You could always buy a sailboat, then you wouldn't worry about the keyboard(s).
No, then you'd have to worry about finding a WATERPROOF keyboard..!
True story... I used to windsurf a lot, and still have a few bits of gear with rust on them from seawater dripping onto the gear off of sails and booms hastily stowed in the back of my van! There were some beach gigs I used to do where I would rig a board, and just go sail about on my breaks! That always got a good laugh, as I came in dripping wet to start the next set...!