Basher said..
Board size is always an interesting topic and when we discussed big waveboards on another site recently it was clear that bigger guys were still trying to sail boards where the volume in litres matched their weight in kilos. Whereas the lighter guys were consistently reporting they were using excess float nowadays. So 100kgs sailors said they had 100litre boards, whereas 70kgs sailors said they often used 80litre boards.

And in my case, I can talk about float a lot, because i have several wave boards.
With my weight at 75kilos my 'go to' wave boards are 80-85 litres and then the differences between the three options I have in that volume range are as much about rocker lines as about their measured volume.
My 85 litre board is +10 in excess float for me, but it also has a fast rocker, meaning I get early planing in iffy winds or in white water conditions.
I also have a 95 litre wave board which is then +20 litres of excess float, and that float is so helpful on some of the rippy, messy, onshore wave days we get here. But the board still has a wave rocker, so it will turn well on a wave.

That same design comes in a 115litres version, so that would provide +10 litres of float for a 105kgs sailor. But he will also find that board has a flatter rocker than the 95 later version.

And, on topic, there lies the problem for board shapers and for the industry. When they produce a 115litre board is it for light wind blasting for average weight sailors, or is it for tight turns on the wave face for the heavier guys? if they produce a massive wave board with loads of rocker then the market for that would be limited. If it was tested against other boards of a similar volume it might also be damned as being slow to plane. And the chances are, that none of the 115litre boards being tested would get anywhere near a wave face.