Painting props

[skipjack27]

My props (Volvo Duoprop 290 leg - contrarotating) are heavily subject to electrolytic corrosion - for complex reasons I won't bore anyone with. One of the best defences against this, I have been advised, is a really solid antifoul/paint coating that stays on.

Does anyone have any advice as to the best coating that will insulate the prop metal, and continue to do it over a season of use?

 

[Bob_VT]

Re: Painting props

Most prop paint vanishes due to cavitation burning ...... if it is aluminum I would just use some zinc chromate primer and then spray with enamel

Powder coating lasts the longest

Who cares if paint is missing......... no one watches the prop at work!!

 

[TilliamWe]

Re: Painting props

I don't know what it's called, but it's green. I have seen B3 props painted with it. It won't solve your problem, despite what you are hearing, but it might help.

 

[DuckHunterJon]

Re: Painting props

Just curious, assuming aluminum - would anodizing do any good?

 

[Fireman431]

Re: Painting props

Powder coating and anodizing are good for the finish, but it doesn't stop the electrolysis, which is essentially heatingup the props and causing damage. First work on curing the problem, whether it's better grounding or additioanl zincs (caareful not to 'over zinc' it), then go back to prime/paint on the prop.

 

[soggy_feet]

Re: Painting props

Green stuff... etching primer? Usually greenish/yellowish, and helps paint hold to aluminum a LOT better than without.

 

[dockwrecker]

Re: Painting props

You're gonna be spending a lot of time trying to make paint stick to an aluminum prop. Too much flex and won't do anything to prevent cavitation burns. I had Volvo 280's on one of my past boats and the best thing I could come up with was annual prop balancing to try to extend the life. I don't know why they like to eat aluminum props but they surely do! Stainless props fix the issue but at a risk with older Volvos because of the shear shaft design of the lower unit which is why I never put them on mine.

 

[Bob_VT]

Re: Painting props

Green stuff... etching primer? Usually greenish/yellowish, and helps paint hold to aluminum a LOT better than without.

Zinc Chromate is the green stuff

 

[Texasmark]

Re: Painting props

Zinc Chromate is the green stuff

and made especially to protect aluminum in highly corrosive environments. I saw it used exclusively as primer for such in the aircraft industry.

On painting the prop/lower unit, my Merc service manual has quite a write up on how to do it so that it will be in factory condition......more than I care to do. I'd Zinc Chromate prime it, get a Valspar or suitable marine epoxy paint and paint it shortly thereafter...while primer is still "green"....condition of primer applicatrion, not what it is. Then let it set till thoroughly dry, buff it up with a 000 wool and shoot it again with the epoxy till glossy. Then let it sit for a week or two and thoroughly dry.

My 2c.

Mark

 

[BonairII]

Re: Painting props

Wouldn't be much easier just to clean off the corrosion periodically, instead of going thru the hassle of painting/treating the prop?