Looking for a primer for a galvanized steel hull

[Outdoorcat]

I'm in the process of docking a 63 year old galvanized steel lifeboat. In places the galvanized has rusted through, though the hull is still in pretty good condition. Can anyone suggest a primer suitable for this substrate and to be applied in outdoor winter conditions - and that hopefully isnt too expensive. Has anyone else found a method of treating this problem? Many thanks

 

[vyv_cox]

You need an etch primer for good adhesion on galvanised surfaces. I have used Hammerite's version on my garage doors, very successfully, but this is not quite the same thing as a lifeboat hull. Suggest you Google 'etch primer galvanised' where you will find lots of advice.

 

[VicS]

As Vyv says you need an etch primer.

International Yachtpaint do one. It is a 2 part product. It should be used exactly as specified on the product data sheet. Unfortunately it can only be used at temps above 15C.

Maybe if you search for other makes you will find one that can be used at lower temps but I expect they may all be similar.

I would definitely be looking at two part products not single pack ones that you might find on the domestic market.

Hammerite may just about be OK for garage doors but I can tell you that the coatings technologists where I used to work did not consider it much cop.

 

[Conachair]

book download

I'm in the process of docking a 63 year old galvanized steel lifeboat. In places the galvanized has rusted through, though the hull is still in pretty good condition. Can anyone suggest a primer suitable for this substrate and to be applied in outdoor winter conditions - and that hopefully isnt too expensive. Has anyone else found a method of treating this problem? Many thanks

Very good book on the subject here available as a download.
http://www.lulu.com/product/download/metal-boat-maintenance-a-do-it-yourself-guide/4735597

Agree with Vic, temperature is going to be a problem, maybe a tent and heater would help.

 

[oldsaltoz]

.
I would have thought your first priority would be to remove the rust and replace the lost galvanising with a coat of zinc to prevent further rusting, the zinc should be about 75 microns, too thick it will 'mud crack' and be useless, too thin and it will not provide protection.

This often followed with an epoxy based product to seal out any moisture, then some epoxy primer prior to the top coat of your choice.

Note, any sand blasting should be to class 2 and a half.

 

[Sailfree]

While you want a primer for galvanising that is only te cosmetic part of the work. Your real problem is the rust. For this you must get it clean to SA 2.5 standard which is usually achieved by sandblasting then a quick coat of a zinc rich primer preferably 2 pack is required.

Get it right and it will lsast for years get it wrong and you could be doing it again in 6 months!

 

[JimC]

I would first attack the places where the galvanising has gone by abrading down to bright metal and then coating with Galvafroid cold galvanising. You will then effectively have a fully zinc-coated hull again which will resist further rust. What you then paint it with depends on how much you want to spend. A coat of etch primer would be advisable to provide a key and then the Rolls Royce solution would be 4 coats of International's InterProtect. This goes on in alternate white and grey coats so you can see if you miss a bit. It is a solventless 2 part epoxy. Don't use epoxies containing solvents (e.g. Blakes primer/undercoat) because they will react with the Galvafroid. International Primocon is a cheaper (but still good) single part underwater primer. There is a lot of information and advice about painting boats made out of various materials on this site. www.yachtpaint.com/uk/