Stephen, IMO we were talking about max gusts.

That is what I believe everyone was talking about. Anyone going out in sustained 100knt/mph or kmh gust would be stupid in the extreame.

How do you calculate the average ?

I would say my method for deciding to sail at Grafham (3x1.5 mile lake) is wind strength(and direction), forcast, temp of air and water.

I would not be going afloat if the wind is not dropping below F6 and if there are gusts more than this I would be taking things carefully (Temps / forcast etc).
I would be coming ashore if there are many boats already upside down (don't want to make more work for the rescue services, if I was to join them), I am getting cold in any way, or there is a sustained gust of F7+8 plus.


I sail on a lake and so the waves do not play such a great part in the equation, the largest we usually get are only a couple of feet high so don't make that much difference. This also allows us to always be able to find a windward shore to land on and take sails down if required.

Sailing on the sea / large lakes is a totally different matter.