HMVS Cerberus Conservation Management Plan

September 2002

Prepared by Ross Anderson Maritime Heritage Unit Heritage

CONTENTS

Acknowledgements

1.0 Introduction 1.1 Scope of Conservation Management Plan

2.0 Definition of the site 2.1 Position of the Cerberus 2.2 Area of the rectangular Protected Zone

3.0 Statement of cultural heritage significance 3.1 International 3.2 National 3.3 State 3.4 Local 3.5 Aesthetic 3.6 Archaeological 3.7 Historical 3.8 Technical 3.9 Scientific 3.10 Recreational 3.11 Ability to demonstrate

4.0 Elements of historic fabric 4.1 and turrets 4.2 Collapsed hull 4.3 Buried hull

5.0 Conservation policy 5.1 Conservation options 5.1.1 Managed collapse and cathodic protection 5.1.2 Removal of deck to a land-based display and more stable environment 5.1.3 Stabilisation of deck in-situ with supporting structure

5.2 Conservation of elements 5.2.1 Guns and turrets 5.2.2 Hull 5.2.2.1 Intrusive materials 5.2.2.2 Destructive works 5.2.3 Buried hull 5.2.4 Timber deck 5.2.4.1 Maintenance 5.2.4.2 Removal

5.3 Support substructure

5.4 Risks, public access and risk management 5.4.1 Assessment of risk 5.4.2 Public access 5.4.3 Risk management

5.5 Flexibility of conservation policy

6.0 Care of Fabric and Maintenance

7.0 Documentation

8.0 Planning and management structure for future work and maintenance 8.1 ‘Save the Cerberus Alliance’ committee members 8.2 Historic Shipwrecks Advisory Committee (HSAC) and Heritage Council

9.0 Bibliography

Acknowledgements Many people have assisted with their comments toward the final version of this document. Thank you to my Heritage Victoria work colleagues Peter Harvey, Cassandra Philippou, Ray Tonkin and Sue Balderstone.

Also to members of the Victorian Heritage Council’s Historic Shipwrecks Advisory Committee, the Save the Cerberus Alliance, the National Trust’s Industrial Heritage committee, Dr Mike McCarthy and Dr Ian McLeod of the Western Australian Museum, and Ray Tyshing from GHD Engineers.

I would also like to acknowledge the efforts of all those who have campaigned for the stabilisation, restoration and recognition of the Cerberus over the years.

Cover photographs:

VR insignia on muzzle loading gun in aft turret (Heritage Victoria)

Queen's Birthday on Board HMVS Cerberus: Man & Arm (State Library of Victoria)

1.0 Introduction On 26 December 1993 the intact buoyant hull of the HMVS Cerberus shipwreck built in 1867, scuttled in Half Moon Bay since 1926, catastrophically collapsed in a south-westerly storm. The collapse is recorded on video taken by Black Rock Yacht Club members filming the ferocity of the storm from their clubhouse. A subsequent major collapse occurred in November 1994. Such a catastrophic collapse, rather than gradual deterioration, had been anticipated for at least half a century (Effenberger, 1995: 16).

Prior to this collapse, community support for schemes to ‘Save the Cerberus’ by refloating it and towing it to a berth in Williamstown or next to the Polly Woodside, relied on the buoyant hull of the Cerberus being repairable and restorable. A survey commissioned by the National Trust in 1969 however found that the hull was structurally too corroded to support the weight of the Cerberus (Effenberger, 1995: 9). Ultimately any thought of pursuing this preferred course of conservation/ restoration was rendered impossible by the 1993 collapse (Colquhoun, 1994: 1).

In 1970 Prince Phillip revived interest in the Cerberus with a letter of support for its historic status and preservation. Following this the Cerberus Preservation Trust, later the Maritime Trust of , was formed in 1971. This organisation was unsuccessful in its bid to reach a target of $500,000 in a public appeal to salvage the Cerberus and tow it to Duke and Orrs dry dock. Efforts to secure $3.5 million in federal government funding in 1985 and corporate funding from BHP in the 1988 were also unsuccessful (Effenberger, 1995: 9). Notably all public and community funding proposals to preserve the Cerberus have budgeted for public access with museums, walkways and site interpretation.

Suggested conservation options for the HMVS Cerberus shipwreck post-collapse of the hull have included filling the hull with sand, concrete or foam, building a cofferdam around the site to create a ‘Cerberus Island’ and raising and stabilising the intact deck, turrets and guns with a supporting framework. The next major stage in the collapse of the Cerberus is predicted to be the breaking up of the deck as it is further stressed and hinged out of alignment by the weight of the armour, turrets and guns, without the even support previously provided by the buoyant hull (Colquhoun 1994: 2; MacLeod 1999). In a wreck inspection by the MHU in April 1999 the stem-post was observed to have split, indicating the Cerberus is entering into this final stage of collapse.

The unique structure of the Cerberus can be described as a tank mounted on a barge. The ‘tank’ consists of 1800 tons of 8-9 inch thick armoured deck, breastwork, turrets and guns, that have predictably ‘squashed’ the lightly built, 300 ton, corroded hull of the ‘barge’. As the technical, aesthetic and historic significance (see 3.0 below) of the Cerberus is primarily the substantially intact ‘tank’, post-collapse efforts to preserve the Cerberus have focussed on supporting and conserving the intact deck in-situ (see Strachan, 1995).

In the 1990s community lobbying by individuals and members of the National Trust, World Ship Society, Maritime Museums of Victoria, Historic Shipwrecks Advisory Committee, Maritime Archaeology Association of Victoria and the ‘Save the Cerberus’ group have ensured that the Cerberus does not sink beneath the waves as a heritage issue. The Australian and international conservation and maritime archaeological community has also offered support to encourage any efforts to stabilise and conserve the historic fabric of the Cerberus (McLeod, Dr. Ian, 2002, pers. comm., Broadwater, John, Curator USS National Marine Sanctuary, pers. comm. 2000; Gould, Prof. Richard, pers. comm., 2002).

Additionally the recognition of iron and steam shipwrecks in Australia as an archaeological resource with historic, industrial and technical values has gained momentum since 1985 when Australia’s first ‘Iron and Steam Shipwreck Archaeology’ conference was held in Fremantle, Western Australia (McCarthy, Ed., 1988). For this site type Victoria is fortunate to have the first screw steamship to cross the Pacific Ocean and first screw steamer to travel between Sydney and (SS Conside (1852)), the first ship to travel directly from Belfast, Ireland to Melbourne (SS Ant (1862)) the first American steamship to cross the Pacific Ocean (SS Monumental City (1853)), Australia’s earliest located steamship (PS Clonmel (1841)) and the world’s only remaining twin turret breastwork Monitor (HMVS Cerberus (1867-1926)).

Since 1994 the MHU has commissioned an HMVS Cerberus Archive Directory (Effenberger, 1995), corrosion and ultra-sound surveys (McLeod, 1994; 1999) and an appraisal of cathodic protection options (McLeod, 1999). A Cerberus Project Team was set up and a Conservation Plan project progress report with corrosion survey report, transitional conservation policy, recommendations, material costings on immediate actions required with costing estimates for other long term actions was prepared (Strachan, 1995).

In May 2000 Heritage Victoria let selective tenders for engineering advice as to the practicality of raising and stabilising the intact deck, armoured breastwork and turrets to its pre-collapse level. The successful tenderer Gutteridge Haskins Davey (GHD) provided a methodology that met the conservation aims of stabilising the deck of the Cerberus. GHD advised the next step was to conduct an engineering parameters survey to determine the structural strength of the Cerberus structure, and geological survey of surrounding seabed for calculations of piling required for the jacking process.

1.1 Scope of Conservation Management Plan This aim of this CMP is to investigate the significance of the structure in its current form, and to clearly state the components of the structure that must be retained. This will be done in accordance with the Burra Charter (1999), the accepted standard guidelines for the management of sites of European cultural heritage significance in Australia. All definitions are in accordance with those as defined in the Burra Charter.

The CMP has also been produced to complement a proposed action plan, to guide engineering parameter surveys and possible major engineering works to be undertaken on the site of the HMVS Cerberus shipwreck. These works are intended to investigate a) the feasibility of stabilising the site and b) support the deck structure sufficiently to prevent further collapse. The proposed works involve piling, jacking, destructive testing and intrusion of modern materials. Following the testing phase, and subject to funding, further proposed engineering works will involve the installation of a support structure on the site to raise the Cerberus to its pre-collapse level.

The CMP also discusses options for conservation management of the site.

2.0 Definition of site

2.1 Position of the Cerberus Latitude South 37 degrees 58.1’ Longitude East 144 degrees 0.4’ (Victoria Government Gazette, 6 October 1994 p. 2684)

2.2 Area of the rectangular Protected Zone Approximately 0.5 hectare, with longer sides parallel to the length of the Cerberus and at a distance of 25 metres from the longitudinal centreline of the vessel, and the shorter side 5 metres to seaward from the peak of the bow and stern respectively. (Victoria Government Gazette, 6 October 1994 p. 2684)

The perimeter of the Protected Zone is marked by floating tethered buoys surrounding the wrecksite, clearly marked with the words ‘Protected Zone’ and ‘No Entry’.

The associated breakwater pier structure south-west of the Cerberus (and constructed after the Cerberus’ scuttling) is not included in the Protected Zone area, and is not considered within the scope of this document.

Fig. 1 Aerial photograph of Half Moon Bay with HMVS Cerberus, 13 October 1994 (Qasco/ VicImage)

3.0 Statement of cultural heritage significance The Cerberus’ primary historical significance is as a unique example of an important early stage in the technological development of the modern . The Cerberus has other aspects of cultural heritage significance which are listed below.

3.1 International The Cerberus possesses considerable international historical significance as it was an experimental vessel, being the first unrigged British-built iron breastwork Monitor ever constructed depending entirely on steam for propulsion. Its construction led the way for acceptance of designs for sea-going unrigged steam turret ships. As the first of a class of seven coastal defence ‘Monster’ Class ships constructed 1867-1870 the Cerberus represents a radical break with British building and naval tradition including ironclad wooden ships, and iron hulled ships mounting broadside armament such as the HMS Warrior (1860). Its delivery voyage to Australia via the was the longest voyage ever undertaken by a Monitor Class vessel, and it is believed to be the first ship destined for Australia to use the Suez Canal.

Nathaniel Barnaby, Reed’s successor in the role of Chief Constructor, followed the designs of Reed to produce the sea-going breastwork turret ships HMS Devastation and HMS Thunderer in 1873, which were basically an enlarged Cerberus design. This class of ships became the mainstay of maritime nations’ naval strength until the introduction of the class of big gun in 1906. Thus the Cerberus represents an experimental, formative stage in the design of the modern sea-going battleship.

The known resource of either Monitor-class or turret vessels that is available for research and study worldwide is limited, consisting of the following seven vessels:

• HRMS Buffel (23/7/1868 –still floating) – ironclad single turret-ram, built Robert Napier and Sons, Glasgow, on display Rotterdam Maritime Museum.

• HMVS Cerberus – (1867-1926) twin turret breastwork monitor, designer E.J. Reed, built Palmer and Sons, partially collapsed shipwreck site scuttled as a breakwater.

• Huascar (1865 –still floating)– 1130 ton ironclad single turret ship built for Peruvian Navy, designer Capt. Cowper Coles, built Laird and Birkenhead, currently berthed in Talcahuano, Chile as a museum ship.

• Lajta (ex Leitha)(1871 –still floating) – single turret river monitor built for Austro- Hungarian Navy, hull only (engines and boilers removed) berthed War History Museum, Budapest.

• USS Monitor – (1862 – 1862)- single turret monitor, designer John Ericsson, two Dahlgren cannon, US National Marine Sanctuary historic shipwreck site, 70 metres depth, Cape Hatteras USA. Currently being archaeologically excavated and conserved by National Oceanic and Atmospheric Administration and US Navy. Artefacts and major components of historic fabric including the propeller and turret/ guns have been excavated and recovered for conservation. The five year effort is costing US$14 million (AUS$ 26 million) and a new museum is being constructed at a cost of US$30 million (AUS$56.9 million).

• HNLMS Schorpioen – 2175 ton ironclad single turret-ram (1868 –still floating), Royal Dutch Naval Museum, Middelburg.

• Solve – (1875 – present/ still floating) 460 ton monitor built Norrkoping, Sweden, decommissioned 1920. Single non-rotating turret, was converted to oil barge, currently under restoration at Gothenburg Maritime Centre, Sweden.

Of these vessels the Cerberus is the only breastwork Monitor, and only twin turret Monitor still in existence. It is also the only one of the above ships not being restored as a museum ship, or with an associated museum.

The HMS Captain (1870), a rigged twin turret warship designed by Captain Cole (who died along with over 400 men when the ship capsized in a storm) is an as yet unlocated shipwreck site, lost in deep water in the Bay of Biscay off Cape Finnisterre, Spain.

3.2 National Two months after Federation, on 1 March 1901 the Australian states transferred their naval forces and personnel to the Australian Federal Government, but they continued to be administered by the states until the Commonwealth Defence Act 1903 was enacted on 1 March 1904 (Department of Defence: p. 12). The Victorian Colonial Navy was the largest of the colonial navies, and as the largest vessel the Cerberus became the Commonwealth Naval Force’s first .

When the was constituted on 10 July 1911 the Cerberus continued to provide service as a based at Williamstown. Though by this time an ageing relic, the Cerberus was still considered serviceable enough for the RAN to designate it as Port for in . On 1 April 1921 HMAS Cerberus was renamed HMAS Platypus II and acted as a tender to the fleet of six J-Class based at Westernport and Geelong.

The current RAN shore training facility HMAS Cerberus is named after the Cerberus. HMVS Cerberus was listed on the Register of National Estate on 25 March 1986 (Record Number 005787).

3.3 State Designed and built to the Victorian colonial government’s specifications as a harbour defence vessel the HMVS Cerberus was the flagship of the Victorian navy, the most powerful of the Australian colonial navies. Based at Williamstown for almost its entire service life, it was designed to steam within the relatively sheltered confines of Port Phillip. The Cerberus was vital to the defence strategy for shipping in Port Phillip and the ports of Melbourne and Geelong. It was intended to eliminate the necessity for expensive shore fortifications and provision of troops in Port Phillip by having a mobile floating battery. The Cerberus reflects the increase in colonial Victorian wealth and consequent move towards self-protection in the event of an invasion or attack by an enemy power. The Cerberus has a long association with the defence of Port Phillip, which continued when the RAN designated it Port Guard Ship for Port Phillip in World War I.

The Cerberus was first registered as an ‘historic building’ by the Victorian Historic Buildings Council on 20 August 1982. On 6 October 1994 it was gazetted as an historic shipwreck under the Historic Shipwrecks Act 1981 with a 0.5 hectare Protected Zone surrounding it. The Historic Shipwrecks Act 1981 was subsumed by the Heritage Act 1995, and the Cerberus is listed on the Victorian Heritage Register as Item S117.

The Cerberus’ position within Port Phillip demonstrates an unbroken association with the Bay, and “.she has closer ties with the history of Melbourne than any other vessel” (City of Sandringham: p. 4).

The HMVS Cerberus is part of a small and significant colonial naval shipwreck resource in Australia that includes HMVS Countess of Hopetoun (Swan Island, VIC), HMVS Lonsdale (Queenscliff, VIC) and HMSAS Protector (Heron Island, QLD).

3.4 Local The Cerberus was obtained by the then Sandringham Municipal Council on 2 September 1926, to be sunk as a breakwater for the Black Rock Yacht Club at Half Moon Bay. Since then the Cerberus has become a landmark heritage feature of the local land and seascape, and has strong local community associations with regard to sightseeing, swimming, diving, yachting, boating, fishing and social activities. It was used to fire starting guns for yacht races, and its centenary in 1968 was celebrated by simulating its warship role with loud shots and smoke (Effenberger,, 1995: 8).

The cultural re-use of the Cerberus in a ‘defence’ role against natural forces as a breakwater has led to the association of the Cerberus with Black Rock and the Sandringham Municipal Council – renamed the City of Bayside - for 76 years. The current owner of the Cerberus is the City of Bayside.

The Cerberus is listed as a navigation mark for mariners in this locality (Australia Pilot Vol II, 1982: 85).

3.5 Aesthetic In visual terms the Cerberus presents the unusual and striking form of a shipwrecked battleship close to shore. The Cerberus is a dominant cultural heritage feature of Half Moon Bay, and is a major cultural heritage feature of the Port Phillip maritime land/seascape generally.

The existing fabric, prior to its collapse in 1993, demonstrated the above water profile and low of a Breastwork Monitor Class turret ship – as if it were still afloat. The intact breastwork, deck and turrets are an important aesthetic feature, and if the deck continues to collapse and possibly break into sections, much of the site’s aesthetic significance will be lost. It is this aesthetic significance that is hoped to be retained through the emplacement of a supporting structure.

3.6 Archaeological There are no surviving builder’s plans or drawings of the Cerberus. However there are later ‘as fitted’ plans prepared by Chatham Dockyard (Nicholl: p.66). The remains of the Cerberus hull, superstructure, armament, machinery and fittings are therefore a significant source of technical and archaeological information. While it was sunk as a breakwater after having been stripped of fittings, individual artefacts have been recovered from the site indicating the site is not sterile.

There exists potential for artefacts to be located within the hull and seabed exhibiting aspects of its service life throughout which it was permanently manned by Victorian Naval and Royal Australian Naval personnel living onboard. One source has stated that the Cerberus had its Lowmoor iron removed prior to scuttling (Noble:p.100). Evidence of removal of armour from the aft turret exhibits this aspect of the Cerberus’ history, however the removal of armour for scrap was deemed to be too difficult and uneconomic by the Melbourne Salvage Company (Effenberger, 1995: 7). This is evidence both exhibiting human behaviour and explaining the Cerberus’ existence in its present intact condition.

Fig. 2 Iron cut and removed for scrap from aft turret, prior to Cerberus being scuttled in 1926 (Photo: Dr Stefan Csordas, Polly Woodside Maritime Museum Collection).

Architectural rubble is recorded to be the ballast used in the towing and sinking of the Cerberus as a breakwater (Effenberger, 1995: 8), and it is expected that this material remains within the hull of the Cerberus.

3.7 Historical The Cerberus can be directly associated with the following historical figures: Hugh Childers – Victorian Government Auditor General, Collector of Customs, Commissioner for Trade and Customs, Member for Portland in Legislative Assembly, Victoria’s First Agent- General in England, Junior Lord of the Admiralty (1864), First Lord of the Admiralty (1868) Edward J. Reed – Admiralty Chief Constructor, builder of the Cerberus Captain Cowper Phipps Coles R.N.– Naval theoretician and tactician, designer of HMS Captain (1870) and Coles turrets.

3.8 Technical The reverberations of the 1862 battle between the wooden ironclads USS Monitor and CSS Virginia (CSS Merrimac) were felt in navies, and by naval architects throughout the world. The Admiralty’s chief constructor E.J. Reed learnt many valuable lessons from the US Civil War, Crimean War and from ongoing Admiralty ironclad and floating battery experiments. Reed’s design for the Cerberus borrowed features from the Monitor such as steam propulsion, revolving turrets, armour plating and low freeboard. The double bottomed hull concept was an innovation used for the first time in Brunel’s SS Great Britain, and later used by the Admiralty in HMS Warrior. Reed incorporated new innovations to improve seaworthiness and safety for the crews, such as the thickly armoured breastwork encasing the holes in the deck for the turrets and engine, longitudinal framing, watertight bulkheads, twin deck, buoyancy chambers, and the valves and pumps used to sink it to a lower profile when engaging the enemy. It was the first unrigged Monitor to incorporate both fore and aft revolving turrets (being unrigged allowed maximum use of field of fire). Reed noted that the cost of these many innovations was the number of lives lost in iron-clad experiments. It is a tribute to Reed’s design that after the controversial capsizes of similar top heavy and low freeboard turret ships USS Monitor (1863) and HMS Captain (1870), and with the additional top weight of bulwarks and rigging for its voyage to Australia, the Cerberus did not capsize despite listing a reported 40 degrees in a Bay of Biscay storm.

The existence of the intact deck, breastwork and both Coles turrets with rifled muzzle loading guns and operating mechanisms in situ is of tremendous significance to the understanding and interpretation of the technicalities of the Cerberus, and early turret and Monitor class generally.

With reference to the iron plating used in the Cerberus’ construction, the breastwork armour is a key innovation developed by Reed, which at a stroke solved the problems of armour protection for the crew and enclosing the openings in the deck to render the Monitor design more seaworthy. The breastwork demonstrates the fact that the Cerberus was built to defend itself from above-water battery fire. Juxtaposition of the relative thicknesses of the hull plating and armoured breastwork demonstrate the Cerberus was constructed prior to the acceleration in the development of submerged attack and mine warfare, which was occurring even as the Cerberus was being launched.

3.9 Scientific Scientific studies have been carried out on the Cerberus by practitioners in the disciplines of archaeology, conservation, metallurgy, engineering and marine biology. As a historic structure with a variety of known metal thicknesses the Cerberus has value as a scientific study in corrosion and collapse, and maritime archaeological site formation processes.

3.10 Recreational Recreational activities such as sightseeing, swimming, diving, boating, fishing and partying have all occurred on and around the Cerberus prior to it being declared a Protected Zone. A key objective of the stabilisation works is to enable safe public access to the structure, such as for tourism or diving activities. As a visible historic shipwreck close to shore within Port Phillip the Cerberus has significant value as a recreational and tourism drawcard, and for interpretation of maritime heritage.

3.11 Ability to demonstrate In terms of its ability to exhibit aspects of social and cultural life in Victoria, the Cerberus demonstrates: • the design, layout, armament, technology and fittings of a Monitor Class war ship • an integrated coastal defence system for Port Phillip • Victoria’s/ Australia’s colonial dependency on Britain for engineering and defence solutions • increasing colonial self sufficiency for funding and implementation of defence solutions • life on board a Monitor Class war ship

The Cerberus should be understood and interpreted in context with existing related artefacts and sites of 19th century Victorian naval and maritime history, including: • possible gun-raft submerged wreck site at Port Melbourne (Port Melbourne Unidentified No. 1) • Beaconsfield Parade Defence Reserve, Sandridge • Muzzle loading cannon removed from HMVS Nelson (various locations) • CSS Shenandoah cannon, Churchill Island • HMVS Countess of Hopetoun 1st class submerged wreck site, Swan Island • HMVS Lonsdale 2nd class torpedo boat wreck, buried in landfill in the grounds of Queenscliff Maritime Centre • South Channel Fort (artificial shoal fort) • Popes Eye Annulus (uncompleted shoal fort foundations) • Williamstown defences • Point Nepean fortifications • Fort Queenscliff • J-Class submarines (Cerberus in role as HMAS Platypus II, 20th Century defences) • Osborne House Naval and Maritime Museum, Geelong

All of the above aspects of significance have been taken into account in the formulation of the conservation policy.

4.0 Elements of historic fabric The current existing remains of the Cerberus can be categorised into three major elements. 4.1 Deck and turrets: The intact armoured deck, breastwork, fore and aft Coles turrets and muzzle loading guns, and topmost armoured sheer strake of the hull. This is the structure that is intended to be jacked to its pre-collapse level and supported, and contains most of the most important technical and interpretive features of the Cerberus. It also includes the original deck planking with its evidence of removed deck fittings. 4.2 Collapsed hull: The submerged collapsed and twisted remains of the buoyant hull plating, bulkheads and frames that have been squashed by the weight of the armoured deck structure i.e. the structure between the deck and the seabed. This is the structure that will require cutting away to an as yet undetermined extent to allow jacking operations to be successful. Some areas of hull plating including the intact stern have not yet collapsed. 4.3 Buried hull: The buried remains of the buoyant hull including the keel, which is predicted to be mostly intact, and forms the archaeological component of the site where any artefacts are likely to be preserved. Some destructive intrusion may occur to this part of the site during engineering jacking and supporting works, which will require archaeological supervision and mitigation.

Fig. 3 Section through No. 3 bulkhead recorded by naval architect A.B Colquhoun’s survey of the Cerberus post-collapse. The ‘After’ diagram shows the three main elements of the existing historic fabric. 1. The intact deck and turrets; 2. Collapsed and bent hull plating, frames and bulkheads, and 3. The intact buried remains of the lower hull (from Colquhoun, 1995).

5.0 Conservation policy The conservation policy for the Cerberus may be simply stated as retaining what historic fabric remains as completely as possible in the course of stabilising the structure.

A conservation policy submitted to Heritage Victoria’s Cerberus Project Team by Strachan (1995) stated that a conservation policy for the Cerberus should: • conserve all existing fabric • retain and keep accessible the structural and spatial relationship between the most significant features including the sternpost, upper hull structure and plates, deck and timbers, guns and mechanisms • maintain the significant visual profile/ silhouette • keep the Cerberus in Half Moon Bay, Victoria

Collapse of the deck will result in the loss of most of the above i.e.: the spatial relationship between significant features, accessibility of the deck and significant visual profile.

Accepted guidelines for the stabilisation of historic vessels state recommend “ identifying, retaining and preserving to the greatest extent possible original or historic fabric, as well as material, elements, and features that are important in defining the historic character of the vessel” , while not recommending “irreversibly altering the essential form of the vessel during the stabilisation process.(Standards for Historic Vessel Preservation Projects, US National Park Service)

Constraints on conservation works to stabilise the deck to date are a lack of detailed data on the mechanical strength of the vessel to sustain a lift, engineering design and logistics (due to the shallowness of the site) and resourcing (Strachan, 1995: 7). The former two constraints are being addressed by the geotechnical and engineering parameters study currently underway, and this will provide an accurate costing for the proposed works.

5.1 Conservation options 5.1.1 Managed collapse and cathodic protection It may be logically argued that an effective conservation policy for the Cerberus is to let it become completely submerged, and thereby enable more complete cathodic protection using the sea as an electrolyte. This option is a non-interventionist policy, and if the stabilisation project does not occur, this option will be the natural sequence of events for the Cerberus site anyway. The management of this collapse would include risk minimisation by continuing to restrict public access to the site by the extant Protected Zone, recording the stages of collapse and installing a cathodic protection system using sacrificial anodes. This option is the most simple and cost-effective option, but is most likely to result in the break-up of the deck and loss of the site’s aesthetic, technical and recreational significance.

5.1.2 Removal of deck to a land-based display and more stable environment Since the collapse of the hull - and as the deck, turrets and guns are the most integral and significant feature of the Cerberus - various proposals have been put forward to salvage and remove these elements either individually (eg; the guns) or wholly to a land-based display area for public interpretation. This would be similar to the approach adopted by NOAA to the USS Monitor. The advantages of this option are that the deck can be removed to a less corrosive environment, and this would allow more effective long-term conservation of the fabric. Any conservation of the Cerberus in-situ is only arresting the rate of decay, and will not result in permanent stabilisation of the fabric (Milner, P. in Appendix 1, Strachan, 1995). The disadvantage is cost, mainly for the construction of a gantry on-site to lift the turrets out, estimated to cost $10 million plus (ibid). A shipwreck ‘footprint’ would remain below sea-level in the form of the buried hull and cut-off plating to mark the wreck site. The undesirable aspects of this option are that it removes the Cerberus from Half Moon Bay and disperses the major elements of the site, constituting a loss of its local and aesthetic significance. It should be noted that the proposed stabilisation of the deck option (see 5.1.3 below) does not preclude this option 5.1.2 from occurring at some future date, and in fact will ensure it remains a possibility.

5.1.3 Stabilisation of deck in-situ with supporting structure In 1994 Colquhoun proposed a number of options to “retain the historical significance of the Cerberus while reducing dangers to the public” such as 1) pouring an artificial concrete hull/ skirt to support the deck; 2) filling the structure with sand to above high water level to support the deck; 3) cofferdam the site and fill with sand; and 4) (a variation on 3) increasing the cofferdam area to create an artificial island (Colquhoun, 1994: 3).

In-situ stabilisation was the preferred option of the Heritage Victoria Cerberus Project Team in 1995 and is the approach being further investigated and costed by the Save the Cerberus Alliance in 2002. The favoured engineering solution proposed is that the deck is supported with beams and jacked to its pre-collapse level as outlined by Gutteridge Haskins Davey engineers (GHD, September 2000). In-situ conservation of the deck can then be undertaken following these stabilisation works. This option retains the historic, local, technical and aesthetic significance of the site.

Fig. 4 Proposed sequence of in-situ stabilisation works (from GHD, 2002).

The disadvantages of this option are that major intrusive elements are introduced to the site in the form of the supporting beams and piles. There is also an element of risk to the intact deck during the lift (the extent of which is currently being investigated by GHD to see if it will withstand the loadings). Similarly the necessity of cutting away hull plating, frames and internal longitudinal and lateral bulkheads constitutes irreversible damage to these elements.

Stabilisation of the structure is desirable for the following reasons: • it retains the aesthetic and historic significance of the Cerberus as a ‘floating’ Monitor Class warship (retention of significant character or quality) • engineered support will preserve the surviving intact deck, breastwork and turret components of the Cerberus in an intact form (retention of significant character or quality) • it allows the site to be visually interpreted by a wide sector of the general public (allows continuation of function or changes to a new or compatible use i.e.; tourism, interpretation) • it demonstrates concern and appreciation for the significance of the structure as an important part of Victoria’s, Australia’s, and the world’s maritime heritage (allows continuation of function or changes to a new or compatible use i.e. tourism, interpretation).

5.2 Conservation of elements 5.2.1 Guns and Turrets As the functional part of a merchant ship is its box shaped hull for cargo carrying capacity, so the functional part of a warship is its deck as a platform whether for mounting guns or carrying aircraft. The Cerberus can be defined as a floating platform for its revolving Coles turrets and 10” rifled muzzle loading (RML) guns, two in each turret.

The guns and turrets are a defining feature of the Cerberus, and the turrets retain all aspects of their original layout (allowing an understanding of loading and firing procedures), including sliding gun carriages, buffer stops, lifting and elevating gear. Removal of all four guns for jacking operations is deemed necessary in order to reduce the weight of the superstructure by 72 tons (estimated weight 18 tons per gun) (GHD Engineering Feasibility Study: p. 3). Removal of the guns will require removal of some of the carriage and turret fittings, and “…cutting free of any corroded members will be minimal” (ibid). The turrets, while weighing an estimated 230 tons and being a “substantial concentrated load” are proposed to be left in place due to difficulties in removal, and are to be incorporated into lifting proposals (ibid).

The removal of any gun carriage and turret fittings, and any cutting required should be done under the supervision of an archaeologist to ensure the systematic recording and safekeeping of all removed historic fabric components. Any small loose components removed should receive conservation treatment at this stage if required.

Any conservation or engineering works involving removal of the guns must ensure sufficient funds exist to replace the guns in their turrets following the work, and replacement of all associated historic fabric. It should be noted at this stage the costing does not allow for replacement of the guns or associated components – removal was costed at $55,000 (GHD Engineering Feasibility Study: p. 8).

5.2.2 Hull The buoyant hull of the Cerberus is also a key feature of the ship, designed to support, float and sink the deck, and incorporates a number of important innovations (see 3.8 Technical Significance above). The relative thinness of the hull plating (0.5” thick) as compared to the heavy deck, upper hull strake and turret breastwork (up to 10” thick) exhibits the function of the Cerberus in times of pre-torpedo and technology, with the emphasis on above- defences.

There are few sections of intact hull plating remaining; most notably the submerged graceful elliptic form of the counter stern is still intact with its protruding propeller shafts and sternpost. This section of hull is therefore highly significant as being one of the only non-collapsed parts of the hull, for exhibiting the original layout of the Cerberus’ twin screw propulsion, and for interpreting the hull’s original height/ depth. Individual pieces of sprung hull plating lie on the seafloor, and these exhibit hull plate dimensions and their riveted construction method. It is recommended that all intact remains of the hull are identified and retained where possible.

Following the collapse precipitated by December 1993 storms, a survey of the wreck was undertaken by naval architects Colquhoun and Associates (Colquhoun: 1993). From being a grounded vessel with a corroded, though intact buoyant hull, Colquhoun et al reported the Cerberus had suffered the following: • the buoyant hull had suffered catastrophic collapse, and was declared to be beyond providing buoyancy as a floating hull. All visible buoyant hull framing has been bent, fractured or distorted beyond recognisable original shape or form. • the armoured breastwork and deck had dropped about six feet and assumed a list of 4.5 degrees to starboard, a trim of about two feet by the bow, and sag of one foot. • the upper deck is completely immersed at high water • the deck has “hinged or tripped” about three feet to starboard, and the stem post has assumed a list to starboard. • the armour sheer strake and deck 2.13m in height is supported on a 1.2 - 1.5m thick cushion of crushed hull frames and plating of indeterminate combined compressive strength.

Fig. 5. View of deck at bow before collapse, taken in 1994. (Heritage Victoria)

Fig. 6 View of deck at bow after collapse, taken in 1995. (Heritage Victoria)

Bayside City Council has since been monitoring the collapse of the Cerberus along X and Y axes using total station survey. One axis runs stem to stern and the other across the of the deck – four reference points are surveyed being the points at each end of each axis. Since 1994 the wreck has collapsed nearly a further 0.5 metre (data as at 20 September 2002). The site is still collapsing at a rate of 20-30mm per 6 months (Palich, Graham, Bayside City Council, pers. comm.)

On 13 April 1999 the Maritime Heritage Unit visited the site with conservator Dr Ian McLeod to obtain corrosion data. Findings from this inspection were that: • The stem post has split, “indicating the vessel is in the first stages of final collapse” (MacLeod, 1999). • The counter stern is still intact, but with a large scour hole evident

Colquhuon also stated in his report following the collapse, dated 4 February 1994 that “... the fore and aftermost sections of the hull and upper deck, being less well supported than the remainder, may soon hinge downward out of alignment, and so materially reduce the historical significance of the ship, unless these are provided with additional support before they drop” (Colquhuon: p. 3).

Following the wreck inspection in April 1999 MacLeod stated that the development of a scour hole around the stern is of concern, as a lack of support in this area could result in the deck breaking off approximately in a line with the rear turret (MacLeod, 1999).

Fig. 7 Stages of collapse: buoyant hull below armoured strake on port side partially collapsed – note sprung rivets in iron plating and dislodgement of marine growth. (Heritage Victoria)

Fig. 8 Port hull in advanced stage of collapse, note bent frames and completely dislodged/ sprung plating. These are the hull plates that appear in Colquhoun’s ‘After’ cross section in Fig. 3. (Heritage Victoria)

It is a prime objective of the conservation and supporting engineering works that the deck, armoured breastwork and turrets retain their integrity as a single platform.

There is a good possibility that the keel, fixed on bedrock, and at least some part of the buried hull structure remains intact: “..with the possible exception of some structural members below sand level, all buoyant hull framing is bent, fractured and distorted together with much hull plating...” (Colquhuon: pp 1-2).

Engineering parameter surveys and infrastructure for the support works will require cutting of the hull, drilling and tapping for bolts and welding of loops and attachment points for jacks and piles. These works can be divided into two types of activities:

5.2.2.1 Intrusive materials Any modern intrusive and additional metal fabrication should be reversible, to allow it’s grinding or cutting off following the works. However it may be decided that part or all of any additional fabrication may be left in place to allow for further jacking or other engineering works designed to support the Cerberus.

5.2.2.2 Destructive works Engineers GHD have proposed the attachment of longitudinal beams to the historic fabric with drilled and tapped bolts at 1.2 metre intervals to transfer weight to lifting points and thence to the jacks and piles (GHD Engineering Feasibility Study: p. 4). This will involve some destruction of the deck’s historic fabric which is considered acceptable in order to stabilise and support the deck. The holes left from drilling and tapping will remain evident following completion of the engineering works.

As far as possible any cutting and removal of historic hull and deck fabric should be researched to minimise the loss of any structural support afforded by historic fabric. Any visibly intact sections of original hull and plating such as at the counter stern, should be left intact. In terms of extent, as little material as necessary should be removed.

The recommendation of Colquhuon “…as an urgent safety first measure, that all jagged metal protruding from the ship’s side and sandy bottom be trimmed off and removed from the area” (p. 3: emphasis added) is therefore not included as part of the conservation policy for the site at this stage.

All destructive works such as hull plate cutting or drilling and tapping should be documented graphically on a scaled plan and diarised in a log of works (see ‘Documentation’ below). The remains of plating and bent frames provide evidence of the site formation processes affecting the Cerberus, and should be retained wherever possible. In the interests of worker and public safety however the cutting away of some dangerous sections of this structure will be required.

5.2.3 Buried hull It is considered likely that the buried hull consisting of the double bottom and its associated technical features (see 3.8 Technical Significance, and Fig. 3 above) exists in an intact condition.

GHD have reported that in order to achieve a synchronised lift of the deck structure, once the weight has been taken off the crushed hull underwater work will include “…water jetting of the sand in the collapsed hull and cutting free of the twisted remaining framing of the hull”. This work is necessary to “…disengage as much of the collapsed hull as possible from the superstructure to reduce the lifting requirements of the jacking system” (GHD Engineering Feasibility Study: p. 5).

The use of powerful water jets by commercial divers will involve disturbance of the archaeological stratification of the site. Wherever possible water jetting should avoid disturbance to the interior of the hull spaces. While the archaeological deposit is unlikely to be rich, as the hull was stripped before scuttling, neither is the site considered sterile, and this work should be supervised by an archaeologist. A diving inspection of the site by a maritime archaeologist following water jetting operations during this stage of operations should take place to inspect the site for any loose or disturbed artefactual material, and for recording if necessary.

It is reiterated that the remains of the buried hull, collapsed hull plating and frames are evidence of the Cerberus’ innovative hull construction and site formation processes, and should be retained wherever possible.

5.2.4 Timber Decking The planked weather deck timber was thought to be teak but tests have given a result of Danzig oak . A report by Dr Glen Agnew of Parkdale Research has provided evidence that the planking is being attacked by marine borers (Agnew in Strachan, 1995). Elimination of marine borer damage requires the deck to be removed from contact with water. Continued marine borer damage will result in the relatively non-corroded metal of the deck being brought into a more active corrosion zone. Dr Peter Milner states that “Complete stabilisation is not possible in-situ: the best that can be expected is a rate of arrested decay. The rate of decay can be reduced by removing both timber decking and metal parts from constant contact with sea water” (Milner, 1995).

5.2.4.1 Maintenance The deck planking requires a program of maintenance using a non-toxic timber preservative such as TIMBOR ® which is water soluble and non- corrosive to ferrous metal (Birkholz).

5.2.4.2 Removal The decking is original fabric and therefore should be retained wherever possible. Issues will no doubt arise as the decking becomes degraded, possibly becoming loose and detached presenting a small boat navigation hazard. Damaged or loose decking presenting a foreseeable hazard should be repaired or fixed wherever possible. However, decking beyond repair may be removed and replaced in accordance with the documentation procedures below. Some of the decking retains evidence of removed deck fittings and any evidence of such features should be recorded prior to removal.

Fig. 9 Corroded deck fitting (capstan). (Heritage Victoria)

5.2.4.3 Replacement Any damaged or lost decking that requires replacement should be done with similar materials and in a manner consistent with the original methods. Any replacement decking should be recorded as an addition in accordance with documentation procedures below.

5.3 Support substructure By necessity an engineered support structure will be large and intrusive to the site – however the proposed works anticipate Cerberus being raised to pre-collapse level. The supporting steel beam substructure is intended to be submerged and not visible above sea-level, with only the historic deck structure to be visible above sea-level

Any supporting structure must not be cathodic to Cerberus, and therefore detrimental to the preservation of the remaining fabric of the Cerberus.

GHD have recommended that the support substructure will be connected to the jacking piles, outside the hull of the Cerberus. However the support substructure will also require additional support columns placed “…in some areas, i.e. under the turrets….for support of the upper deck” (GHD Engineering Feasibility Study: p. 6)

The placement of additional support beams within the interior hull spaces of the Cerberus will affect the archaeological deposit and the installation of such support beams should be minimised if possible. If support beams are to have bases on the seabed involving excavation or cutting of the Cerberus’ hull these areas should be excavated under archaeological supervision.

5.4 Public access and risk management 5.4.1 Assessment of risk The Cerberus at present is highly risky as a site in terms of allowing public access, and it is primarily for this reason that the site has been declared a Protected Zone (no entry without a permit). Visits to the site are weather dependent and require calm weather and seas. Risks to visitors and divers include injury and possibly death from jagged, rusting and sharp corroded metal, slippery decks, angle of lean of deck, entrapment, fouling of gear, reduced visibility by siltation, and structural collapse. There is a danger to boats of striking submerged objects if moored up to, or motoring near the wreck’s side.

5.4.2 Public access It is notable that all proposals for Cerberus stabilisation and restoration have featured plans for reopening of the site for visitation, whether by boat or walkway, or with relics removed to a museum. This indicates the level of community support for reopening of the site for visitor and diver access, and its recreational potential. Stabilisation of the deck will negate the major danger of collapse, and allow consideration of reopening of the site to visitors and divers. Such a decision would require a more in-depth tourism impact study of the site infrastructure required to allow public access, numbers of visitors expected, liability and insurance, and assessment of positive or negative impacts to the wreck arising.

5.4.3 Risk management At this stage it is recommended that enforcement of the Protected Zone to protect the site from uncontrolled site visitation continues. The recent introduction of Penalty Infringement Notices (PINs) for offences including ‘entering a Protected Zone without a permit’ under the Heritage Act 1995 will greatly assist local police and appointed historic shipwreck inspectors (Fisheries and NRE officers, Victoria Police, Water Police, Search and Rescue Police, Heritage Victoria staff) to manage the site.

Uncontrolled or controlled site visitation may be reconsidered if stabilisation works are completed. Other risk management measures already in place are the Protected Zone perimeter buoys, jetty warning signage and mesh placed over hatches and openings in the weather deck preventing internal hull access.

5.5 Flexibility of conservation policy This conservation management plan may be revised by any further collapse or significant event that causes a substantial change from the current condition. It should be reviewed following the jacking and stabilisation works. Any changes or deviations from the conservation policy in this document must be ratified by the Historic Shipwrecks Advisory Committee and the Executive Director, Heritage Victoria (see Section 8.0 Planning and management structure for future work and maintenance).

6.0 Care of Fabric and Maintenance

“...if we are to be successful in preserving iron ships, we must accept that even a minor degree of corrosion is too much” (Birkholz, 1997).

Fig. 10 Detail of corrosion on surface of turret armour plate, above the high water mark. (Heritage Victoria)

As an iron ship in a hostile marine environment exposed to prevailing winds and seas all surviving ferrous components of the Cerberus are suffering from corrosion, above and below the high water mark. The corrosion is estimated at an average of 8mm/ 68 years for the varying thicknesses of metal on the Cerberus (MacLeod in Strachan, 1995: Table 4). While it is considered impossible to completely halt the forces of corrosion on the Cerberus in its present condition and location, all possible efforts to slow down the rate of corrosion and protect the existing fabric must be applied.

The difficulties of conserving a massive corroded and collapsed ferrous/ timber composite object in an exposed marine/ air environment are acknowledged by this conservation policy. Following the stabilisation works, it is recommended that further detailed professional conservation advice is sought for the best strategy by which to protect the remaining structural features and fittings of the Cerberus.

Such a conservation strategy is likely to involve the application of cathodic protection, rust converting products such as Xtroll and protective films and coatings such as Fishoilene. This work is likely to involve a maintenance schedule for repeated applications. Such work can be effectively carried out by trained volunteers, and costs minimised by corporate sponsorship in the form of donated materials and products. Different components will require different treatments, depending on their location on the vessel eg; submerged or exposed.

7.0 Documentation It is recommended that documentation of any works to the Cerberus includes as a minimum: • daily log of activities to be maintained throughout the engineering parameters survey, and any future engineering works • at completion of the parameters survey, and at completion of any future works, any additional or destructive works are graphically recorded on a scaled plan of the Cerberus • photography and video, including underwater photography and video records are kept documenting all works impacting on the historic structure • City of Bayside continue to survey and monitor the position of the Cerberus at regular intervals by Total Station to record any incremental shifts or collapse.

8.0 Planning and management structure for future work and maintenance ‘Save the Cerberus’ Alliance’ is a committee made up of the owners and stakeholders committed to the Cerberus stabilisation project. The committee was set up in 2001 to provide a forum for the owner and community and government stakeholders, to best coordinate conservation planning, sponsorship and fundraising, and emergency work to stabilise the Cerberus.

It is recommended that the ‘Save the Cerberus Alliance’ continues indefinitely as a discussion and management forum for the planning of any future conservation works to the Cerberus, and for monitoring the implementation of site works.

8.1 ‘Save the Cerberus Alliance’ committee members

City of Bayside is the owner of the Cerberus, and a repository for historical archival documents relating to the Cerberus.

Friends of the Cerberus are an interest group with a commitment to the preservation of the Cerberus.

Heritage Victoria is the state government authority responsible for the management and protection of the Cerberus under the Heritage Act 1995, and the Executive Director issues permits for works to sites on the State Heritage Register. It provides archaeological and conservation advice, and is a repository for archival documentation.

Melbourne Convention and Marketing Centre has an interest in the Cerberus from a tourism perspective, and has expertise in publicity and fundraising.

National Trust has held a long term interest in the Cerberus as part of Victoria’s heritage and has lobbied for its preservation since 1970.

Parks Victoria is the state government authority responsible for the management of the waters within Port Phillip Bay outside the shipping channels. It has a stated commitment to the preservation of cultural heritage sites within Port Phillip Bay, including a thematic focus on colonial defences.

Changes or additions to the above management structure may be ratified with the agreement of the majority of committee members.

8.2 Historic Shipwrecks Advisory Committee (HSAC) and Heritage Council The HSAC is a statutory advisory committee to the Heritage Council of Victoria, which advises the Minister for Planning and Heritage on heritage matters.

Any management decisions and actions recommended by the ‘Save the Cerberus Alliance’ impacting on the Cerberus must be approved of by the Historic Shipwrecks Advisory Committee.

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