119 posts
There's only the Archimedes principle, the rest is 'sensation'.
So if you want to test the volume the easy way, go to a body of fresh water standing still. Bring weights and keep adding weight to the board upto the point where the last piece of 'skin' is still just above the surface. The weights you've added + the weight of the board itself equals the volume.
A more techical solution would require a 3d scan of the board or pretty accurate measurements in autocad.
The easiest? Just stand on it in that body of fresh water. If it sinks, the volume is less than your weight. You could do the same in salt water, the difference is marginal.