PY adjustment for non-spin Mirror or Cadet

It is possible that a tiny boat on a fluky pond is faster without the spinnaker. In a Mirror, singlehanded without a kite is deemed 10 points faster, which is probably underestimating the advantage on our pond. With a crew, I started to be beaten by a Mirror with spinnaker once the breeze got the sail filling properly. As soon as lulls or shifts had it collapse, a spinnaker was fun, but break even at best, unless the team were properly slick.

I might be able to help, I did some calcs back when I was messing about with Peakys "Fuller number" if I can a) find the computer I did it on and b) Those numbers are even relevant to todays situation I got stuck on the differences between Syms and Assyms if I remember correctly, I'll have a look and report back.

Originally posted by CT249 if anyone has an idea of the adjustment for a fully-crewed but non-spin Mirror or Cadet,

Back in the day the difference between single handed full rig and singlehanded single sail Mirror was 0.5%. Bearing in mind skill levels and all the other variables then its probably neither here nor there, but if you are using VYC then I suggest 0.5, maybe 1 point at most.

Originally posted by rich96 Originally posted by Woodburner OK found it, so would need the following. Boat Length, size of the main, average crew weight, Hull & Rig weight and size of the spinnaker in question. At the time I was working on what a Farr PY should be with and without. So without the PY should be 1071 (with a 70kg crew) but with a 12mtr kite it drops to 1067. Or say an RS400 which my system gave a handicap of 956 (with 2x80kg crew) but if you remove the kite (13.94sqm) it rises to 961.  The RS 400 with/without PY numbers are way out An RS 400 with no kite would be lucky to beat a Scorpion/Finn similar on the water  Planing spinaker boats are hugely handicapped when they cant use one. Only the heay ones that plane less are less affected (L2000, Wayfarer etc) The Farr numbers also dodgy - how could more than doubling its sail area have virtually no effect ? The system may need tickling ?

Well I was tickling it but lost interest, but the reason the kite doesn't have as much effect as you might think is the sheer time that it comes into play as a percentage of the 'hour' I guess all this was drawn up on. An RS 400 well sailed I would think would destroy a Scorpion over the water with or without kite in it's conditions as to the Scorpion PY I've never looked, strange since we used to be a Scorpion Club. So yes I know it needs tickling and it was started at a time when all the handicaps were way different to what they are now and this particular calculation was designed to build a system that individuals could dial in their own weight. So for instance the RS400 I just picked because it was the first with a kite I came across is assuming a crew weight of 160 and all up weight 140 which of course could be wrong. Here's another the 470 was 973 with the 13 mtr kite which removed gave it 977 which in my mind wasn't enough because the 470 could deploy it's kite more than assyms (which is where I was stuck) (My thinking based around triangle sausages which we were using back then. Any way, it's not a 'thing' just offering some help and context. Oh and I did the Miracle (which was a bloody Bandit anyway round here back then) With kite it came out 1181 and without 1183 which given they use 1200 is kind of back to the drawing board wrong.

Edited by Woodburner - 02 Sep 22 at 8:44pm

The kite on an Asymmetric Canoe was worth under 4%, and they had monster kites, some 200% of fore and aft area. The real difference in round the cans performance is much less than people think. There's the "how long is it in use thing" as above, but add to that the actual speed increase available on a dead run is strictly limited.