Being as you have not mentioned what sort of motors or speed controllers are installed or will be installed in the ship, it's hard to say what sort of batteries you will be able to use...
It would not be very nice if I was to say, put some 2s lipos (7.4 Volts) if the motors are 12 volts.. then you would need 3s lipos..
The amps just refer to the amount of time you would like to spend on the water.. the higher the amps, the longer the run time..
Other than that, you can put in any batteries you would like, of course they would need to fit the space you have..