819 posts
Hey Paducah😀
I’m a big SailGP and America’s Cup fan too. Watching their speeds when maybe I’ll reach 20 something knots someday— its comparing different worlds. I have no need to go much over 20 on a foil board, the impacts from falls are too much for me, but I would like to get upwind better so I can ride more waves. I hope we can get some trickle down!
The Cup boats blow my mind with their upwind VMG. They can sail upwind at close to 40 knots, with VMGs in the mid-20s (source ChatGPT). They have enormous righting moment (but only when foiling🙃) and very low aerodynamic drag. Not to mention a huge wing sail that can be deep and cambered or flat and twisted at the push of a button. The crew is faired in and the bustle on the hull just kissing the water. There has got to be more gains available in windfoil by closing the gap with the water through technique and board shaping. To spawn some creative brainstorming thought, what about something sail like below the board? Maybe its leading edge is a ride height wand, and the sail/end plate extends and retracts into the board with wand motion, think sail fish or tuna dorsal?? Okay maybe that's too creative;) The boards with bustles did not seem to catch on but I still feel like there is low fruit there.
The Moth versus iQ comparison is interesting and more to scale. They carry almost the same sail area—8.25 versus 8.0 square meters—but at recent Moth Worlds the top boats reportedly averaged 22–23 knots upwind and exceeded 36 knots downwind, compared with roughly 18 and 29 knots for the iQ. Those numbers are also from ChatGPT, anybody line those two craft up on the water? Now that the iQ can foil tack it's got to be a closer contest. The iQ might have the advantage in marginal foiling conditions using kinetics, but once both are powered, I reckon the Moth should be faster. I know when I see my buddy coming out in his Wasp (sim to Moth) I go look for some flat water to freestyle in rather than line up with him! It would be cool to compare the aero drag (and total drag) between the two (IQ vs Moth), shrouds, spreaders and racks are speed bumps, but the lower half of the sailor should blend into the rack. And the rack gives them more RM. With the iQ the sailor is completely in the wind. The iQ is a one design from years ago, a brilliant design for its time. We need open design coarse racing to push us forward. PWA foil slalom is great to watch but I want gear that can go upwind.
The one thing ALL the boats are doing that we are not; they use adjustable flaps and or adjustable rudder foils to create stable flight with smaller foils. All of them but the silly IMOCA 60's, I don't get why they have not changed their rules yet but that's a rant for another time/forum.
There isn’t much love for the adjustable foil idea in our community, judging by the negative response the topic usually gets on this forum. I get it, I sail at the beach, sand is a nightmare for fiddley ****, but the performance differences are hard to ignore.
VIC
3539 posts
I’m loving the racing too. I think it comes down to having an excessive amount of horsepower available to use. The foils are still cavitating but they have the power to push a little further into the edges of the envelope. The new foil design has helped too. I noticed in the last race meet the amount of twist that they can tweak into the sails. Amazing for a solid structure.
I always remember a conversation I had with Mal Wright about foil design . He believed that you could build a foil that you could jump on and glide across the water for 50 m or so. That was back in 2004 at Speedweek, way ahead of everyone.
