Super Snoopy 050 9:42am, 11 February 2013
There's been a mini debate going on around the photo of my shaft anode and I thought I'd widen things out to see what big and little Achilles owners do about anodic protection.

On Snoopy (A24) when she had an outboard, there were no anodes. True, there were very few skin fittings, but the heads had bronze fittings that had been in place since manufacture, and showed no sign of erosion. When we fitted the inboard, we put a shaft anode on because other boats had shaft anodes and we didn't want to be left out. We changed that anode every two years.

On Super Snoopy (A9m) there are the original 33yo bronze skin fittings on the heads, sink and engine inlet. None appear to be eroded. The original engine has internal anodes that get replaced infrequently and a shaft anode that is changed every 2 years.

None of the skin fittings appear to be bonded to anything. Is this normal - what do you have on your vessels?
admin
NormanKlipspringer 6 years ago
Just to clarify - there are anodes on outboard motors.
busy home [deleted] 6 years ago
Carrie has two anodes on her prop shaft .... and a flexible coupling on the
gearbox , not wired over .... the engine is the original yse8 .. no internal corrosion , the anode was 75percent gone ..
Neil will give us ALLL the info Im sure ...
sailing bye1 6 years ago
Sailing Bye has a shaft anode (replaced every 2 years) a torpedo anode on the hull with 2 holding bolts terminating in the locker under the quarter berth. There are 2 skin fittings on the toilet (blakes) which are still acceptable according to the survey last November, but recommended replacement of the sink, sea water intake to the sink and engine intake. All skin fittings, keel bolts are bonded to the anode including the engine block.
The survey has also recommended a new propellor, the prop and shaft are not bonded, hence the shaft anode, assumed no electrical path through the gear box due to oil in the gear box.
Skykomish E29 6 years ago
we have only a small engine anode on our boat about an inch long that screws into the heat exchanger unit otherwise none whatsoever she has sat in a marina for three years with no apparent corrosion issues, however after speaking to the McDuff rep at the boat show I am going to use a hanging anode in future this literally hangs over the side of the boat on a cable that is attached to the prop shaft, this means no drilling holes in the hull and can be lifted out before leaving the berth
rothwell_neil 6 years ago
I have the following arrangement. A circular anode bolted to the prop shaft. after a full season virtually no loss and a clean prop shaft. I do antifoul the prop and only protecting stainless so doing very little. I also have a hull anode that is earthed to the engine but not the through hulls. This also does not seem to corrode and probably due to the fact that it is doing very little. This in theory should protect anything with a conductive path through the cooling water intake. I always turn off the intake when leaving so this won't work then. The engine has a screw in rod anode and this is slowly corroding so is working. I have indirect cooling so the only thing on the engine that needs protecting is the raw water passage to the heat exchanger.

The through hulls are all monel, original, are isolated and in good nick and I grease these every year.
Freebird 1011 6 years ago
We have a bit of a problem on Freebird. When we bought her she had no anodes fitted and no sign of problems with the 4 original bronze skin fittings or the prop, prop shaft or engine (Sole 17hp)
During last winters refit we added a shaft anode and a large pear anode to the hull which we bonded to the keelboats, skin fittings and engine. To our horror when lifting out last autumn the pear anode was completely gone leaving only the fixing plate. (Shaft anode only normal wear)
We have no shore power 220V whatsoever and live on a swinging mourning I don’t really understand this and would appreciate any advice anyone has to offer.
The plan at the moment before spring re-launch is to replace the pear anode, remove the bonding and have a good look at the electric bilge pump which may be causing stray currents.
rothwell_neil Posted 6 years ago. Edited by rothwell_neil (member) 6 years ago
Sounds to me that you have a earthing problem as this should not have gone. Probably driving it from the battery or alternator. I would disconnect all strapping and start again as likely to be earth leakage. Possibly through the bilge pump?

I don't bother earthing the keel bolts as the threads don't corrode and a good paint system is good enough for the outside.
Red Marlin 6 years ago
There is another bronze skin fitting on the 9 metre you have not listed. It is the exhaust outlet. We had a small leak we could not find, especially in a following sea. Tiny pinpricks around the exhaust fitting were the cause.
Tony
Freebird 1011 6 years ago
Thanks Neil and Tony, i have started to re route all cables from the bilge and engine area and fit a new bilge pump with non return value (not fitted before) so left a bit of water constantly lying there. We will then just go through all the electrics and bonding looking for faults. Fingers crossed it should get fixed. Our exhaust fitting is ss but will give it the once over while at the other jobs.

Duncan
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