Killed Batteries ?

[Capitain Mike]

Chat to a local garage they usually have commercial battery testers and maybe for a small remuneration. You never know your luck you don't know unless you ask!

[Capn Morgan]

In a setup with batteries in series just one failed cell will bring the whole system down. Identify it/them and replace. Don't throw them all away just yet. See Nigel Calder's Boat Owner's Mechanical and Electrical Manual.

On the water in the bilge subject, you have a hull to keep the water out. If there is water inside it find out why and stop it. IMHO bilge pumps are there to buy you minutes in an emergency. My bilges are dry except for the one where I dump the condensation from the aircon, which works only when I am on board.

Above all, best of luck and tell us what you find.