Spray Cold Galvanizing Experience

Hi Everyone,
This is actually the first time I am posting my own thread to the site, so hope this works.

After reading many experiences of folks using cold galvanizing spray to prevent barnacles on the shaft and props, I decided to give it a whirl this past season. Boat is located on the south shore of Long Island, NY in East Rockaway. Splashed late April and pulled out for winter storage 3rd week of September.

I sanded smooth the shafts and props prior to spraying the 93percent cold galvanizing paint I purchased from Home Depot. This is essentially the same product as the Petit that can be purchased for much more money at marine stores.

The boat was kept at my yacht club on a face dock, with the port side facing west (lots of sunlight) and the starboard side against the face dock (essentially in shade), from April until mid August when it was moved to an inside slip in the marina.

Being on the face dock made it difficult to run the boat due to prevailing winds causing problems docking without people around to help. So not much boat movement.

The attached pictures (hope this works) tell the story. The port side (sunny side) had unbelievable barnacle growth on shafts, yet not on props. Also, on large zinc grounding plate (never experienced this on any boat I've owned). The starboard side (in the shade) had almost no growth on the prop and shaft.

The struts, well that's another story

So for next year I will use the spray galvanizing again (lots of scraping of barnacle to do) as the boat will be in a regular slip , essentially in shade on both sides.

People offer mixed results....too many variables to correlate from random posters....so...all you can do is try for yourself....

If vital to keep it all clean....best to go with products with a higher percentage of positive experiences.

Check the bonding wire to that zinc. You usually get very little fouling on zincs that are bonded to the bronze and other metals due to the electrolysis action. If the wire is broken or not attached the zinc isn't doing you any good plus it gets covered by barnacles like you see.



David

About the same here but a little better. The pics are post pressure wash. Last season I went with the same ablative paint as the hull with much, much better results.

chiropaul: What if anything did you use on the struts?
Why do you think the growth on the port side avoided the prop while infesting the shaft?

The zinc doesn't work. I even had a friend who smeared Ihle's Paste on his sailboat wheel. I tried zinc paint on the running gear and its only benefit is the boat looks good when you toss it in the water. Works great above the water, I use it on my turnbuckles and I never get barnacles on them!

Xsbank said:

The zinc doesn't work. I even had a friend who smeared Ihle's Paste on his sailboat wheel. I tried zinc paint on the running gear and its only benefit is the boat looks good when you toss it in the water. Works great above the water, I use it on my turnbuckles and I never get barnacles on them!

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Horses for courses? Depends upon local conditions?


Zinc paint spray on our prop in the relatively cold waters of the NE has worked well for us the past few years (vs nothing, or anti-foul, on the prop). A few, but easily scraped off, barnacles.

I don't think it matters much if you don't use the boat.

I have used prop speed on my charter boat (15 knot cruise) with good results. Didn't work well on my 7 knor trawler. You need significant water flow (speed) to throw the baby barnacles off. Zinc spray worked much better on the trawler. I applied the zinc spray 18 months ago and it was effective for about 8 months of cruising. Imo, the outer surface of the spray loses it's effectiveness in the same way as bottom paints do over time. Fouling of the running gear after 8 months, was much greater on the zinc spray when the boat wasn't used. My takeaway was that most anti fouling works better when there is lots of water flow (boat gets used)

On my trawler, I will continue to use the zinc spray as it's proven to be the most effective for me. Unfortunately, it's effective life is much shorter than my bottom paint. So, the solution is most likely monthly hull and running gear cleanings.

Ted

I used cold galvanizing spray paint on my prop three times. Prior I’ve used ArmorAll squirt spray. And now I’ve gone back to the ArmorAll. I sand the bare prop lightly. Then wipe down the prop w acetone a few minutes before applying the ArmorAll. I spray it on and then brush it all around evenly w a small throwaway brush. Then put it in the sun to dry.

Another variable is that my Willard only puts 37hp into her 18” prop. Lightly loaded.

As Hawkins says about the NE we are in the PNW with relatively cool water.

As DJ said ohm out that zinc / bonding system. I am betting that it is not working and your prop is taking the hit. That is not the cause of your barnacles however the zinc if working correctly will not grow barnacles and the prop more likely will.

MR Herrishoff claimed to understand fouling on the boats performance , just imagine the prop blown up to the full size of the boat.

djmarchand said:

Check the bonding wire to that zinc. You usually get very little fouling on zincs that are bonded to the bronze and other metals due to the electrolysis action. If the wire is broken or not attached the zinc isn't doing you any good plus it gets covered by barnacles like you see.



David

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It looks like a bronze ground plate to me. They do get covered with marine growth. Maybe the OP mistakenly called it a zinc?

boomerang said:

It looks like a bronze ground plate to me. They do get covered with marine growth. Maybe the OP mistakenly called it a zinc?

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Agree....though it doesnt look installed flush like I often see them....though I am not positive they should be.

On the north shore of LI sound we have got very good results using the cold galvanizing spray from Home depot the past 10+ years. On both the props and the shafts (SS) we apply two medium coats of the zinc spray on very clean and dry running gear at each season start and it easily lasts the entire season - typically 7 months or so. We did travel often each week but rarely had the boat sit for a few weeks in very active waters - not a dead end slip where growth was limited.

I am completely convinced that moving and even running the boat in place have the most influence...even in most bottom paints too.

The exact same products have such varied results unless in a fairly strict a paint test...which I have never seen where movement was involved.

Why would a barnacle happily stick to a poor zinc but eschew sticking to zinc paint? Not logical. If it really did work, wouldn’t you expect bottom paints to include vast proportions of zinc? As much as I hoped it would help, there is no logic here therefore don’t waste your time.

One possible advantage “might” be that the barnacles can’t get as much of a grip on paint and might release easier, but my pressure washing experience says that is not the case. In any event, the little buggers still cling on.

psneeld said:

I am completely convinced that moving and even running the boat in place have the most influence...even in most bottom paints too.

The exact same products have such varied results unless in a fairly strict a paint test...which I have never seen where movement was involved.

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For a number of years we put primer and bottom paint on one side and penaten zinc rich diaper cream on the other.
Then we put primer and bottom paint on one and the cold galvanize paint on the other.
They all worked for a while but these were the differences:
- penaten works well for about 12 weeks or so , then it begins to lose its ability to avoid growth and is impossible to recoat in the water.
- primer and bottom coat work equally as well as the cold zinc spray for a single season. After one season the bottom paint still has the ability to avoid growth but requires much touch up in many spots and often needs spot cleaning during the end of the season.
Because we came out of the water each season in the northeast (Northport NY) it was easier, and quicker and more economical to stay with the cold galvanize spray.

Typical for us anyway with between 20-22" dai 4 blade NiBral props and SS shafts in Long Island sound on a boat that does higher than hull speed for about 7 months.

And your tests were good for you, but they may have no bearing on other boats and their use/location/ etc...

In my mind it is not a product with great repeatability or reliability between users compared to other products.

Users should be warned that their results with cold galvanizing spray could be completely unexpected.

psneeld said:

And your tests were good for you, but they may have no bearing on other boats and their use/location/ etc...

In my mind it is not a product with great repeatability or reliability between users compared to other products.

Users should be warned that their results with cold galvanizing spray could be completely unexpected.

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Exactly , absolutely - just like all other products, the are of use as well as the application and usage of the boat will vary results.

Thanks to everyone for their responses. Yes, it is a zinc "Diver's Buddy" plate that I installed last spring, and yes all bonding wires throughout the boat are intact and terminate at this locations. So not sure why this occurred.


If you look at shaft zincs and rudder zincs, they show signs of activity. Again don't understand the plate situation.


The boat had been hauled in August 2017 shortly after I purchased it and the bottom cleaned and painted with an ablative Interlux paint. Not sure which one. Boat hauled for winter in late Sept. 2017 and relaunched April 2018. The winter storage fee includes painting in the spring and it's possible those doing the painting forgot to do the struts and rudders. The hull held up great, not a barnacle in site.


I just wanted to post my observations for those on the forum who were contemplating the zinc spray approach.


My prior boat, which was kept in Tampa Bay had used Propspeed which was the best product to prevent barnacle growth I had ever used. Was able to have it done cheaply as yard I was in had some left over that they wanted to get rid of.

Oh, regarding the zinc plate. That is located on the port side with the western exposure. In 2017 when I purchased and hauled the boat for painting, this plate was about 1/3 gone, so bonding system was working with no changes to it since I became owner.

If the results prove disappointing, you can’t go wrong to just fork out to a professional to apply PropSpeed - properly. Hence the professional recommendation.

I have owned various boats, pleasure and commercial, in BC, Canada, for 45 years. I pull my vessel every year normally the except 2017 when I skipped to a two year pull. Never again!

I have never seen barnacles on any of my zincs, even the two year time before pulling. I have used the cold spray on my prop(s) on some years with varied results. I still see build up of barnacles though I find it easier to remove them if the prop(s) were cold sprayed.

In 2018, for the first time, I sprayed the props, struts and shafts. I had only done the props previously. Will be interesting when I pull the boat next spring to see results.

My experience is similar to most folks. The more I use the vessel the less build up I get from barnacles.

I wish you luck, but why not just use that bottom paint? It looks to be doing a very good job.
Honestly though, in over 5 decades of messing about with boats, mostly professionally, I haven't found a single thing that actually works, even on boats like sports fishing boats that operate almost full time and much of that time at high speeds. The barnacles are just tenacious creatures.
At one point, chasing the big blacks out of Cairns OZ, we were chroming our wheels (very slippery stuff that), more to attract fish than keep the growth down on the wheels, and it did neither!
A couple of years back the Propspeed reps did our prop for free and it didn't impress me enough to pay for the stuff the next year.
The best I've found is regular old antifouling paint, not to say that that stuff does what it is advertised to do well, either.

Re AF on props won’t the copper and bronze together cause problems?
I thought you wern’t supposed to paint props w AF.

Nomad Willy said:

Re AF on props won’t the copper and bronze together cause problems?
I thought you wern’t supposed to paint props w AF.

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There's no electrolytic action between copper and silicon bronze (marine bronze), or stainless steel, to speak of. Not that there's much copper in antifouling these days.

I've been painting the running gear on vessels of all types, even steel, with antifouling for over 5 decades and I haven't noticed any indication of it doing any harm.

We had similar experience. the yard guy said we had sanded too smoothly and recommended we use a rough-ish sandpaper or grind to give more tooth to the coating. We'll see next haul-out.

Nomad Willy said:

Re AF on props won’t the copper and bronze together cause problems?
I thought you weren’t supposed to paint props w AF.

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Practice here with ablative hull a/f,unless using Propspeed,is hard a/f on running gear props/struts/shafts. Ablative is too "ablative" and won`t last. Primer on bare metal (if required),+ 2 coats of hard a/f.

we have used rustoleum cold galvanizing spray for 6 full seasons on 2 boats: one in long island sound (branford, ct) and the other in florida and bahamas (marsh harbour) with extremely good results. i do a light sand of previous year and then 2 spray coats. no barnacles on the parts i spray (props, shafts, and trim tabs).

Would be nice to know where green cove springs is. I wish people would put the state they live it so we have an idea where people are.

But Duetto,
I found it works too. But Armor-All works better where I am. Most of my experience has been in SE Alaska .. as in cold water and far less light. I don’t just dab on a little I flood the blades w a brush 3-4 times and sand w fine before. Next time I’ll do hard AF w a primer.