Not at all saying that what your as saying is wrong, Wouter, as a freshment marine student I really have not startet my education yet, but according to my text-book in Marin technology Intro, the maximum speed of a wessel in dispalcement mode is 1,33 * the root of its waterlength (speed given in meter per second). If you say that the waterlength for the Taipan 5,7 is 5,7 meters, that gives a theoretical top speed of 6,07 knots. This book is written by Anders Endal, a professor in Marine Technology and a legend at the department of Marine Technology. He is now 70 years old, and have been teaching for the last 30 years I think. His knowledge of hydrodynamics is great, however I do think his knowledge of beach cats is somewhat limited <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" /> Please understand that I'm not at all questioning your knowledge of hydrodynamics Wouter, as you are udoubtedly one of the biggest resources here on the forum concerning science and engineering and therefore I have great respect for your statements. I am simply stating that the myth as you call it of theoretical top speed of displacement wessels is something that marine engineers at the Norwegian University of Science and Technology learn in their first year as marine students...