFACT INVENTORY

Clench Nail Clamp Complete Rivet 7% 3% 17% Tack 8% Spike 4%

Independent Rove 6%

Head with Shaft 55%

Figure 20: Artefact Inventory. The largest number of rivets are classified as head with shaft although some are shaft only and typically undamaged as possibly new blanks. This category is considered as raw material for fabrication and installation of new rivets during boat construction or repair. R. Koehler

Source material: Over 2,800 inventoried and classified rivet artefacts at the Uppsala University-Campus Gotland archaeology lab. Material excavated 2005-2015.

46

Rivet Count - Complete Units Only: head, shaft and rove

90

80

70

60

50

40

30

20

10

0 .05 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0

Summary count by rivet length:

0.5 – 3 2.0 – 77 3.5 – 29 5.0 – 16 1.0 – 29 2.5 – 83 4.0 – 33 5.5 - 1 1.5 – 59 3.0 – 71 4.5 – 6 6.0 - 1

Figure 21a: Rivet summary count by length. Complete (head, shaft, rove) units only. Rivet Size Västergarn Excavation Count .05 3 1.0 29 1.5 59 2.0 77 2.5 83 3.0 71 3.5 29

4.0 33 4.5 6 Sizes in the 1.0 cm to 3.0 cm range fit a profile for rivets 5.0 16 removed during repair work on upper level boat strakes 5.5 1 and scarves. (Credit: Hurstwic.org) 6.0 1 Figure 21b: Rivet summary for Västergarn excavation years 2005-2017. R. Koehler

47 3.10 Chapter Summary

Västergarn excavations to date (2017) have produced no confirmed artefacts for boat carpentry or smithing tools, slipway foundations, or remains of identifiable to ship/boat building or repair yard functions over the history of the site. Maritime occupational activities are seemingly well discussed in historical literature, but the reality of continuous ship or boat building is arguable in the absence of archaeological debris evidence that would have been created by an active maritime facility. The typological variability of fasteners and similar closure category items found in the Västergarn landscape is well illustrated by the wide menu of rivets, nails, bolts, spikes, and similar clinching or closure elements, the sum which leads to some classification issues because of their wide distribution and relational (or non-relational) contexts. There are however some defining parameters for boat rivets starting with design and supporting information on this subject is generally in agreement. Literature illustrations of various rivet types are generally similar in configuration, but not always in terminology. Especially confusing can be agreement on definition of fastener terms such as nail, spike, bolt, rivet, blank, tack, bracket, clench and clenching. In a strictly functional sense Viking Age and Medieval Age boat rivets are subdivisions of a broad-based fastener community of clinching type commodities created in great quantities by contemporary ironsmiths, but boat rivets have their own specific markers. Over 2,800 inventoried and classified rivet artefacts at the Uppsala University-Campus Gotland archaeology lab provide a tangible starting point in the discovery process of validating a Västergarn shipyard (Figure 20). The artefacts profile late Viking Age boat repair with only minimal evidence of Medieval ship building activity. Construction or repair of cog class ships at Västergarn is an inconclusive issue based on archaeological evidence to date, notwithstanding some suggestions of cog ship building at the neighbouring Kronholmen area that is today part of the mainland, but an island in Västergarn’s Medieval timeline. (Carlsson 2011: 42 : Zwick 2014: 50).

48 4. Landing Places and Harbours

4.1 Where Sea and Land Meet

This chapter is the last link in the maritime thread that opened with merchant vessels and boatyards in Chapter 2. The focus here is specifically on an accepting Västergarn coastal landscape and natural environment that would have been essential to support a Medieval maritime service model. Shoreline parameters are the defining specification, but in concert we consider the earthen embankment that defines Västergarn on three sides, about 1000 meters in a rough semicircle configuration and open to the sea. It is the distance of about 600 meters across the open end that has our attention.

4.1 Landscape Overview

The coastline fronting Västergarn is open both westward to the Baltic sea and eastward to its’ adjoining hinterland, it is a flat coastal plain with no natural harbour to service deep water ships today nor was there one in Medieval times. A shoreline of mixed sand beaches and rock with virtually no tidal action offering little natural protection from the sea, it is a marine environment in continuous transition shaped by effects of a northward littoral drift and shifting sedimentation prone to building sandbars and silting of the adjacent Västergarn coastline. Middle age Västergarn was a gateway, or to say a figurative bridge between elements of sea and its’ hinterland where cultures, technologies and dependences would have mixed in a welcoming coastal frontage. Across Gotland’s Middle Age history the entire island coast line is referred to in some sources as a Peace Zone, i.e., described as an area being a distance of “eight fathoms (8 arms)” or about 14 meters prevailing inland from the beach high water mark, an area where, “When people of many tongues gathered on Gotland, they swore the peace all around the coastline each and every one should be granted eight fathoms of land to better salvage their goods” (Gustafsson 2020: 82-83). Visiting merchants were presumably offered legal protection on

49 the Gotlandic coast under this edict (Cassel 1999: 14, cited in Hansson 1967: 30) in a type of a free-trade or open access special economic zone where those who came ashore were assured peace and markets. The legislation for this 14-meter allocation of seemingly unhindered access to trade and sanctuary is founded in a Visby City court document, the ca 1340 Town Law of Visby (Gustafsson 2020: 82) charter providing a protection zone extending around the whole of Gotland’s coastline (ca. 800 kilometres) in principle, but with some restrictions. With allowances for modern day translations, it is not clear if the term “salvage” in the Visby Town Law was intended to mean the unmolested safe keeping of a merchant’s goods stowed in their vessel upon landing at Västergarn, as being an example harbour, or as the salvage of a boat and contents by a third-party claiming custody of an unattended vessel on shore. As a counter reference, Guta Lag seems ambiguous on the subject as shown here: “If someone finds an unattended small vessel out on the shore, the one who has found it is to take possession of it, if the other (i.e. the owner) is not so near that he hears his shout, if he has shouted three times. A boat is not to be without supervision, otherwise whoever wishes may take it”. Guta Lag, Article 36, “Concerning the care of ships” (Peel 2009: 47). Guta Lag, or the Law of the Gotlanders, makes no reference to a “Peace Zone”, but in a historical perspective the foundations of Guta Lag are attributed to probably the early 10th century (Schück 1924) and well in advance of the Visby Town act of the 13th century that established the Peace Zone. It is worth highlighting the contradictions here in examination of Västergarn’s role as a destination with open or restricted trade policy. The historian Adolf Schück believed the expression Peace Zone was aimed at several places along the Gotlandic coast that served as meeting and trading places such as Visby, Västergarn and Fröjel (Cassel 1999: 15, cited in Schück 1924: 3f) as the largest locations, although a more contemporary study by Dan Carlsson suggests that there may have been upwards of 10 identifiable sites on Gotland that archaeologically support Late Iron Age until early Middle Age trading activity (Carlsson 2018). Visitors with trade goods, and their boats, would be secure within the designated peace zone, but not necessarily safe beyond that demarcation boundary, especially if the visitor arbitrarily comes ashore outside recognized boundaries of trading settlements.

4.1.2 Västergarn – A Special Economic Zone (FTZ)?

In modern terms a foreign-trade zone (or free-trade zone) is a specified geographic area, typically in seaport or airport zones, where foreign goods may be imported duty free, stored or re-manufactured for reexport free of taxes. Similar rules apply to the raw materials needed

50 for manufacturing or a value-added remanufacturing process. One of the FTZ attractions is the employment opportunities it brings to the local populace. Foreign Trade Zones are promoted as a catalyst also for secondary investments by investors who become suppliers to the foreign investors. As an analogy, we can say that Västergarn was perfectly positioned to act as a catalyst for investment growth in its immediate area of western Gotland and I feel comfortable there was some level of foreign involvement if not direct investment. The physical evidence of a living community is supported by archaeological artefacts to date in limited numbers; beads, scales, coins, chalk pipes, knives, but also in large quantities of pottery. Martin Holmbäck’s detailed master thesis on morphological analysis of Baltic Ware pottery of Västergarn gives great insight into pottery sources and community uses of pottery with both imported and locally produced pottery cited as supply sources. (Holmbäck 2017). But were all the “imports” really imported, or simply residuals left by visiting Slavic merchants, or alternatively as goods created at Västergarn by foreign artisans living and working within the embankment, i.e., the Peace Zone, making products for both domestic use and export? If considering the evidence of Russia as a pottery supplier, we must also consider the boats that carried them to Gotland, and the arguments of “square shaft vs round rivet shaft” in Chapter 2 (See 3.4.1). Holmbäck dates Västergarn’s life cycle and use of Baltic ware in this period at approximately 1100-1250/1300 AD (See Appendix G for a copy of Martin Holmbäck’s map). Both the date and intent of the earthen embankment itself are disputed, some suggesting it was a defence wall to protect Västergarn’s populace and churches, but the idea of defensive barrier is unrealistic. With a wide open 600-meter front to the sea there would be no need for adversaries to scale a wall only about 3 meters in height and constructed of earth with sloped angles. I agree with Kerstin Cassel in that the embankment was a type of delimitation marker that identified areas for specific purposes, foreign and local (Cassel 1999: 50). This would include the area dedicated to boat construction and repair and it follows the Peace Zone trading place model.

4.2 Discussion: Landing Place and Harbour

In contextual literature Västergarn is referenced variously as a landing place, a harbour or a port, the terms used sometimes without contradiction in the same material source. For purposes of this paper and topic clarity, landing place is the operative term I use as representational of maritime activities associated with Västergarn.

51 4.2.1 Landing Place:

From a mariner’s viewpoint good landing places offered a level of natural or man-made protection from the elements, particularly wind and waves, and suitability as a trade meeting place (Sindaek, 2009: 103; Ilves 2011: 2; Nitter 2013: 3; De Graauw 2019:1). Iron Age and the Middle Age rowing vessels were of shallow draft design and navigable by oars onto inclined beaches and into narrow inlets. (Ulriksen 2008: 1), and oars remained the primary way of propulsion until sail was introduced in the 8th century (Crumlin-Pedersen 1997: 190). When sail took over it was more difficult to manoeuvre vessels in shallows or narrow inlets, where a broader seaward approach was preferred. Physical beaching of the boat was not an absolute necessity although boat design played a defining role. Viking Age design cargo boats with 20 to 30-ton cargo capacity could have drafts of 1 to 1.5 m with some hindrance in direct beaching. Naturally occurring features of landing place coastlines could be improved by man, while the relatively shallow beach gradients at Västergarn provided suitable conditions for shoreline-based boat building and maintenance while supportive of trading activities.

52 Figure 22: Västergarn coastal zone of today. It is possible to visualize this beach area in a landing place category. Note shallow beach area gradients (red arrows) suitable for beaching Knärr type vessels but not cog-class Medieval ships. The dark yellow line is the approximate path of rivet artefact finds. Google Earth Pro May 20, 2020

4.2.2 Harbour

Harbour basins can be natural or artificial, but to achieve true harbour operating capacity requires a range of purposely executed man-made protection barriers. Various forms of breakwaters, sea walls, and jetties are required to safeguard against wind and storm (Bruun 1976: 69 f). In any context the creation of a harbour represents significant site planning by the local community to provide safety and meet service and supply needs of visiting ships. In this context “community” means the resident Västergarn society and immediate hinterland. Evidence of permanent harbours date from pre-history providing safe mooring to their service communities (De Graauw 2019:1), but with harbour designation come additional design parameters for storage and support services. A full-time working harbour is both a provider and consumer of services and materials, thus transforming the community from seasonal to permanent occupancy. A permanent harbour means significant landscape changes with quay construction to counter continuous surf and tidal site conditions (Bruun 1976: 146 f), operating conditions that would have been known to the maritime Västergarn community over time by practical experience and testing. Small harbour type facilities to service local fishing needs, provide small boat repair and construction would have been met by scaling up from the landing place experience. A landing place is elective by short term needs and prevailing beach conditions, flexible in location and with less dependence on man-made improvements. Harbours, conversely, can assume a semi-permanent to permanent identity in a short time with continuous improvements for vessel safety and operations. At least 60 locations around the Gotland coast line are identified as possible Viking Age harbours or trading places (Carlsson 2018). While a majority of these coastal locations were undoubtedly rural fishing sites that did not require significant man-made improvements for functional purposes, others appear to have been positioned by geography to function as a transit site and long distance communications node, a role suited to Västergarn.

4.2.3 Port

53 The working profile of a “port” is discussed in this section for orientation purposes in establishing a Västergarn maritime profile, although I do not consider that a level of true port operations was ever reached at Västergarn. By characterization, a port facility is a year- round operation and expected to offer an extended selection of continuous services for vessel resupply, permanent warehousing, and perhaps a full-scale shipyard offering new vessel construction and maintenance. There is no material evidence yet to support such a facility at Västergarn. In a modern-day analogy, a strong service-supply industry would grow around the port in response to the requirements of a full-time operating facility (i.e., 12 months a year); a service profile logistical system that is supported in a modern shipyard by a global network of suppliers. In a contemporary Västergarn life cycle scenario the “service-supply” logistical system would have created an extended reach well into the Gotlandic hinterland for raw timber, food, tar, sail making, warehousing, and skilled maritime craftsmen. Merchants and land tradesmen looked upon ports as places of both commerce and community in a nodal point model, a secure place of business transaction and communication (Sindaek, 2009:103).

Figure 23: Västergarn coastline today looking southwest from a small boat harbour jetty. The shallow off-shore sea bottom offers no protection from high winds and aggressive wave action. (Photo: R. Koehler)

54 4.2.4 Overview Cross sea Baltic trade required navigation and seamanship skills in addition to dependable ships such as the Knärr, but when approaching a landing place the relatively shallow Baltic water depths closer to shore also created dangerous surf conditions when combined with strong gale force winds. This was especially true when entering and exiting the mooring areas with a Knärr that relied on oars for close to shore propulsion and manoeuvring. Harbour or port enhancements by dredging, jetties or rock boulder breakwater features to ensure safe entry and egress during inclement weather were for future generations and new technologies. Baltic sailing conditions were reversed in winter when both darkness and penetrating cold weather greatly restricted or precluded altogether Swedish coastal navigation via the archipelago network. In a historical foot note, the Norwegian Konungs Skuggsja (i.e., the King’s mirror ca 1260) makes reference to Baltic Sea sailing conditions noting that cross-Baltic voyages should not be taken after early October (Zwick, 2016:23). Presumably there were some similar references for start of the spring season, but that information is missing from the record. Toward the end of the 13th century Knärrs were replaced by ships of greater cargo capacity, typically those of the cog class.

4.3 Chapter Summary

This chapter has reviewed two proto-type maritime operations; landing place and harbour, that have been linked to Västergarn in general contexts. Each operation has been addressed in a present-day framework to achieve an understanding of labour, tools, subsistence and raw materials the resident Västergarn community would have been expected to supply. The connecting thread of harbour back to Chapter 2, Ships and Shipyards, is observed. An operational shipyard for new construction or repair of cargo vessels in the larger Knärr class is dependent on a protected harbour with slip-way for ship launching and recovery. Smaller coastal class cargo vessel construction/repair could be expected with an expanded landing place. Variations across terminology sets in a landing place/harbour/port dialog are multiple. For example, “a dock” or “a docking place” does not mean that a permanent structure is required as long as the configuration complies with other criteria such as safety, accessibility, resupply, etc. Indeed, a dock can be floating as long as it meets operating requirements. There is wide understanding across literature that a harbour is a location where ships can seek shelter, but no agreed definitions on what “shelter” means in expressions of physical assets,

55 particular advantages or services, or perhaps it is that “shelter” simply implies a place that may have been used by seafarers seeking refuge from the elements. In a closing dialog on key terms: landing place, harbour and port, we can turn to the Directory of Nautical Words and Terms , a volume of over 8,000 expressions and definitions on modern navigation, seamanship, meteorology, and naval architecture (Layton 1994). Definitions of the three terms in full text:

“Harbour”: Port or haven in which a vessel may lie in good safety “Port”: Harbour or haven in which shipping can lie in safety “Landing Place”: (This term is not mentioned in the volume)

Archaeological findings to date support that Västergarn was realistically an expanded landing place capable of servicing large beachable clinker construction class vessels and provide a desirable trading place, but it was never a true harbour or port by contemporary maritime definition. The bay is too shallow for large Cogs with a 2 to 3-meter draft and there is no evidence of permanent dock construction suitable for such deep-water vessels.

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5. Summary and Conclusions

In this thesis I follow an investigative empirical methodology that is reinforced by reconstructive archaeology in classifying Västergarn rivet artefacts and their life-cycle. I apply a “missing boatyard” classification profile across selected period (ca1000-1400) deep-water cargo category ships and boats that could have called at Västergarn in trade or diplomacy. The artefacts have messages to be extracted by comparison with both primary and secondary material in contextual settings. I balance the mute Medieval artefacts and static secondary literature sources with personal empirical experience at Västergarn as a student in the 2007 excavation, frequent Västergarn site visits, and private industry experience with engineering and construction of deep-water harbour and port facilities in Venezuela, Singapore and Malaysia. The similarities with Västergarn in how contemporary docks and harbours are constructed to meet vessel requirements are profound. Medieval Västergarn examples the second law of Sullivan’s basic design model at work (Chapter 2) i.e., to match maritime support facilities, docks and harbour designs with vessel profiles. An excellent example of this in a more appropriate Västergarn time frame is cited by Sven Kalmring wherein the harbour at Hedeby had to be expanded to meet growing dimensions and draft of cargo ships if Hedeby was to survive as a maritime trading place (Kalmring 2009: 250). New demands on maritime towns to provide improved harbour capacities, shipyards and support services were significant with far reaching effects across the Baltic trading network. Not all communities adjusted to increased demands for change in their waterfront facilities, some could not change for economic reasons and others perhaps were hindered by the natural landscape of their harbour not being suitable for expansion. The geological conditions at Västergarn offer proof that nature was a strong contributing factor in the failure of this maritime community. In tracing a boat rivet structure for Västergarn we had to also consider iron production on the Swedish mainland from raw ore collection and bloomery smelting to import of iron production bars to

57 Gotland. A thorough study of the entire iron supply chain is outside the scope of this study, but sourcing of iron is fundamental to understanding the relative position of boat rivets in the Västergarn economy. A quick way to visualize this is by a practical exercise with the Work Breakdown Scheme (WBS) described in Chapter 2 (Figure 9, and Appendix E). In an overview it is obvious that any large volume of boat rivets produced on Gotland would have originated from smelted iron imported probably in the form of currency bars (Hyenstrand 1979: 147). Imported iron bars smelted to wrought iron would be reforged at Västergarn suitable for rivet production, a process that is suggestive in part by slag deposits found in Västergarn excavations, but a foundry site has not been confirmed. In the supplier resource base of Västergarn’s trade network boat rivets theoretically could have been imported as finished products for direct use in boat construction, but that is an unrealistic assumption. Each new vessel would be custom built on site with its own particular specifications and rivets would be fabricated to match dimensions. This means on site smithing, and essentially the same situation is true for vessel repair wherein rivets had to match existing conditions, a process that would be accomplished only by custom (smithing) fabrication. The importation of prefabricated rivets is not supported by artefacts. While archaeological evidence provides numerous Västergarn examples of trade goods and continuous urbanization there is only conditional proof of marine vessel construction, repair, importance or influences on the economy. Cargo vessels of boat and ship classifications would have been the economic life-lines for trade and supply of basic commodities to community populace, but evidence of a harbour is lacking. Additional research is needed on how the Västergarn trading system operated across the supply chain-consumer matrix in a specific maritime context as it transitioned from barter to monetary exchange, for example where silver marks were the medium of exchange for iron raw material from mainland Sweden and associated freight servicing Medieval Gotland needs (Söderberg 2007: 134). In summary, Västergarn excavations to date (2005-2017) have produced no confirmed artefacts for boat carpentry or smithing tools, slipway foundations, or remains of docks identifiable to ship/boat building or repair yard functions over the history of the site. Maritime activities are seemingly well discussed in historical literature, but the reality of occupational shipbuilding activity against historical documents alone is arguable in the absence of archaeological evidence. An active maritime facility would have created a recognizable debris field profile.

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6. Discussion and Recommendations

6.1 Interdisciplinary Approaches to Västergarn

Archaeological evidence of trade and lifestyle at Västergarn is well documented but the supporting marine infrastructure that allowed Västergarn to exist is not represented in depth. Medieval ship/boat types, shipyards and trade networks are part of the Västergarn mosaic although mostly silent in historical records and archaeological material aside from cultural artefacts, but there is an even greater silence about the people who made the society function. Can boat rivet artefacts help define ship origin and classification? Indeed yes, in my opinion, but what else can they tell us; what of the population within the embankment? In the following outline I inject interdisciplinary and societal perspectives in profiling the Västergarn Medieval community. The foundation for this comes directly from material sourced for this thesis, and while visually a maritime outline created across shore-based support services, it is in reality a profile of the Västergarn community that is silent in record, and it is people of the community made it work. The Missing Boat Yard case continues with a human element. Visualize people in all the following scenarios, not only material things.

a) Material sourcing : who determined rivet specifications and quantities for boat building/repair?

What does a continuous source of imported raw iron material mean in terms of shipyard survival? How were rivets produced, and where; on site at Västergarn or other locations on Gotland? What were the iron raw material sources? Imported, but from where and who organized it?

b) Rivet and rove design : who determined design, and why?

What can design form and function tell us about rivets, but especially with the roves? Is there room for cultural influences in

59 design? What levels of craftsmanship were required in rivet and rove production? Are styles Gotlandic or fashioned by visiting ironsmiths; or by slaves?

c) Shipyard facilities and labour : who created the shipyard oper tional layout?

d) What was required as a work area for vessel construction: who was responsible?

Were vessel construction and installation skills separate functions from rivet forging? Were the manufacturing forces a permanent segment of Västergarn society or was labour imported on a project-by- project basis? Was new construction separated from repair and/or demolition services?

f) Supply chain dependencies : who determined and controlled the supply chain? What was the social hierarchy?

In an overview, what can rivet artefacts tell us about Västergarn’s logistical supply chain in perspectives of labour and materials, both domestic and foreign?

g) To what extent did foreign suppliers contribute to shipyard functions? Who produced the tar, caulking material and sails?

To correctly appreciate a Medieval Västergarn working shipyard profile is first to develop an interdisciplinary appreciation for soft subjects, or the human side over material objects. There are many open questions on infrastructure and support systems within which shipyard services took place, but too often overlooked or identified in passing name only is the sustaining role of local society. This human profile must be recognized for its role and importance, and from that profile we can begin to develop a functional Västergarn matrix. Nothing works without people. The WBS (Work Breakdown Sequence) diagram in Chapter 2, Ships and Shipyards, diagrams events but each event is processed by humans. The WBS can be tested with personnel descriptions and work responsibilities alongside the material objects. Of course, it is not only the Västergarn resident community to be considered, but also cross- cultural exchange with foreign suppliers and visitors who landed from other countries, i.e., the Peace Zone.

The silent boat rivets are not so silent in reality.

6.2 Future Research

60 The interesting similarities across Martin Holmbäck’s pottery distribution and shoreline map, and that of rivet artefact concentrations should be studied together in detail, especially around blocks HG6 and HG8. While it is difficult to attach an immediate connection between pottery and rivets, both areas speak to high human activity zones and possibly production sites. A house foundation has been identified near HG6, a site I suggest may have been an open-air workshop for boat construction or repair. Near-by large rivet concentrations and 60 kilos of slag in trench 22 support this projection, but ideally I hope to determine rivet trace elements with ICP-MS or SEM technology to follow the iron material supply chain to country of origin and supporting trade matrix. I was not able to accomplish the last step as part of this thesis, although research time was petitioned. I hope to accomplish it in future research study.

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List of Abbreviations:

LoA Length overall (boat classification) LwL Length at waterline (boat classification) MASL Meters above sealevel WBS Work Breakdown Structure

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67 Shipwrecks : Maritime Archaeological Approaches, 2014, ed. Jonathan Adams & Johan Rönnby. 2014: 46-71

Haapalau Boat. Personal email correspondence: Mr. Edvards Puciriuss

29/30 June 2020; 01 July 2020; 06 August 2020

Figures:

Cover: Abandoned clinker-built fishing boat on Gotland west coast. Stora Karlsö background. Photo R. Kohler Figure 1: Open area within the embankment wall with access to Peace Zone. Figure 2: Chronological distribution of vessel terms. Simek: 33 Figure 3: Knärr (Knörr) cross-sectional elevation Simek, 33. Figure 4: Knorr II remains Roskilde fjord. 1030-1050 AD. Heide, 107 Figure 5: Gokstad Boat. Photo Werner Karrasch. Copyright Viking Ship Museum, Denmark Figure 6: Haapalsu Boat. Photo Valerji Larionov. Copywrite credit Larionov Photo, Estonia Figure 7: Rivet Comparison Chart, by author. Figure 8: Medieval Cog motif, Sanda Church. Photo Christoph Kilger Figure 9: Work Breakdown Structure model. By author Figure 10: Paviken shipyard harbour artefacts. After Lindström 1981 Figure 11: Paviken wharf structures supporting boat building. Dan Carlsson Figure 12 : Kronholmen cog wreckage near Västergarn. Dan Carlsson Figure 13: Stora Karlsö rivet artifacts. Gustafsson 2016: 273 Figure 14 Complete Boat Rivet Artefact. Excavation year 2011. R. Koehler Figure 15: Mixed Rove examples Excavation years 2005- 2013. R. Koehler Figure 16: Mixed Västergarn excavation year 2008 (R. Koehler) Figure 17: Spiksökare tool. Sigtuna Excavation. Photo: Edberg 2013: 202 Figure 18: Rivet artefacts excavation year 2011. R. Koehler Figure 19: Corrosion effects across rivets. Excavation year 2005. R. Koehler Figure 20: Artefact Inventory & Classification Distribution. By author Figure 21a: Rivet summary count by rivet length. By author Figure 21b: Västergarn rivet summary excavation years 2005-2017. Author Figure 22: Västergarn coastal zone of today. Google Earth Pro May 20, 2020 Figure 23: Västergarn coastline today. R. Koehler

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