How can I reduce drag from hull and foils in a dinghy?
Dan Dickison responds:
You're not alone in your quest for reducing drag. In fact this is an ongoing pursuit for any serious racing sailor. The first way to reduce drag is to reduce wetted surface area. By that I don't mean reconfiguring the hull of your boat, but by getting as much of it out of the water as you can. This involves lightening the load carried in the boat and adjusting your own body weight while sailing. Here's an example: I race on a 28-foot boat called an E-Scow. One of the keys to performance in this boat is to achieve the proper heel angle so that we have a minimum amount of wetted surface area (read drag). Of course we carry the minimum amount of gear necessary (life jackets, bucket, etc.), but we're always trying to be cognizant of how much heel we have when sailing.
The other way to have an impact on drag is to make sure that your hull and appendages are as fair and smooth as possible. Since you sail a dinghy, I'm going to assume that you don't have any bottom paint on your boat. What you need to do is to make sure that the hull is as smooth as possible from the bow aft at least halfway to the transom. Aft of that, the flow over the hull is so turbulent that spending additional time smoothing it won't have much effect. Do the same thing with your blades (rudder and centerboard). I recently raced at the Acura SORC in Miami, and one of the top boats there (a boat that is drysailed and therefore has no bottom paint) had a common lubricant applied to its hull to combat drag. I don't like the negative consequences for the environment that this application carries, but you have to admit it is a novel approach. I've even heard of some dry-sailed boats using teflon wax on the hull and blades.
A source of ours who specializes in bottom preparation for racing says that he's gotten great results with high-grit sandpaper. That's high grit as in 1,000-grit paper. My experience is limited to 600-grit paper, but I'd recommend you try the 1,000-grit route and see how that works. Best of luck.
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