Originally Posted by Dockhead
Well, actually, it is a law -- a rigid law of physics.
The thing is, however, that the law applies in different ways to boats with different hull
, and power available. Some displacement hull
boats can exceed hull speed
fairly easily; for others it's like hitting a brick wall. Most are somewhere in between.
All the law says is that it takes a relatively speaking additional amount of force to exceed this speed in a pure dispacement hull with no hydrodynamic effects other than the speed of the bow and stern waves.
Few boats actually have their hull speed
exactly at the hull speed due to other factors, I.E. changes in LWL as boat approaches hull speed, (designed or incidental), lift
from hull curvature, or induced turbulence, ...