I can say that we averaged slightly over 15knots from Islamorada to Tybee Island last year and got to use our chutes most of the way. However, I was pretty surprised that our peak speeds were around 20 to 21knots....but then again, we were sailing in anything BUT flat water and the GPS was probably not recording data points fast enough to record the blast off trip down the face of each 4 to 6' swell at those kind of speeds.