I mentioned this in passing in another part of this forum but I think it is worth its own topic. In an e-mail conversation I had with Bill Lee a couple of weeks ago he said that he thought the next leap in big monohull design would be the addition of hydrofoils to a canting keel equipped boat. I told him of my on going experiments with a similar system and we discussed it at length.
Open 60’s with their wide beam and shallow rocker are particularly suitable because the critical ingredient in a system like this would be to be able to retract AT LEAST the main foil reducing wetted surface for light air and non foiling conditions.This boat would have only two hydrofoils(and a canting keel): one on the rudder and one on a central daggerboard. The Open 60 is a good candidate because it is possible that the hull section in way of the hydrofoil could serve as the bottom of the foil with a simple cover used as the foil is deployed downwards. The standard twin asymetrical daggerboards could be used for lateral resitance in non foiling conditions and they could be retracted as the foil with its vertical fin is deployed.
On models a hull that is wide enough for a retracted foil would probably be slow in non foiling conditions so I’m working on using a narrow hull with removable foils to test the concept. The first experiment I tried turned out too heavy; the second won’t…
Personally ,hydrofoils on a multi or mono at sea worry me what with the contamination of the ocean with so much heavy flotsam at or just below the surface but for maximum speed in an offshore mono foils may be an answer…And definitely will be in models- both versions with a canting keel(F100) and versions with an on deck Trapeze PBS(microMOTH).
doug i could be wrong and probably am. but are not the foils job. to get the hull out of the water. if that is the case , then turning the boat would be like tilting the wings on an airplane. would you not lose the balance of your hull and then come nose diving into the water?
cougar
No Cougar turning stability would be just fine; the closest to this now are the full size Moths and David Luggs I14; the Moths tack and gybe while up on foils. And the canting keel ,particularly with a flap, would add to turn stability.
okay . i think i see where you are going with this. but with an airplane the flap increase lift by directing the air flow down, but it also increase drag almost 1-1. does this not seem like a step forward then a step back?. i see you video and like the boat in a stiaght line but i do see it nosediving, in the turning action
am i wrong?
cougar
When the Open 60s are racing throught the southern ocean on a braod reach in 50 to 60 knot winds and 40 to 50 foot waves, they are already on the ragged edge of control. Nosediving into the next wave as you surf down another one is a major problem and leads occasionally (about once or twice a day as far as I can tell from emails) to unintended gybes which broach the boats.
I can only imagine the carnage if the boats were going 30%, 40% or even 50% faster when they hit the backside of that next wave. How many more broaches would there be? Would the sailing techniques have to change so that you sailed on a higher heading so as not to be slamming directly into the waves? Would you ride the waves more like a surfer - cutting back up the face of the wave with tight “S” turns.
Another option would be to try to fly high enough to avoid hitting the next wave. This would mean hydrofoils that would lift the boat 40 or 50 feet into the air!!! I can’t imagine!
Or perhaps the Open 60s will attempt wave piercing technology ala Team Philips…
One thing being learned in the foiler Moths is that there is a lot of technique to handling those boats thru tacks, gybes and waves. I’m sure the same thing will e true for the keel boat on two lifting foils as well.
And , I believe the retractability is going to be a key feature of ocean going monohull foilers. You don’t fol in conditions that are too dangerous or too light.
Altitude ,among other factors, has to be based on how far you’re willing (and able) to fall.