Anodes on cutless bgs.

[Gordonmc]

Have just managed to rebuild my cutless bearing. Bought the closest size bearing I could get the a 1 and one-eighth inch shaft and a friend turned the brass liner down and also took a few thou off the internal diameter of the housing to get rid of ovalling. Now united and looking good.

Luckily pinking of the housing bronze was found to be surface only, which brings me to today's question - what to do about protection. The arrangement had been oblong anodes mounted on either side of the deadwood, actually touching the housing where it screws onto the sterntube. No wiring in evidence.

The problem is that in that position the anodes blocked up holes which allow water ingress to the bearing itself for lubrication either side of the housing .

Should I relocate the anodes and wire to the bearing? If so can I get away with a piece of domestic 2.5 copper wire epoxied to the hull with anti-foul over? I don't want to link to the main hull anode which is wired to the engine.

I have had the new propshaft made slightly longer to give room for an anode but I am assuming the shaft will be isolated from the cutless bearing and sterntube.

Any thoughts out there?

 

[johnlilley]

Hi
beware wiring any anodes, particularly to the stern gear as it is not uncommon for the chemicals created at the point of contact of anode and metal item to be protected to attack and destroy the timber surrounding these parts. In particular the deadwood internally around the stern tube exit and the planking at the anode securing point. A common giveaway is the build up of soft crystalline compound similar to battery terminal sulphating around the connecting wires.
Regards
John Lilley

John Lilley, John Lilley & Associates, Web site www.seasurveys.co.uk for osmosis /timber problems

 

[Peterduck]

A couple of points which I would like to make:
1. Don't over-anode; a single one should do the trick.
2. Make the best electrical contact that you can between the bearing housing and the anode. If you cannot actually solder the ends of the conductor to the anode and the housing, lay a patch of solder on to the housing where the conductor is to be attached, and also on the conductor itself. The solder will not corrode or tarnish like copper will.
3. A narrow strip of copper sheet is a better conductor than wire, or at least it is commonly used as a conductor for anodic protection. It can be nailed to the plnking or deadwood. If it has to change direction, fold it over so that a "bend" is formed.
4. The effects mentioned by John Lilley can be avoided by putting a plastic separator betwen the anode and the planking / deadwood. On my boat I use short [about 1/4" - 3/8" long] lengths of a thick-walled plastic tubing around the screws to form these spacers.
Peter.