Help Steel sloop- paint under water line

[RaymondR]

Originally Posted by JPA Cate

Imo, the OP has shiny spots because someone simply scraped the bottom. A barnacle used to live there. We have no reason to think there is an anode problem: he does not mention other places where paint is blown off, just shiny because it was scraped and washed.

A.

Correct,

One of the things I learned from maintaining drilling rigs for about 30 years and a steel boat for 26 is that if paint has a good hold on the steel leave it be and concentrate on the parts where it does not.

You need a very low viscosity primer and then a couple of coats of coal tar epoxy on the bald patch then another coat of the primer as a barrier coat and the antifoul.

[Fore and Aft]

Gio1973 how about posting a picture of your steel yacht bargain? I have surveyed a few steel yacht bargains here in Oz and am curious as to what a bargain looks like over there?
Fingers crossed it is just a few patches of paint that are damaged. I once observed a steel yacht lose most of its paint below the waterline just from being water blasted.
Cheers

[oceanshoretiga]

Personally, I don't think you have a big problem (based on the description).

I've had steel yachts for 38 years. Some points in my experience and when having had paint and cathodic protection specialists in to evaluate my issues.

First, zinc rich paint is simply another anode and while it protects the steel will cause paint to flake off. I blasted my zinc paint of the hull years ago and epoxy painted as mentioned elsewhere.

Second, each anode, no matter what size, will put out the same amp/volts. My 36 footer requires only 2 anodes. I had 8 little ones and the paint kept blowing off. If you can get a underwater guage, hang it off the deck and check out. The reading. I'm sorry I don't remember what the reading should be but if it is too high you have too many anodes.

Third, this last haul-out I had some of those 'clean steel' bubbles and the assessment is they are from stray current. The current could be from inside your boat or from the surroundings (eg pilings, other boats). I'm told if the bubbles haven't all burst but still have water in them, they are probably from an intermittent sources. I touched up this spots with epoxy then anti-foul primer; then anti foul.

Fourth, shiny steel under these bubbles is not necessarily a bad sign - the steel is not corroding (and is unlikely to do so underwater anyway).

Short term, I'd say you are ok, as others have said. Long term, get good advice and good paint.

Enjoy steel; it is special.

[lamadriver]

Joton 87 stuff is awesome - ,

clean, scuff, acid wash then hot coat with a few coats of j87 , then hot coat the first coat of anti foul over the j87.

by a cheap needle gun.

spend some time on you tube

buy one of these and learn how to use

https://www.boatzincs.com/corrosion-...ode-specs.html

[mvmojo]

I've had great success with the Ameron system of paints. Blast to bare steel, paint with Catha-coat 302H inorganic zinc primer followed by several coats of 235 Bar-Rust then 2-3 coats of 5 year ABC-3 bottom paint. We get 4 years out of the ABC-3 bottom paint and are always amazed at how good the bottom looks when we haul - I always think I could have gone another year!

[Triumphant]

Steel boat owners for many years

Not having access to sand blasting where we are, what we do is

1. Get the steel as clean as you can, shiny, with grinders and stainless steel brushes
2. De-grease and paint the clean steel with Phosphoric acid and leave overnight
3. If the steel is still shiny the next day wash off the area with water and let it dry
4. If the steel still has black pit marks, there is still rust present so you may have to repeat Steps 1 & 2 until you achieve 3
5. Apply 3 – 4 coats of 2 part Interprotect 2000E (best primer I have found yet in my part of the world)
6. Apply 2 – 3 coats of 2 part Coal tar epoxy
7. Apply top coat, ensure you have the overcoating timing right or be prepared to lightly sand if you get the timing wrong

We have often had small blisters on the bottom of the boat, when you pop them, strange smelling liquid comes out and steel underneath is shiny clean, I have been told this is called paint osmosis. It you follow the list above they do not re appear.

One final point
As the boat is new to you, I strongly suggest you haul it out before you go poking around the hull underwater.

Good luck

[Capt. Ray]

I have a 97-foot steel ketch that I just hauled in Yucatan at a very good rate. Days later I had her sandblasted and zinc primed to stabilize prior to some hull work, then will epoxy and anti-foul.

In your case as you are hauling in a few weeks I simply would not worry about the few spots of bare steel, just get her hauled out and look at the overall paint situation. If it looks good and you can scrape to a nice surface below the old anti-foulant then maybe another coat of epoxy first after spot-filling the bare steel which you will simply grind to white steel with an angle-grinder.

If the main paint is generally failing as I suspect it might be then you should sandblast to white steel and recoat. It is so satisfyiing!!! You don't need zinc primer, I did it because of the work schedule not because it would normally be needed with excellent epoxies these days.

[gio1973]

Originally Posted by Mithril Bham

Sounds like you need to haul, sandblast, primer and bottom paint or else you will be dealing with this constantly.

You mean primer and antifouling?

[gio1973]

Originally Posted by RaymondR

Correct,

One of the things I learned from maintaining drilling rigs for about 30 years and a steel boat for 26 is that if paint has a good hold on the steel leave it be and concentrate on the parts where it does not.

You need a very low viscosity primer and then a couple of coats of coal tar epoxy on the bald patch then another coat of the primer as a barrier coat and the antifoul.

Thank you, can I use the same LV primer as a barrier coat b4 antifouling?

[RaymondR]

Originally Posted by gio1973

Thank you, can I use the same LV primer as a barrier coat b4 antifouling?

Should be OK, a barrier coats purpose is to provide a surface the next coat will bond to and help adhere any loose material from previous substrates and thin epoxys of any sort do this well.

[Mithril Bham]

Originally Posted by gio1973

You mean primer and antifouling?

Of course. Call Awlgrip rep and ask them. You don't have to use their paint. More than just primer & antifouling. Probably six coats in all.