|Topic Review (Newest First)|
|03-02-2009 06:17 PM|
Originally Posted by lancelot9898 View Post
|03-02-2009 03:49 PM|
Pettit Zinc Spray
I have a max prop on my boat for the past 24 years and have tried all sorts of things to keep it clean including a labratory grease which seem to promote barnacle growth rather than deplete it. For the past 10 years I've been using a hard bottom paint, but I do prep it with a underwater primer before application. This includes first sanding the prop, wipeing down with a solvent, then applying interlux vinyl lux primewash and then the primocon primer before the putting a hard bottom paint on. I keep the boat in the Cheaspeake and haul out just every two or three years diving on the boat maybe once a season with minimual cleaning. The boat is used heavily throughout the year only sitting in the slip during the winter months. It is a PITA to prep that prop and I hear that Max Prop is recommending the use of the Pettit Zinc Spray. I am thinking about switching since it seems like a easier application, but I'm not sure if I can get multi season use out of that product. The jury is still out...
|03-02-2009 02:40 PM|
Originally Posted by Idiens View Post
Please, please, please do not use a copper base anti-fouling on a prop. While the Max-Prop is made of Nibral, PYI does not recommend the use of a copper based anti-fouling paint as it can cause galvanic issues!! NiBrAl is Nickel, Bronze, Aluminum.
Many props are made of Manganese Bronze, though some like the Max-Prop 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..
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 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..
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...?
I paint my thru-hulls but not my prop, shaft or strut..
|03-02-2009 02:11 PM|
OUch... how come there aren't any on the prop??
Originally Posted by boatpoker View Post
|03-02-2009 12:27 PM|
Originally Posted by Idiens View Post
The Pettit stuff works great...if you question my advice speak to the people at PYI PYI Inc. Max-Prop PSS Shaft Seal Seaview Radar Mounts R&D plus you can order the Pettit and a MaxProp grease kit while you are on the phone.
|03-02-2009 12:16 PM|
|boatpoker||How could this not cause vibration ?|
|03-02-2009 12:09 PM|
And his boat says AFLAC....
|03-02-2009 01:04 AM|
|sun37||My prop is a 3 blade Flexofold, described by the manufacturer as: Cast Nickel/Aluminum/Bronze (NIBRAL), high strength, corrosion resistant and 82% copper for anti-fouling. I am not sure the anti-fouling features is working because the prop has to be cleaned every 3 to 6 months to get rid of the barnacles otherwise the motoring speed drops by 1 knot. The boat is in the Med, sailed most days from April to November. Is this to be expected? Any solutions, including anti-fouling and vaseline?|
|11-17-2008 10:49 AM|
|JimsCAL||I've always painted my prop with the same paint I'm putting on the bottom. Never had a problem with it not staying on and barnacles haven't been a problem. Prop is a Martec folder.|
|11-16-2008 08:20 PM|
Nine years ago we moved our boat from a fresh water lake to the Chesapeake Bay. Mid summer we were motoring and the engine kept overheating. We phoned our diesel guy and he said "Bad year for barnacles-call the diver." Sure enough-after a good cleaning the engine ran fine.
We've never painted or used the vaseline trick. Does winch grease do the same thing as vaseline?
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