What about preventing the capsize with a device attached to the ama?
Let's say a parachute hung on the side of the ama in a bottomless square box in such a way that a lead weight - like an achor is tied to the top of the parachute and you have some kind of panick lever that will release the anchor into the water when the ama is on an angle LW, so anchor in the water, flollowed by parachute to stop the ama from flipping. This lever can be engaged by a sliding weight - imaging one of those round weights used by body builders, and a long rode where this weight donough center rides. If the ama is lifted to leward then the weight will fall to leeward and it would pull on a lever that would realease the anchor and consequently the parachute stoping the movement of the ama.
To recover the system you will need a lead line to pull the top of the parachute to drain the water
I can see it in my mind but have a hard time explaining it - kind of like a short drogue
Chris Ostlind <Chris@...> wrote:
So, Mike, what if a mast head flotation system could be built that actually enhanced the anti-capsize function while having a positive gain on aerodynamics? Would that get your interest?
I've had conversations with three racer/cruiser open deck catamaran manufacturers about masthead flotation systems. All three chose to avoid them because the extra windage that high is pretty significant, and also because they wanted to avoid weight at the masthead.
One manufacturer decided to avoid righting systems altogether, one went with a compressed-gas system that will inflate a bag at the masthead, and one has yet to unveil its new righting system.
A schooner rig with wing masts would likely offer enough flotation. I'd still consider a compressed-gas system as well. Either that or I'd keep an inflatable dinghy ready, as well as a spare halyard, and make sure I had a system to hoist it up the masts when the boat is on its side.
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Did some rough calculations on the Harryproas stability at 90 degrees. Empty, a Harry is stable on its side but not by a large margin. Probably the resistance...
Hi Rob I do not have experience with the bouy at the top mast but I wonder how much a cleated sail in the water acts as a fulcrum to force the mast to go under...
Hi Carlos, My own experience with lots of capsizes in small boats and windsurfers is that the sail damps the initial rotation and then if you don't uncleat you...
... Brian Phipps does it successfully with Darts, AFAIK. But a standard Dart will not normally turtle immediately anyway. ... Don't forget that in strong winds...
I agree. Beyond the lower righting moment when reefed, buoyant sails would also be less useful once you uncleat the sheet in order to right the boat, allowing...
So, Mike, what if a mast head flotation system could be built that actually enhanced the anti-capsize function while having a positive gain on aerodynamics?...
What about preventing the capsize with a device attached to the ama? Let's say a parachute hung on the side of the ama in a bottomless square box in such a...
<<what if a mast head flotation system could be built that actually enhanced the anti-capsize function while having a positive gain on aerodynamics? Would that...
OK, Mike... and everybody else who may have an opinion on this. Located in the Files section is a folder titled End Plate Sail where I have put a collection of...
-In -http://groups.yahoo.com/group/kssboat/ there are a series of well referenced posts on the problems of capsize after a post by Derek Kelsal about a...
... He doesn't seem to have deployed anywhere near enough parachute with anything like the right amount of tether line. It sounds like some pretty skilled...
That's about as good a masthead flotation system as one could imagine. Nice design, pretty aerodynamic, and it doesn't look like the hobie "training wheel"...
Note , if you are careful with the weight distribution in the ww hull with batteries and water storage you can just bring it back the other way, but it is...
Oh, I forgot... The full treatment to the sail also includes a boom like you would see on the really spendy, mega-yachts where there is a decided wingish,...
An interesting idea, alltogether. Bouyant panels and endpieces. I will discuss this with a sailmaker. I´ll relay his opiinion. Thanks, Peter ... like you...
G'day, Agree with your comments except for the mast angle. I suspect it will be pretty close to 90 as the lee hull will be partially in the water. As long...
-my calculations are in the order of 3-5 degrees and have tried to imagine the circumstances where the wind wave would work together. It would be coming off...
... degrees. ... stop ... situation ... big ... the ... I just don't see the point. The HP is the most stable multihull design in existence relative to the...
One of the big reasons I started looking at passive, functional flotation at the mast head was the complexity factor of anything with moving parts such as an...
Very solid arguments for fixed masthead buoyancy. The potential failure of an active system, and the problems of re-arming it in nasty seas, are tough to...
... My guess is that mast buoyancy or leepod are only good to deal with errors of judgement in moderate conditions. If you flip a cruising multihull by...
<<My guess is that mast buoyancy or leepod are only good to deal with errors of judgment in moderate conditions.>> I agree. I'm not sure that anyone here...
A fully flooded Harry lw hull will have in the order of 300-450kg bouyancy and you would need to move ~9 tonnes of water to fill the hull. It would be easier...
<<It would be easier to lift the 350kg weight of the hull... This is only 700-900kg off a 3m gantry.>> Good point. Not unimagineable once the weather has...
-If I had the drogue set up I would be wanting to avoid being side on, lying ahull. I feel surface area is too great to withstand such a hit of white water....
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