Painting Propellers

TonyMills

TonyMills

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I have a three bladed bronze(?) prop. It resides under my boat in the Swan River in Perth West Australia. Each year when I haul out it is always covered in barnacles and during the year I have to make periodic trips into the murky depths to clean it off.

I have primed it with an epoxy paint and followed up with two coats of hard racing anti-fouling and two coats of coppercoat ablitive. It doesn't last!!

Some have said that bronze props should not be painted.

Any thoughts/ideas on the best way to treat them (or not to treat them) which keeps them clean??

Regards
TonyM
 
Hi Tony
I use Range Black or Zebro Bright. It is the stuff that is used for polishing up fire grates and the old black ranges. It is in common use over here and available in most hardware stores. I believe it works well because it has a large lead content. It will leave your prop black, but polishes off at the end of the season. My prop used to have a lot of weed on it and now I have nothing at all. I'm not sure about barnacles but I don't see why not. It would be interesting to know if it works for you. good Luck
regards Ian
 
Coppercoat will eat bronze props. You may be alright if you have an absolute epoxy sheath on there first, but I would watch for any sign of pitting or corrosion.
 
This response is in no way intended to undermine the answers of previous posters. I'm no expert (indeed I'd like a definitive answer to the prop fouling problem myself). I remember the subject of Zebo black lead came up in PBO some time ago. I've looked it up and pass it on for you to make up your own mind.
The original suggestion was in issue 395 (in case you can access it) and there was a letter in issue 398 from a guy with C.Eng,MRINA,MIMarE after his name. To quote his letter -
"xxx recommended applying Black Lead (or graphite powder) to propellors to protect them from marine fouling. This is a very risky practice because graphite is probably the most noble material in the galvanic series. Consequently all other marine metals can be expected to erode due to galvanic action when placed close to it. Consequently the propellor shaft, propellor, local hull fastenings and the rudder pintle/gudgeon pair should all be expected to corrode due to black lead coating.
Some protection will be gained from placing a sacrificial anode close to the stern gear; but with the graphite applied directly to the surface of the propellor, there must be some degradation of the propellor material.
We should also question the need for painting a bronze propellor since the copper should provide some antifouling properties. Perhaps just polishing the propellor would work just as well? "
End of quote.

I don't mean to cause panic if someone has their prop blackleaded. I'd be interested to hear from those people to find out if they ever cleaned off the blacklead at fit-out time and noticed anything amiss. Presumably not those whose answers appear above. Perhaps there are knowledgable types here on the forum who can give some input on the subject. I speak as someone who went out and bought a tube of Zebo after seeing the mag article but never applied it after reading the above letter.
Incidentally fishing vessels and merchant vessels always have their props polished at drydock/haulout time.
 
My ship spend the winter of 1994/95 in Sada(NW Spain) on a buoy and I used it only occasionally. In june of 1005 the ship would barely move on the motor. It turned out that there were so may barnacles on the propellor that there was hardly any screw-form left. In other words tunrning the propelleor was more like turning a cilinder in stead of a screw. Conclusion: The copper of the propellor does not prevent the grow of barnacles. Remember that brass is an alloy of copper and zinc and bronze of copper and tin. I would gladly use the Zeba black. However, since it seems to contain lead, it probably is forbidden as are lead-containing anti-foulings. Henk.
 
Thanks for the info all. I have 398 and note the ed. recommended looking at 'Metal Corrosion in Boats' so I'll see if I can get a copy. The original writer in 395 also suggested that Zebo may be available overseas through Reckitt & Coleman so I'll see if I can find it.

Regards
TonyM
 
The thing is, fishing boats and merchant vessels, do not always have there props polished, not in the med they dont, they antifoul them. But the other thing is, fishing boats and merchant vessels are alway in use, so the barnacles, dont normally get chance to grow on the props, like they do on pleasure boats who suit still for long periods. Zebo works and I've never seen any degradation of my props etc. mine are bonded to a big anode each side, so maybe thats why I dont have a problem. If you dont want your tube of zebo, PM me and I'll buy it off you, having trouble finding it in Barca.
 
Sorry, you will have to educate me. Why would coppercoat eat a bronze/brass prop, when the main constituent of bronze/brass is copper? I may well be missing something here and would like to know.
 
International's Trilux works better than nothing. Without it , prop gets covered in barnacles. With it the barnacles are restricted to places where the trilux falls off - looks like it needs a well polished degreased prop to start with, theres never time between tides...

Thats on a 2 blade 13x8 attached to a Yanmar 1GM7.
 
I've gone the antifoul route as well, and still do, it's better than nothing!! I epoxy prime my prop first and the antifoul stays on. I admit my props only turn at max 500 rpm. 2000 engine Rpm, 4:1 reduction boxes, effin big props!
 
I've found painting propellors to be a waste of time.

The important thing is to have a mirror finish on the prop, not obtainable using even the most fine wet&dry. I use a 3M metal finishing pad, used by metal workers to get a mirror finish on Stainless steel.

Others swear by black-lead or hot-applied anhydrous lanolin. Personally I've found no perceptible difference using these and suspect the "results" reported are due to the preliminary polishing rather than the finish. Still we won't know until a proper controlled experiment is mounted.

Lack of use is the major contributory factor to prop fouling and different moorings vary wildly from each other and from season to season.
 
Yes, I tend to agree Charles. My procedure, (noted on a similar thread a week or so ago) may seem OTT, but we never get a barnacle or weed on the prop. /forums/images/graemlins/smile.gif

First I polish the prop with 1500 wet 'n dry used dry (if needed - about once every two years) then use a Makita sander/polisher with Farecla No 6 compound to produce an extremely smooth, polished surface. This is followed by either the No 10 compound or (more usually) with Teflon based polish. I've used Starbrite this year 'cos I couldn't get 3M at the time.

The prop therefore goes in absolutely gleaming (far shinier than new) and emerges at the end of the season dull but totally clean. The only barnacles anywhere (perhaps 6 tiny ones) tend to adhere to the prop nut which I can't polish. /forums/images/graemlins/frown.gif

Ok, my swinging mooring is on a tidal river, where the flow on the Spring ebb can reach 2.5+ knots, and we often have to motor to and from Plymouth Sound (or part of the way) so this may be a factor in keeping the evil little things off. However, we used exactly the same procedure when cruising in the Med/Caribbean with similar results, though the prop did get a complete covering with tiny barnacles while we were in Antigua at anchor for about 6 weeks on the last trip.

We tried A/fg a few years ago, but felt we were actually feeding the blasted things, hence seeking an alternative. /forums/images/graemlins/cool.gif

Cheers Jerry
 
Re: Propspeed

I used propspeed, actually an oz product i believe. Quite expensive, it's some 2part silicon summink than you roller on after thoroughly sanding and then cleaning (eg acetone) the props. Leaves them looking like "wet varnish" and kept barnacles off for ages. However, i ruined a year later next time the boat was out it by speculatively boshing trilux over the top of it, which somehow melted the Propspeed, and everything has come off. I think i will try propspeed again tho.
 
I have to confess I am repeating the wisdom of a couple fo old ex-service salts. I believe the theory is that the old marine bronze being phosphor-bronze is lower down the electrolytical table and the copper in the coppercoat will attempt to leach out the copper from the bronze if any unprotected electrolysis starts up.

I don't know about brass - this will be more protected because it's higher up the electrolytical table, but still below copper.
 
Lot of rot talked about bronzes, most are really just stronger brass, but I still dont see how the coppercoat leeches out the copper, the zinc I could believe, but the copper being leeched by the copper?? Now that is clever!
 
last season cleaned prop then because of hearing that lonolin works thought I would try somethin a bit more tacky.
Link life (motorcycle shop) in aerosol form. Spray it on let it set (25 mins) pop boat in warter, little bxgxrs carnt get a grip.
not one on prop. You can get all over prop nut and into small crevises as well.
When I said let it set, its very oilly to start with. I think it must be some sort of thining agent, so when used on bike chains it can seep into link pins.
 
From new prop: Yr 1, Lanolin - end of year, plenty barnacles. Yr 2, highly polished - eoy, some barnacles, but not a lot. Yr 3, polished and then Blake's prop a/f - had to relift after 2 days, and about 10 engine hours, found most of the a/f had gone.

Conclusion I draw is that polishing and plenty of passage-making are best.
 
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