Propeller Antifouling Experiment Results

[CaptNemoO2]

Last summer I tried using Desitin to keep growth off the prop. It worked ok for about half the season but there was still some barnacles and was stinky and a pain to apply. It can be reapplied in the water, but that's an even bigger pain. This summer I tried using cold galvanizing compound from Home Depot for about $6.



Attached is a picture of the results after being in the water from mid April to today. The boat was pressure washed when it came out, but over the years, I've never seen them take any barnacles off when they do it. And due to my marina being a basin with a 50 foot wide opening, I never trusted the marina got enough water turnover to be clean enough to swim in (rather I never trusted the other boaters not to direct discharge). That being said, I never got into the water throughout the season to clean the bottom, so the picture, for the most part, is the growth for the entire season. It's really only the beginning stages of barnacle growth, the stage that's easy to scrape off.

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[rdempsey]

I applied the same in October as a test.

I hope mine turns out as good as yours.

[ggray]

I have used Prop Speed with very good results. It is expensive though. When you have small props as I do, of course you don't need but the small kit. But it is difficult not to see how much more you pay per unit with the small kit.

Last time I went in with a power boat friend who had big props, so I saved a lot. He no longer owns a boat, so scratch that plan.

Anyway, somewhere, maybe here, I read of accomplishing much the same by using zinc chromate paint as a base coat, and when barely dry, paint with silicone sealant that had been thinned with a solvent to a brushable state. Not sure what to thin with, but would try denatured alcohol.

Has anyone heard of or tried something like this?

Would there be a better solvent to thin the silicone? Acetone? Laquer thinner?

[SVNeko]

I've used the Petit Barnacle Barrier, which I think is the same thing but more $$, also with good results.

[BandB]

We use Prop Speed and we're in the worst part of the country for growth. We've been very pleased.

[wsmurdoch]

Originally Posted by ggray

Anyway, somewhere, maybe here, I read of accomplishing much the same by using zinc chromate paint as a base coat, and when barely dry, paint with silicone sealant that had been thinned with a solvent to a brushable state. Not sure what to thin with, but would try denatured alcohol.

Has anyone heard of or tried something like this?

Would there be a better solvent to thin the silicone? Acetone? Laquer thinner?

I have been brush painting my lightly sanded bronze prop with silicone caulking thinned with either Coleman fuel or with naptha. I have done it annually in November for seven years or so. I have used several different silicones. To date the sort used to glue aquariums together works best. This year I am using GE silicone for metal hoping for better adhesion. We motor from North Carolina to Miami in January, cruise the Bahamas till June, then sail back. The prop stays clean until August or September when it needs scraping especially on the leading edges. After the first scraping all benefit is gone.

I got the idea from some anti-graffiti paint we used at work in England. With one prop, I have no real way of evaluating the idea. I figure at worst it does no harm, and at best it saves a few trips swimming over the side with a putty knife.

[Island Time O25]

For about 3 seasons now been using Rustoleum's zinc spray can with 93% zinc content. Don't remember the full name but any Walmart or hardware store has them for about $4-6. One can is good for about 3 double or triple coats of prop and shaft. Prior to that used a $30 WM can at $30. Same, if not better, results with Rustoleum.