I guess my lack in mastering the english language in combo with my typing skills is to blame here.

the phrase :

No Grob, this is completely wrong and most fundamentally flawed scientifically. Wave-making drag INCREASES when the hull speed is lowered ? ...


Would have been better if written down as.


No Grob, this is completely wrong and most fundamentally flawed scientifically. It is illogical to claim Wave-making drag INCREASES when the hull speed is lowered. ...


Extra explanation

This would either mean that wave-making drag is high when the boat is motionless, which is to weird to consider seriously. Or for some weird reason is is zero when motionless then increases with speed only to decrease again after Froude's law max hull speed and possibly increase again with additional higher speed. This would be weird as that that would predict heavy monohulls to NOT be held back at the max hull speed rule of thumb as we know they are. Either way you run into a contradiction with well documented real life phenomena.


Also I've lost sight of my own "red line" now.

Basically my model is :

-1- Both wave-making drag and wetted surface drag increase with increasing boat speed.
-2- Wetted surface drag is a significantly larger component at low speeds (below Froude's speed)
-3- At higher speeds wave-making drag starts to become a significant factor when compared to wetted surface drag. The transition to this situation is to be found around the Froude speed. (and is what the Froude law actually says)
-4- Overall wave-making drag on cats doesn't seems to be a very large component of the total drag.
-5- Wave-making drag is not very dependent on hull length beyond a certain min prismatic hull ratio.
-6- Wetted surface drag is always strongly dependent on the total wetted surface area.


Wouter