Alloy prop.

[tom52]

I have the bog standard two blade Volvo light alloy prop (aluminium ?) fitted to my saildrive.
It used to be covered with some kind of black plastic coat but last seasons exertions seem to have pretty much finished off the coating, apart from the odd patch, and the prop will have to be taken back to bare metal.
What should I do with it then ? Paint it ? Coat it with something ? Polish it or go commando and leave it bare aluminium ?
Also when I took off the prop I noticed my anode was loose (again !). It obviously cannot work properly unless it is making good contact. Any tips on how I can stop the two screws working loose. Is Loctite up to it... underwater and being constantly vibrated when the engine is running.... or is there another solution that will still allow me to get the anode off when it needs replacing.

Advice please. Thanks


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[dog]

Had similar problem with Volvo duoprops last season. Volvo took them away and stripped/re-coated in gloss black. Also part of the drive had been stripped to bare metal during a brief encounter with a sandbank at 17knots!!! I sanded/ cleaned thoroughly and etched primed. I then applied 3-4 coats of Primocon (suitable for aluminium), antifouled and forgot all about it for 14 months!!! When it came out last week, Volvo paint was slightly damaged on props, but leg was still 100%. I wouldnt advise leaving ali naked!!! The above worked well for me, others may have better advice.

Brian.

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[philwebb]

Hi Tom, I`m in the same position as you. I have used Jotun 2- pack polyurethane paint
on the prop as I had some left from painting the hull. It seems to be sticking. I have used Loctite on my ring anode bolts to good effect, however I once lost the complete
anode when crossing the channel when I picked up a length of fishing net. The threads
in the casting were not very good after this and I resorted to putting in helicoil inserts.
These are working well. The kit to do this cost about 35pounds but its cheaper than
a new part from Volvo and worth it for the peace of mind.
Regards, Phil

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[Birdseye]

I run a Silette catamaran drive leg with a three blade aluminium prop. For the past 6 years I have given it a 2 pack epoxy undercoat and a 2 pack poly top coat. I have been surprised by how well it has lasted - typically 2 seasons to touch up and re-paint after 3 years. Mind you, the cat drive leg is lifted when the boat is moored so the paint isnt always submerged.

An alternative might be cellulose. Apparently, this is just about the hardest single paint you can get which is why it was used on cars

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[snowleopard]

international now do a spray-on antifouling for props and saildrive legs. have a look on their website.

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[Ric]

Regarding your shaft-anodes that work loose, I always have the same problem with anodes that are fixed while the boat is out of the water. They last about a month or so before the fall off. If I replace them underwater with scuba gear, they stay on for ages. I suppose it is something to do with differential expansion rates of all the alloys in the shaft, anode, and bolts.

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[John_Clarke]

I apply Volvo Penta waterproof grease to the threads and under the heads of the fixing screws which allows them to be tightened firmly and yet they are reasonably easy to unscrew. I do the same with the propeller cone and locking bolt. After 7 months they are always firm and this has been my experience for the 4 layups I have done on the boat.

I use 5 generous coats of Primocon which works well and because it is a one part paint is easy to touch up the a few chips in the paint each winter.


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[DickB]

Hi... I have a three bladed ali prop on my volvo saildrive that now has some nasty pitting because the anode worked loose and the ali started to rot. I had covered the prop with some spare Gelcoat as a token gesture but this had all warn off over the year. (The black coating had started to peel). Sounds like something stronger/tougher is required!!!

Also the anode had rotted away around the bolt holes hence it had worked loose and could be heard rattling around when running last summer!!! Someone on one these postings advised putting a dab of paint around the screw hole to prevent early rotting. Not sure about that since the screw acts as a very good conductor.

Looks like I might have to buy another prop!

Good luck...

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