I'll second that, theoretical hull speed is no hard upper limit, it's only the point where it starts to take a lot more sail energy to go faster due to the bow wave having a wavelength longer than the boat, and the stern falling down off the wave crest. I've often sustained 8.5-9.5 knots per GPS surfing downwind in my Catalina 22 (6.0 knot hull speed) coming back downwind from Catalina Island on a windy afternoon. The C22 rudder isn't quite powerful enough to control the boat at those speeds, and it will broach easily. This article by our list member Dr. Judy Blumhorst does a good job of explaining why this is possible: http://potter-yachters.org/manyways/hullspeed/ Tyler ----- Original Message ----- From: swwheatley@comcast.net To: "For and about Montgomery Sailboats" <montgomery_boats@mailman.xmission.com> Sent: Wednesday, July 20, 2016 9:38:21 AM Subject: Re: M_Boats: 1) BBQ 2) m23 speed You guys are talking about theoretical hullspeed, which is more like a rule of thumb than a law of physics. Boats with displacement hulls can and do exceed their theoretical hullspeed all the time, including by heeling (which lengthens your LWL), or by surfing along the front of a wave (which turns your displacement hull into a planing hull, albeit briefly). For an M23, 6.5 kts heeled and 8 kts surfing are both very plausible.