Well, we seem to have a big "hole" in the Boat Info. tab for the newer 31, but the '99 310 specs. show a hull speed of 7.1 knts. You might compare your loa-low, etc., but my guess is that with a clean bottom, best sail configuration, and folding prop. you should see mid 6s in 12-15 knts of wind, especially with wind off the quarters.