Galvanic Corrosion

[Venus]

The owner of the berth adjacent to mine has sub-let it for the winter. The temporary incumbent is 10 tonnes of steel 2 fenders width away.
Can anyone advise if there is an increased risk to my plastic boat due to electrolytic action, if so is there any action I can take to reduce it?

 

[peteandthira]

This frightens me a bit too. Watching with interest!

 

[KellysEye]

>increased risk

Shouldn't be any problem provided the steel boat is set up properly (we have a steel boat but that sentiment applies to all boats). It's highly likely they will be properly set up because if they aren't the steel boat owner would have noticed some very serious problems on his own boat.

 

[VicS]

If you both have shore power connected, plugged in that is, not necessarily in use, you should fit a galvanic isolator if you do not already have one. Until then unpug yours if you do not need it on all the time.

I'm not suggesting there will be a problem just a way of avoding a possible one

 

[Venus]

we both have shore power & no galvanic isolator. Next door is a live aboard & I keep a dehumidifier running so there may be a problem. I'm lifting out for a couple of months so the immediate problem goes away next week, but I may need to do something before I launch next spring.

 

[VicS]

Yes it is not really a short term problem more of a potential long term one. Fitting a galvanic isolator is a sensible precaution if you are normally connected to shore power however.

I assume you have a "proper" shore power installation on your boat with the negative side of your 12volt system and anodes etc connected to the earth. If you only have a lead to supply the dehumidifier or battery charger then the problems should not arise and you should not need the galvanic isolator. Hardly practical to fit one anyway.

Take a look at the anodes (and other underwater metal bits) when you are lifted out for excessive wastage of the anodes or signs of corrosion of other bits eg pink looking brass or bronze bits.

 

[fireball]

Question:
If you isolate the shorepower from the boat - so no earth connection through to the anodes (or other underwater bits) then you shouldn't need a galvanic isolator?
Not ideal maybe - but a short term solution - still advisable to have an RCD breaker in, but you can get 13amp plug in ones that you could then plug the dehumidifier into.

 

[VicS]

[ QUOTE ]
If you isolate the shorepower from the boat - so no earth connection through to the anodes (or other underwater bits) then you shouldn't need a galvanic isolator

[/ QUOTE ] Yes that was the logic behind the sentence, in my post, beginning, "If you only have a lead to supply ........"

To get the sort of problems that are caused by boats connected together via the shorepower earths you need a circuit, through the wiring, from the underwater bits on one boat to the underwater bits on another. Break that circuit somewhere by pulling a plug or by not having the underwater bits connected to the earthing sytem then you should stop the problem. However the recommended practice is for the negative side boats 12 volt system to be connected to the shore power earth which may mean that some of the under water bits become connected to is as well.

RCD's are vital when mains electricity is taken on board. You should have your own, in addition to the one on the pontoon supply, which you should test periodically with its test button and even consider having it fully tested, including its speed of response, from time to time.