So you'd think. But since I bought a steel boat, I've seen some horror stories on other steel boats. As far as I can tell, it's a fundamental shortfall in understanding how electricity works in creating galvanic corrosion.
Marinas frequently don't get it right, either, and they have incentives not to electrify their basins.
Theres isnt a lack of understanding. On a steel boat in particular, there is a compromise between ultimate electrical safety
and induced corrosion
. Then add cost on top of that and you get all these conflicting rules and regulations
and suggestions and codes of practice.
Just to summarise,
(a) In my opinion steel boats need an isolating transformer, if you intend to bring AC onboard. Stray current
corrosion is real big issue in steel. Isolating traffos, effectively remove this issue. Galvanic isolators are not good enough
(b) The DC neagative and AC protective earth in such a case as above, should not be connected. Use RCD's on the shore power
input and on the output of the traffo. These are your main protective devices. Traffos remove the most common problem of AC shorts to ground.
(c) Not connecting the DC and AC ( I completely disagree with ABYC on this point) does not significantly compromise safety
( with RCDs) and isolates each section from stray current
and load dumping into each others circuit.
(d) If you can isolate your engine
block, isolated starter and alternator
, not difficult.
(e) I am not convinced of the merits of whole boat bonding, ( Michael Kasten has a good run down on this). Whole boat bonding is an American thing. Its rarely if ever done in Europe
. ( and we build a lot of steel boats)
Note that Galvanic corrosion, will always occur, where disimilar metals are connected via a dielectric, induced or stray current corrosion is what we are trying to prevent here, while remaining within a overall safety paradigm.