Curved Lifting Daggerboards

....courtesy of www.sailingscuttlebutt.com

CURVED LIFTING HYDROFOILS DO BOTH
If you have seen photos of the America's Cup multihulls, or any of the modern, ocean crossing, record setting multihulls, then you have seen the trend toward curved daggerboards. The Morrelli & Melvin Design & Engineering team has been participating in BMW Oracle's America's Cup developments, and in this report has tried to simplify the principals for those of you who have a phobia for math, physics and applied sciences. This excerpt is enough to make you dangerous:
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Both the BMW ORACLE trimaran and Alinghi catamaran use curved daggerboards (hydrofoils) to provide necessary lateral lift/resistance and they also lift the leeward hull up. The same board is used to reduce sliding to leeward or leeway and also provide vertical lift. The current variations that are being experimented with by both teams, tradeoff more vertical lift for less lateral lift or vice versa.

Upwind these boats still need a fair amount of lateral lift/resistance to prevent excess leeway due to their enormous sail plans and the fact that they essentially are always going upwind. These boats sail at apparent wind angles downwind that are only about 10 degrees more than upwind!

Downwind, the sails are never really eased and the apparent wind never goes very far aft. the wind is always in your face on these boats. The apparent wind is so far forward on these boats that you always feel as if you are going
upwind.

Complete report:
http://morrellimelvin.wordpress.com/2009/11/04/getting-up-to-speed-on-foils/