Folding prop hub anodes

PabloPicasso

PabloPicasso

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I have a two bladed folding prop on a 110 sail drive. It eats the anodes. This seems to be a well known problem. What would be wrong with drilling three bigger pear drop anodes and fitting them instead of the piddling tiny ones that are offered by Volvo and Macduff ( and probably others). I'm more worried about corrosion and not having to lift or dry the boat as I don't race her. A smidgen extra drag from bigger anodes ain't gonna make me lose any sleep
 
Yes maybe. I'll see if I can try without too big a difference. But don't shaft drives have one bolt on large teardrop anode without a problem?
 
PabloPicasso said:
Yes maybe. I'll see if I can try without too big a difference. But don't shaft drives have one bolt on large teardrop anode without a problem?
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But normally with a shaft drive you can connect the shaft to an external anode, or use a shaft anode, or on some an anode on the prop locking nut. None of these options is available for a saildrive prop. You can only attach anodes to the hub and the maker casts the hub with mounting points to take the anodes. so you are stuck with what the maker provides.
 
PabloPicasso said:
This is unsatisfactory. There has to be a better way
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Sorry to keep saying the same thing. It is unsatisfactory. The maker has now changed the material on later props and they are better. As I have said many times, there are props that will fit your drive that do not have the same problem but they cost close to £1000 - or fit a standard aluminium prop. If you don't race the standard prop is perfectly adequate, just a bit more drag in light airs. But better motoring and no corrosion worries. You can get one from Sillette for about £250, but you will need a cone and lockbolt (if you have not got one) which will bring it to just over £300.
 
I know nothing of saildrives but is it not possible to get the prop electrically attached to the gearbox and thus use external anodes? Even if it means drilling right through the prop and shaft?
 
Yes drilling and tapping more anode attachment points seems to be worth a try, as its all gonna end up as scrap after a few more seasons anyway
 
alahol2 said:
I know nothing of saildrives but is it not possible to get the prop electrically attached to the gearbox and thus use external anodes? Even if it means drilling right through the prop and shaft?
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The very last thing you want to do with a saildrive. The prop is deliberately isolated from the shaft by a rubber bush, specifically to avoid the possibility of galvanic action between the two. Doing what you suggests will wreck the saildrive housing.

The problem the OP has is with the materials the prop is made of which has stainless steel in contact with a brass type alloy which dezincifies easily and the anodes are not very big - and no practical way of increasing their size.
 
Tranona said:
The very last thing you want to do with a saildrive. The prop is deliberately isolated from the shaft by a rubber bush, specifically to avoid the possibility of galvanic action between the two. Doing what you suggests will wreck the saildrive housing.

The problem the OP has is with the materials the prop is made of which has stainless steel in contact with a brass type alloy which dezincifies easily and the anodes are not very big - and no practical way of increasing their size.
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Yes that sums it up very nicely. But solutions is what this forum is about. I know the problem! :mad:
 
PabloPicasso said:
Yes that sums it up very nicely. But solutions is what this forum is about. I know the problem! :mad:
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You could try a large collar type shaft anode clamped round the hub of the prop. You said you are not concerned by a bit of extra drag.

Z_Guard_Zinc_Sha_4f0ed03a15b58_90x90.jpg


or maybe cut down a globe type

Shaft_Anode___Zi_4d43f3a78db5c_90x90.jpg
 
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VicS said:
You could try a large collar type shaft anode clamped round the hub of the prop. You said you are not concerned by a bit of extra drag.



or maybe cut down a globe type
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On second thoughts a globe type would be more streamlined. It could be slotted maybe to fit round the blades a little it would also have a smaller surface area in relation to its overall bulk and therefore be consumed more slowly.


On third thoughts use an aluminium one to avoid adding too much weight to the prop

Next problem requiring a solution please.
 
But its about 100mm dia .... I've not seen a globlr anode of that size in my local chandlers! Perhaps we should approach MG Duff to see what it would take to manufacture a larger anode. They would be very popular?

BTW: Looking around the boatyard last yeat I saw a 1996 boat with a Volvo saildrive hub that didn't have a slot or anode. The hub and blades were in perfect condition. I therefore assumed the original hubs were not isolated from the shaft.
 
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