Prop anode disappeared.

[FairweatherDave]

Dried out to wipe the slime off my bilge keeler and to my suprise noticed my prop anode was gone. Nothing there. All that remained is the bolt. It was fitted new at the start of the season (April 23) so it is not wastage. I probably reused the old bolt and the new anode was the same as the old one (Solent Anodes). Any theories why or similar experiences? And how urgently do I need to fit another one? Presumably the shaft collar anode will give some protection. Thanks for any replies.

 

[vyv_cox]

When stainless steel bolts are used to attach anodes it often happens that the zinc or aluminium adjacent to the bolt is consumed rapidly. The anode can the fall off. The anode can be isolated from the bolts using varnish, washers, etc, or the bolts can be made of nylon, which is how my Bruntons anode is fastened

 

[coopec]

Precisely the same thing happened to me.

I fitted the anode while the yacht (Helen) was on the hard at Lancelin. Helen was transported to Two Rocks Marina and launched for the first time. (The anode was definitely bolted on when Helen was launched.

We motored Helen about 40klm to Hillarys Marina to get her rigged. When she was lifted out the brand new anode was gone but the bolt was still there. A guy who has been in boating all his working life (40 years?) insisted the anode had been stolen.

I am bewildered. I think there may have been a fault in the anode and it split or maybe a fault in the design.

The anode fits over the propeller nut then it is held in place by a bolt the screws in to the propeller shaft.

I think I better look at these two YBW threads.

Missing Anodes!

Prop shaft anode

 

[jwilson]

Has happened to me too: most years on liftout the conical prop anode is still there though a bit eroded. I always put a new one on anyway. One year nothing left - just the bolt. I also have a shaft collar anode.

 

[coopec]

When stainless steel bolts are used to attach anodes it often happens that the zinc or aluminium adjacent to the bolt is consumed rapidly. The anode can the fall off. The anode can be isolated from the bolts using varnish, washers, etc, or the bolts can be made of nylon, which is how my Bruntons anode is fastened

"the bolt is consumed rapidly."

In my case the s/s bolt was still there but the anode had gone

 

[rogerthebodger]

When stainless steel bolts are used to attach anodes it often happens that the zinc or aluminium adjacent to the bolt is consumed rapidly. The anode can the fall off. The anode can be isolated from the bolts using varnish, washers, etc, or the bolts can be made of nylon, which is how my Bruntons anode is fastened

The anodes on my steel hull are 316 stainless steel welded to the steel hull and in all the time boat afloat since 2009 no issue with anodes falling off

Different matter with shaft anodes the do erode quite quickly propeller is also stainless steel so no yellow metals involved

https://flic.kr/p/WooVJA

https://flic.kr/p/WM5MoM

 

[VicS]

"the bolt is consumed rapidly."

In my case the s/s bolt was still there but the anode had gone

Re read Vyv's post

He says, " the zinc or aluminium adjacent to the bolt is consumed rapidly."

 

[coopec]

Re read Vyv's post

He says, " the zinc or aluminium adjacent to the bolt is consumed rapidly."

WOW!

In a matter of a week or so? (Another AUD50 down the drain).

 

[Tranona]

Dried out to wipe the slime off my bilge keeler and to my suprise noticed my prop anode was gone. Nothing there. All that remained is the bolt. It was fitted new at the start of the season (April 23) so it is not wastage. I probably reused the old bolt and the new anode was the same as the old one (Solent Anodes). Any theories why or similar experiences? And how urgently do I need to fit another one? Presumably the shaft collar anode will give some protection. Thanks for any replies.

What propeller is it? Or is it a prop nut anode as in post#6?

 

[FairweatherDave]

Fascinating, glad I posted. Sounds like a blob of sealant on the bolt or maybe some duralac?
My prop anode is this one
Beneteau type zinc anodes for conical propeller nut. Shaft sizes 22mm to 60mm
So strictly speaking a prop nut anode

 

[Tranona]

Fascinating, glad I posted. Sounds like a blob of sealant on the bolt or maybe some duralac?
My prop anode is this one
Beneteau type zinc anodes for conical propeller nut. Shaft sizes 22mm to 60mm
So strictly speaking a prop nut anode

Yes, that has relatively small bulk compared with say a hull anode and is directly connected to the prop and shaft so will disappear fairly quickly. Then the shaft anode will take over. Nothing to worry about, it did its job. A hull anode will last much longeer because of its bulk, but if you can go a season with just the nut anode going and little of the shaft one then no reason to change.

 

[coopec]

Yes, that has relatively small bulk compared with say a hull anode and is directly connected to the prop and shaft so will disappear fairly quickly. Then the shaft anode will take over. Nothing to worry about, it did its job. A hull anode will last much longeer because of its bulk, but if you can go a season with just the nut anode going and little of the shaft one then no reason to change.

Tranona
My anode is as in #3 (above) I assume the zinc(?) is "consumed" adjacent to the SS bolt so that the anode can fall off the shaft and disappear.

Would the answer be to use (say) a Nylon bolt?

 

[vyv_cox]

Tranona
My anode is as in #3 (above) I assume the zinc(?) is "consumed" adjacent to the SS bolt so that the anode can fall off the shaft and disappear.

Would the answer be to use (say) a Nylon bolt?

My Bruntons anode are similar to those shown in the link in post #10 but only two bolts. It seems to vary according to the exact model: mine come with nylon bolts but others come with stainless. No idea why this shoul be but my anodes easily do two years with a painted prop.

 

[Bobc]

If you paint some Hammerite on the bits of the anode adjacent to where the bolts are (before fitting it, and let the paint go hard first), you create an insulation layer between the anode and the screws and the anode then wastes elsewhere and not around the bolts.

 

[Tranona]

Precisely the same thing happened to me.

I fitted the anode while the yacht (Helen) was on the hard at Lancelin. Helen was transported to Two Rocks Marina and launched for the first time. (The anode was definitely bolted on when Helen was launched.

We motored Helen about 40klm to Hillarys Marina to get her rigged. When she was lifted out the brand new anode was gone but the bolt was still there. A guy who has been in boating all his working life (40 years?) insisted the anode had been stolen.

I am bewildered. I think there may have been a fault in the anode and it split or maybe a fault in the design.

The anode fits over the propeller nut then it is held in place by a bolt the screws in to the propeller shaft.

I think I better look at these two YBW threads.

Missing Anodes!

Prop shaft anode

View attachment 164895

That type of anode has limited bulk and I guess there is something going on that has caused it to go so quickly. Is that the only anode for the prop or do you have a hull anode to which it is bonded. Have you been on shorepower and is your engine and box electrically isolated from the shorepower circuit?

In answer to post#12 it is difficult to say whether a nylon bolt or painting the mating face for the bolt head would help. the Beneteau type that the OP is using has a thick end so quite a bit to go before the hole is as big as the head of the bolt so the anode comes off leaving the bolt. Not sure about the type that you have used but it looks in the photo that the end might be quite thin. The bolt head does not have to have electrical contact with the zinc for it to work, only the zinc in contact with the propeller so it may well be worth isolating the head from the zinc. however I would still be nervous about using such a small anode as the only protection for what I assume is quite large propeller.

 

[Plum]

Fascinating, glad I posted. Sounds like a blob of sealant on the bolt or maybe some duralac?
My prop anode is this one
Beneteau type zinc anodes for conical propeller nut. Shaft sizes 22mm to 60mm
So strictly speaking a prop nut anode

That is the same type of anode i have. Once the screw is tight i fill the counterbore/recess in which the screwhead sits with mastic. I found this prolongs the life but still only lasts 4 months. Other users have reported the same. I do have a hull anode too to ensure protection even after the prop nut anode has gone.

 

[blush2]

If you paint some Hammerite on the bits of the anode adjacent to where the bolts are (before fitting it, and let the paint go hard first), you create an insulation layer between the anode and the screws and the anode then wastes elsewhere and not around the bolts.

We used to do this on the three part anode on Blush's Volvo folding prop. It was a great way to use up all those little car touch up paints from years ago.

On the other hand, when we went off for a year to the Algarve, Canaries and Azores the anodes didn't need replacing.

 

[Thresher]

Dried out to wipe the slime off my bilge keeler and to my suprise noticed my prop anode was gone. Nothing there. All that remained is the bolt. It was fitted new at the start of the season (April 23) so it is not wastage. I probably reused the old bolt and the new anode was the same as the old one (Solent Anodes). Any theories why or similar experiences? And how urgently do I need to fit another one? Presumably the shaft collar anode will give some protection. Thanks for any replies.

I've recently lost the split ring anode from my volvo saildrive, it was 3 months old. Can't understand it, the last one was 3 years old and still had some life in it. It's a twin keeler and I'm just waiting to dry out to fit the replacement. This time I'll use loctite and check it regularly.

 

[FairweatherDave]

Thread update .....just dried out yesterday as before for a light scrub and a check of the prop anode.....so just over six months since last inspected, and there was barely anything left of the anode I had put on. Fortunately I had a spare but not in a position to experiment with mastic or duralac, I was stretching over from the dinghy above mud not water and didn't want to drop the anode, bolt or posh ratchet socket drive. It was messy enough as it was. Note to self : if drying out at East Head and you want hard sand to dry out aim for more like 3hrs before low water, definitely more than 2 hours . I couldn't get under the boat properly at all, maybe that was my unconscious intention!

 

[Plum]

Thread update .....just dried out yesterday as before for a light scrub and a check of the prop anode.....so just over six months since last inspected, and there was barely anything left of the anode I had put on. Fortunately I had a spare but not in a position to experiment with mastic or duralac, I was stretching over from the dinghy above mud not water and didn't want to drop the anode, bolt or posh ratchet socket drive. It was messy enough as it was. Note to self : if drying out at East Head and you want hard sand to dry out aim for more like 3hrs before low water, definitely more than 2 hours . I couldn't get under the boat properly at all, maybe that was my unconscious intention!

Oh dear, not nice working over mud, mut at least you did it! My prop anode does not last much beyond 3 or 4 months. I always keep a spare, and a spare fixing screw, on the boat.