I am moored in probably the worst place in the world for marine growth.
The small fishing harbour where I am has no flush though.
The only water movement is the tide which is not substantial.
Just outside the harbour mouth is extensive aquaculture.
Oysters, kelp, a variety of seaweeds and scallops.
So each incoming tide flows brings all those little buggers in where the happily cling to everything.
On top of that my boat is moored stern to south, so the low winter sun penetrates around the rudder and prop.
I dive and scrape her off in summer, but that is the only time that the water is warm enough. I don't have a wet suit!
When I motored across to the boat yard full speed was 3 knots.
The Prop Speed coating lasts 6 months, so this year I decided to give galvanized spray a go.
The bloke in the boatyard had never heard of it but said ."There is only one way to find out."
Will let you know the results in 6 months or so.

You go Gary!
It will be fascinating to revisit in 6 months and see the result. Propspeed is expensive enough that I'd wager everyone would be interested in this little experiment.

What metal is your prop? Is there a barrier coating from the zinc? Or is the idea that as it corrodes the fouling falls off?

Last year when I was on the slip there was a French design aluminium yacht being antifouled with zinc powder mixed into a solution I tried to get more info from the owners but all they could tell me was it was the designer's specifications, they had been doing it annually and were happy, as far as I could tell the growth fell off as the zinc fizzed away, no need for anodes either. I have been keeping an eye out for it on the slip to have a sticky beak

any update on this test? @garymalmgren

Hi Lenn
The short answer is , Yes. Gal spray paint works. (not perfect though)
The long answer is
I splashed in mid April 2022 ( 10 1/2 months ago).
Dove on the boat in late August ( boat had been in the water for 4 months) and was a little disappointed to find about 4 or 5 very small barnacles.
Scraped off and felt that it was a failure.
Water has been much too cold to dive and check since then. (7 degrees now).
However. I am still motoring at 5 knots which means the growth is less or as much as I would expect from the Prop Speed treatment that I was using up till now.
I haulout every 18 months or so , so will give a full report in August.
If at that stage the growth is the less, the same or a little more that usual years I will definitely use the Gal spray again.

The Gal spray costs $16 a can.
I sprayed about 4 coats. The first being light.
I didn't build up real thick.
I scrapped a bit of the first coat with a paint scrapper on the prop and shaft to see if it was adhering.
Goes on well and seems to adhere well enough.


Gary

Next haulout Gary try a topcoat of the silicon clear over the galvanising paint. It's available separate these days. I would be interested how that goes. There are a few people who have used it over ordinary metal primer.

Re try a topcoat of the silicon clear over the galvanising paint.

Will do Ramona and thanks for that tip.
Searched for silicone topcoat spray on Google Japan and came up with some (spray can) stuff with this description.
Looked great until I read the second part.
Do you have an example of the stuff that you mentioned?
My daughter is coming out to Japan form Oz in a month so that is an option.

About this item Country of Origin: Japan Made with a durable acrylic and silicone resin, this coat creates a durable and stain resistant coating film that can withstand UV rays, emissions, snow, and acid rain Lacquer type with excellent luster and quick drying properties. *Lacquer solvent may cause damage to the surface of the substrate coating, so please make sure to test application before applying it

Non-painting: Non-iron metals (stainless steel, aluminum, plated, brass, copper, enamel), plastic, styrofoam, glass, cars, motorcycles, luxury furniture, floors, places that are constantly submerged in water, vanity, MDF boards with large suction, high temperatures of the stove
Paint Type: Lacquer spray
Tools cleaning: lacquer thinner

Everything else I found was industrial quantities, and didn't have good product details.

maybe this?

www.bunnings.com.au/boyle-400g-clear-gloss-spray-sealer_p1857850

Select to expand quote

garymalmgren said..
Re try a topcoat of the silicon clear over the galvanising paint.

Will do Ramona and thanks for that tip.
Searched for silicone topcoat spray on Google Japan and came up with some (spray can) stuff with this description.
Looked great until I read the second part.
Do you have an example of the stuff that you mentioned?
My daughter is coming out to Japan form Oz in a month so that is an option.

About this item Country of Origin: Japan Made with a durable acrylic and silicone resin, this coat creates a durable and stain resistant coating film that can withstand UV rays, emissions, snow, and acid rain Lacquer type with excellent luster and quick drying properties. *Lacquer solvent may cause damage to the surface of the substrate coating, so please make sure to test application before applying it

Non-painting: Non-iron metals (stainless steel, aluminum, plated, brass, copper, enamel), plastic, styrofoam, glass, cars, motorcycles, luxury furniture, floors, places that are constantly submerged in water, vanity, MDF boards with large suction, high temperatures of the stove
Paint Type: Lacquer spray
Tools cleaning: lacquer thinner

Everything else I found was industrial quantities, and didn't have good product details.

I saw a smaller tin awhile back but you get the idea.

www.ebay.com.au/itm/285100909313?hash=item426156a301:g:tYcAAOSw9LRjuNg4&amdata=enc%3AAQAHAAAA4ER4F7ZamE6NKuowxxfr3CcylehXQQi1Hs
L6Gv3q24hAltSgsehdZp52NH9x5OoYceOQql13vhwuSbE097XFoMfw%2BpzoRYxv2JBTygRtRMpfCHHyASwKOfhMoBYQBp%2FDrOpyXBPQ1IY

www.ebay.com.au/itm/255843310869?hash=item3b91731d15:g:PEwAAOSwYGljfoq7&amdata=enc%3AAQAHAAAAoPuU4ZryKGlzOGwUfeX9dS3sbLHl4q0No1QIjBAiySsQYYfwKndtliIS5DuoGx0nIr8%2BMCXwalyKKptBB07uNRi8nVcP%2FK6akrYBxwKzElozgS8lySPMcxWxOFdrnTb9RZG9GIziPOEAjWaPKHSGsZZPXZ3aaUZNOhuSt3XcA1lzmiLWK%2B26A%2BEz1lvyZxRtIrlvXR2oBVUVBZ7hz9uRjUU%3D%7Ctkp%3ABk9SR_yKx5LUYQ

You can also make your own from a cartridge of non acetic silicon and thin this with a paint thinner. You will have to experiment to find the correct thinner. We will all be waiting for the test results! There is a thread on sailing anarchy about it somewhere.

Select to expand quote

Lenn said..
maybe this?

www.bunnings.com.au/boyle-400g-clear-gloss-spray-sealer_p1857850

Not this one sorry - it's for 'fixing' artwork done in pastels,charcoal, pencil etc. Seals it so the medium doesn't come off the paper. Usually interior only.

Select to expand quote

garymalmgren said..
Re try a topcoat of the silicon clear over the galvanising paint.

Will do Ramona and thanks for that tip.
Searched for silicone topcoat spray on Google Japan and came up with some (spray can) stuff with this description.

Re: Alternatives to propspeed.

I roll my own. Here's my recipe.

Ingredients: Epoxy thinner, a cheap tube of clear silicone, the type that doesn't have the vinegar smell, small can of etch primer.

Clean your propeller with very fine sandpaper or emery paper.

Place silicone in a jar or other container, add epoxy thinners and stir. After a while the silicone will start melting into the epoxy thinner. You want a mixture like thick paint that applies easily.

Paint the propeller with etch primer.

Now the critical step - before the etch primer dries, and it dries quickly, you need to paint the prop with your silicone. You need the etch primer to still be wet and tacky because then the silicone and primer will bond. If you let the primer dry before you paint the silicone it won't work, or only partially work.

Works as well as any commercial product.

The end result.
Painted with Gal spray April 2022.
Scraped a bit August 2022.
Hauled out to day (august 2023.)
Oh well, Back to Prop Speed.

gary