I USED TO DO THIS JOB ON CRUISE SHIPS.
Basically, chances are that the ship will have everything you need for the job - however you may find that you can't borrow tools. So, you might need a simple multimeter (to test batteries, speaker ohmage), a few screwdrivers, soldering gun, needle-nose pliers, etc.
Just a few basic tools. You won't need more than a handful. Good luck.