I've recently had the pleasure of chatting to a few shapers etc about this subject.
In the Old Days, they used to actually put weights onto a board in a tank and then roughly guess the volume. Since the introduction of design software this is automatically calculated without the epoxy, carbon wood etc, that is the foam volume. Some boards are made with the same foam shape but different layups so this does actually change the volume as the board is supporting its own weight too.
I recently did a test in my pool. I have a Patrik QT 113 wave board and an Exocet X wave 101.
When I stood on the 101 it pretty much just floated above the water, the 113 was slightly better but I'd say not masses more buoyancy.
I'm 92 kg, my rig is 9kg, harness and wetsuit 2.3kg, board weight wet, 8.5kg ( and thats a light carbon board ). Thats a total of 111.8litre that I'm using on a 113 litre board, thats only 1.2 spare litres. I can uphaul this board, just.
I was really quite surprised about how wobbly the board was without the rig and could barely stand on it.
Anyway just thought it was an interesting experiment and wanted to share it.
