Prop anti-fouling treatments-is it worth it?

Hi all, I am a new member and have purchased a 36' single screw trawler. I am having the bottom painted and was asked if I want the prop treated as well with anti-fouling paint as well. I am not familiar with this & have not had a boat with it done. Is it worth-while to have done & how long does it hold up? Thanks

Welcome Aboard!
Yes, you should antifoul or otherwise treat the prop and associated parts, like support brackets/skegs, prop shaft, collectively called "the running gear". If you don`t you will get all kinds of growth incl shell, with loss of speed, and vibration.
If you use antifouling,it should be a hard type, not an ablative soft type you might use on the hull.
The best treatment for the running gear is Propspeed which I will do next time.
I am surprised the yard would ask that question.Maybe it was about using Propspeed.
How long a/f lasts depends on location. You`d hope the hull and running gear last as long as each other.

I've been using Prop Speed for four or five years now. It really makes a difference. In the past the prop was the first place I got fouling. Now the prop stays clean about as long as the bottom. I don't have the bottom cleaned for a year or more after getting new bottom paint, then the diver stretches it out to about two years before I haul and paint again. Prop Speed is expensive but I think it's worth it.

gar said:

a 36' single screw trawler

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Single screw ah ? hmmmmm

Welcome aboard..

Depends on where your boat is, I think. Up here while the yard we use is happy to apply Prop Speed or another of the various coatings the yard is pretty ambivalent as to their effectiveness. If pressed the yard manager will tell you he thinks Prop Speed is not worth the cost in this climate.. Hull growth is not a huge issue here unless a boat mainly just sits.

A prop treatment they have been using a lot lately is what he calls "zinc in a spray can." It's pretty effective, he said, but it's only good for about a year. Most people here haul for bottom paint every two or three years, so their running gear has no anti-fouling for the last year or two. Which he told us kind of negates the advantage and cost of putting it on in the first place.

He asked how often we use our boat and when we told him he said if it was him he wouldn't bother with any prop or shaft treatment at all. Particularly since we, like a lot of people in our marina, have the local dive service check the boat twice a year. If barnacles get a foothold on the running gear, through hulls, or rudders it's an easy thing to knock them off.

But that's here. In warmer waters with lots of sunlight anti-fouling on props and shafts sounds like a smart thing to do judging from the comments and experience of our members in the southwestern Pacific. If one hauls once a year the zinc-in-a-spray-can might be a more cost effective solution than Prop Speed.

Here in Auckland NZ which has a temperate climate (never snows and water temp varies from 12 deg C to 22+ deg C) absolutely everyone I know uses Propspeed. Got 30 months out antifoul, propspeed and zincs last time round. But, as Marin says, it may not be necessary in colder waters.
I'd still use it though, because you know your prop will always be clean and prop fouling slows a vessel down more than hull fouling.

I'm yanking my boat out tomorrow here in Stuart, FL. I might consider Prop Speed if it doesn't cost me a fortune, but I heard it does. My diver says that my running gear is pretty covered each month when cleaning, but the Trinidad bottom paint keeps the bottom relatively unaffected.

I was in the boat office no more than five minutes ago and while I was there a bloke was quoted $740 for Prop Speed for a twin!

I have used prop speed on our boats a couple of times but have given it away as I didn't notice any major benefit over the years. The standard 3 coats of hard anti foul we now apply seem to have about the same life expectancy as the hull antifoul does, which in our part of the world is about 15-18 months. So when the boat is lifted both the hull and props are done at the same time. My two cents worth.

Bendit said:

Here in Auckland NZ which has a temperate climate (never snows and water temp varies from 12 deg C to 22+ deg C) absolutely everyone I know uses Propspeed. Got 30 months out antifoul, propspeed and zincs last time round. But, as Marin says, it may not be necessary in colder waters.
I'd still use it though, because you know your prop will always be clean and prop fouling slows a vessel down more than hull fouling.

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I absolutely endorse and confirm the above, I have managed to get 3 yrs out of my last a/f and propspeed here in warmer Queensland waters. It still seems to be so good in terms of lack of vib's and hull speed I'm going to very interested in the shape of it all when it does come out in our (so-called) winter.

healhustler said:

I'm yanking my boat out tomorrow here in Stuart, FL. I might consider Prop Speed if it doesn't cost me a fortune, but I heard it does. My diver says that my running gear is pretty covered each month when cleaning, but the Trinidad bottom paint keeps the bottom relatively unaffected.

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Point of order healhustler...if you go with PropSpeed you must not have it brushed/cleaned as it will come off. That was one reason given to me why I didn't use it earlier was the scary story of it being all rubbed off if you run aground in sand or similar and the prop spins up a lot of bottom. I have decided I'd rather just risk that now it is so good, and be plenty careful not to kiss the bottom. Not such an issue with prop-protected single screw - more of an issue with some twins anyway I suspect.

I've used ArmorAll for 7 years or so and not had any fouling but most all of that time has been in Alaska.

Marin when you say "zinc in a spray can" do you mean aerosol can galvanizing? I modified an anchor w the addition of a piece of mild steel and put that stuff on and it held up really well. I was very surprised. I'd be hesitant to put it on a prop before I found out if it could damage the metal the prop is made of. What do you know about that?

I just prime and paint it like the rest of the bottom and it does fine.

You need the prop treated with something anti-fouling. I used to have them do it with regular bottom paint but it wore off pretty quick. Using Prop-Speed now and very happy.

Spray zinc galvanizing normally won't harm the prop (we zinc the shafts and rudder to protect them anyway but checking the contents would probably be a good idea just in case depending on your can) but where I am the zincs get covered with growth faster than anything...

gar said:

Hi all, I am a new member and have purchased a 36' single screw trawler. I am having the bottom painted and was asked if I want the prop treated as well with anti-fouling paint as well. I am not familiar with this & have not had a boat with it done. Is it worth-while to have done & how long does it hold up? Thanks

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Hi Gar,
Congrats on the new boat. I see your in Cape Charles. I have had good success with Rustoleum Zink Galvinizing Primer in Deltaville, Your waters are the same as ours and you should have similar results. The bottom needs diving on a few times a summer but for $10 a can it's a good deal to me. Please tell us more about your boat and as always we need pics as many are not here for the articles

If the opinion of a hull cleaner with 18+ years of experience means anything; PropSpeed works well but is expensive, short-lived and difficult to apply. Pettit Zinc Barnacle Barrier also works well, is inexpensive and very easy to apply. Lasts as long as PropSpeed, IMHO. I don't find that PropSpeed has any advantage over the Pettit product that even comes close to justifying the expense. That's my $.02.

manyboats; said:

Marin when you say "zinc in a spray can" do you mean aerosol can galvanizing?

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No, it's a name brand product specifically made as an anti-fouling coating for propellers. I used to know the brand name since we were considering it for our boat. I think it's about $40 a can, it takes about one can to do a prop. For our twin boat the product, prep, and application would have cost some $250-$300 IIRC. Carey had it done last year on his lobsterboat.

This subject has been covered numerous times on this forum over the last 5 yers.
Prop Speed wins hands down every time.
I have a timber boat and haul it every 12 months and mostly get at least 24 months out of my prop Speed (as long as no one inadvertantly gives it a scrub or a brush)
Do a search and you will find heaps on this and I have attached a couple of photos.
Hauling out and going back in.This was after 18 months , I had delayed the haulout and boat wasn't used much. The Prop Speed was left intact.
Over the last 17 years I had tried all sorts of coatings but have settled on Prop Speed for the last 6. One very happy customer.
Cheers
Benn

Tidahapah said:

This subject has been covered numerous times on this forum over the last 5 yers.
Prop Speed wins hands down every time.
I have a timber boat and haul it every 12 months and mostly get at least 24 months out of my prop Speed (as long as no one inadvertantly gives it a scrub or a brush)
Do a search and you will find heaps on this and I have attached a couple of photos.
Hauling out and going back in.This was after 18 months , I had delayed the haulout and boat wasn't used much. The Prop Speed was left intact.
Over the last 17 years I had tried all sorts of coatings but have settled on Prop Speed for the last 6. One very happy customer.
Cheers
Benn

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Hey Benno,
Mate, what's the name of the fitting on the prop shaft in the last pic?

Many Thanks to all. I never thought I would get so many replies from near and far. I am bringing the vessel up to the lower Chesapeake in April & will post more info and pics then. I will ask the marina in North Carolina what brand of treatment he plans to use-he did not specify in his quote. Thanks Again.

Hendo,
That's the outer prop shaft bearing carrier.
Can be either a composite bearing or as in my case a grease lubricated white metal bearing.
Cheers
Benn

Tidahapah said:

Hendo,
That's the outer prop shaft bearing carrier.
Can be either a composite bearing or as in my case a grease lubricated white metal bearing.
Cheers
Benn

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Ah ok cool. Thanks for that mate. Thought it was a shaft seal or somethin and thought that, that would be a great idea.

The first time I had the Coot hauled out in order to repaint the bottom there were barnacles growing on the propeller after being in the water about 18 months. So, had the propeller treated. We'll see how that works out during the next haul out.

Have tried a number of "home remedies" over the years and settled on two coats of black Sharpie marker. Lasts all season here in the Northeast. Also use same on my FL boat but that gets moved at least weekly.

BruceK said:

The best treatment for the running gear is Propspeed which I will do next time.

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Several years ago I tried Prop Speed and as I recall the bill was in excess of $400. Since I have a diver who cleans the bottom and prop every 4 weeks, (in the summer) I decided not to opt for the Prop Speed at the last haul out. The prop looked fine, which was the result of the diver's effort.
In my case, with frequent bottom cleans, I don't think it's worth it. Now, I have noticed that my gph has creeped up from 4 gph to 4.2 gph at 2000rpm (FloScan) and my diver has informed me that it's time for new bottom paint.
It's been 2.5 years since the last bottom job.

From posts here and other opinions, Propspeed is a favored product, but zinc treatment is worth exploring.
Has anyone in Australia used it in any form? I`ve not heard of it or seen it for sale as an antifouling product.
Would one of the cold galvanizing brush applied products do the job?
Does the zinc coating become an anode, how would that affect the running gear?
Does it last for the life of the hull a/f?

BruceK said:

....but zinc treatment is worth exploring.
Has anyone in Australia used it in any form? I`ve not heard of it or seen it for sale as an antifouling product.
Would one of the cold galvanizing brush applied products do the job?
Does the zinc coating become an anode, how would that affect the running gear?
Does it last for the life of the hull a/f?

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I'd forgotten the name so I just called the yard we use and the spray-can product I was referring to earlier is Petit's Barnacle Barrier. It's a single-season coating, or as the yard manager told me, good for about a year. A can is $30-$40.

This yard no longer uses it but not because it doesn't work as advertised. They started getting flack from some environmental groups that make it their business to "patrol" Puget Sound waterfronts, shipyards, etc. looking for environmental "problems." Because it's a spray-on coating and there are contaminants in it the environmental people were saying that it gets into the air and thus into the water.

Rather than deal with the hassel the yard simply stopped using it themselves. But it is available locally at places like Fisheries Supply and there is nothing to prevent an individual boat owner from buying it and applying it him/herself.

So, works good but only for a single season or so.

That's the same material that Platypus recommended to us last spring. They actually talked us out of Prop Speed. Same deal - we bought the zinc paint at a local chandler and put it on ourselves. As I recall I put one can on each prop and got about 3 coats per prop that way BICBW.

I don't know why anyone thinks zinc has anti-fouling properties...it's not a significant portion of any anti-fouling paint and sacrificial zincs get covered with marine growth as fast as any other underwater part that does not have anti-fouling on it.

It may be used to assist some biocides or used in a paint for other reasons...but just plain old zinc or galvanizing zinc I don't think does much as evidenced by growth on every zinc you strap/bolt on.

Brooksie said:

Have tried a number of "home remedies" over the years and settled on two coats of black Sharpie marker. Lasts all season here in the Northeast. Also use same on my FL boat but that gets moved at least weekly.

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Oh please don't start this again. It's been proven that the black pen trick is fake.