What to do with old anodes!

Nostrodamus

Nostrodamus

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www.cygnus3.com
After replacing a couple of anodes I was wondering what to do with the old ones as I hate throwing away something that may be useful.
Does anyone hang old anodes over the side when in a marina. Do they have to be connected anywhere in particular?
 
Nostrodamus said:
After replacing a couple of anodes I was wondering what to do with the old ones ... Does anyone hang old anodes over the side when in a marina. Do they have to be connected anywhere in particular?
Click to expand...
I've bought anodes for this purpose, so no reason why not. Mine are connected to the engine/saildrive.

Alternatively, you could re-cast them.
 
hi

i was thinking that the other day as i have a box full of old ones , they have gone very expensive and the boat yard is full of them lying around on the ground

how do you melt them and what do u use as a cast

adrian
 
duckingswan said:
how do you melt them and what do u use as a cast
Click to expand...

You need to separate Zinc (MP 420 °C, SG 7.1) and Aluminum (MP 660 °C, SG 2.7) using the SG. Measure the volume of the old anode by immersing in water, then weigh it. From this you can calculate the SG.

Aluminum is hard to melt using a simple furnace, but Zinc is OK. I built a furnace out of fire-bricks, fed by a large propane torch plus coal or charcoal. WARNING: do it in the open air, and don't inhale the fumes.

To cast it, make a mould out of fine sand dampened with PVA adhesive at 4:1. Ideally you should start with a wax model of the new anode, but you can often get away with a direct cast. Let it dry thoroughly before use.
 
Nostrodamus said:
After replacing a couple of anodes I was wondering what to do with the old ones as I hate throwing away something that may be useful.
Does anyone hang old anodes over the side when in a marina. Do they have to be connected anywhere in particular?
Click to expand...

If you are going to hang them over the side then connect to the thing you want to protect, in your case the saildrive. So Stainless wire to a bolt on the saildrive housing. However, means running a wire through the boat and over the side, plus on your boat (and many others with saildrives) it is not easy to suspend the anode close enough to the drive to be effective. Little value in doing it unless your saildrive anode has a short life, and the extra over the side may assist a bit. BTW won't do anything for your prop as that is isolated from the drive, so you have to rely on the prop anode.
 
duckingswan said:
how do you melt them and what do u use as a cast
Click to expand...

Fine, clean sand dampened just enough to hold its shape (think sandcastles, but you want to use the minimum amount of water). Tamp it down in a suitable container/bucket to make a base a few inches thick. Place a suitable former on the sand. Tamp more sand firmly around the former. Carefully remove the former and you will then have a cavity in the sand giving the shape of your final anode. Gently pour molten zinc into the sand mould. If you are wanting it to hang off a wire then suspend the wire in the zinc as your pour it. It solidifies quickly and can then be removed from the mould.

Can also be done to make a lead line.

But keep the water content of the damp sand as low as possible. Too much water and it is dangerously explosive when the water turns to steam. Just damp enough for the sand to hold the shape.
 
Another option may be to attach to the risers of your mooring, they may help to reduce the corrosion of the shackles and swivels, particularly if in a corrosive area as I am- lots of ww2 scrapped metals around my location on the Hamble.

ianat182
 
I strap two together attached to a stainless riser, then 4mm2 copper (above the water level) onto the bonding CCT. This s left dangling when on the home mooring.

I also cast pencil anodes for the engine using 22mm copper pipe with a stop end slipped over. Cast them about 50 mm long as the slag occupies the first 10mm. The finished anodes I turn in the lathe to 17mm dia x 37 mm long with a 45 deg cut at one end. The other I drill and tap M8 to suit the brass holder plugs.

I use MAPP gas turbo torch, and melt the zinc into the mould and keep that hot as well until the mould is full. Leather gloves and do not inhale the fumes. When they have cooled they slip out if the tube, and I get several from one piece if off cut copper tube.

Not sure what the finished composition is but they work a treat.
 
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