How do you keep your prop clean?

[Dalliance]

Sailing in cold fresh water, I get slime on the hull and tough white scale on the prop and shaft. Nothing like the kind of hard growth salt water sailors deal with, but still annoying. Every year before launch I've been laboriously cleaning hard white scale off the prop and shaft with a Scotch Bright pad only to see my nice bright bronze prop turn brown within two weeks after splash and white with scale within a month.

Last spring I cleaned the prop and shaft as usual, and then coated the prop with LanoCote. It definitely made a difference. With a mid-May launch, the prop stayed a nice bright bronze color until about mid-August, then started to collect the usual white scale. After haul out in mid-October, I did a quick finger nail test. The relatively thin layer of scale scratched off easily and the prop was still yellow under the scale. I've never been able to scratch off that scale with my fingernail before. I haven't cleaned it all off yet. That's a spring job, but I expect it to be a much easier job this year. I'll try to follow up with an update, in April-May on what I find then, but I think I may be a convert.

I first saw LanoCote marketed for use on props last year. It appeared to me to be the same as the the LanoCote I had on hand for use on bolts, battery terminals, etc. and that is the one I used on my prop last spring. Not so much frugality as being wise to, or cynical about, corporate marketing tactics.

I applied it with a cotton rag in 50 degree weather. Had to liquefy it with with a heat gun and also warm the prop so it didn't solidify to un-spreadable goo on contact. Lake Michigan didn't get over 72 degrees last year. I don't know how, or if, warmer water temperatures would affect results.

This was the first year I've applied anything to my prop. What are others doing to keep their prop clean?

 

[Gunni]

Anyone have experience with Lanocote on a prop in brackish/salt water?

 

[jibes138]

Petit makes a spray can anti fouling paint for use on propellers. I tried it last haul out and the barnacles and oysters love the stuff, my last dive I had a blast cleaning them all off with a plastic scraper and 5 in one tool. A Ziploc bag with rubber band might be a good choice if you remember to remove it when you use your engine.

 

[Gunni]

Yeah, that is the zinc barnacle buster - I use it to protect my expensive MaxProp, but it is marginal for hard growth. Once barnacles get started, they won't slough off.

 

[heritage]

I'll try most anything once,,, especially if it is cheap. So I tried this that was recommended by the marina yard owner for painting the prop:

 

[Rich Stidger]

Yeah, that is the zinc barnacle buster - I use it to protect my expensive MaxProp, but it is marginal for hard growth. Once barnacles get started, they won't slough off.

I used to use that Pettit product, but now I use "Cold Galvanize" from Ace. Bigger can, 1/3 the price, same % of zinc, same ingredients. I find that it works as well as anything else I've tried since they outlawed the really good stuff back in the early 90's.

 

[John T1594]

I don't know how many times I have posted this advice but here it goes again:
I have used the same method for the past ten years and never have more than one or two barnacles on my prop or shaft. I clean the stainless steel shaft and bronze prop down to clean metal with a wire brush on an electric drill. Wipe with solvent and apply two coats of a non-metallic primer. I have used Interprotect successfully but other non-metallic primers work as well – even Rustoleum primer. I then apply two coats of any available copper based hard epoxy bottom paint and splash the boat. Don't prime or paint under or over the zincs. As I said, little to no fouling after six+ months. I use the boat almost every weekend and motor perhaps for 30-60 minutes total each time we take the boat out. By the end of the season, the paint has mostly worn off the tips and parts of the prop blades but is intact elsewhere.

I have tried this method without the primer and always got bad fouling of the prop and shaft. Interlux outdrive spray works well if used with their primer but is more expensive. I have heard others theorize that the electrolysis current set up between the metal shaft/prop and plain copper paint somehow keeps the copper inactive and thus allows barnacle fouling. A non-metallic barrier coat of primer stops this interaction and allows the copper to inhibit growth.

I sail in the salt waters of Barnegat Bay NJ and keep the boat in Forked River - a somewhat brackish river feeding the bay.

 

[njlarry]

Hi John,
Keep up the good work. Your system makes sense.
For those of us who do not use a hard epoxy on the bottom, would 90% zinc over the non metallic primer be an alternative?
( This is a popular topic so I suspect you will be reposting for some time. )

 

[Dalliance]

I was at the boat yesterday and took this photo of the prop condition I described in my original post. In previous years without the LanoCote, it came out of the water completed crusted with white scale. That's my fingernail scratch test in the center. Not sure what the black specs are. Don't recall seeing them before.

John's method certainly makes sense. Might be a little more work than smearing on heated LanoCote, but if it works, it's worth the effort.

 

[RobG]

I've had good luck with the Pettit product also. Great tip Rich. I ran out last spring so I'll be going with the Rust-Oleum now.

 

[Don Lucas]

I've been using the Pettit spray for years. It works well and the "secret" is you need to apply a lot of it (use the whole can). One year I couldn't find in time and tried that hardware store zinc primer stuff, it didn't work except to allow provide a nice primer for the growth to take home.