My wife and I had a great afternoon of sailing Sunday. It was cool but the wind was strong and not too gusty. We sailed with 1 reef and the 110 jib at near hull speed all afternoon. It was great. We tied up at the dock as the sun disappeared and it was dark by the time we were in the car. Except for being a little cool it was about as good as lake sailing can get. We are going to be a little bored when the seasons change and we get those days of 5-10 knot light and varible winds. The boat always seems to do better in winter for a given wind speed. I know that pilots compensate for temperature ,humidity and altitude when planning to take off,especially for a short runway. You calculate a density altitude and the pilot's operating handbook for a particular airplane tells you how long it will take to get airborne for a given wing loading. Has anyone worked out some of this perfomance data for sailboats?? For a Cessna 172 you can get 20% better performance going from 95 degrees to 50 degrees. I'm guessing that some racers have worked this out at least for their boats. It may not be as dramatic for a sailboat as part of the airplanes problem is that the engine doesn't work as well at higher density altitudes( assuming no supercharging).