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Hanging anodes


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Has anyone fitted hanging anodes to their boat? Where did you make the connection?

 

Background:

 

Looking to move a boat onto an end-on-to-pontoon, side-by-side mooring with all boats on shore power. So

boats      -> |||||||[occasional finger, not many]||||| <-more boats

pontoon -> ______________________________________

 

So, whatever GI etc I have still plenty of scope for 'current leakage' around the hull. Boat is 70ft with only 4 anodes (one on each 'corner' so to speak). Boat yard agree it could do with more but don't want to weld onto the sides due to the spray foam insulation. So, we've agreed to replace the existing anodes, welding onto the bars there, and fit a few along the centre line on the baseplate.

 

Would like to try a hanging anode or to on each side. Thinking they could be suspended from the roof finger rail like fenders to be easily lifted for cruising but not sure where best to make the connection. Could scratch off a little paint on the underside of finger rail and clamp on but feels wrong to be taking paint off! Could potentially add a connection to a window frame? Any better ideas?

 

Thanks!

Edited by TheMenagerieAfloat
wobbly spelling
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Many NBs are now having the anodes bolted onto the hull to avoid welding, (this has always been the normal method for lumpy-water boats - particularly GRP) and to make it easier to replace next time.

A bolt is run thru' from the inside and a nut wound down the bolt clamping the hull in between -  leaving a 'stub' of bolt, anodes then mounted onto the stub, and clamped in place with another nut.

 

With regard to 'hanging anodes' you need to make sure that you have a good electrical connection so paint will need to be removed, alternatively drill thru the cabin side / handrail or wherever and use a bolt in a similar method to that described above.

 

You can test if you have continuity by using a meter set to 'ohms'. Touch one probe onto the hull and one to the anode, if the reading is Zero then you have a good connection.

 

You can just see the bolt protruding in this picture (down and to the left of the toilet flush inlet pipe)

 

And with the anode in position.

 

The 'bolt' is electrically bonded with the metal of the toilet inlet sea-cock

 

 

17-10-19e.jpg

20191017_135026.jpg

Edited by Alan de Enfield
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40 minutes ago, TheMenagerieAfloat said:

 Boat yard agree it could do with more but don't want to weld onto the sides due to the spray foam insulation. 

 

The amount of welding involved in attaching an anode won't do significant damage to the sprayfoam.

 

Edited by David Mack
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1 minute ago, Alan de Enfield said:

Just get your waders on (or lean over the side) with a spanner, remove the old bits of anode, bolt a new one on.

Yep. I had to do this a few years back. The yard had put the boat back in early, neglecting the fact that the 2 front anodes were still on the ground by the boat. Luckily the weed hatch was in. Top tip. Tie the spanner onto your wrist if you ever need to do this.

 

Ask me how I know, go on, go on....ask me!

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31 minutes ago, system 4-50 said:

Have your hanging anodes made long and hollow and they can double up as wind chimes.

Never! That might disturb the coots in the tyre I'm fitting (in addition to fenders and specifically for the purpose of water fowl nesting).*

 

*And you don't know that I'm not even joking...

29 minutes ago, David Mack said:

 

The amount of welding involved in attaching an anode won't do significant damage to the sprayfoam.

 

Ooh, super-interesting, thank you. But doesn't make me brave enough to insist they do it given how much fit-out there is on-top of the foam making 'fire watch' trickier...

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Re-bolt-on ones thank you all - the pictures help lots. I'd seen some where there was (I think?) a welded on sort of holder/set of bolts with just lozenge shaped anode-ish parts bolted on and I was a bit concerned you were reliant on continuous supply of exactly the right sized anodes and also welding in the first place. The single bolt ones get around both those things ?

Making the connection on the inside might be good too actually. I have one capped little pipe in a hole (it is a couple of inches along from, and the same size and at the same height as a used outlet but the other side of a bulkhead - suspect a drilling error during fit-out TBH) which I could easily un-cap to pass a cable through.

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8 minutes ago, TheMenagerieAfloat said:

Making the connection on the inside might be good too actually.

You do not need to 'bond' the component parts if you have a steel hull.

My cruiser components are bonded as the hull is GRP so there would be no continuity between the sea-cock and the anode without a physical connection (a length of copper wire terminated on the sea-cock at one end and the anode fixing bolt at the other)

 

I have 11 below water line 'holes' (sea cocks) that are all bonded and, of course, the two prop shafts.

 

 

Edited by Alan de Enfield
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41 minutes ago, Alan de Enfield said:

You do not need to 'bond' the component parts if you have a steel hull.

My cruiser components are bonded as the hull is GRP so there would be no continuity between the sea-cock and the anode without a physical connection (a length of copper wire terminated on the sea-cock at one end and the anode fixing bolt at the other)

 

I have 11 below water line 'holes' (sea cocks) that are all bonded and, of course, the two prop shafts.

 

 

I was thinking I needed one connection - 'wire from anode to some part of hull' - and then it wd hang in the water near the hull?

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4 minutes ago, TheMenagerieAfloat said:

I was thinking I needed one connection - 'wire from anode to some part of hull' - and then it wd hang in the water near the hull?

Yup - that's the way, clipit / screwit / boltit to the handrail and "Richard is your Fathers brother"

 

You do realise they are quite small and very expensive £88 for an 800g version)

 

 

https://www.asap-supplies.com/anodes/mooring-hanging-anodes/mgduff-magnesium-hanging-anode-md57-812129

 

If you do buy one (or try to make one up) remember to buy a MAGNESIUM anode (for fresh water) Aluminium is for 'Brackish' water and ZINC for Salt water.

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Yep. (And do appreciate the size/cost thing doesn't help either.) 

 

Fortunately the only acces to mooring where they will be used wd be via non-moored boat into small, very overlooked, basin (with very limited pre-booked visitor mooringings the other side of razor wire to mine) or via swimming. Then walking along gunnels of my boat immediately adjacent to two others. All of us liveaboard. 

 

I may pop them into a scruffy bag / under an inverted plant pot or smthing when they sit on roof for cruising. 

 

 

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  • 1 month later...

My mushroom vents are already screwed on to my roof! I'm not sure why this hadn't occurred to me before... If I unscrew one of the screws pop the little loop on this https://www.asap-supplies.com/anodes/mooring-hanging-anodes/mgduff-magnesium-hanging-anode-md57-812129  around it and screw it back in that should get me the anode on without damaging any existing paint work etc.

If I don't take the mushroom vent off (literally just one screw out and back in again with vent in situ) I presumably won't need to reseal? Or do people put silicone (or...?) over each individual screw? Not an issue either way, just not done before.

 

Thanks!

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1 minute ago, system 4-50 said:

Great idea.  Should reduce the corrosion on your mushroom vents.  :)

Are we saying mushroom vent screws won't connect to steel of boat?

 

I mean, I appreciate this isn't an idea that will appeal to all but wd genuinely appreciate opinions on efficacy/feasibility given that I'm going to try something like it anyway.

Edited by TheMenagerieAfloat
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Not really. Just trying to say in the gentlest possible way that its a daft idea, without my having any scientific evidence to justify that belief.  On the one hand, since its you, I would suggest that you accept that you're doomed.  On the other hand, if it were me, I'd be very anxious about my neighbours in the marina collandering my boat, and that's why I don't moor in marinas except as a last resort. 

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Ah, but you see, I *like* people. And choose to be around them for education, employment and so forth.

I am undoubtedly doomed. But wish the hull of my non-cruising boat to stave off the inevitable for as long as possible (it is currently, in at least the n places the survey looked at, within tolerances for 'new' steel despite age).

Barley recollected physics tells me I'm probably OK but limited relevant engineering experience means I value others'.

  • Happy 1
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