Rudder Paint Gone

[JamieM]

I just hauled my Pilot 34 for the season and upon inspection I noticed that the rudder was down to bare metal. In the spring I had ground off all the paint to bare metal and then applied 3 coats of Interlux Primocon metal primer. I followed that with two coats on anti-foul. Is it possible that propeller wash simply wore all the paint away? My thought is the primer failed as the rudder was previously painted with anti-foul only and this did not happen. Perhaps it may also be an electrolysis issue. Anyone have any thoughts?

 

[rgano]

How many hours did you put on the boat at what sort of speeds? After removing all traces of coating on my rudder, I put two coats of Interlux 2000 on it followed by Sharkskin hard bottom paint. I have had little time on it, and the boat lives in a lift, but it is holding on OK. I have always had issues with the propeller and rudder paint holding on my boats. After a year the outer third of props was always bare metal and rudders showed signs of wear.

 

[AKDoug]

I refresh my rudder paint every year since the prop wash is directly over it and there is obvious thinning of the paint. It's fiberglass though, and the rudder shoe is stainless, and only the rudder and shoe get refreshed. It's the rudder shoe that loses it's paint, and one year I went bare to see how it fared. Stuff grew like mad on it, so back to painting it, but I have never primed the shoe under the bottom paint.

Just sand blasted it clean yesterday, next going to find the "right" primer before applying bottom paint and hope I get better results. It sounds like you did it right... I run about 600 hours a season, so there is lots of prop washing.

 

[JamieM]

How many hours did you put on the boat at what sort of speeds? After removing all traces of coating on my rudder, I put two coats of Interlux 2000 on it followed by Sharkskin hard bottom paint. I have had little time on it, and the boat lives in a lift, but it is holding on OK. I have always had issues with the propeller and rudder paint holding on my boats. After a year the outer third of props was always bare metal and rudders showed signs of wear.

This was my second season with this boat. I did not have an issue in the previous season when the rudder was coated with many years of anti-fouling paint. I ground the rudder off this year to make it as smooth as possible to help with cavitation issues. I put about 180 hours on the boat this summer. I cruise at 2800rpm so perhaps 90 to 100 hours at that speed. I think the Interlux Primocon primer failed. Might not be the right product to use. Next year I’ll try a two part primer like Interlux 2000. Perhaps I’ll just leave it uncoated as there were no signs of growth on it.

 

[Hippocampus]

Found leading and trailing edges of anything do worse. Hard paint or ablative. Always do an extra coat on them. Breakwater, keel, aft of thruster hole, rudder(s) etc.
Found 2000 needs sufficient build and you need to follow directions meticulously but it’s a great product. Did the failed bottom paint flake off? Suggesting poor chemical bond. Or bubble off? Suggesting electrolysis. Where did it wear off the most? Leading and trailing edges just suggests not enough was put on.

 

[Nomad Willy]

Re the OP he has very high velocity propwash and that may be a problem.

I just paint the rudder when I paint the hull. And it’s no more a problem than the hull.
But I’ve got a 6 knot boat w almost 3-1 reduction on the prop.

 

[Duetto]

hi,

i use 2 coats of rustoleum cold galvanizing zinc spray on all running gear, including rudder, and no problems or growth. we're in mystic ct.

 

[Comodave]

I would try the Interlux 2000 as a primer and then anti fouling paint.

 

[JamieM]

Found leading and trailing edges of anything do worse. Hard paint or ablative. Always do an extra coat on them. Breakwater, keel, aft of thruster hole, rudder(s) etc.
Found 2000 needs sufficient build and you need to follow directions meticulously but it’s a great product. Did the failed bottom paint flake off? Suggesting poor chemical bond. Or bubble off? Suggesting electrolysis. Where did it wear off the most? Leading and trailing edges just suggests not enough was put on.

Thanks for the reply. The paint just flaked off the entire rudder. After talking to others around the yard the general consensus is that the primer failed. Perhaps the wrong primer for the bronze rudder. Interprotect seems to be the way to go. I’ve used this for years on my previous boat (sail) and it’s a bit fussy but I have never seen it fail when properly applied.

 

[rgano]

This was my second season with this boat. I did not have an issue in the previous season when the rudder was coated with many years of anti-fouling paint. I ground the rudder off this year to make it as smooth as possible to help with cavitation issues. I put about 180 hours on the boat this summer. I cruise at 2800rpm so perhaps 90 to 100 hours at that speed. I think the Interlux Primocon primer failed. Might not be the right product to use. Next year I’ll try a two part primer like Interlux 2000. Perhaps I’ll just leave it uncoated as there were no signs of growth on it.

You'll be a lot happier with the 2000. Putting that many hours on the boat over a summer, MIGHT allow you to have some success with going bare, but you should still lean off the swimstep and use a boat brush occasionally to get the precursor slime off of the rudder.