Reply To: Speed in 18th century (merchant, cutter, East Indiaman, naval brig)

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Frank Scott

    This is a very complex subject.

    How a vessel was loaded and trimmed made a lot of difference, this applied not just to merchant ships, but also to warships, whose performance could be improved immensely by loading to ensure best fore & aft trim.

    Then you have to factor in captain & crew, because a theoretically inferior vessel with a superior crew invariable won in chase situations. In a square rigger or large schooner the range of movement of the centre of effort is substantial, which makes it all too easy to get the rig out of balance. The most obvious sign of this is excessive weather helm, which makes it more difficult to steer, and significantly slows down the ship. In general sail should be taken in from aft, keeping the angle of heel relatively low, all while taking careful note of the helm carried. Reducing sail in order to go faster may seem counter-intuitive, but being over-canvassed & thus sailing with massive angles of heel only increases drag and leeway.

    It is not so much top speed or average speed that counts as speed differential. Then there is the issue of how well a vessel points when going to windward (how close to the wind it could sail). Here the Royal Navy benefited from having top quality canvas, closely woven and made from long fibre flax.

    Note that coppering only comes in at the end of the eighteenth century, and that ensured that speeds within the fleet became more consistent, making it easier to keep together; and overall fleet speed increased, because even those ships longest out of dock were much less foul and thus quicker than in the pre-coppering era.

    The ‘super-frigates’ that came in with the US Navy were heavily armed and very strongly built, but some of them were poor sailers compared to the smaller British frigates designed at the beginning of the Revolutionary & Napoleonic wars. For example, in the war of 1812 Samuel Leech observed that even in a patched-up condition the smaller Macedonian was a far better sailer than the United States, whose crew had nicknamed her ‘the Old Wagon’.