VMG

Originally posted by iGRF So, are these 'polars' available for different boats, when was that one issued for the RS100? Where can I order one for the Alto and the EPS? Then the next question (blindingly obvious even to an idiot) if there are such things, that are calculated on fact rather than anarchic fiction like club returns, why is it so difficult to have a given boat a permanent handicap calculated for it?

Too many variables.

A possible scenario for the future though could be a simulator. Maybe (fantasy) the designer could submit a bang on accurate 3d model to a PY com who then run the model on a sophisticated simulator that uses all the known variables to calculate a number......effectively a same helm same conditions comparison with other boats  

Originally posted by iGRF I assumed that compass thing with the electronic read out that some folk use did all that, why would it restrict itself to just compass angle degrees? Anyone can wear a wrist mounted GPS device, I must have done at one time or other. So, no, don't tell me, it's not permitted because of 'the class' they will not 'allow' a polar thing to be constructed for their craft? Oh and does this mean it's also illegal to take an iPhone out according to some classes? Given it's GPS and various tracking apps?

Edited by 2547 - 06 Sep 13 at 9:51am

I assumed that compass thing with the electronic read out that some folk use did all that, why would it restrict itself to just compass angle degrees? Anyone can wear a wrist mounted GPS device, I must have done at one time or other.

So, no, don't tell me, it's not permitted because of 'the class' they will not 'allow' a polar thing to be constructed for their craft?

Oh and does this mean it's also illegal to take an iPhone out according to some classes? Given it's GPS and various tracking apps?

Polars are rarely - if ever - available for dinghies because they are affected to a much greater degree than lead-mines by waves and crew mass. Also, I know of no class where the carrying of electronic aids is permitted (TacTic excluded), so you don't know how fast you're going anyway.
I also assume that the theoretical polars determined by the designer will be modified by on-the-water experience into a 'real' set. (e.g. Do It Yourself!).
Finally, race lengths come into it too. A tiny speed advantage over 24 hours can amount to significant distance. One fluffed tack will have a much greater impact in a 15 minute upwind dinghy leg. 

Originally posted by cad99uk Originally posted by Rupert I'm not a yottie, but I have read articles where they are talking about knowing that is a certain breeze, a certain boatspeed will give best vmg, so they will bear off from the highest angle they can sail until they have that boatspeed. I guessing this is done by spending a lot of time practicing and taking readings, and I would imagine is still only a rough guide. Reference to a boat's polars helps here too.