That is not entirely true. The overall drag will ONLY increase when the increase in wave-making drag (absolute sense) is more then the decrease in wetted surface drag. If it does not then the overall drag will actually reduce when making the hulls shorter. But because of the curved nature of these dependencies you will find that reducing hull length beyond at certain hulls length will increase drag again.
It seems as these arguments tend to forget that form drag consists of two components, and wave drag is one of them. Even submerged submarines and airplanes at lower speeds are subjected to form drag even when no waves are produced. Hence, increasing cross-sectional area increases form drag even when wave drag is (almost) constant.
No it is not, you are trying to insert the word *always* again.
I have been trying to interpret your arguments that the shorter 16-foot hull should produce less drag than a 19-20 foot boat (that this thread was about).
I cannot agree that introducing the observation that sailboats almost always tend to be at maximum class length, or mentioning 'planing' or 'semi-planing' (either defined as transition between modes or as part of the boat being dynamically lifted), can be brushed away as simplistic absolutes: "always" or "never".
Rather to me it seems that absolete denial of the possibility that beach cats are subjected to some dynamic lift, or that 'semi-planing mode' does not exist, classifies as absolutes.
I am not at all an expert in boat design. Furthermore, the texts that I read tell me that several different mathematical models/algorithms are being employed to model different phenomena of hydrodynamics and boat design.
Hence, I fully agree that we as amateurs should be humble and careful when trying to discuss these matters.
This is a great forum, and the possibility learn is great because people like Wouter try hard to help and explain. We have to live wih disagreements and uncertainties of what is really correct until somebody comes along and brings us hard empirical data.
Stein
