Maxprop corrosion - advice sought!

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Nudge

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Hi,

Got this boat a year ago and she had a 3 y.o. Maxprop; anode partically corroded as you would expect, so for launch, polished up the prop and shaft, fitted a new prop boss anode and an additional shaft anode.

Lifted out last week and the anodes completely gone, prop blades badly corroded to the point of a 5 mm dia hole in one. Corrosion is on the blade faces, tips are fine...

Puzzled by this as I can't understand why this should have happened - prop was perfect 12 months ago..

The only change I can think of is that I discovered that the expesive after market alternator wasn't actually connected to the batteries (not a recent installation...) so I hooked the output up to the batteries and the charging was fine. Engine is a 3GM and has a Martec FW conversion. The boat is rarely on shore power as my berth doesn't have it. Calorifier has power but doesn't heat up domestic water (you can see that I'm struggling for a likely cause..)

Naturally concerned about this so any advice on root cause and countermeasures would be appreciated.

Anyone got the Maxprop spares agent contact details?!

Nudge
 
The Maxprop anodes are very small and can wear a lot faster than the main engine anode.

Make sure you get their new ones with the central bolt fitted. It needs an adaptor plate that Darglow sell.

For extra security use nylon bolts in the outer holes of the anode as well.

Having said that, ours now wear a lot slower since we fitted a galvanic isolator.
 
Thanks

SolentBoy and Scottie,

Thanks for the responses; was at the boat all day yesterday so didn't reply. Galvanic isolator is definitely going on and I'll get the updated anode on after the prop repair.

Scottie, I think the reason that the alternator was not connected was mis-fitting. There was no cable or evidence of a cable to the batteries from the alternator and if that had been a problem I would have unhooked the cable but not stripped it out... I think the clue is in the fitting instructions - it doesn't actaully "state" that they should be connected up and the diagram doesn't show the connection; merely show "alternator output" in the schematic. But thena again, you never know.

Any other suggetions welcome.

Nudge
 
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