Effect of Prop Antifouling on Prop Anode Wear?

[a64pilot]

If any one is interested, this is an Autoprop zinc, to the left of the prop of course

[deblen]

Came across this post yesterday on YBW. Dr. Barnacle Grease for props.
No personal experience-just an FYI

Underwater grease

[AussieCat]

My thoughts are you have serious electrical issues if you going through anodes at that rate. As already pointed out it may be one or more of your neighbours. Suggest you get a sparkie to check it out. We always Prop-speed our props and sail drives. We've just fitted 2 x Gori 3 blade props on the new FP Belize (had on last boat and loved them) and get two years out of the main anodes but need to replace the small one on the end each year as well as the rudder anodes. Also two years on the sail drive anodes. Installed split anode kits to sail drives so now everything is changeable in the water. Prop speed on props last two years and three - four years on the sail drives. We get a diver to give a (very) gentle clean every 3 - 4 months. Soft plastic scraper and thick cotton gloves only! Anything more will do damage to paint and reduce it's life. Hoping to extend anti foul to 2 years.

[sneuman]

Originally Posted by Dockhead

Most people around here polish their props and leave them as bare metal. And I also do that. For some reason, the prop doesn't foul all that much.

But my prop anodes wear intensely, and are gone in 4 months, which is the limiting factor for me for a lift out.

For some reason, having a shaft anode on doesn't seem to make a lot of difference. I don't understand that.

I wonder if I were to paint my prop with antifoul, whether that would slow down anode wear by reducing contact with sea water?

Anyone have any experience?

Don't waste your time or your money. The anti-fouling almost instantly strips off. I have seen this happen even with expensive anti-fouling designed especially for running gear -- that stuff is a rip-off.

[Rustic Charm]

Originally Posted by sneuman

Don't waste your time or your money. The anti-fouling almost instantly strips off. I have seen this happen even with expensive anti-fouling designed especially for running gear -- that stuff is a rip-off.

Why is it then that in this part of the world, hardly anyone, if anyone at all, polishes their props and leave them bare

[fstbttms]

Originally Posted by AussieCat

We get a diver to give a (very) gentle clean every 3 - 4 months. Soft plastic scraper and thick cotton gloves only! Anything more will do damage to paint and reduce it's life. Hoping to extend anti foul to 2 years.

It is, obviously, a best practice to always clean your anti fouling paint as gently as possible. But if you need a scraper of any kind to plow through the slime, you have already waited too long to clean it. Here in the States, the 3M Doodlebug pad is the hull cleaner's tool of choice. Just which pad he uses is entirely dependent upon the condition of the anti fouling paint and frequency of service, which is, of course, dictated by the boat owner.

In California, we typically get 3+ years of good performance from a high quality hard paint. Ablatives do not normally last quite so long, but any paint that doesn't work well for at least 2 years is considered inferior.

[sneuman]

Originally Posted by Rustic Charm

Why is it then that in this part of the world, hardly anyone, if anyone at all, polishes their props and leave them bare

I can't speak for others. All I can do is speak from my own experience and what I've personally witnessed happening on other boats. I suspect the answer is that they don't see their prop immediately after running it with newly applied anti-fouling. So, they lift the boat months later, see the paint gone and assume that this has happened over a several month period, when in fact it happened in the first 20 minutes of operation.

[AussieCat]

Anti foul is for boat bottoms and is not designed to hang on to spinning props, shafts etc. As Rustic Charm pointed out I don't know any one who polishes their props. Check out Propspeed it's well worth the cost but make sure you get someone who knows how to apply it correctly or you'll just waste your money. Props need to be primed and the Propspeed applied at the correct time intervals between coats. Email Propspeed and they may be able to put you in contact with someone in you area. Cheers

[Pete7]

In the past I have used a wire cup wheel in an angle grinder to clean any old paint of the prop which gives a good clean surface. The two coats of International Primocon followed by a couple of thin coats of what ever the hull antifoul is. After a season most is still on and in good condition.

This year I picked up a mint spare prop for £25 as ours is looking a little worse for wear after 28 years in saltwater. Only problem the previous owner decided to polish it like a mirror so any paint will be straight off. Out with the 80 grit sandpaper and 10 minutes later it was now nicely roughed up. Then I mixed up a batch of VC tar epoxy paint and scratched it on with another piece of sandpaper. Everything would have worked but the epoxy hasn't set despite my best efforts warming both the prop and epoxy in the oven

So we will see, but I think if the prop is cleaned and prepared then quickly painted properly then it will last a season.

The total lack of shore power or generator anywhere near our mooring us means the anodes will last two years.

[GILow]

+1 for the propspeed.

As for sacrificial anodes on the prop, we have a system whereby the prop and shaft are protected by the conventional tear drop shaped anodes attached directly to the hull. They are connected to the prop shaft using a length of woven earth strap looped loosely around the shaft, with a decent weight at the bottom of the shaft to keep good electrical contact.

The anodes last about three years and are dirt cheap. The prop is 30 years old and still looks ok. I replaced the 30 year old drive shaft a couple of years ago for other reasons, I cut the ends off for a taper reference and there was no evidence of corrosion.

Matt


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[Pete7]

Matt, sadly Propspeed is dealer application at £150 a time only, so you can't buy it for DIY in the UK.

Pete

[goodoldwoody]

Hi All,
I use "Propspeed" antifoul specially formulated for propeller and I'm pleased to say that that antifoul lasts up to two years, in salt water. I haul out every year and I'm pleased to say only reasonable depletion of the anode is the case. At that time I always replace the anode.

The Propspeed seems to isolate / insulate the prop.

My prop shaft is isolated by a flexible coupling. There is a anode fitted to the shaft near the prop. I now get Propspeed applied to the shaft as well. I dive down and simply wipe the prop & shaft gently with a sponge every 3 months or so. Whatever is on there simply wipes off.

I can't believe how good it is as before Propspeed I was replacing shaft anodes every 6 months or so. Sometimes they would simply fall off. Now I don't even think about it.

I'm told that regular "wiping" is essential if you want it to last two years.

Propspeed is available down under here in Australia. I don't know what it's called elsewhere. It is expensive but it's worth it!

Good luck

Woody

[GILow]

Originally Posted by Pete7

Matt, sadly Propspeed is dealer application at £150 a time only, so you can't buy it for DIY in the UK.



Pete

Ouch! Not a nice price.

We are paying around AU$150 for the application by our yard master. I could probably reduce the price if I went DIY but I trust the yard master to do a better job than I ever will.




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[GILow]

Originally Posted by goodoldwoody

I'm told that regular "wiping" is essential if you want it to last two years.

Interesting. I had not heard that but it is good to know. We only got 18 months from our last application, I'll try wiping it and see if that extends things.


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[leftbrainstuff]

Originally Posted by sneuman

I can't speak for others. All I can do is speak from my own experience and what I've personally witnessed happening on other boats. I suspect the answer is that they don't see their prop immediately after running it with newly applied anti-fouling. So, they lift the boat months later, see the paint gone and assume that this has happened over a several month period, when in fact it happened in the first 20 minutes of operation.

Zinc coat if done right, acid wash first, degrades slowly. Slapping on some prop paint will wear off very quickly.

I can see our maxprop zinc coat is still visible 9 months after last haulout. Its mostly absent at the leading edge of the prop. Otherwise it's still intact.



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