Galvanic Isolator

[Genie]

Hello all
As a novice to boating, I have been told that fitting a galvanic isolator to my boat (with shore power in a marina) will help reduce corrosion and preserve anodes.
What is the feedback on these gadgets? Are they worth the money or is the benefit negligible?
Any tips advice greatly appreciated!
Rob

 

[adrianm]

If your boat is made of steel then it's a "must".

I don't really know enough about GRP or wooden boats to comment on them.

 

[rickp]

A galvanic isolator can certainly help - and with the cost of zinc going through the roof probably a good idea. A dig with google will show you how you can make your own - its just a couple of heavy duty diodes, I think. (Though of course - if you're unsure - best buy one and have someone competant install it for you).

Better than a galvanic isolator is an isolation transformer, possibly even one that uses switch-mode technology (as they're a fair bit lighter than the transformer based ones) - but they are considerably more money.

Rick

 

[Genie]

Its a GRP hull, 22ft, volvo Gxi duoprop.
Thanks
Rob

 

[Genie]

Thanks Rick
I had not heard of one of those - if I get anything fitted it won't be me as unfortunately i'm the kind of person who nails his won hand to the wall putting up a picture, and my medical insurance may not extend to electrocution/combustion!
It's just that as soon as I mentioned my shore power, a few folk started sucking in air through teeth and saying an isolator would be a 'must have'.
Thanks for the feedback - it is appreciated!
Rob

 

[msimms]

It is worth it, I went from 80% anode wear pre galvanic isolator to about 10/20% wear post. This was on the bar and triangle anodes on the legs and trim tab anodes. The ring anodes did not wear nearly as much but were still down to about 30% left. This year I've only needed to replace the ring anodes. I also try and make a point of disconnecting from shore power when we're not onboard.

 

[ostria]

Yes do fit a galvanic isolator or even better an isolation tranformer. Makes a great difference for me as well!
And as mentioned before unplug your boat from shore power each time you leave. /forums/images/graemlins/wink.gif

 

[jimmy_the_builder]

Hi Rob

This was discussed a little while ago - have a look here. I've got a galvanic isolator on my boat and I have definitely noticed a difference. I'd recommend getting one.

Cheers
Jimmy

 

[DavidJ]

Sealine and probably all the other major manufacturers fit them as standard on mid size boats so I guess they must be worth it. Best bet is not to leave the boat with shore power on unless you need it for dehumidifiers or engine heaters.

 

[Gumpy]

Given the choice go for an Isolating transformer.
there are some circumstances where if you have electronics on board that has switch mode power supplies ( PC, TV, Video etc) the RF that is dumped on the earth lead by the filters in the power supplies can cause the GI to go into conduction and thus be useless.
Note I am NOT talking about AC as this can be bypassed by a capacitor.
Also be wary of certain isolating transformers that have the interwinding screen connected to the boat earth, if there is a fault on the shore side within the transformer case it can cause the whole boat to become live. If anyone is intereseted in which one ( its a well known make) PM me, I have named them on several public forums but not sure if it would be allowed here.

Julian

 

[Genie]

Thanks very much for the tips and advice everyone - very useful and I will certainly look to fit something, as the benefits seem to be quite noticeable and worthwhile.
Cheers!!
Rob

 

[KevB]

Mark, got a new boat yet?

 

[msimms]

It's getting closer!

Ours went through the survey yesterday with only a couple of cosmetic items picked up. The surveyor was very complimentry about her which was nice.

Survey due on the new one on the 8th Feb, if all okay the new electronics and heating will be fitted before delivery to Port Solent for sea trial end of Feb.

If everything goes according to plan we should have her on the berth first week of March.

Saw your out now - the copper looks to have stood up well

Cheers

Mark

 

[Frontier]

I fitted new anodes in April they were virtually gone in October. I was shocked, so I fitted a GI. So far so good, but its early days yet.

I hope it works as I keep heating and a humidfier on during the winter. I dont know why the anodes went so quick in the summer with less electrics permanently on, although I think I often left the engine power isolators on when I was onboard, so all the gadgets on the helm station would work. That possibly caused erosion of the anodes.

If you done get around to if for a while PM me in the future and I will let you know if theyhave done any good.

 

[PCUK]

Would you like to elaborate Adrian. I have had my steel boat for 21 years and never used an isolator. Anodes last for years and there is no hull corrosion.
I only have shorepower on when I am on board. not continually.

 

[adrianm]

[ QUOTE ]
Would you like to elaborate Adrian. I have had my steel boat for 21 years and never used an isolator. Anodes last for years and there is no hull corrosion.
I only have shorepower on when I am on board. not continually.

[/ QUOTE ]

It's something every book I ever read about steel boats recommends and the dutch yard that built my hull agreed. I have an isolation transformer.

If you've only every used your boat in properly wired marinas then I doubt you'd see any problems especially as you only have shore power plugged in when you're on the boat. Given the amount of money it costs to replace the batteries on my boat (over 20 of them) I prefer to keep the chargers going.

I suppose it's one of those things that we're all happy doing our own way. My boat might be fine without an isolator but I'd rather not chance it.