iceboats

[rlawler]

I was reading that iceboats can travel up to 10 times windspeed and can sail at just 7 degrees off the wind. I assume that is possible solely because ice is such a superior surface for sailing compared to water. Will sailboats ever be able to achieve performance like that? Have we reached a plateau with sail boats in which all the major innovations have already been thought of, leaving a future of merely incremental progress on those elements (sails, hull/foils)? From a physics standpoint, have the current fastest boats begun to approach the theoretical performance limit of wind-powered craft?

[Doug Lord]

Originally Posted by rlawler

I was reading that iceboats can travel up to 10 times windspeed and can sail at just 7 degrees off the wind. I assume that is possible solely because ice is such a superior surface for sailing compared to water. Will sailboats ever be able to achieve performance like that? Have we reached a plateau with sail boats in which all the major innovations have already been thought of, leaving a future of merely incremental progress on those elements (sails, hull/foils)? From a physics standpoint, have the current fastest boats begun to approach the theoretical performance limit of wind-powered craft?

I've heard 5 times for ice boats. No, I think there is a long way to go yet....

[jehardiman]

Wait a moment, that wind angle and speed ratio is based upon apparent wind, not true wind. Ice and land yachts are still have limits just like water yachts, just because you are going fast doesn't mean you are going to weather. Marchaj goes over this well in Aero-hydrodynamics of Sailing, devoting a whole chapter to the subject.

Edit to add: As far as performance goes, we are just begining to have the material knowledge to build theoritical "sailing" craft postulated in the 50's and 60's. As I have said in other posts, is someone hasn't broken 100 knots on water in the next decade or so, they really aren't trying.

[Marvout]

I was reading about offshore power cats in ProfBoatBuilder last night. Turns out they use the space between the hulls as a big foil/wing for wing-in-ground effect. I never realized that. As with the V-39 Albatross using a wing for lift, I was wondering if a sailboat couldn't be built with a hull shape to capitalize on WIG effect between two cat hulls. I don't know what the minimum speeds are before WIG makes sense, but I do know that some of the 'wings' are just fabric over frames. We should have material to make it work where weight wouldn't be a problem.

I wonder what is yet possible, but I'm curious how much of the tech that will make more speed/efficiency possible, will end up limited to specific conditions, boat sizes or require such design constraints as to render them as good as useless for anything other than breaking a record. We have impressive 'out of box' designs like TriFoiler, but it is hard to think of them as 'boat' anymore. I don't see much of TriFoiler's attributes trickling down into 'regular' boats.

[Doug Lord]

Originally Posted by Marvout

I don't see much of TriFoiler's attributes trickling down into 'regular' boats.

-------------------------
I don't know about the trifoiler but I do about the Rave: the Rave wand system was copied directly by John Ilett and used to start the bi-foiler revolution and help produce the fastest sailboat under 20'-the Moth. Thats trickle down that has made high speed sailing accessible to many more than did the boat it was copied from.....

[Marvout]

Agreed. There is trickle down, my hypothesis would be that 99% of the trickle down will be in like-kind, just like your example. Expensive stupid-fast boat ends up sharing tech with less expensive stupid-fast boat.

[jehardiman]

There will be some trickle down. My minivan has alloy rims like a F-1, soon we will see CF decks on pontoon boats .

[Doug Lord]

Originally Posted by Marvout

Agreed. There is trickle down, my hypothesis would be that 99% of the trickle down will be in like-kind, just like your example. Expensive stupid-fast boat ends up sharing tech with less expensive stupid-fast boat.

-------------------
I think it is sort of the reverse: the Rave never cost more than 1/2 what a Moth costs.... And as much as I admire and respect Dr. Sam Bradfield(designer of the Rave and mentor to me) the Rave was never as fast around a course as the Moth is.

[PAR]

Thanks I needed that John, I laughed for 5 minutes . . .

[Submarine Tom]

I sailed my DN (Detroit News) ice boat for three years near Calgary Alberta Canada.

I never took any precise measurments but I would say 4-5 times the speed of the wind and 15 - 20 degree off true wind.

The rate of acceleration was staggering. The sailing was pretty exciting too. Noisy.

-Tom

[magnus]

Tom

Nice to see contributions to an old thread. A while ago I experimented with sailboards which would travel on ice, snow pack and water. I built plugs and molds and a complicated spring suspended stainless steal runner/skeg system and came up with a snow/ice/ski/sail board. With a good breeze I could play with the ice boats but I always backed off at around I would guess 45mph, it hurt too much above that speed to get a gust leaning back and slam in, even with full hockey pads. But when you mention the noise that was the unexpected eperience for me; the chatter of the equipment on ice and to a lesser degree on hard pack was distracting. The compromise in my design was one could not travel very far on open water without coming off plane unless it was very windy, but it was fun to buzz shore on the ice on inland Minnesota lakes in Spring and skip the 50 feet of water/melt at shoreline and hit the beach standing. I suspect I was only efficient up to 30 degrees upwind, but a reach with wind was very fast.

Jim