I have had more than enough time to think about the wind recently, having ridden out two overnight blows while tied to the dock on the Oregon Coast. The first storm had short gusts to about 90 knots(100 mph) and the second was a little one with sustained stuff of about 50 mph. You get a lot more sense of wind power while in a boat, as the weather service records wind gusts using a 60 second average, whereas we boaters care about and feel the effects of even short gusts of 5 or 10 seconds. In case you have never tried to think of wind power in terms of horsepower here are my shorthand calculation formulas that you can work in your head. Most sailboats will reach hull speed with a wind of about 17 knots assuming the main and jib are full up. If the wind speed goes up by 50% say to 25 knots then the power will double. In other words if the boat requires say 40 hp to reach hull speed then it takes 40 hp to make an equivalent wind power at 17 knots. It will take 80 hp to equate to 25 knots, it will take 320 hp to equate to 50 knots and it will take 1280 hp at 100 knots. All this was estimated on the original assumption of a boat of about 40 feet in length needing 40 hp to reach hull speed. Remember the power goes up by the square of the wind speed. You can estimate the wind pressure on a power boat with no sails by taking the lateral area EXPOSED to the wind, which would be the entire side, or might be just the exposed transom area and using the square footage as if it were a sail and running it through the formula for calculating the wind force. There is no quick and dirty way to relate the wind force on the power boat to speed through the water and the equivalent horsepower like the sailboat example above. But, you can quickly see that given the amount of windage that most power boats have, at elevated wind speeds it can require a fantastic amount of horsepower to maneuver in any direction except downwind. (This compounded by the usual lack of a serious keel). The 40 hp to hull speed is a pretty conservative number as most power boats will require some to a great deal more just to reach hull speed although they have less sail area than the average sailboat with sails up, they most likely have more "sail" area if the sailboat has it's sails down. This analysis is only a rough and dirty way of considering the forces involved and is not meant to be an accurate way of describing the forces at play. Mike Capt. Mike Maurice Tualatin(Portland), Oregon