put the board in a pool and load it up with weights until it sits flush with the top of the water.
weight = volume
It's a hardcore freeride/wave 260-60-110thick fiberglass there are numbers on the stringer but none are volume they are 260x600x400x310x110 . I don't know what the outher measurements are for?
yes it's true, and it is how board volume is checked within the industry.
So if a board weighs 6kg it will only displace 6L of fresh water under it.
put 70kg on the board and it will displace 76L of fresh water and if its a 76L board this is where it starts to sink. For anything to float all it needs to be is less dence than water in my case im more dence so I sink
A sinker will sink but flaten it out and add sides and it will float. material dosent change the laws of displacement its the volume and weight.
Seawater is taken to be 1.025 kg / L, in actual fact this too varies with water temp and is correct in water of 4degC, (ie I'll never sail in that density)![]()
So a 100 L board in seawater will float the same as a 102.5 L board in fresh water.
Oh yeah and don't forget, if your weights go under water, you're also measuring the submerged part of their volume.