Painting a rusty rudder

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steve yates

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Quite interesting looking at my old threads about issues with bethfran when I got her, one question was about the rusty rudder , grind off and paint was one of the suggestions.
Now I'm finally treting her to all these jobs, here is the rudder at the moment. Would a tin of hammerite be fine to paint this with after I remove the flaking sheets of rust?
Should I grind back to bare metal once flakes are off or not? Thanks.
 

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I treat my steel boat with hydrochloric acid to remove all the rust before painting.

Once its an even gray colour it should be good to paint. I use epoxy tar below the waterline.
 
Hammerite has been living on a reputation which it earned during the last century.
It has been rubbish for ages.
The rusted metal needs stripping. Try a garage. They use needle-pin air guns to clean up discs, brake drums, suspension arms etc.


 
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Mercury Rising said:
Hammerite has been living on a reputation which it earned during the last century.
It has been rubbish for ages.
The rusted metal needs stripping. Try a garage. They use needle-pin air guns to clean up discs, brake drums, suspension arms etc.


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That's what I use before I use acid to remove ALL the remaining rust.
 
Hammerite is a different formulation to what it was years ago and my experience of it underwater are very poor. I would grind the rust away with a finger belt grinder which is a terrific tool and then prime and coat with the best available treatment, not sure what that is?
 
Rogershaw said:
I treat my steel boat with hydrochloric acid to remove all the rust before painting.

Once its an even gray colour it should be good to paint. I use epoxy tar below the waterline.
Click to expand...

Just looked up coal tar and epoxy tar, wow its expensive stuff, looks like coal tar was banned last year too. I can get a new galvanised rudder for £80, which is the intention, just wanted something to tidy it up in the interim and wait till winter to replace.
 
I painted rusty bilge keel. I attacked them with a twisted wire cup brush in a grinder. Savage beast they are!

On to bare metal Rustins anti corrosive primer. What we used to call red lead. Then primocon. Then antifoul. Seems good a year later.
 
steve yates said:
Just looked up coal tar and epoxy tar, wow its expensive stuff, looks like coal tar was banned last year too. I can get a new galvanised rudder for £80, which is the intention, just wanted something to tidy it up in the interim and wait till winter to replace.
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In that case I would grip blast the existing rudder (to remove any paint and other crud) . then have it galvanized.

If the rudder is hollow you must have vent holes to allow the air inside to escape and the zinc to drain out.

I would also weld studs on to the rudder so that zinc anodes can be bolted on to the rudder to protect the galvanizing.
 
If it has only to do one more season just slap a few coats of Primocon* on it and go sailing.
In the good old days primocon used to contain a lot of bitumen, if you used white AF it bled through turning it brown but it was effective in containing rust on iron keels as long as you put enough coats on.
*In my experience Jotun Vinyguard 88 is a much better underwater primer particularly for metals, it is cheaper too, about £9 a litre, but you may have to buy 5. Not to worry, it keeps and is the best primer you will find for all sorts of jobs, I paint my cradle with it. and it is a good weather resisting outdoor primer for wood too, (though not recommended by Jotun for that purpose).
Gael force sell an imitation (probably made like their AF by Flag), not a patch on Vinyguard.
 
burgundyben said:
What we used to call red lead.
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Have you ever used red lead? It's nothing like rustins ?
Would rate red lead as one of the best single pack rust prevention paints.
Have tried most on a 74 yr old ship I do maintenance on.
None of these paint on anti rusts are that great. Shot blasting and two pack seems the only long term solution, and galvanising..
 
Slap some phosphoric acid on it to push the rust back a little, paint it with whatever is on your shelf, then sit back and plan replacing with something better?
You could build a new rudder to a good standard for less effort than fettling what you have.
Move your boat forwards rather than treading water.
Not knocking your boat, just suggesting a big picture view of things. Do something that will pay dividends in 5 years time when it doesn't need doing again.
 
Rappey said:
Have you ever used red lead? It's nothing like rustins ?
Would rate red lead as one of the best single pack rust prevention paints.
Have tried most on a 74 yr old ship I do maintenance on.
None of these paint on anti rusts are that great. Shot blasting and two pack seems the only long term solution, and galvanising..
Click to expand...

Yes. I have a tin of crystalline red lead powder used it for years on wooden boats.

Red lead, red oxide, whatever. All I know is the screwfix red oxide is rubbish and the Rustins did really well on my keels.
 
Red oxide paint in many paint forums has been described as worse than useless and you would be better off using oil based undercoat ! It is really rubbish for steel.
Red lead paint is very heavy, has around 98% lead and has no solvents. It's linseed oil based and you can instantly know it as it smells of putty. It's a superb paint for woodEN boat bilges. Its suggested that the lead kills any bacteria so the bilge water stays clear.
It's very hard to find nowadays. Many think it's banned, maybe that's why there is very little demand? The golden gate Bridge use to be painted with red lead, hence the colour.
The rustins is something I've never tried but have heard of it.
It sounds interesting from reading their Web site.
 
Rappey said:
Red oxide paint in many paint forums has been described as worse than useless and you would be better off using oil based undercoat ! It is really rubbish for steel.
Red lead paint is very heavy, has around 98% lead and has no solvents. It's linseed oil based and you can instantly know it as it smells of putty. It's a superb paint for woodEN boat bilges. Its suggested that the lead kills any bacteria so the bilge water stays clear.
It's very hard to find nowadays. Many think it's banned, maybe that's why there is very little demand? The golden gate Bridge use to be painted with red lead, hence the colour.
The rustins is something I've never tried but have heard of it.
It sounds interesting from reading their Web site.
Click to expand...

Galvafroid tins are notably heavy. Zinc.

The Rustins is heavy. Very thick. I tried to piss it down a bit with white spirit and it wouldnt. Had to slosh a drop of celly thinners in it so I could get it on. I rate it highly.
 
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