One of our sailing club Bards presented a very detailed description of generating and using Polar Diagrams to improve preformance on the race course. I had put together a similar presentation for our local Multihull association on how to use your inexpensive GPS to maximize windward and leeward performance without needing to generate Polar Diagrams. It won't necessarily help you win races but it is a very simple way to improve your upwind and down wind speed. A complete description is on my web site: www . wingsailor . com by clicking on the "VMG & GPS" tab.