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Aircraft need to be designed with stability issues in mind that don't apply in the same way to boats. A fixed wing aircraft may go into a spin. It's stabilisation in pitch and roll while in the air is different from that of most boats. You will need to talk to aircraft designers about those...

That makes it harder for me to understand what advantage your craft offers. If helicopters pick up casualties, why transfer them? Every transfer is a risk. Every transfer takes time and fuel while the helicopter hovers. If you intend your craft to offer medical equipment and services that a...

I did not think a pilot would bank at low altitude. I am saying that even in perfectly level flight, the lower the wings, the tamer the sea state that can lead a wingtip to dip in. Also, the lower the wing, the more likely it is to slam. By committing to a wing that low, you seem to be...

The wings look to be very close to the water, closer than in any seaplane I ever saw except wing in ground effect craft (and at least one of those has high wings). I think that raises a few questions: 1) Keeping in mind that waves are not a constant height along their crests, and that more...

If you keep the same planform to skeg and rudder, improvement is likely to be too little to be noticeable, even if you were racing other Tiki 21s. If you install kickup rudders with a good profile and deeper draft, you can get, as you say, more lift and less resistance. However, I expect...

How committed are you to this shape? This looks to me like it puts a lot of flat surface quite close to the water. Taking casualties in through a bow ramp means taking them in at a point that moves a lot relative to the water surface when the craft inevitably pitches. The craft will usually...

I think you have several choices, depending on how you switch between different modes: 1) Something like what you have now, hulls wide enough to be used separately, only lighter. 2) Narrow hulls, still open and just wide enough to sit inside. Tie together as a catamaran, like here: Sea-Scouts...

You might get oddly-shaped speed to drag relationships, because of wave interference between the hulls reducing waves at some speeds, but increasing them at others. Anyway, have a look at this: The Breakthrough QE IV Ferry - Professional BoatBuilder: An IBEX Technical Journal...

What does the hull shape look like? To get the centre of buoyancy aft of the centre of floatation, the waterplane aft of the centre of floatation needs a higher water plane loading, or greater average draft, than the part of the waterplane forward of the centre of floatation. The ways I know...

I stole the idea from Sven Yrvind, who uses a balanced lug. For easy reefing and stowing away, look up Matt Layden's roller reefing design: I wrote a short article for the AYRS journal Catalyst #42. You need the distance between the masts to be at least twice as much as the portion of...

I would consider a pair of short masts, side by side in tabernacles near the bow. For wind up to about 110 degrees from the bow, use only the leeward sail, balanced by a board under the bow. Further downwind, use both sails. Close to dead downwind, use them in a V configuration, for self...

Is 18' a length limit imposed by storage, or by weight? If weight, does Makahiki inspire you to invest the material into length first? Have a look at David Coy's Proa Makahiki http://www.pacificproa.com/davidcoy/ and read what Rob Denney has to say about infusion: Intelligent Infusion —...

I know of only two examples. There was Jean-Yves Terlain's Gautier 1, possibly the ugliest boat that ever raced. Perhaps not a good example, as it seems to be pointy at the waterline. Those raked pram bows were probably for dynamic lift when immersed...

Depends. If the lace runs between stringers and you use constant thickness foam, it does the same job as the skin. You might as well use a stronger or more tightly tensioned skin. In theory, you might save some skin weight by having a double skin. The inner skin would sag, like the cables of...

Will the skin be supported by stringers at the chines and gunwales only, or also in between? Skin on frame will be pushed inward by water pressure, the more so the greater the unsupported span. If you plan on stringers at chines and gunwales only, I expect that especially the lee side will be...

In principle, yes, but it was Robin Blain instead of Sven Beardson, it was 1983 instead of 1952, and it was a commercial product instead of a one-off. I had the same idea as you, and two weeks later I saw Robin Blain's ad for what he called the swing rig. And I am not sure Robin was the first...

Sounds like a directional stability problem, not a rudder balance problem. If the centre of pressure of hull and fixed appendage is ahead of the centre of gravity, then any small deviation from a straight course will be amplified by centrifugal force. That centrifugal force acting on the...

Sounds good to me. I agree, but I don't yet understand how you can achieve that. You get some negative feedback by the foil getting more efficient as it is more deeply immersed. I think an old Russian design for passenger transport on rivers relied on that. This is a powerboat, not sailing...

I had no problem with the diagram. Double-ended arrows were for lever arms, single-ended arrows for forces. "Weight" on the arrow showing lift from the foil had to refer to the magnitude of the force. It was not difficult. That should avoid hitting the forestay, though it may be necessary to...

Matt Layden's chine runners are similar, though with less span and likely less effect, and placed further forward. Layden deliberately loads up the rudder, which is relatively much larger than on the vessels described in the pdf. He often has a rudder head as deep as the hull (not in the boat...