Antifouling a Prop

[Little Otter]

WOW I figured ater all this time it would have been gone completely

[MagnusS]

Understanding cupper antifouling and zinc anodes:

http://www.cruisersforum.com/forums/...0&postcount=23

[mydauphin]

Marker idea works until it gets wet. Anti-Foul paint works until it is removed by the cavitation.
Actually, another idea that does work is to cover prop with heavy duty tuff garbage bag. Tie opening around shaft. Barnacles will no live without water flow. Make sure your zinc are up to date and check regularly because without free water flow electrolysis might be more. Works on rudders too.

[Monka]

I tried six coats of egg white on my bronze prop and cooling water inlet cover with amazing results!! Absolutely NO growth at all after 9 months! Just slipped the boat yesterday and was astounded at how there was no growth whatsoever! as was the marina manager and quite a few onlookers at the marina..yes! i have witnesses!....So,you have now all been informed on this very cheap alternative! This is no yoke!

[Roy M]

I think there is a misspelling. It should read "this is no yolk!"

[Cherp]

I just had a good idea. We can get around the growth problem on props by removing them when they are not in use, drying them over mild heat on the stove, washing them with fresh water and drying them with a towel and stowing them in a warm dry place until they are required for the next trip. I notice the fouling only takes place when they are left unattended in the water.

[Monka]

"Yolk or no Yoke".....there is no egg on my face!!....

[SurfNRG]

Monka, You beat me to it. As soon as I read "No Yoke" I was gonna reply with the "Egg on your Face". Quite humorous you are.., And I guess that explains why the blades on my egg beater never rusted too, eh?

[Jim Cate]

I would like to point out one discouraging fact:

Copper sheathing on old wooden ships was not applied as antifouling in the modern sense, ie to stop barnies, tube worm, coral and soft growth, but to prevent the dreaded shipworm (terado (sp)) from infesting their hulls. If you read Cook's journals, you will note that they frequently were forced to careen their ships to remove -- you guessed it -- barnies, weed and all the gunk that we worry about... off of their copper sheathing.

So, my friends, I fear that copper plating on our props will not solve the vexing problems of fouling. Might look nice for a while, tho...

Cheers,

Jim and Ann s/v Insatiable II lying Gladstone Qld Oz

[orion1]

Magic marker does not work.

[Maine Sail]

Props and thru-hulls are generally made of different bronzes. Many props are made of Manganese Bronze, though some are NiBrAl.

Manganse Bronze has a considerable amount of zinc in it depending upon the composition used to make the prop. Most marine grade Manganse Bronze is comprised of roughly 58% Copper 39% zinc 1% iron 1% tin. Though different alloy compositions of Manganese Bronze can see zinc content as low as 25% and as high as 39%. The copper in bottom paint can lead to de-zincification of a Manganese Bronze prop which is not good for it.

Thru-hulls & seacocks are generally, and I use generally carefully as who knows what's coming out of China these days, made from a very low zinc content bronze. This Bronze for valves and thru-hulls is usually referred to as Silicon Bronze and is comprised of roughly 96% copper 3% silicon 1% Manganese. Again, who knows what is what these days so a call to a manufacturer is sometimes a good idea. Silicon Bronze has virtually no zinc so should not suffer from de-zincification like Manganses Bronze or Tobin Bronze. Painting thru-hulls should pose minimal threat if they are in-fact made from silicon bronze but painting a Manganse Bronze prop or Tobin Bronze shaft, with copper based bottom paint, is not generally a good idea..

Prop shafts made of bronze were mostly made from Tobin Bronze which also has a higher zinc content and also does not like copper anti-fouling paints. If you paint a Bronze prop shaft or prop you should really keep up with your zincs so the high content zinc in the shaft or prop does not become the sacrificial material. Better yet it may be wise to use a paint that is safe for underwater metals rateher than a copper based paint..

Bronzes are not all the same and there are many different grades of bronze that really should almost be called a brass due to the zinc content but because of the added tin or other alloys they are referred to as bronze instead of brass. I've personally never understood why most props have such a high zinc content and are made from Manganse Bronze and not something with more corrosion resistance...?

My prop was painted by an un-knowlegable yard ape, or should I say "slathered" with paint, on the way back from Florida in one of those yards that does not allow DIY. Rather than have them strip it off the PO, & good friend of mine, launched and figured he'd just keep up with the zincs. By the time I bought the boat and stripped the copper based paint off the prop it was already de-zincified and pretty much toast despite the PO keeping up with teh zincs on the prop shaft!!


I paint my thru-hulls but not my prop, shaft or strut..

[dirtydon]

anyone try powdercoating there props?

[Wotname]

Just remember that powercoating is porous.

[Monka]

SurfNRG,I'm unable to explain why the blades of your eggbeater has no rust? I just checked mine and was disappointed to find a few rust spots! but,the disappointment soon turned to glee when i noticed that there was absolutely no marine growth whatsoever!!.....
Seriously,I can understand that alot of sane,thoughtful folk would be thinking, how on earth could egg white possible stop marine growth You would think that the first few revs would wash the stuff off and with a bit of luck and a cupfull of sugar,you may have some meringues pop up out of your wake!
But,the truth is,it works!! or it did for me! and the procedure is simple...
Just clean prop to bare metal,I used wet/dry paper (120grit from memory),then paint on six coats of egg white,allow to dry between coats(I used a hair dryer,as it was quite cold 9 months ago)..that simple!!..and to best of my limited knowledge the egg i used wasn't laid by the hen (or a golden goose!) on a full moon with it's bum pointing to the prevailing trade winds....
So,I do hope that others who read this,will give it a go and come back and confirm the wonderment of it all....best to leave the magic markers for marking magic! and the money saved from useing prop-sped would be better spent at the bar

[barnakiel]

It is also possible to fold a folding propeller and keep it in etui. Some say it is better than the pink marker.

;-)))
b.