Does this anode need replacing?

M

mbailey

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I bought a boat last June and am just getting it ready to go back in the water for the new season. Am not sure if I need to replace this anode (or indeed how long they should last - I guess it differs depending on the location).

I would guess that this anode has been on for at least two years. Is it good for another season?

Martin B
 
I would not discard that (unless it has gone from new to that condition in a very short time). It still has more than 50% of the zinc remaining.

I cut them back to bare metal using an angle grinder and a twist-knot wire brush.

The founder of Colman's Mustard Ltd used to say that he made his fortune out of what got left on the side of the plate. I reckon anode makers, MG Duff, make their money out of what gets chucked in the boatyard skip ;)
 
Probably OK, yes. Until you've chipped off the white deposits, you won't be sure how much metal is left - but it looks promising for at least one more season. Pure zinc is pretty tough stuff and I've used a welder's chipping hammer in the past.

Rob.
 
Will the boat be moored in a different place to the previous berth?

If in a marina, some are worse than others for anode erosion.

Better safe than sorry?
 
mbailey said:
I bought a boat last June and am just getting it ready to go back in the water for the new season. Am not sure if I need to replace this anode (or indeed how long they should last - I guess it differs depending on the location).

I would guess that this anode has been on for at least two years. Is it good for another season?
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I've just had one that size and condition replaced with a new one one twice the size ... but that's because access to the back of it is appalling, a skinny wee engineer was to hand and I would rather not have to worry about it again for as long as possible. If those aren't issues for you I'd have thought there would be a year or two left in yours - as others have said.
 
Baddox said:
I’d be wary about using the wire brush at the high speeds an angle grinder runs at. Any wire breaking off will be thrown at some speed into the first thing it hits.
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I've been using wire brushes in grinders for years. Three tips:

  1. Use the proper brushes, made for use at 14,000rpm. Those for electric drills won't do - even if you can work out a way to fit them.
  2. Change the brush when the wires start coming out. They sting a bit if they hit you through cloth, and rather a lot more if they hit bare skin.
  3. WEAR GOGGLES
 
You do not know how long that anode has been in the water so the best step is to replace it now. That way when you next lift out you will have an idea of how long they last and if erosion is slow you will be able to re-use the anode you currently have and which still has meat on it. So it wont cost you anything long term.

Risk is you could be looking at just 3 months erosion and putting the boat in the water could leave you with no anode during the season - you just dont know.
 
Replace it now ..as Bosun Higgs say's you do not know how long it took to get to where it is. However, another concern would be that erosion may have occurred around the mounts...a bit more and it might fall off in the near future well before the remaining bulk has eroded.
 
Ricd said:
Replace it now ..as Bosun Higgs say's you do not know how long it took to get to where it is. However, another concern would be that erosion may have occurred around the mounts...a bit more and it might fall off in the near future well before the remaining bulk has eroded.
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Good point. When I had Jumblie's anode replaced (I am too fat to get to the mounting point inside myself) the stud just fell to bits ... a new anode on that would not have stayed on long. Which, quite apart from lack of electrolytic protection, could have given me an embarassing 1/2" diameter hole well below the water line...
 
Baddox said:
I’d be wary about using the wire brush at the high speeds an angle grinder runs at. Any wire breaking off will be thrown at some speed into the first thing it hits.
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Thanks for your concern but I'm not talking about the kind of thing you would use in a Black and Decker drill!

As Ubergeekian says, you must use the proper brushes designed to be used with an angle grinder. And ensure that the safe operating rpm stamped on the brush is not less than the angle grinder's rpm - and use goggles.
 
Skysail said:
Will the boat be moored in a different place to the previous berth?

If in a marina, some are worse than others for anode erosion.

Better safe than sorry?
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Yes, currently it's on the Thames. We will shortly be moving it round to North Fambridge.

I think I'll err on the side of caution and replace it. As you say, at least I have some sort of gauge then...

Thanks for all the replies.
 
mbailey said:
Yes, currently it's on the Thames. We will shortly be moving it round to North Fambridge.

I think I'll err on the side of caution and replace it. As you say, at least I have some sort of gauge then...

Thanks for all the replies.
Click to expand...

Here's a thought - if your boat was kept in a more fresh water environment like the thames, are not anodes for fresh water made of a different metal? I bought my boat from a guy in the Netherlands who kept it on the IJsselmeer, occasionally venturing into the North Sea. The anodes were a much lighter metal, apparently designed for fresher water. I replaced them with heavier zinc ones before launching in the sea here in the UK.
 
Ricd said:
Magnesium
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Yup - remember now, I was told by the seller that the lighter anode was magnesium. Point is, if the anode in the OP photo is magnesium, it will not last long in salt water - so strengthens the case for replacing it. However, it does not look like eroded magnesium, has the look of eroded zinc.
 
Zinc for salt water, but it becomes coated in oxide (carbonate ?) in brackish or fresh water that renders it ineffective.

Aluminium ( actually an alloy containing zinc and indium) for salt water or brackish water but not fresh.

Magnesium for fresh water, but it is far too reactive for salt or even brackish water.
 
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