In a message dated 1/17/04 12:06:51 AM, trawler-world-list-request@lists.samurai.com writes: << The only problem I've ever heard of with paint build up is flaking whiuch during the season may expose portions to accelerated marine growth and roughness from edges,prior peels,etc which may have some drag on faster boats. >> Competitive sailors are very concerned about paint flaking because rough bottoms increase the skin friction component of drag. This is especially harmful at slow speeds in light air, usually at S/L ratios of less than 1. A rough bottom is estimated to produce 5% more drag than a smooth one, enough to spell the difference between victory and defeat. As a result most competitors spend hours burnishing the bottom to remove any imperfection. However at speeds above S/L ratios of 1, form drag is so much greater than skin friction that surface roughness is largely irrelevant. All rough bottom paint costs the typical trawler owner is a few extra gallons of fuel per year. Larry Z