For a very very simple example Wouter, a knike blade run through a fluid sharp edge leading, offers very little resistance to the motion of the blade, BUT turn it at ninety degrees and run it through the same fluid in the same way and the resistance is very very noticable! Same knife, same surface area, same motivation, different drag induced, fairly obvious that a hull that is "finer" through the water offers less resistance to forward motion than one that is "fat"???