My two cents worth: I calculate my M15's hull speed at 5.69 knots, or 6.54 miles per hour. (I used 18', since I don't know her Water Line Length, and the constants of 1.34 and 1.15.) Lacking a knot meter as of yet (any recommendations, ANY of you?), I don't know how fast my current M15 Rejoyce goes yet when pressed. My previous M15, Joy, had just the "Knotstik" to measure speed, and sailing on windy Stockton Lake in Southwest Missouri in November of 1989, with reefs in both sails, and winds measured on a hand-held instrument showing a steady 32 miles per hour, occasional gusts to 40, she rolled along at six knots. My last boat, a Charles W. Wittholz designed Cape Cod Catboat, circa 1963, The Old Cat (for obvious reasons), 18' 6", displacement 2,850 pounds, sail area (in a single quadrilateral gaff) 261 square feet (well over twice my M15's 122 in two sails) often exceeded her hull speeds of 5.76 kts/6.63 mph. My journal for 1/12/00 (sure, I sail all year around) reads: "A sustained puff on a broad port reach had us booming along at 6.72 knots." Later, on 5/12/00, ". . . logged a top speed of 7.39 knots on a very broad reach." (She carried an accurately calibrated electronic knot meter.) Summation, as others have more eloquently stated: Hull Speed is not a maximum speed. Keep on sailin', y'all! No, my e-mail address is not salacious, it just refers to my last sailboat, "The Old Cat." Check her out at <http://www.unicorn-systems.com/theoldcat.htm>