Fitting a hull anode

[eddystone]

Sorry this may be idiot question but I've never changed an anode. Do you need 2 people to do this - one inside the hull stopping the top nut form turning while you tighten the other end from inside the boat - or are they self tightening!??

 

[chrishelen]

I changed my through hull anode last year, it was held on by two rusty bolts which I found easier to cut off with a angle grinder rather than struggle with the bolts, it is much easier with a extra pair of hand when doing up the new bolts, but I was on my own so I used mole grips inside the boat.
Good luck.

 

[MoodySabre]

It is certainly much easier with two. Once the anode is bolted on the studs then it just an easy job for someone to push it up the holes (filled with Sika) whilst you do up the top nuts. They are not self tightening.
Good guide to the order of things http://www.mgduff.co.uk/leisure-craft/fitting-instructions/fitting-bonding.html

 

[eddystone]

thanks

 

[l'escargot]

The studs should be fixed through the hull with their own nuts inside and out so they don't move (and maintain a seal against leaks). The anode is then held onto the studs with it's own nuts.

 

[CFarr]

The studs should be fixed through the hull with their ownbolts inside and out so they don't move (and maintain a seal against leaks). The anode is then held onto the studs with it's own bolts.

+1

 

[VicS]

thanks

I think you should read the fitting instructions on MG Duff's website as suggested by Moody Sabre


They do not suggest fitting the anode to the studs first!

http://www.mgduff.co.uk/leisure-craft/fitting-instructions/

 

[Kwik Decision]

I would also ask the question do you need a hull anode? What is it bonded to? What is it protecting? I got rid of mine, as it wasn't bonded to anything, and there is half a chance you could do the same.......

 

[eddystone]

I would also ask the question do you need a hull anode? What is it bonded to? What is it protecting? I got rid of mine, as it wasn't bonded to anything, and there is half a chance you could do the same.......

Its bonded to an engine mount - I don't really understand electrolysis (or electrics for that matter) so I just try to replicate what's there on the basis that the previous owner did!

 

[roblpm]

Actually maybe someone could explain how they are supposed to work. I put an anode on my prop shaft last year which is very worn so i will replace it. However the hull anode hasnt worn at all.

Is something bad going to happen??!!

 

[Tranona]

Its bonded to an engine mount - I don't really understand electrolysis (or electrics for that matter) so I just try to replicate what's there on the basis that the previous owner did!

It is there to protect your prop from dezincification which might occur because of the difference in potential between the shaft and the prop. The anode needs to be electrically connected to the shaft. Bonding it to the engine may achieve that. If the anode is depleting that suggests it is working as it is the zinc in the anode that is eroding rather than the zinc in your prop.

 

[Tranona]

Actually maybe someone could explain how they are supposed to work. I put an anode on my prop shaft last year which is very worn so i will replace it. However the hull anode hasnt worn at all.

Is something bad going to happen??!!

See my reply above. Your shaft anode will deplete first because it is closer to the two components it is protecting. If your hull anode is not depleting it suggests it is not properly bonded or the prop anode is sufficient on its own.

 

[Kwik Decision]

Actually maybe someone could explain how they are supposed to work. I put an anode on my prop shaft last year which is very worn so i will replace it. However the hull anode hasnt worn at all.

Is something bad going to happen??!!

If I were you I would remove the hull anode, as it isn't doing anything, and make sure you replace the shaft anode every year. If you are concerned the shaft anode isn't big enough for a season on it's own, then fit two.... If you do a search on here you will find lots of advice on fitting shaft anodes. It is important that they are secure, because if they work loose they will clatter about on the shaft, and (as the electrical contact is reduced) will be less effective as an anode.

 

[alahol2]

See my reply above. Your shaft anode will deplete first because it is closer to the two components it is protecting. If your hull anode is not depleting it suggests it is not properly bonded or the prop anode is sufficient on its own.

The best way to check if the hull anode is capable of doing anything is to measure the resistance (using a multimeter) between the anode and the prop. There should be a relatively low resistance. If there is no continuity then the anode will be incapable of protecting the prop. You then have two options, make the connection between prop and anode or remove the anode and rely on the shaft anode.

 

[eddystone]

The studs should be fixed through the hull with their own nuts inside and out so they don't move (and maintain a seal against leaks). The anode is then held onto the studs with it's own nuts.

Does that mean you can leave the nuts inside the boat alone if its not a through bolt (assuming its one nut plus locking nut) and just take off outside nut holding on anode - its pretty corroded so I was thinking of using my 24" breaker bar.

 

[VicS]

Does that mean you can leave the nuts inside the boat alone if its not a through bolt (assuming its one nut plus locking nut) and just take off outside nut holding on anode - its pretty corroded so I was thinking of using my 24" breaker bar.

The correct studs have a fixed square plate that goes on the outside if the hull. Inside nuts and locking nuts should hold it secure allowing the anode retaining nuts to be removed from ousde and the new anode fitted

Follow the links two of us have already given you in this thread to the fitting instructions on MG Duff's website and all will be clear!

Dont forget the new backing pad.


If the studs are knackered or not the correct type replace them........

 

[l'escargot]

Does that mean you can leave the nuts inside the boat alone if its not a through bolt (assuming its one nut plus locking nut) and just take off outside nut holding on anode - its pretty corroded so I was thinking of using my 24" breaker bar.

Yes. The new anode should come complete with two new nuts with star washers to hold them and a plastic backing pad to insulate the anode from the hull. All the new components should be used to replace the old ones. If the nuts are seized on to the stud I would use a nut splitter rather than getting too enthusiastic with anything else otherwise you could turn the studs and damage the seal, giving yourself more work.

 

[eddystone]

Yes. The new anode should come complete with two new nuts with star washers to hold them and a plastic backing pad to insulate the anode from the hull. All the new components should be used to replace the old ones. If the nuts are seized on to the stud I would use a nut splitter rather than getting too enthusiastic with anything else otherwise you could turn the studs and damage the seal, giving yourself more work.

Have to find another solution - no access for nut splitter as nut is recessed in dome of anode. Can't use heat either as risk to GRP hull.

 

[l'escargot]

Have to find another solution - no access for nut splitter as nut is recessed in dome of anode. Can't use heat either as risk to GRP hull.

Can you get hold of something like a Dremmel with a metal cutting disc and take off one side of the nut, cutting into the anode if need be?

 

[eddystone]

Ah I do have one of those yes thats a good idea.