Mains charging a battery while afloat - basic question

[PaulRainbow]

The only reasons not to fit one are if the boat is never left with the shorepower connected or if only a temporary hook-up, like that mentioned earlier in the thread, is used with no connection between the anodes and the earth conductor.

There is no need to fit a GI to a vessel that has no connection from the incoming shore power Earth to the anode bonding circuit. Millions of boats were built without such a connection, over decades, before it was made a requirement in the RCD/ISO.

Anyone with an older boat, with no Earth connection to the anode circuit, would be completely wasting their time and money fitting a GI, it serves no purpose whatsoever.

 

[VicS]

It should solve problems arising purely from "galvanic" or "dissimilar metal" sources but a GI could fail ... for example due to a high current fault to earth in the AC system .. they are now required to "fail safe" but safe means maintaining the integrity of the AC system earth connection, not maintaining the protection against galvanic corrosion.
It must also be remembered that a GI wont prevent electrolysis caused by leakage from the 12 volt DC system.

The only reasons not to fit one are if the boat is never left with the shorepower connected or if only a temporary hook-up, like that mentioned earlier in the thread, is used with no connection between the anodes and the earth conductor.

And also if the boat is fitted with an isolation transformer with no connection between the shoreside earth and the boats systems