New Trimaran/Skiff Design

[Chris Ostlind]

Thank you RR,

Things are coming along as I can get to them. If you write me directly, I will answer any questions you may have. You can reach me at: Chris@Wedgesail.com

[PortTacker]

The H16 hulls are WAY too heavy. My H16 hulls weigh 85lb each! EVen tho common, cheap ones are getting old, and are most often soft.
Great idea for recycling old Hobies for a cheap build (think: Tremolino,) not a good idea for a high perf boat where every pound will count big time.

And cat hulls CAN plane - this pic proves it! -

Since this a design forum it would be nice to get some technical details,like:
Is the CB of the heeled boat ahead of the CG?

[grumpy old man]

never said multis couldn't plane ...there is a ply cat called the paper tiger about 14' that was hard chined flat hulls and not much rocker that got on the plane on both hulls when conditions were right and with a skilled skipper sailed well above their vyc rating.. not many around now though .. the arrow cat was very similar in perfomance ...hard to translate that performance to bigger boats with power /wt ratios ....and flat bottomed multis are old hat

Yves Parlier's stepped cat planed as well-as did two small tri's I built and sailed...and according to the west coast dealer(and others) so does the Weta. Which brings up an interesting question: how will this boat be righted? Will it turn turtle?

[ThomD]

I think the whole Hobbie idea is pointless these days. There was a time when the Hobbie was the largest fleet in america, and designers of larger multis thought this meant business for them down the road. Olin was a visionary. But these days you can make a stressform hull of better quality in a day, with less compromise in shape weight, attachments, cost, etc... So it makes more sense to start with fresh ideas as here.

[johnelliott24]

I tried a few designs like this. The goal was to have the interior room of a monohull, with the performance of a skiff and the stability of a tri so my wife could come along. I tried different sized amas and foils for stabilization. I even tried some planing skis on a suspension that would ride over the waves. All the designs worked well. The amas generated lift so the skiff planed earlier. The trick was to find the best balance of how much ama to stick in the water to optimize lift versus drag. The best design was with sharp keeled amas. They were 8 ft long on a 14 ft skiff and weighed 12lbs each. They greatly improved pointing and sliced through the water very nicely. In light air they slowed the boat due to windage, but as soon as the wind came up they were great. Small amas like this also provide incredible stability against capsize because they cannot support the main hull. To capsize the whole ama has to sink which is virtually impossible to do accidentally. I tried steady 50mph + winds once off of a bulkheaded shore which made huge waves from the ricocheting waves hitting the incoming ones. The only way she would go over was to pitchpoll.

The other design that was pretty good, because of its simplicity, was a long board that strattled the skiff and stuck out on both sides. You could hike on the windward side and the leeward portion would provide stabilizing lift only when heeling and in the water. This allowed me to pile on sail area and hold her down alone with just the addition of a long board.

An 18ft skiff with just some simple small amas under the racks would be easy to sail and a thrill. From my experience it would be considerably faster to windward and almost impossible to capsize. You could take non-sailors out, no problem, and then if you wanted to turn it back into a real skiff just remove the little amas.