Hi, if you're on a boat in a lake, and using a tripod with a gimbal head (I'm using the Canon 100-400 m2, Manfrotto tripod and Nest NT-530H MKII gimbal), would you leave stabilisation ON or OFF?
I would leave the tripod and head on the floor of the boat and shoot hand-held with stabilization on.
If you're on a small boat which could overturn, I agree with Hector. If it is a large boat with minimal vibration and you can shoot at a high shutter speed and you need the gimbal for panoramic shots I'd turn off image stabilization. If you don't really need the gimbal, I'd ditch the tripod, leave image stabilization on and shoot hand-held.
All boats with engines running vibrate - tripods will transmit all of that directly to the camera, whereas your body will damp it. I agree with Hector. One "boat" from another - Nikon D 750 HH.
+ the above Aeroplanes also vibrate. The human body at least has some damping qualities. Whether you can use image stabilization with the camera on the tripod depends on the camera and the stabilization method and generation.
Are there cameras that sense something in the tripod socket? Otherwise, as far as I know, cameras that sense that they are on a tripod do it by sensing unusually low camera motion. Lower than even the best hand. I suspect that the vibration frequency spectrum and amplitude from boat motion is different from hand motion, and might not be optimal. Even so, I would expect on to be better than off.