Bottom Contour

« Displacement Hulls

3 Comments

Kevin Lee says:
A surfboard cannot be a displacement hull! By definition a displacement hull is a hull which cannot get up over the top of its own bow wave and plane.eg, TUGBOAT! I have rode the type of boards the article refers to for a long time mainly Greg Liddle shapes and also lots of Richard Brewer type shapes as well. It is true that some bottom contour and rail combos give a more connected feeling to the water going under the board,however both fun shapes and gun shapes are functioning as pure planing hulls. To surf a wave any board has to plane! Its not a semi planing hull or a semi displacement hull, its a planing hull! The wider plan shapes seem to rely on resistance when put on edge to harness the energy moving up the wave face which is translated into thrust. It is not displacement , it is the increased flotation that forces the water around the board. Sort of like squeezing a wet water melon seed out between your fingers. I can still remember riding my Liddle at Kaisers in Waikiki getting spit out of the tube and flying down the line coming off the top of the wall. I guarantee you, the board was planing!!!

Denny Grant says:
Thanks you Kevin Lee,I was going to say the same thing. I wish more sharpers would read a Book on Boat Design before they started talking Hydrodynamics.

miguel arag√£o says:
Would add... The rider making his board to start planning, is becoming a surfer.





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