For you freshwater sailors this isn't a concern ,
but us salty folks have to be concerned with chlorine gas , very deadly , made by adding saltwater to a 12v or any DC battery setup .
Ask any old submariner .
I don't like taking the chance of turning my Ariel into a gas chamber thank you very much .
And water has been over the cabinsole in #45 by at least 6" judging by the watermarks , but not on my watch .