I take offence at that! I'll have at you just as soon as I've finished this pie.
Seriously though, boats do carry fitness equipment. Most fleet boats will carry at least on concept 2 and a bike of some sort, along with some sort of selection of weights etc. Bombers carry more.
The problems on a boat are time, with 99% of the ships company watchkeeping it means training off watch, and the boats programme. Depending on what the boat is doing there may be restrictions on the use of the equipment. Plus, if everyone was a fittie the showers would get hammered and the MEs would need to make more water. Not always practical.
There are some who'll tell you that it's unhealthy to train in the enclosed atmosphere of a submarine, but they're mostly fat.
Bombers have shit loads of gym stuff - usually 2 or 3 concept rowers, couple of bikes, treadmill, possibly versa-climber plus free weights and a bench. Water's not an issue on patrol, and usually gym not used alongside or on work-up so showers no probs. And youre right - its only the fat cnuts who say its unhealthy to train on the boat!
So that was the clank I heard as we were trying to keep silent, as it hit our saddle tank when it drifted passed into the deep. All I was trying to do was get some shut-eye after a spell in the control room, the things we stokers did!!!