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Get a battery isolation switch if it hasn't and isolate anytime it is not in use.

If you pull up all the floor and floatation and give it a good high pressure water blast all that chalky oxide...

Yep then take all that out and waterblast really closely.....a decent one will take out the white powdery stuff and whoever will both be able to see what is involved and have a easyer job.
Do that...

As above if you have got it early and its just a few spots no dramas to spot weld them.....if its wide spread depending on the size of the hull it would be more economic to rehull from the chine...