Anodes, I have a problem...

[Islandmike]

Last year I had a new engine, new shaft and new prop installed. The problem, there is not enough room between the prop and shaft log to place an anode, it looks as though the shaft should have been longer, story of my life... and there is also not room at the end of the shaft, there are two lock nuts. I am a little perplexed as to what to do?

I know I should have noticed this at the completion of the work, however, that is another story for another time. I moor the boat, I do not have an external AC hookup, although I will have a 1500 watt inverter. Am I screwed here? The boat was at a mooring last summer, there did not appear to be any issues yet. I just put the boat back in the water yesterday, I know I am playing with fire here. any suggestions?

[Sandero]

What is the clearance between the prop and the cutlass bearing? Mine is rather small being 1 1/8" and I have to mill down a doughnut zinc to 7/8 or so. You need clearance so that the cutlass bearing can receive water for lubrication.

[Islandmike]

That clearance is maybe 3/8".... I may have to cut down the bolts holding the prop on. This may give me enough behind the prop.

[MidLandOne]

If the shaft and prop are insulated from the engine nor bonded to any bonding system AND they both came from reputable manufacturers (so not an el cheapo prop) then I suspect you will be fine. Stainless steel and bronzes (including the CORRECT grade of manganese bronze which a good prop manufacturer will have used - manganese bronzes are actually brasses).

Our own prop and shaft were built purposely not needing anodes and has been fine for many years now. After the boat was built we lifted it several times over the first few months to check all was ok with that and other things and then again after around 9 months. So if the above applies regarding quality suppliers and insulation then I would tend to just keep an eye on things, particularly the prop for dezincification.

If the prop and shaft are not insulated as above I would be the last person to give you any advice without seeing the boat for myself and can only suggest that you find someone who has a good knowledge of corrosion to look and give you advice. Problem is it is probably easier to pull your shaft and replace it than it is to find someone who has reliable knowledge at a professional level. The electrical engineers in a big yard building metal boats are usually the best but they are not easily accessible to most people.

[Steve Pope]

You can buy a prop nut that is made for a zinc to be bolted on to it. I have it on my setup and find I get a year at least before the zinc is 1/2 gone.

[senormechanico]

I had the same problem with my (new to me) boat. There was only about 1/4" of space.

I added a flexible coupling behind the transmission and it gave me just enough to add a collar zinc.


Steve B.

[MidLandOne]

A couple of words got missed above (not my fault I am sure ) -

Originally Posted by MidLandOne

Stainless steel and bronzes (including the CORRECT grade of manganese bronze which a good prop manufacturer will have used - manganese bronzes are actually brasses)...

"...generally go fine together without anodic protection".

John

[Inthewind]

You may be able to add a drive saver, lots of added benefits with one of these. Check it out. Drivesaver Marine Couplers

[fstbttms]

Originally Posted by Island Mike

Last year I had a new engine, new shaft and new prop installed. The problem, there is not enough room between the prop and shaft log to place an anode, it looks as though the shaft should have been longer, story of my life... and there is also not room at the end of the shaft, there are two lock nuts. I am a little perplexed as to what to do?

Your best bet is to install a zinc on the prop-

[Steve Pope]

Good one FSTBTTMS that is exactly the setup I have.
Mike do away with the locknuts and fit the above, you may have to drill a hole in the shaft for the split pin but that shouldn't be a major.

[Islandmike]

Steve,

I have seen that type of zinc, but I have never seen the other pc, does that come with the zinc? thanks for all of the suggestions..

[Alan Wheeler]

The above Zinc/nut is a good solution. One other solution is to ensure your shaft is bonded by fitting a shaft brush. This maintains an electrical contact and thus your main Zinc offers protection.

[Islandmike]

Actually after reading Steves post I did some more research and found a couple of places where I could get the Zink/Nut combination. I think that will solve the problem. Thanks a million guys, as usual this forum is the best....