Borobudur 1 Pm
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BOROBUDUR SHIP RECONSTRUCTION: DESIGN OUTLINE The intention is to develop a reconstruction of the type of large outrigger vessels depicted at Borobudur in a form suitable for ocean voyaging DISTANCES AND DURATION OF VOYAGES and recreating the first millennium Indonesian voyaging to Madagascar and Africa. Distances: Sunda Strait to Southern Maldives: Approx. 1600 n.m. The vessel should be capable of transporting some Maldives to Northern Madagascar: Approx. 1300 n.m. 25-30 persons, all necessary provisions, stores and a cargo of a few cubic metres volume. Assuming that the voyaging route to Madagascar was via the Maldives, a reasonably swift vessel As far as possible the reconstruction will be built could expect to make each leg of the voyage in using construction techniques from 1st millennium approximately two weeks in the southern winter Southeast Asia: edge-doweled planking, lashings months when good southeasterly winds can be to lugs on the inboard face of planks (tambuku) to expected. However, a period of calm can be secure the frames, and multiple through-beams to experienced at any time of year and provisioning strengthen the hull structure. for three-four weeks would be prudent. The Maldives would provide limited opportunity There are five bas-relief depictions of large vessels for re-provisioning. It can be assumed that rice with outriggers in the galleries of Borobudur. They sufficient for protracted voyaging would be carried are not five depictions of the same vessel. While from Java. the five vessels are obviously similar and may be seen as illustrating a distinct type of vessel there are differences in the clearly observed details. The depictions are probably not all by the same artist. Following van der Heide (1929), I shall use the plate (Afbeelding) numbers from van Erp’s (1923) paper to identify the Borobudur ships. Volume Component Calculation basis Amount Weight <2 tonnes Water for approx Thirty persons, twenty-five days, not 1500 including drinking and 33m less than 2 litres per person/day litres containers, cooking Average 50kg per person Ships' Sleeping space 1.6m x 0.45m for 25 1.5 tonnes compliment persons 182m Thirty persons, sixty days, 0.5kg per approx Rice day 900kg 1.53m A fire would be kept smoldering at all Firewood for times when a stronger fire was not ~1 tonne 23m cooking required Salt fish, plantains, tubers, tamarind, ~0,5 tonne 0.53m Other foodstuffs etc. Approx 2 tonnes of spices and other Cargo ~2 tonnes 43m high-value commodities Personal belongings, e.g. sleeping ~0.5 23m Other mats, tools; spare ship's gear; tonnes The total stowage space indicated by these However, these are not sailing vessels — they are approximations is 133m. The weight calculated is motorised and use multiple stays to hold up the approx 8.5 tonnes. Depending on design, the vessel outriggers. Sailing vessels impose much more load might also need to carry a tonne or two of ballast. on their outriggers and outrigger booms. The Approximately 182m of sheltered space would be largest sailing outriggers of recent decades have required for most of the ship’s company to sleep. been the perahu sande and perahu pangkur of the It is assumed that some persons would be on watch Mandar people from the west coast of Sulawesi, at all times. and some very large jerangkat built on the western coast of the Gulf of Bone and used as FADs (Fish MAXIMUM SIZE OF OUTRIGGER SAILING Aggregating Devices) anchored in very deep water VESSELS to the south of the Gulf. These vessels have been There are vessels without outriggers depicted at up to about 10-11m length and the largest pangkur Borobudur but the five large vessels depicted in have been able to load more than 5 tonnes. detail all have outriggers. In the first half of the 20th century, outrigger perahu The Borobudur ships appear to be fairly large. paduwang from Madura were probably slightly Sizes up to 25m have been posited for the largest larger than the vessels mentioned above. However example: Erp 6. Heide (1929) offers a more sober they seem to have regularly employed human estimate of 12-15m based on the number of oar ballast on the weather outrigger to enhance ports. This allows about 1m for each oarsman. stability. In recent decades some very large outrigger vessels The largest pangkur, sande and jerangkat had very have been built in Indonesia and the Philippines. large and long bamboo outriggers. Pangkur and boom is increasingly susceptible to breaking off when pitching into a headsea. A Selat Badung jukung with a 6m long hull has outriggers 9m long, mean diameter at least 125mm and buoyancy of about 100kg. (0.0625 x 0.0625 x π x 9m = 0.1103m) Using these proportions and assuming that the largest bamboos would have diameter about 200mm, the largest possible outrigger canoe is about 10m long. perahu pangkur Extrapolating from that calculation, outriggers of sande usually have outriggers more than 150% the about 300mm diameter with buoyancy of about length of the hull. They normally depended entirely 1.3 tonnes would be required by an outrigger vessel on outriggers for stability and sometimes made a little more than14m long. Such a vessel, designed fairly long, open-sea voyages. with a long narrow hull would scarcely have the The maximum size of pangkur, sande and jerankat capacity to carry the proposed passengers, is probably determined by the maximum size of provisions and cargo. Therefore it can be bamboos available. Since the sail area that imposes concluded that it is not possible that an outrigger heeling loads increases as the second power of the vessel, designed to derive all its stability from length of the vessel, the volume (buoyancy) of the outriggers, could be built of a size large enough to outriggers needs to increase at the same rate. In carry the proposed passengers, provisions and other words the diameter of the outriggers must cargo. increase in proportion to an increase in hull length. This leads to engineering problems as size The outriggers shown on the Borobudur ships are increases: if the length of the outriggers increases not like the long outriggers of the large outrigger in proportion to the hull length, the long projection vessels of the 20th century. They appear short and of the outriggers forward of the forward outrigger small relative to the size of the ships. THE DESIGN AND PURPOSE OF THE BOROBUDUR OUTRIGGERS The relatively small outriggers of the Borobudur ships, with their short projections forward and aft of the booms would be relatively robust but they would provide little buoyancy and stability relative to the size of the ships and their sail area. Single or double outriggers? In four of the five Borobudur ship depictions only the windward side of the vessel is shown. Whether 19th century perahu paduwang the vessels are double outriggers with another dhoni means “pilgrimage boat”. Single outrigger canoes are used on some parts of the north coast of Central and West Java. They have a single outrigger boom and they shift the outrigger from one side to the other when changing tack. The arrangement is simple, loose, and temporary in appearance. It is not suitable for larger sea-going vessels. The Borobudur ships have three or four outrigger booms of complicated construction: it does not look like an arrangement that could be shifted when changing tack. Large single outrigger, non-shunting, canoes were outrigger on the leeward side or single outriggers built at Macassar, South Sulawesi. These vessels carrying a flying outrigger on the windward side were built exclusively for racing and were a single only cannot be determined with certainty. outrigger version of the double outrigger However, Erp 10, which has its sail partly furled, jerangkat. They had one very large outrigger and has that sail on the side of the mast towards the employed a lot of movable human ballast when viewer which suggests that we are looking at the racing (Collins 1936). leeward side. Four of the five depictions show the It seems unlikely that the Borobudur ships were port side of the vessel but Erp 9 shows the single-outrigger craft. starboard side so outriggers are seen on both sides Double outrigger canoes are not widely used on of the hull though not simultaneously. the coasts of Java but they are more common on Most single outrigger vessels are designed to tack neighbouring islands including Madura and Bali by “shunting” in order that the outrigger remains where sophisticated designs exist. on the windward side when they change tack. When a vessels tacks by shunting it reverses The Borobudur outriggers have a number of direction and reverses ends — the bow becomes characteristics that make them significantly the stern and vice versa — the steering gear must different from the outriggers of sailing canoes of be shifted from one end to the other and the rig more recent times. reconfigured to drive in the opposite end. Such vessels are necessarily longitudinally symmetrical Length of the outriggers — the ends are very similar — and they have a The outriggers of Indonesian vessels, including simple rig usually with the mast positioned those first depicted by Europeans in the late 16th midships. century, have generally been similar in length to The Borobudur ships do not exhibit longitudinal the hulls of the canoes they were fitted to. In many symmetry and do not have rigs that could be easily cases they are longer than the hulls. The Borobudur reversed. ships all have outriggers shorter than the waterline There was a type of a large single outrigger vessel length of their hulls.