Ottomans seem to have been aware that the copper-sheathing technique, when it first appeared in Europe in the second half of the eighteenth century, had offered significant advantages. Among them were protection from wood-eating worm; the creation of a surface on which external weed and shellfish could not grow; an increase in sailing speed that not only reduced voyage times but made navigation easier, since if a vessel could move in light winds it was less liable to drift on ocean current; the applicability of copper sheathing to any shape or size of hull; providing an outer skin of copper protecting the hull to some extent; holding caulking materials in position; and reducing maintenance costs between voyages.
The disadvantages, such as high material and application costs, the risk of galvanic action and the deterioration of iron fastenings, and the fact that a coppered vessel could not be grounded in harbour without considerable risk to the sheathing and thus was restricted to harbours with water at all tides, could not prevent the Ottomans from adopting this technology. However, some of these disadvantages were unknown to them initially. The Ottomans learned about these as a result of prolonged naval experiences. Thanks to academic work from the 1950s onwards, the nature, type and properties of the molluscs and crustaceans hazardous to the timbers in the seas surrounding Turkey have been identified.
There is considerable evidence indicating the existence and application of this technology in ships built specifically in the reign of Sultan Selim III. There were at least 40 ships that were sheathed with copper between the years 1789 and 1802, mostly galleons, frigates and corvettes. This figure must have been higher considering the imperial edict issued in 1795–96. Indeed, it shows that the application of copper sheathing to ships proved to bear good results and it led the Sultan to order the authorities to try hard to outfit the remaining ships using this technology. Firmans ordering the copper sheathing of ships were issued repeatedly. For instance, in a firman dated 1795–96, copper sheathing and painting were ordered for river ships (ince donanma gemileri) when they were at anchor. Following the copper sheathing of Arslan- i Bahrî and fiehbâz-i Bahrî, the same application was ordered in 1795 for Pertev-i Nusret, Ejder-i Bahrî, Âsâr-i Nusret, Bahr-i Zafer and another three-decked galleon under construction. The estimate amount of raw copper required for all five ships was around 60,000 kiyyes. Since this process required casting very thin copper sheets processed twice, the copper coming from Gümüşhane would not be suitable; instead, that from Kastamonu or Ergani would be needed. It seems that copper-sheathing technology was limited to warships at the time.
Mahmut Raif Efendi described copper sheathing in his account as well. He wrote that all the shipmen shared the idea that copper sheathing was the best way to protect ships. He noted that three ships, a three-decker of 67 zirâ and six kâne, a frigate of 55 zirâ, a corvette of 37 zirâ, and a boat (filika) for the Sultan were launched in a single day, which was something previously unseen. The year before (1797), all of them had been sheathed with copper, and more ships were to be sheathed in 1798. Therefore, it would not be misleading to regard most of the ships, especially warships constructed after 1795–96, copper-sheathed. Also, the prize ships and the ones received as presents would increase the number of shipped that were copper-clad at the time.
The earliest document found during this study indicating the Ottomans’ application of the copper-sheathing technique dates back to 1792–93141 In that year, the Ottoman government ordered the copper sheathing of a new galleon, and copper merchants were ordered to prepare copper planks on certain models. Once the copper sellers saw the model, they declared that the production of the model was different and would be more difficult than the one they had used previously, and therefore it would require more labour and money. Then the merchants were presented with lumps of unrefined copper for the production of the copper plates for the sheathing of the galleon in question. They were given 55 akçes per vukiyye, whereas it had been 35 akçes in the past. However, since the new technique required the use of copper nails, which were expensive, they found a solution by producing a new type of nail made of raw copper and zinc (rûy-i mâye) mixed in equal proportions. In order to test the efficiency of the new nail, they first produced five or ten test nails. After applying them to the copper plates, the authorities were convinced that the new method would work, so copper merchants were commissioned to cast this mixture in return for 50 akçes per vukiyye. It is noteworthy that such a decision was taken with the collaboration of the port commander (liman reisi), the chief architect (baflmimar), the chief augerer of the naval arsenal (tersane burgucubaşisi) and copper merchants (bakirci esnafi). The raw materials were provided by the state from the mahzen-i sürb.
On 30 August 1795, 5,000 vuk›yyes of raw copper were demanded urgently from the Darphâne-i Âmire. For the copper sheathing of a three-decked galleon under construction at the naval arsenal, 10,000 vukiyyes of raw copper were required on 20 October 1801. Since there was not enough copper at the mahzen-i sürb, it was provided by the Darphâne-i Âmire, two-thirds of it low quality and one-third high quality. The cost, 6,666.5 kuruş, was met by the seferiyye akçesi.
It seems that copper sheathing caused further changes in the structure of materials used in the construction of ships. It was noted on 14 September 1796 that it was a tradition that bearing pintles (inecikler) mounted on the rudders of the imperial galleons were made of iron. However, this traditional application was changed with an imperial edict ordering the introduction of copper sheathing of the ships constructed at the Tersâne-i Âmire and other sites outside of Istanbul. From then on, the former iron bearing pintles of the sheathed ships were replaced by ones made of bronze (tunç). Four vukiyyes of tin (kali), 32 vukiyyes of raw copper (nühâs-› hâm) and 64 vukiyyes of zinc ferment or alloy (rûy-i maye) were needed for every 100 vukiyyes of bronze bearing pintles. Also, one k›yye of hark-i nâr was required for every ten vukiyyes of the product. It seems that new regulations were applied to a new frigate under construction on Limni on the same date. It was declared that eight bearing pintles for rudders (465 vukiyyes) would be produced by Dimitri, the chief founder at the Tersâne-i Âmire on 3 September 1796. The Ottoman authorities continued the copper-sheathing applications in the following years. On 3 January 1806, 30,000 kiyyes of copper were demanded from the Darphâne-i Âmire for the re-sheathing of five naval ships with copper plates (nühas tahta) and the repair of the copper elements of some other ships at the naval arsenal.