It's a function of surface area, aspect ratio and a balanced location when you are looking at a proper "keel" form for sailing.

There is a function in which a shorter, wider board is probably a better solution and that would be frequent visits to really shallow water. The EC event in the Watertribe features lots of situations like that described above, so it's not a bad idea to have a slightly less deep board for that particular event. Likewise, there is going to be limited, upwind sailing during a "normal" EC experience, so a shorter board can be used as a pragmatic design solution for the times when a shallow draft boat is critical.

For most other sailing purposes, having a higher aspect board will give you the ability to point higher into the wind and allow for more efficient upwind travel. Additionally, when mounted to a low heel design such as your trimaran style conversion, you can eliminate the thinking surrounding the possible need for twin boards as the single board will always be deep enough to prevent leeway, regardless of point of sail. The double leeboards style of design solution is all about boats that heel a lot, such as monohull sailing canoes. With double boards, there can be a small advantage in generated lift with the use of asymmetric foil sections as has been previously described. There is also a penalty with the extra weight, extra complexity and extra fiddle factor while sailing. Only you can decide what would work best for your boat and how you would like to sail it.

Once you get this dude rigged and out on the water, you'll be able to see all the benefits of a longer, well shaped foil surface. You can run it straight up and down for amazing pointing ability, rake it aft a bit when reaching up tight to reduce drag and still yield good tracking and then, pull it completely out of the water when running so that all execess drag is eliminated for the most efficient sailing performance.

This whole thing is your adventure to behold, John. From where I sit, it looks like you are having one dandy time of it.

Chris Ostlind