Onno Meyer schrieb: >> Not with a length of 120 feet, it's not. Speed of a displacement boat >> is limited to about 1.35 * sqrt (LWL). (LWL is length on water line, >> typically less than overall length). To go faster, you need to >> plane. To plane 700 tonnes, you'd need quite a bit more power. >> > > Speed Minimum LWL > 10 55 > 20 220 > 30 494 > 40 878 > > Assuming that speed is in mph or knots and LWL is in feet, that > doesn't feel right. Destroyers do 40 knots without the length of > a cruise liner, but they don't look like planing hulls to me. > > compare > http://en.wikipedia.org/wiki/G_and_H_class_destroyer > > Onno > _______________________________________________ > GurpsNet-L mailing list <[email protected]> > http://mail.sjgames.com/mailman/listinfo/gurpsnet-l > > The formula 1.35 * sqrt( LWL ) is a given fact for ships with a conventional hull form (whatever "conventional" means in this context).
But boat builders have invented special shapes for boat hulls in the 1910s (namely Claus Engelbrecht and Arthur Tiller) that allow higher speeds for displacement vessels. One attribute of such a hull is its length-to-width ratio of 5:1 up to 10:1. Looking at the G and H class destroyers Onno mentioned, they have a length of 323 ft at a width of 33ft, so this may fit here. This special hull forms allowed 25% and more speed above the "bare hull speed" (up to 160% as stated in one article ...). To be honest, I do not understood the hydrodynamics behind this, although the articles are written in German. But it looks like that the Archvillain's Yacht COULD be as fast as stated by Onno, even by the given length, if it will have the proper hull shape and enough power (I did not check the power). As Engelbrecht and Tiller made their invention around 1910 also the time frame fits (there is a newer concept, called DG Hull, invented by Theodor Eder in 1990 that looks for me to be even more efficient). Any specialists for hydrodynamics on the list? As I said above already, I am not sure if I got it all correctly, so perhaps someone may lookup the sources (using Google) and correct me where I am wrong. Regards -- Thomas Thrien Obermarkstraße 3 Berghofer Mark 44267 Dortmund Allemagne Tel. +49 231 7285456 Mobil +49 171 5289503 Geo 51° 28' 12" N 7° 32' 17" E _______________________________________________ GurpsNet-L mailing list <[email protected]> http://mail.sjgames.com/mailman/listinfo/gurpsnet-l
