There is a lot of talk about volume in surfboards and since tungsten also mentioned the importance of volume (great post btw) in kite surfboards I thought I'll start a thread about it. What I don't understand is how the volume can affect how a board rides when you're already riding on top of the surface with just a tiny bit of the board being below the water level and acting as an upward force. I understand that there is a huge difference in how a board paddles when surfing without a kite and being a surfer myself I'm very aware of this. I have boards that I cannot paddle with a wetsuit but worked fine in boardies and the low amount of salt in the water here also gives a little less flotation.
There is no correlation between rails and volume. A board can have a doomed deck (a lot of volume) or a concave deck (less volume) and still have the same rails.
There is no correlation between plane and volume. A board can be x wide and y long ( x * y = plane ) and still have varying volume (z) depending on the thickness.
What I'm saying is that when a board is paddled almost the whole board is submerged. If a board for instance has 36 liters of volume it's upward force is almost 36kg (minus the weight of the board minus the board that is above the surface). These almost 36 kg is making the surfer 36 kilos lighter pushing the surfer 36 liters above the surface making it a lot easier to paddle.
When surfing (riding), the board is skimming on top of the surface and since a board is heavier than air and more than half the board is on top of the surface it's only acting as a downward force together with the surfers body weight.
I'm no physicist and I'm not sure if a got it all wrong but can someone please explain why volume is important on kite specific surfboards (or skimboards for that matter) because I'm not buying it.