Galvanic Isolator Are they worth fitting

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Doods

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Just had my boat lifted to have the bottom scrubbed and found that the anodes are totaly shot after 7 mths. Never had this problem before I changed boat and mooring. Any opinions on galvanic isolators are they worth fitting and what ones can you recomend.
All input welcom.
 
I am in the same marina as you and our prop anode lasted 3 months . The anode on the transom does about 7 months and I do have a Galvanic Isolator . I had the boat for 3 months with out it and the same time with it and it does not seem to have made any difference.
 
A well covered topic. People I know who have had them fitted say they are excellent. I have often thought about it like you but need more convincing!

My anodes last about 6 months so this seems like a good option. Boat is for sale so I have put off paying for the change.

Interested in other forum comments.

I also bolted on 2 more large anodes to the legs but this made no difference. They look good as new despite the prop anodes looking well shot.


CD
 
My boat has the 'Mercathode' system installed - it's disconnected.

I asked the Mercruiser agent to re-connect it. He said, 'I will if you want me to - and charge you for it - but they're a complete and utter waste of time - they don't offer anything by way of protection'. /forums/images/graemlins/confused.gif

Does this apply to all of 'em, or just the Mercruisers ?
 
I have 'Mercathode' on my BravoIII drives on my Sunseeker. For ome rason also not connected up!!

French Marine who do my engine servicig connected them up for free (all the wiring is there).

I am waiting for this season's lift out but burnt through anodes in about 4 months before having them on and can see new anodes have lasted 6+ months and still have meat on them.
 
Mercathodes slow the erosion of regular anodes in normal conditions.

They can't cope with an earth leak fault condition.

That's what a galvanic isolator stops - they are completely different things and I wonder if they are being confused on this thread?

The galvanic isolator goes in the shorepower lead earth. It allows a big (fault) current to pass so your boat is protected as it should be by the earth lead but does not allow small leakage currents to pass - the type that allows your anodes to protect the whole pontoon.

Note also the galvanic isolator does nothing whatsoever when not plugged into the mains.

The mercathode works all the time but uses power so shorepower is an advantage.
 
A galvanic isolator is more or less essential to prevent excessive wastage of anodes if you leave the shore power connected all the time. (Not necessarily in use just connected).

If you do not leave the shore power connected then it should not be necessary.

I doubt if there is anything to choose between what is available just get one that has an appropriate current rating. That is in excess of your main circuit breaker rating.

Surprised to hear that the Mercathode system is dismissed as useless. It and the similar Volvo system should take over from the sacrificial anodes and prolong the life of those while it is in operation at the same time as optimising the protection of the drive. It is vital to keep its own anode and the reference electrode clean and to observe the recommendations about not antifouling right up to them. It won't avoid the need for a galvanic isolator though.
 
Interesting comment. When I had my Tremlett 21 with a Mercruiser engine/outdrive at Cobbs in the days before they changed the all metal pontoons I was changing, I mean replacing the trim tab anode about every 2 - 3 months. I always knew when because the steering would be pulling to one side. Then I installed the Mercathode system and I never had to change the trim tab anode again, so I cannot understand your engineers statement, would be interesting to find out why.

Steve
 
I always disconnect my shore power when not on board. Iconnect the shore power lead straight to my dehumidifier and tube heaters via a piggy back rcd in the winter.It also pays to keep your stern away from metal pontoon piles etc.and not moor next to a steel boat.
 
[ QUOTE ]
I connect the shore power lead straight to my dehumidifier and tube heaters

[/ QUOTE ] Presumably then you do not have a "proper" shorepower installation. If you do not have the shorepower earth connected to all the metal work and the DC system ground as is recommended for shorepower installations then you should not have the corrosion problems that can occur with a proper fixed installation, but you fall a little short on safety aspects.
 
Just been reminded (by SB1) you have a S34, I think you will find that a galvanic isolator is fitted as standard, they certainly are on a S28.

Steve
 
Steve
Thanks for the advise on one being fitted on the S34. I cant find any details in my specs saying its been fitted, I will check next week end. I hope that I havent got one fitted then I can fit one and and save a fortune on anodes.
Thanks
 
Also at same marina, and have had anodes on for 2 years, with very little wastage, but then I'm dry berthed /forums/images/graemlins/smile.gif . That's one way to solve problem if small enough.

Isolator worth fitting if you keep shore power connected. If you don't, then that's not the problem, and it won't help.

Most chandlers sell 'em for about £80, I think. Can't see that there is going to be much to choose between any supplier, so long as rated for shore power current, presumably 16 amp.
 
Hi
Cannot answer your question about a S37, all I know is that a Zinc Saver 11 galvanic isolator is factory fitted to my S28 (2001 model) and all the others I have worked on, it is fitted in the end compartment of the aft cabin, on the bulkhead behind and above the hot water tank.
There is no mention of it in the S28 Owners Manual or the wiring diagrams so I would have a look around on your boat, you may well find you have one!

Steve
 
Steve
Not had chance to get down to the boat, But will have a good look around. I know that its not fitted on the Port side in the engin bay as I re-fixed all
the Hot water tank and pipes. It may be mounted on the STD bulkhead near the battery charger ?? but I dont remember seeing it. Thanks for the advice I will definately have a good look for it.

If anyone knows the location please give me a clue
 
Plug an extension lead into a socket and lead it back to the shorepower inlet.

MAKE SURE THE SHOREPOWER IS UNPLUGGED!!

Measure the resistance using a multimeter between earth on the inlet and earth on the extension lead.

If it is zero or near zero you have no isolator.
 
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