Changing Anodes

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Laundryman

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I bought my Beneteau Oceanis 3 years ago and have had it lifted and scrubbed regularly. Each time, the job has been done in my absence by the Marina. Each time, I've asked the Marina about the level of fouling and they've felt that it was nothing out of the ordinary. My next lift out is 24th July and i have arranged to allow 1 hour in the slings. Am i right in thinking that having not changed the anodes yet, they are probably due? I live 100 miles from from the boat so do I drive down to replace the anodes myself ( I've never done the job before ) or just get one of the companies on site to change them for me. I'm not bad mechanically but is there anything I should know about changing anodes should i decide to do it myself? Thanks Alan
 
Laundryman said:
I bought my Beneteau Oceanis 3 years ago and have had it lifted and scrubbed regularly. Each time, the job has been done in my absence by the Marina. Each time, I've asked the Marina about the level of fouling and they've felt that it was nothing out of the ordinary. My next lift out is 24th July and i have arranged to allow 1 hour in the slings. Am i right in thinking that having not changed the anodes yet, they are probably due? I live 100 miles from from the boat so do I drive down to replace the anodes myself ( I've never done the job before ) or just get one of the companies on site to change them for me. I'm not bad mechanically but is there anything I should know about changing anodes should i decide to do it myself? Thanks Alan
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Advice on fitting anodes on MGDuff's website might be of interest to you. http://www.mgduff.co.uk/leisure-craft/fitting-instructions/fitting-bonding.html
 
Anodes are normally checked annually and when to change depends on the extent to which they have depleted. Shaft anodes rarely seem to last more than a year so I would be concerned if I were you. It's often an expensive mistake to not have anodes checked and changed.

Yoda
 
You probably have only one anode on the end of the prop. Surprised if it has lasted 3 years. If you have a hull anode bonded to the stern gear then the combination of the two could well be OK. Best to see what you have before you decide. Both types are readily available and easy to change.

Might be worth buying the prop one in advance. The hull one is probably a pear shaped one which pretty sure the chandlery in PS will have in stock.
 
Nigel Calder's well-respected 'Boatowner's Mechanical and Electrical Manual' has clear guidance and advice on this topic. I strongly encourage you to get a copy PDQ ( Amazon ) and read up on his comments. I would then expect you will certainly want to see - and photograph - the condition of your existing hull, sterngear and engine anodes.

I suspect most would be surprised if there's any service life left in any of them after at least 3 years inattention. That being so, there is more than a passing risk of considerable damage to expensive components from electrolytic corrosion.... which may already have taken place. I further suspect that you will want to check the 'bonding' arrangements on your boat - or have this done for you by a reliable and competent tradesman.

One doesn't wish to be alarmist, but bad e-corrosion can - as Calder points out with examples - sink a boat, and has done.
 
As others have said, they seldom last more than a year so, even if the boatyard has changed them in the past, assume you need to change them this year. Is it a saildrive or shaft drive? Saildrives, the anodes just bolt on - make sure you have a range of spanners, screwdrivers and alan keys to cover all bases. Shaft drive anodes also bolt on but, as I discovered, almost to my cost, it is often necessary to apply a bit of force to get them to fit well round the shaft. Have a couple of heavy hammers, or a hammer and a brick handy - the shaft drive anode comes in two halves that clamp onto the shaft to form a ring - they tend to make them with the hole down the centre very slightly small so that, when fitted properly, they will get a good grip. The first time I changes one, I just put it round the shaft and tightened the screws. It was only after I had her put back in the water that someone asked me if I had given the two halves a good thump together with a pair of club hammers - which I had not. I was worrying about it for weeks - fortunately, the boat had to come out for some other maintenance and I discovered that the anode was beginning to work a bit lose. If yours is a shaft drive, fit the two halves together round the shaft, tighten the screw(s) a fair bit, then rest something heavy against one side and give the other a few good thumps to bed it down well against the shaft. If you don't fancy hitting something on your propeller shaft, I guess you could use something like a G-Clamp to squeeze the two halves together. However you do it, make sure it is well bedded onto the shaft, then retighten the screws.

If you don't get it adequately tight, it can slip down till it starts catching your P-bracket where it can cause all sorts of nastiness!
 
my anodes don't seem to erode as quickly as some of the posts above suggest. Very definite erosion takes place but they last more than a year. Mind you I'm on a swinging mooring so no mains electric or stray current from adjacent boats.
 
I notice that the anodes seem to erode first around any fixing screws/bolts, So I paint antifouling around the screw/bolt area (ca. cm.) I also fix screws/bolts in place with a good locking glue!
 
maby said:
As others have said, they seldom last more than a year so, even if the boatyard has changed them in the past, assume you need to change them this year. Is it a saildrive or shaft drive? Saildrives, the anodes just bolt on - make sure you have a range of spanners, screwdrivers and alan keys to cover all bases. Shaft drive anodes also bolt on but, as I discovered, almost to my cost, it is often necessary to apply a bit of force to get them to fit well round the shaft. Have a couple of heavy hammers, or a hammer and a brick handy - the shaft drive anode comes in two halves that clamp onto the shaft to form a ring - they tend to make them with the hole down the centre very slightly small so that, when fitted properly, they will get a good grip. The first time I changes one, I just put it round the shaft and tightened the screws. It was only after I had her put back in the water that someone asked me if I had given the two halves a good thump together with a pair of club hammers - which I had not. I was worrying about it for weeks - fortunately, the boat had to come out for some other maintenance and I discovered that the anode was beginning to work a bit lose. If yours is a shaft drive, fit the two halves together round the shaft, tighten the screw(s) a fair bit, then rest something heavy against one side and give the other a few good thumps to bed it down well against the shaft. If you don't fancy hitting something on your propeller shaft, I guess you could use something like a G-Clamp to squeeze the two halves together. However you do it, make sure it is well bedded onto the shaft, then retighten the screws.

If you don't get it adequately tight, it can slip down till it starts catching your P-bracket where it can cause all sorts of nastiness!
Click to expand...

Its a Beneteau which has the shaft coming out of a shaft log, so no P bracket and no exposed shaft to fit a shaft anode. The anode is a button screwed onto the end of the shaft aft of the prop. See my post above.
 
Okay, boat lifted today, report back on both anti foul and anodes. A year since the last lift and I've still not applied anti foul. It is now at least 4 years old. Today's fouling was a little slime, nothing else. Anodes replaced by marine engineer. Bonding checked by meter, okay. Prop anode well worn but still working, pear anode similar. Price of lift and scrub,plus hold in slings for one hour at Port Solent £99. Local marine engineers supplied, tested and replaced the anodes £59. I was expecting much worse! Thanks. Alan
 
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