Mike,
Cheers was an Atlantic proa with unstayed masts. Given the crudity of the rig (box section mast, over engineered, wood, no vang, traveller or headstay tension for the jib, triangular main), it worked very well.
Daniel Charles is a smart guy, but if his boat is caught aback in a breeze, it would be hard work getting it back on track as the sail would be constrained by the rigging.
Arto,
True, as the windward hull suffers from l/b issues if it is too heavy. But I don't think there is an "optimum" weight distribution ratio. It is more to do with what the hulls are designed to take and, as you say, the righting moment required.
Todd,
I suspect you are trying to "peel back my layers" as you did on the other forum. No problems with this, as long as it does not sidetrack the thread.
The beams are for "Rob's boat", which is solitarry. They taper in both diameter and laminate, the laminate is different on the top and the sides and the materials are carbon, glass and plywood. It cost me $1,000 to have them engineered. Will cost you half this if you really want to know the details. The hull weights are on the solitarry spreadsheet.
Beam design is based on the maximum possible load, which is lifting the heaviest hull. For an Atlantic proa (under normal conditions), and a Pacific proa (caught aback) this includes the rig. For a harry, it doesn't as the lee hull incl rig is lighter than the windward hull. I suggest you draw some diagrams before telling me (again) that this is not so.
The torsion difference is huge between the mast on the lee hull vs the mast on the ww hull, as a sketch or model will demonstrate. The beam weight difference will not be so huge, but the harry configuration will always be lighter.
I don't understand your final paragraph. Or see what it or the video has to do with this discussion. No idea what walla is, nor how it proves that buoyancy to leeward of the mast makes a boat more stable, apart from the added righting moment from the mast weight. Assuming the force on the sail acts horizontally through the coe (and ignoring the rig weight), it makes no difference to the force required to fly a hull where the mast is located across the boat. Maybe your rig is a greater component of the righting moment than it would be on a full size boat? Again, draw a picture (or try to unbalance a chair by pushing or pulling it sideways) and this will be obvious.
Removing bits of trimarans is how Newick came up with the Atlantic proa. They are heavier, higher loaded, harder to sail and less livable in than the harry configuration. They are also theoretically faster in conditions where more righting moment is required.
I leave it to others (maybe start a new thread) to decide on the merits of three and one hulled proas based on your models.
By the way, I took your advice and tried to join your chat group to get some specs for the full size versions of your models so we could discuss them. My membership has been "pending" for a couple of weeks.
rob
Cause up till now I never knew how much your beams weigh'd. Your beams
for what boat weigh 40lbs and are 27' what are the other demesions? What
material are beams layed up with? What wall thickness?
The rig weight would be displaced by both hulls not just windward hull.
Placing rig centered between hulls or even windward bias the torsion
would be placed in beams them selfs. The extra weight required for
torsion from standing rigging and beams would be nominal.
In know the video doesn't show that when the sail is at its mast
position near leeward hull the model became unstable, tippy, and
capsized more with the smaller double skin sail. That same day to start
with. It was so obvious I didn't even bother filming just switch sail
mast positions. And walla proves buoynacy to leeward of mast position
with this sail arrangement became more stable with out adding any more
weight. The pivot point of CoE from buoyancy of ama to leeward
lengthened, increasing the effectiveness of buoyancy vs having more
weight to windward.
Todd