Repainting my steel boat

[JimMann]

Hi, looking for some advice!

I’m about to do the bottom paint on my steel boat, the pervious owner isn’t sure what bottom paint is currently on but he said he was going to sand to roughen it up, red lead it and then antifoul. Does this sound right? Any suggestions?



On top,

Any suggestions on how to go about repainting the top?

I’m a total newbie and finding it hard to find the right question to ask to get the right answer

Thank you

[conachair]

Read this from cover to cover

https://www.amazon.com/Metal-boat-ma.../dp/B0070QRME4

[JimMann]

Originally Posted by conachair

Read this from cover to cover

https://www.amazon.com/Metal-boat-ma.../dp/B0070QRME4

Just bought it, much appreciated

[hpeer]

Conachair’s recommendation is a good one; he beat me to it.

Your question is not clear as to what you intend. Presumably the bottom has a barrier coat such as coal altar epoxy or a 2 part epoxy. If it does not have one it needs it. The basic idea is that the steel needs to be isolated from the “bottom” paint to prevent an unwanted reaction.

Any bare Steel needs to be protected first.

Above the waterline if you are going to strip (sand blast) to bare steel then I would use a 2 part epoxy like Ameron 235. If you are doing paint repairs the 2 part is a PITA to mix in small batches. We have been using Petit RustLoc for repairs. Clean the area, remove loose rust, treat with acid, 5 to 7 coats of RustLoc following overcoat times. It too is a PITA, just not quite as bad. For truly small spots you can try POR15. They sell it in small quantities in a 6-pack. But that’s just for where you only need a couple of square inches.

[tkeithlu]

Good to meet you, Jim Mann. I have a Bruce Roberts 44 diesel. My experience has been that unless you are absolutely willing to follow the book inch by inch, base paint on steel is a professional's job, with a penalty in the contract for it coming off. I say this having built mine.

On the other hand, with 14 aluminum plates as anodes, maintaining over a volt on the silver test probe, I've had nothing whatever corrode under the water line, after seven years in salt water. Not even bare metal. I chase rust above the water line with a spray primer and epoxy. It's not beautiful, more minature ship than yacht, but damn, is it ever tough. --Tim.

[JimMann]

Thanks Hpeer,

The boat is epoxied inside and out, I thought red lead was applied to bare metal hence my question. I asked the previous owner if it needed sandblasted but he said absolutely not. (Had it confirmed that it doesn’t) he just said he was planning giving it a coat of red lead and antifoul which seemed strange and as I said before, I’m at a loss to find the correct questions at the moment as I’m a bit overwhelmed

[JimMann]

Hi Tkeithlu,

The only rust on it is from the gunnels, the previous owner drilled holes in the them as they were holding water whilst being stored. I will be grinding them off when I go down next week as they seem pointless without being able to drain.

[JimMann]

Originally Posted by tkeithlu

Good to meet you, Jim Mann. I have a Bruce Roberts 44 diesel. My experience has been that unless you are absolutely willing to follow the book inch by inch, base paint on steel is a professional's job, with a penalty in the contract for it coming off. I say this having built mine.

On the other hand, with 14 aluminum plates as anodes, maintaining over a volt on the silver test probe, I've had nothing whatever corrode under the water line, after seven years in salt water. Not even bare metal. I chase rust above the water line with a spray primer and epoxy. It's not beautiful, more minature ship than yacht, but damn, is it ever tough. --Tim.

If you found a above water rust spot how would you go about sealing it?
Once I grind away the gunnels, I will expose bare metal, how would you take care of that?

Thanks

[Mr B]

If you sand blast it, Paint it immediately as rust will form on the bare steel straight away,
Then it will have a film of rust under the paint you cant see,
Put a steel nail in a glass of water and see how long it takes to rust,

[JimMann]

Ah just realised my question was already answered.. thanks

[redhead]

Originally Posted by JimMann

If you found a above water rust spot how would you go about sealing it?
Once I grind away the gunnels, I will expose bare metal, how would you take care of that?

Thanks

Does anyone use Ospho anymore? I ask because that's what we would have used on exposed metal on our steel boat, but then that was 20 years ago.

[mvmojo]

Above the waterline, for bare steel if there's any rust at all, coat with Corroseal (www.corroseal.com - available from Amazon). This will convert any existing rust (even micro rust you can't see) so that the oxidation will stop. Next, a couple coats of DeVoe Bar Rust 235 2-part epoxy (now Amercoat 235). Follow up with a top coat of your choice. For below the waterline, once blasted or sanded to bare steel, coat with inorganic zinc chromate - Ameron Cathacoat 302H. This must be done immediately after exposing bare steel, i.e., don't let it sit overnight or rust will form. The Cathacoat 302H can be overcoated with several coats of Bar Rust 235 - I used 4 coats on MOJO. (You can use Cathacoat for above the waterline repairs as long as you coat any bare steel within a few hours of exposing it, but is not intended for use over existing paint.) Bottom paint comes next. I use PPG ABC 3 bottom paint, usually 2 or 3 coats. I get 4 years out of this paint (in salt water), and at every haul out it looks clear that I could have gotten 5 years (which is how the paint is advertised!).

We just had MOJO painted, roof line to keel, last summer. All suspect areas were sanded down as far as needed to get a stable painting surface, including taking numerous areas down to steel. Cathacoat was applied anywhere we exposed steel. She got at least two coats of Bar Rust 235, up to 4 coats where we took her down to bare steel. The bottom then got two coats of ABC-3 ablative bottom coat (three coats around the waterline and on the rudder) while the topsides got two coats of Amercoat 450 HSG top coat. Came out fantastic! More pics are at www.mvmojo.com

[crisadee]

Originally Posted by tkeithlu

Good to meet you, Jim Mann. I have a Bruce Roberts 44 diesel. My experience has been that unless you are absolutely willing to follow the book inch by inch, base paint on steel is a professional's job, with a penalty in the contract for it coming off. I say this having built mine.

On the other hand, with 14 aluminum plates as anodes, maintaining over a volt on the silver test probe, I've had nothing whatever corrode under the water line, after seven years in salt water. Not even bare metal. I chase rust above the water line with a spray primer and epoxy. It's not beautiful, more minature ship than yacht, but damn, is it ever tough. --Tim.

Hi Tkeithlu,

Staying in South of France, I'm owning a steel Bruce Roberts Spray (53" LOA Gaff rigged ketch) I bought from german people. I am very interested in your aluminium plates as anode, could you please tell me more? Though professionals told me my boat is not actually concerned (other one told me the contrary, proposing to sand blast and repaint the bottom for "only" 12 000 $!) I am very scared of electrolysis, became a lot of different advices, need to know more about how to avoid it. Thank you in advance for your answer, I'm anyway happy to meet some BR owners, I find they are great seaworthy boats, very rare here on the Med!

[turtleofdart]

First of all don't panic about a bit of rust. it is a process that happens relatively slowly and steel coats itself with a protective layer...above the waterline.
We have a small steel bilge keeler and have replated sections in the bilge where it had rusted quite thin ... between tides and without lifting out... we have found that you can treat rusty steel effectively with owatrol or penetrol after removing loose rust. sveral coats of that and then oil based paint mixed with a bit of owatrol and you can get a good finish that sticks to to rusty steel.

any epoxy based coating is a waste of time unless you get it back to absolutely shiny metal by grit blasting and paint immediately.

I would stick to traditional oil based paint... we use skip paint(dumpster paint) and owatrol for most of the boat....and its cheap!

If the paint is sound, leave it on!... chip and grind any rusty patches, get oil based paint on, antifoul and GO SAILING!

the world's oceans are full of strong, waterproof rusty ships that will do thousands of miles.... don't let them scare you into thinking the paint has to be fantastic and the boat has to be completely rust free before you can go sailing.

if you are really broke and your bilge is very rusty indeed you can even fill the bilge with concrete and scrap metal and she will float for your grandchildren with no further maintenance. I might be exaggerating a bit but don't listen to the fearmongering about steel boats. Steel will cry its eyes out for years and years before any real structural damage occurs. when it does rust through it is easy to weld new plates in!

your boat looks great, my friend! get a compressed air chisel and get the worst of the rust off the bottom, paint with oil based paints and GO SAILING!

youtube: putyoursailsup for a nice little film of our boat and a journey....

[Fore and Aft]

If you are just going to paint over the old antifoul, give it a hard sand then paint it with https://international-yachtpaint.com...imers/primocon
Then antifoul afterwards, this primocon is good to use if you do not know what the antifoul is.
Turtle of dart is right, you can get away with single pack oil based paint. But I only like to apply over a good two pack epoxy paint base.
I painted my non skid areas three years ago with this cheap oil based paint and they still look good. Berger JetDry Concrete Coating Products
Cheers