SeanAUS120 said...barn said...
id say there is no diference, yes salt has more boyancy, but when a windsurfer is planing its skimming across the waters surface, so the fact that there are salt molecules in the water shouldent change its thinkness or whatever affects this phennonomen??
Even when planing, a board has to displace water. So buoyancy (from salt water) would definitely help keep the board floating more and not dragging in the water. I would imagine at 49 knots you are doing a lot more of the "skimming" than at 30 knots but you still need to GET to 49 knots so salt will help.
All the speed records are done on salt (ocean) water. Any sailing I have done on fresh water lakes is 5% slower than similar wind strengths on salt water.
Actually for planing its not so much a buoyancy thing as an inertial thing i.e the water resisting being pushed around. The denser salt water would, I expect, get you planing at slower speeds and higher out of the water with a smaller planing area. I don't know if there's any difference in the "stickiness" of the two.
I don't think having materials that produce air bubbles would help us (open to suggestion though?). We require lift from our fins to generate forward motion, created from the power generated in our sail and transfered from our arms-to-legs-to-fin, whereas a swimmer is trying to reduce drag as much as possible and gets the power from its arm/leg propulsion. So I reckon the bubbles would be counter productive and probably cause you to spin out quite a bit... $700 to Speedo and some duct tape and you can test that theory out for us however ;)
They're always tearing those things. hmmm...
I imagine surface friction provides an appreciable part of the drag and making wetted surfaces as slippery as possible would seem to be sensible. People have tried sacrificial surfaces in the past. I think they are frowned upon as pollutants. I kinda think a soap film might work but its vandalism. hmmm... clean fish.
I think bubbles could provide a friendlier way to lower the surface drag. An emulsion of air and water is going to be easier for a planing surface to rip apart than good old water.
