tow tank/ hydrodynamic testing methiods

[Ad Hoc]

Originally Posted by nwahs

there has to be an optimal form,...

Optimal for what?...think carefully before you answer!

[nwahs]

post # 3 describes some perimiters of what im trying to design, paddelcraft bla bla bla.

i can also mention, pure flat water at the local lake only no heavy sea's here, no cargo space or pay load beside me and a paddel.
im not concered if i get wet all the time and tip it over every once and a while, dose not have to turn well at all

i know its going to be excerize, but im looking to go as fast and efficent as possible per paddle stroke. say 15 to 25 min burst........ that would be optimal for this craft, thx

[tom28571]

Originally Posted by JRD

Thinking about your comment about rider placement, it occurs to me that this is more significant for a kayak than larger boats as the rider is by far the largest mass on the boat. The dynamics of paddling will have the COG continuously moving about which would create a rythmic occilation in trim. When you watch a paddler going flat out the shorter boats can be seen to snake from side to side, and trim up and down at the bow as the paddle force is applied. Its subtle of course, but logically this would set off draggy vortices down each side of the boat on each stroke. Would be interesting to compare a straight line tow test with one where the various dynamics are also applied.

Very pertinent to the discussion and makes the "optimum" kayak hull much more difficult to define. Straightline towing drag tests are not likely to result in such an optimum form. Probably a study of the forms arrived at empirically by the best paddlers will show some of this. Even the stroke used by different paddlers would likely have a significant effect on the best hull form.