With volume measurements, it really depends on who has measured the board as there always seems to be some minor differencs between the various measurements taken.
In the case of the Futura 101 you can be assured it has a minimum volume of 101 lts.
It looks, it floats, it sails and it measures like a very full 101.
Please note that in my (90+kg) opinion of test riding various versions (inc production) Futura 101 I would suggest that 7.5m for 85kg rider is at the practical maximum upper sail limit for reasonable freeride handling. (That comment based on sailing ; ie planing performance - where specific volume plays less of a role, not uphaulability or subplaning) - Typically the sweetspot range for this model is around 5.5m to 6.5m.
Cheers ~ Ian