I'm thinking about using the sail from the goat island skiff (105ft2) and no mizzen. Elsewhere Colin had said a sail of this size might be doable but for the sake of balance the dagger board would need to be moved aft. Was a determination ever made as to how far it would need moved? If it is into the foot well another thing I'm contemplating is a well to drop a hobie mirage drive into. Forward facing, hands-free propulsion, yay. That way the well could do double duty, choosing between mirage or dagger board
Hi Thomas, Apologies for the delayed reply - I only just saw this message. If you're not using a mizzen, it would actually be forward that the daggerboard would need to be moved. Or the sail could be moved aft. As to the exact amount of shifting required for balance, that would require a fair bit of math - calculating the center of effort, center of lateral resistance, etc. You could always experiment with a temportary leeboard to find the sweet spot.
If you opted to bring the mast back a bit for balance, there would be two ways of doing this without compromising the interior space. If it's a deck, stepped mast (using stays for support) you could create a heavy-duty reinforcing arch at the location of the mast. Alternatively, you could use a temportary compression post that comes out when the cabin is in use (and loosen off the stays when you do this. If it's an unstayed keel-stepped mast (like the Bic Open), then it's probably better keeping the current bulkhead location and shifting the daggerboard forward.
Not going to lie, that's not what I wanted to hear lol. But it sounds like what I NEEDED to hear. Thanks for saving me from a mistake! Now I've got some head scratching to do
So I've done a bit of reading, and from what I'm seeing, you place the board like this. Draw a line from the center of the main and the center of the mizzen. The board is placed along this line by proportion of main size to mizzen size, except that the area of the mizzen should be treated as if it was only 50-60% of its actual size. I found the measurement from center of the GIS lug to the mast online. I'm guestimating the measurements for a mizzen I found. Following these guidelines the board would be placed just aft of the cabin, exactly where I was hoping for it to land. My question is, am I talking complete nonsense? Is it even remotely accurate?
@Thomas Krische
Hi Thomas!
I guessed a bit too, still unsure how it's going to work out, but I'm using 2 similar sized sails. Both for an Optimist.
With the Akas being a potential hindrance I moved it even a bit further aft than just after the cabin at about 12cm distance, so that I could lift the board with the akas in place. Thought that's a consideration you would like to be reminded of.
Good luck with your build!
Michiel
@Michiel Kommer Thanks! I haven't started on the outrigger system yet, so I would have REALLY been kicking myself!
