Single Handers to race scratch with the Laserati

Originally posted by Rupert However, as Jim says, why make a boat only for zero wind? Unless you live somewhere with very low average wind speeds, I suppose, but then waterskiing might be more fun?

Its not that hard to make a larger drifting weather boat. The difficult bit is to make one that isn't pants in any breeze at all, 'cos who wants to sail a large slow boat? The fastest boat in drifting conditions I've ever sailed was my modified Skol international Moth, and it might be interesting to try the ideas behind that scaled up. However minimal stability, and extreme difficulty in getting back on board for the heavier sailor are probably not great sales features...

Real drifting conditions are so anomalous for anything else I'm not sure its that useful a target. Even if you don't want a planing demon you at least want a boat that sparkles in a sub planing breeze. Length doesn't help in real drifting conditions, and because long and thin tends to a wetted area penalty it may even hinder. ICs are not great in the very light for example.

Originally posted by Sam.Spoons Originally posted by Rupert I think for the BM, it is the lack of wetted surface, coupled with high rocker and the ability to tack on every shift without slowing, coupled with a big rig. Plus sailors who know what to do in a drifter. Exactly, big rig helps but rocker and narrow beam makes for low wetted area which more than makes up for the short W/L. A 14' 'Britsh Moth Plus' would be faster still.

Originally posted by Peaky Originally posted by Sam.Spoons performance in a drifter is mostly a function of waterline length (long) W/L beam (narrow) and rocker (lots) so trad designs are usually better than modern 'skiff influenced' designs. More sail area helps too but nowhere near as much as you would think. But the most important thing is the crew's ability to find what wind is make the most of it. Remember in an average 1 knot of wind finding a 2 knot 'gust' means you have 4x the power, conversely doubling the sail area in the same wind only increases power by 1.4 (or the square root of 2). (Hope I've got those sums right  ) You’re right about doubling the apparent wind resulting in 4 times the power, but if you double the sail area you get double the power. Which, of course, doesn’t result in double the speed.

Edited by Sam.Spoons - 16 Dec 18 at 9:06am

Originally posted by Sam.Spoons performance in a drifter is mostly a function of waterline length (long) W/L beam (narrow) and rocker (lots) so trad designs are usually better than modern 'skiff influenced' designs. More sail area helps too but nowhere near as much as you would think. But the most important thing is the crew's ability to find what wind is make the most of it. Remember in an average 1 knot of wind finding a 2 knot 'gust' means you have 4x the power, conversely doubling the sail area in the same wind only increases power by 1.4 (or the square root of 2). (Hope I've got those sums right  )

You’re right about doubling the apparent wind resulting in 4 times the power, but if you double the sail area you get double the power. Which, of course, doesn’t result in double the speed.

The main thing that makes a light wind bandit is not just how fast it is in light winds buthow slow it is in stronger winds. In other words it is the relative performance that matters because the PY gets raised by every strong wind outing. Heavy boats with lots of rocker and lack of righting moment will struggle to perform well when windy so will appear to overperform in light winds.