Shipyards and Shipbuilding

 

Patrick Melby, Insatiable Shipyards:The Impact of the Royal Navy on the World’s Forests, 1200-1850 (Thesis), 2012

The Royal Navy demanded 50,000 loads of oak per year to keep its shipyards in operation, while the entirety of the country required only 218,000 loads.

A load of wood = 50 cu. ft.

Newly cut oak = 60 lbs per cu. foot ( http://www.oocities.org/steamgen/woodweights.pdf )

many of the timbers used in shipbuilding were required to be at least 20 inches in diameter, a thickness not reached until an age of at least 150 years.30 Even Rackham places the age of a commercially harvestable oak at up to 150 years.

A great deal of effort went into trying to preserve the wooden hulls of ships. Constant submersion in sea water and exposure to harsh weather hardly provide ideal conditions for wood preservation. Hulls were caulked with pitch and tar as waterproofing, the production of which caused its own impact on woodlands (discussed below), and trees were even harvested during different seasons in hopes that the conditions would provide greater longevity. The Hawke, built at Deptford in 1795, was constructed using half winter-felled and half summer-felled oak as an experiment to test their relative longevity; both halves were badly decayed after only ten years. The Montegue and the Achilles of 1774 lasted about twice as long, lasting over 20 years. These numbers seem to represent the mid-range of life-spans of wooden ships. Although some reached greater ages of 40 to 50 years, those that did were the outliers and were considered very old ships 

In the fourteenth and fifteenth centuries, many ships seemed to require extensive repairs or retirement after only 5 to 15 years. In the 1580s, a group of 37 docked ships were precisely dated in documents of the High Court of the Admiralty in an effort to assess their longevity. Twelve of these ships were 10 years of age or less. Twenty-two were between 11 and 20 years. Only three were said to be older, with an eldest of 50 years.34 Such numbers suggest an estimated life expectancy of perhaps fifteen to twenty years would be an acceptable average for wooden ships. However, these figures are not restricted to naval vessels. Although merchant vessels also faced the dangers of piracy, privateers, severe weather, and other seafaring hazards, the intentional engagement in naval battle and training would naturally reduce the life expectancy of a ship. With all such concerns in mind, current research has settled on an average life expectancy of only 12 years for wooden naval vessels.35 

To further compound the demand for wood needed to build such vessels, many that survived their first decade soon required extensive refitting. The Mary Rose, for example, well exceeded the average life-span, sinking in 1545 after nearly 35 years of service. Though the final sinking of the vessel was accidental and likely the result of a design flaw after a refit, the ship had already been extensively repaired twice in its lifetime. Discovered in 1971 and raised in 1982, dendrochronological analysis of the ship’s timbers show that substantial portions of its stern were cut no earlier than the 1520s and at least one main deck beam dated to 1535, supporting contemporary records stating that the ship was refit in 1528 and 1536.36 As such repairs were common among wooden vessels, estimates on the total number of trees cut for a single ship can be compounded repeatedly as the ship grows in age. Unfortunately, although the timber used for the refitting of a single vessel was recorded at as much as 140 loads,37 data on wood use for this purpose remains too sparse during much of the period in question to draw strong generalizations.

. . . Naval policy required each ship to make port for inspection at least once every three years in a preemptive effort to avoid major repairs. Small repairs could be made relatively quickly and at minimal cost; but left untreated, a little rot or a few cracks could quickly grow into a major problem, requiring several years and great expense to remedy. Of course, major repairs were still necessary from time to time, and even minor repairs represented a constant drain on wooded resources, making repair one of the major contributors to Albion’s argument for the shipyard-driven “timber problem.”38 At the very least, we can assume that the use of wood for repair work offsets the extended life span of outliers like the Mary Rose. A very few ships lasted as long as 50 years, thus not needing replacement for four times the average life-span of military vessels. . . . .

William McNeill’s estimate of an average use of 4,000 mature oaks for a single ship.43 In such a case, the construction of a single ship-of-the-line would require the clearing of eighty full acres of this imaginary landscape. In the year 1790, the Royal Navy had about 300 ships in its ranks.44 To build this navy, at least 1,200,000 good oaks , , , ,

As little as ten and at most fifty percent of each tree felled for ship timber could actually be utilized for that purpose. Warde, “Wood and Wood Products,” 9. Once at the shipyards, the wood which could not be used in shipbuilding did not go to waste. Chips, any piece below three feet of length, were considered property of the shipwrights which they used or sold for firewood or even other building purposes. Often it was complained that shipwrights intentionally splintered the planking of ships under repair or sawed up good wood into three foot lengths, abusing this policy.  . . .

 

Even after trade with the Baltic region and Norway started bringing in larger masts than could be found domestically, many were still insufficiently sized to carry the very large sails of naval vessels, and the difficulty of procuring such great masts only increased over time. For that reason, English shipwrights more frequently were forced to settle for the use of made masts (masts built by binding smaller pieces of wood together with iron bands) until the massive timbers from New England and Canada became available in the early seventeenth century.

Access to American white pine breathed new life into the shipbuilding industry. The size, quality, and abundance of masts to come out of New England and Canada surpassed that found anywhere else, and they were added to domestic oak hulls, and topmasts and planking from the Ukraine, Poland, Norway, and elsewhere to carry the Royal wooden fleet to its peak.  

Furthermore, imported naval stores by no means stopped at timber. Pitch and tar were used for caulking and waterproofing of ships. Such products are derived from the refining of softwoods and can cause a great deal of wood consumption for a relatively meager volume of production. Britain, however, lacked sufficient softwood resources for this purpose, so neither pitch nor tar could be produced domestically to any degree. By the opening of the seventeenth century, Sweden was the source of choice for suitable softwoods, and hundreds of thousands of cubic meters worth of wood were cut and refined for export to England. Little more than a decade later, Russian and North American imports surpassed those from Sweden, totaling approximately 1,500,000 cubic meters of softwood harvested each year. In total, the biggest volume of wood demand for shipbuilding each year was for tar and pitch, dwarfing that of oak or any other solid wood.