[alanw]

Originally Posted by CheapPelican

^ what do you do, just goop the terminals? How do you keep it from sliding around during a surf launch?

You may need some way of keeping the battery from sliding around.. strap it to your scuppers or secure it inside of a box or bag, but it does not have to be waterproof. The battery is already waterproof. A little dielectric compound on the terminals may be all that's needed. A rinse off once in a while is good. If you solder your wires to your battery then you can also coat the terminals with epoxy if you want to not even worry about rinsing.