VMG

So do we calculate this from mark to mark? If the optimum was a straight line from A to B which would be the fastest (if it were possible) then the best VMG would be the boat closest to this? but....how do we know how fast that would be when it is not possible. Or is the optimum the fastest boat over the distance? I have not had a chance to look at the Weymouth traces again yet.

i tick, if we are assuming upwind, currently, then straight to the mark is impossible, and so would be the slowest VMG. Once actually sailing, speed increases as you bear away. If you pinch, you will sail a shorter distance, but at a slower speed. For every class, situation, weather condition and even sailing style, the compromise between boatspeed and height will give a different answer in maximizing VMG. Boats which will plane upwind may well find that bearing off to plane is faster even with the added distance, but it may well be that there will be times when it will pay to maximize height over speed even there.

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.

So the traces from Weymouth give speed and VMG. The VMG must be comparative between boats. Just out of interest an RS400 did about 17 kts I think, not the fastest, that would have been an International 14. The 'boy' in his Byte managed 11.28 another Byte managed 11.57 but you can see from the trace that he was out of control and it ended in disaster! I will look at it all again tonight.

Someone start a thread about polars, I never understood them either..

That's the trouble with dinghyists all so up themselves hardly anyone knows anything yet they all pretend to understand, then say nothing for fear of sounding an idiot, so it's left to us actual idiots who don't care, to ask.

Edited by iGRF - 05 Sep 13 at 4:19pm

Originally posted by iGRF Someone start a thread about polars, I never understood them either.. That's the trouble with dinghyists all so up themselves hardly anyone knows anything yet they all pretend to understand, then say nothing for fear of sounding an idiot, so it's left to us actual idiots who don't care, to ask.