1.Longitudinal swing arms of motorbikes ( I dont wan't to write about MTB misconceptions , 30 years of riding of somebody phantasy design , 26" wheels , short wheelbase , sick frame geometry and milions of followers)
are not designed to carry much of side load. Your idea of use longitudal swingarms one dragged one pushed is not bad however side loads need to be consider.Also twisting forces . So you need double swingarms or massive stif single swingarms.
2.Point where swingarm meet float is extremely important. How you will find proper place?
3.Connection joint is a Cardan so you need at least ropes limiting maximum deflections .Determining the length of these ropes will tune the suspension.Nose diving float isn't what you want.
Thanks much for the input,
@montero. So, side loads--you point out this setup is limited to mostly at straight-line travel, I guess. Not pulling hard lateral Gs from quick turns. So yep, that's an issue, at least it you want to turn fast. The wider the attachment (hinge) at the top, the more bracing you'll have, yes? Like a cantilevered wing. Would that help? Maybe it's a trade-off.
Independent floats should help with handling quartering waves, and that plus free roll should relieve torsion loads when the boat is suspended between wavetops. One hopes. But the width means a flat ride. So more lateral loads, as you can't lean into turns as you do if your thrust is an outboard or stern drive. Would adding, say, a midships skeg or dagger board/centerboard/keel help take some of the lateral loads, and provide something of a pivot to turn on?
I suppose one might use horizontal (or Vee?) foils like ailerons to drive the inner floats down and lift the outer ones up, synched with the rudder. A bit too complex for my application, and draggy. But points to the concept that a fast boat is something of an airplane, as is an F1 car.
An F1 car IS an airplane, in my book, at speed. I don't understand why ailerons (and forward, canard elevators) aren't standard equipment. Let you lean into corners without having to bank turns. Simplifies suspension, maybe. I digress.
On attachment, the thought is that free pitch and roll, in combination with allowance in vertical travel from the suspension, would avoid some of the "spearing" into waves that I gather is a problem for long amas (along with relieving torsion stresses). Shorter, broader floats should help with lower speed planing, and also provide sufficient buoyancy for shallower draft, to float over waves rather than plowing through them at sub-planing speeds. Puts lightness at a premium, and increased windage is a consideration.
Weighting fore and aft--trial and error, in a model. Velcro. Make the attachment well longer than ultimately needed until you find the sweet spot. Weight tending aft, as in any planing boat, to help avoid digging in the nose. Placing the attachments in wells to keep the weight low is an idea from my niece, and I think it's a good one. Nauti-craft 4Play doesn't do this. Good call, niece. Would want self-bailers.
Putting a limit, or stops, on movement in pitch and roll seems a sound plan, and I've thought of it. Might again be a question of trial and error, and speeds and sea states contemplated. Any restriction would seem to add to stresses. Bounding over waves at speed strikes me as most similar to a 4x4 bombing along a rutted road. VERY rutted. So, long travel, very soft "tuning."
