It feels like somewhere in about 2010 boat manufacturers decided to tweak the way they measure gallons so they wouldn't be accused of being small... because I have a Mamba 8.1 (released ~2012) which is supposedly 77 gallons, and a Nomad 8.5 (released ~2003) which is supposedly 78 gallons, and the Nomad is obviously bigger than than the Mamba any way you look at it. I remember seeing a Mamba 8.1, Nomad 8.5, and Mamba 8.6 at Confluence and the 8.5 was clearly in between the two Mamba's size-wise. And it boats that way. The new Nomad 8.6 seems to be about the same size as the Nomad 8.5 or a little narrower, and it supposedly has 86 gallons, which I think confirms my suspicions of a new "standard". Anyhow, Volume measurements seem to have some subjectivity and isn't the best measurement. Look at the recommended weight ranges and make sure you're in the bottom half of the range if you're creeking.