Fastest dinghy?

If you sit down and draw a graph you'll find that the highest theoretical speeds are achieved when you are sailing at 90 degrees plus the apparent wind angle to the true wind

Which is exactly why I still contend that a Tornado is going to the the quickest over 500m 10 feet wide and easier to control than other mono's at those sorts of speeds and when flying a hull you are using all the boat except the lee hull as extra righting moment.

Are 18' skiffs approx 18 feet wide ?  and so giving slightly less that 9 feet of leverage (lee wing acts against the righting moment)

 

 

Originally posted by Scooby_simon Are 18' skiffs approx 18 feet wide ?  and so giving slightly less that 9 feet of leverage (lee wing acts against the righting moment)

The righting moment is created by multiplying the horizontal distance between the centre of bouyancy and centre of all up sailing mass by the total mass.  Hence (assuming the skiff is upright, and the rigged boat minus crew has it's centre of mass on the centreline of the hull) the moments of the wing masses and indeed entire hull cancel out.  

This leaves the righting moment counteracting the heeling force of the sails as only the distance between the centre of the hull and the centre of the crew's mass (horizontally) multiplyed by the crew's mass.  If the wingtip beam of the skiff is 18 feet than the leaver arm for the crew will be 9 feet plus the height up the crews body to their centre of mass (about 1-2 to 2/3 height).  Hope this helps. 

P.S. heeling moment is lateral side force from sails plus side force from hull and foils all multiplyed by vertical distance between centre of effort of sails and centre of lateral resistance of underwater hull profile, thus explaing why lifting the plate when its windy makes going upwind easier (reduces force from underwater profile and also leaver arm)

Originally posted by Scooby_simon Oh yeah, I wouldn't be too surprised if a 29er could drive past a Taipan downwind in 30 knots - for a start Taipans (and most other cats) stop racing at a steady 22.5. Secondly a Taipan is normally capsized or on the beach in a real (not bar talk) 30 knots - as is just about every 29er! Thirdly, yeah the cats are throttling back so heavily for survival and their dash speeds just aren't that fast AFAIK. we don't stop racing in the UK just because it's getting a little breasy Ask anyone who came to that grafham cat open (or even opens, it usualyy seams to blow old boots) Except this year !

Ahhh yes, you're much better and more macho cat sailors than we are - NOT. Can I remind you of the British v  Australian results in the world titles in most of the International cat classes (As, F 18s, Ts, Hobie 16s, etc) and the Little America's Cup?

I don't particularly agree with the way cat sailors stop racing in a breeze, myself. But if we look at the boats we sail v the boats you sail, we can see a clue. You guys often sail boats that are normally 25-50% heavier and shorter rigged. Compare a modern A with a Unicorn or Dart 15 or whatever, or a 180kg Dart 18 with a 120kg (IIRC) Taipan 5.7, or a 104kg Taipan 4.9 with a 130 kg (IIRC) Spitfire. Our boats tend to have much bigger wingmasts as well.

I'm DEFINITELY not saying we are better sailors per se. You've cleaned us up even in 18 foot skiffs, never mind the Olympics. But currently the cat sailing record is pretty one sided. Look again at the F 18 worlds for example - something like 8 Aussies or expatriate Aussie skippers in the top 10, and the best Pom in 10th.

Seems that the cat sailors don't seem to have any empirical data to back their arguements up with whereas Chris and Phil seem to have somewhat more experience and knowledge, and back it up.

I thought this was all about all up straight line speed.  And it looks to me that there is nothing in it at all at the moment, but with the monohulls winning the debate.

how bout two foiling moths with a single trapeze? would need a bigger rig though wouldnt it?

on the topic of foilers, would it be possible to use actual wings like plane to create lift aswell or would the weight of them cancel out the lift?

just a thought....