Shaft anodes

[mbird]

I am currently changing the zinc anodes on the new boat for aluminium. At the moment she only had a pair of hull anodes and one on each trim tab. I am intending to also put shaft anodes on. I just wondered if there was any comment about this? The P brackets and props are bronze, and the only place I can see any evidence of a bit of corrosion are some green crytalline growth on the tips of the prop blades and on the rudder stock cases. Also, where along the shaft is the best place for shaft anodes; nearer the P bracket or nearer the gland seal?

[Antares_9]

Shaft anodes are for low speed cradt really Mark, have a look at the MG Duff site, they will have replacement prop nuts which takes a cone shaped anode, a much more elegant solution as they are in direct electrical contact and it is the props that require most protection because of possible dezinctification and ensuing big bills, also the clamp on shaft ones can come loose and even put high speed shafts out of balance.

http://www.mgduff.co.uk/mgduff-product-catalog/The+%91Martyr%92+range/Martyr+Prop+Nut+Anodes/

[senator]

They will also use more fuel and slow you down too Mark

[wayneakp]

Hi Mark

I too changed the anodes for Ali on Black Diamond.

She does not have shaft anodes. The stern gear is all bonded back to the anodes so all I did was check that was in place and secure. The shafts are also bonded through the drivetrain - there should be a link either side of the rubber coupling to contiune the bond. If you are worried you could also put on a shaft "Electro eliminator" - I know asap do them but as Baz will tell you a strong tide makes them squeek at night!

http://www.mgduff.co.uk/leisure-craft/f ... ectro.html

I am sure you know but the thruster is also likely to have its own anode.

Wayne

[mbird]

I'm glad I asked the question about the shaft anodes then!

I think I'll investigate the Martyr ones first. There doesn't appear to be any cross bonding on the shaft that I can see, so it may be best for the props to have their own protection. What I can't tell is what size I need so I think I'll contact MG Duff. Also, I can't tell how you lock the replacement shaft nut in place, as the normal locking tabs clearly won't work on a flanged nut.

[pks1702]

I ran a shaft anode for one season Mark and never felt comfortable with it. Kiki has a prop nut that being Turkish I could not find a replacement for quickly enough before she was dropped back in so I ran a shaft anode as a very last resort. I was paranoid the wear would allow it to slip and slide back to the P bracket.

As it turned out on lifting it had stayed in place and our yard machined me a prop nut to fit for when she went back in.

The point Ian makes on speed & fuel is valid but that goes for Rope Cutter too I know which one I won't forgo.

[Guest]

A multimeter continuity test between your prop and hull anodes will tell you if you have cross bonding. Also worth checking all p bracks and skin fitting to anodes whist your at it. I found a pair of jump leads attached to the anodeds help with length and a lump of silver foil in the other end to attach The multimeter lead to the jump lead.