Not talking about foiling here, but rather planing like a Laser. My Inter 20 does not have the tendency to plane at speed. Narrow hulls... However, I hear that some F18s (e.g., Infusion) do. I've never sailed a beachcat that readily planes and wonder about some things... Does the F16 Viper also plane in solo mode? Does planing help with converting healing forces into forward forces? In other words, does it allow the boat to shoot forward once you get to that 20 knot range? Does it just pop, pop, pop, across the water like a Laser?
Edited by traphappy on Feb 22, 2019 - 12:38 PM.
F16-F18 planing hulls.
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Posted: Feb 22, 2019 - 11:36 AM
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Posted: Feb 22, 2019 - 12:58 PM
I don't think a beach cat can plane like a laser. At least Blunted of Canadian C-Class fame says they cannot.
I can say for sure though that the eXploder Scorpion gets up on step at approximately 16 kts of boat speed downwind, then accelerates to 19 kts +. The Infusion sort of does this but not as readily and it isn't as fast downwind because the hulls are still quite round aft.
The Viper F16 and C2 are more like the Scorpion with a flat aft hull and will semi-plane.
I don't think this helps with the heeling forces. What helps a lot is the Decksweeper main with noticeably lower center of effort and getting your crew weight low on the wire. Mischa would also regularly go double trap downwind which can pay in big breeze or in medium breeze with 2 light guys and flat water. Keeping the boat flat allows it to plane however and keep on accelerating; the Scorpion is the fastest non-foil assisted beach cat I have ever sailed, we were holding a steady 21 kts in about 25 kts of breeze and flat water downwind and in every puff she just kept accelerating. -
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Posted: Feb 23, 2019 - 12:23 PM
I would like to see someone try a 3 point hydroplane style hull for a catamaran or on amas for a Trimaran. It would get on plane at a much lower speed than any displacement style hull.
Anyone know if that has been tried?
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Posted: Feb 24, 2019 - 01:26 AM
A hobie trifoiler that can't foil? -
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Posted: Feb 24, 2019 - 08:48 AM
My C2 seems it would plane on the fatter sterns. The I20 would get wetter and wetter as it picked up speed. The C2 would smooth out and just go. On the flip side, when it was hardly blowing it seemed the infusion had a cleaner shape and scoot on a little better.
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Offering sails and other go fast parts for A-class catamarans
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Posted: Feb 24, 2019 - 10:56 PM
The C2 is a little flat forward and tends to get beat up in chop and the light stuff as a result. The fatter daggerboards were also a contributing factor. Still, they are solid boats in most conditions. Have a nasty pitchpole mode though, especially if the crew doesn't stay back! The Viper is similar in that aspect as in both cases the volume falls away quickly forward of the front beam as the hull submerge. To me the Scorpion is the best blend of the Infusion and C2 hull shapes (well really Phantom hull shape) going. Round forward and low drag in the light but she gets up and is a rocketship in breeze.
What surprises me the most is the C-Cats didn't take this development path, generally sticking with very skinny hulls. Well I should say until Groupama C which is also very flat aft which I think helps to get up on foils more quickly. -
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Posted: Feb 26, 2019 - 01:20 PM
Thanks for all the great responses and insights. Good information here and appreciated!
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