On most sailboats, heeling them to leeward and slightly bow-down in light air usually reduces the amount of wetted surface, which reduces the amount of drag. When the boat is oriented slightly bow-down, that raises the fat stern, which decreases wetted surface.On small boats, I see the advantage to keeping the boat heeled in light air - to keep the boom in one place and to keep it from flopping back and forth. Ignoring the mechanics of keeping the boom in place, without exception, everyone that I've asked has not had an answer why the boat should be heeled. It makes no sense, less sail area is exposed to the wind when it's needed most. I'd really like to see a real answer to this since it's puzzled me for years.