Coating hull after removing roofing tar.

john.0 · Jul 30, 2015

I have the hull stripped of the tar and what was left of it's paint,it is corroded quite a bit and all over.I have tried mineral spirits and brushes but It is virtually impossible to remove every last bit of tar from the very porous corrosion.When heat is applied tar leaches out from under rivets and from areas that have been cleaned.

I absolutely do not want to re-coat it with roofing tar and I really doubt that painting it in any way would be successful.

I'm thinking of coal tar epoxy but I am not familiar with it and am not sure if it would be compatible with the tar that is left in the pitting.Any ideas or advice would be great.

Johnny · Jul 30, 2015

John, :WELCOME: to Tin Boats.
Please complete your profile when you have time.
Knowing what part of the country you hail from helps
us give you more accurate information.

Do you have any photos of what you are working with ?

Are you working on the bottom or inside of your boat ?

How big is your boat ?

john.0 · Jul 30, 2015

Thanks for the welcome and I will get to the profile soon.

It's an old 13 foot semi v and I'm working on the outside.
My plan was to remove the tar then prime and paint but the way the corrosion is I am unable to get all of the tar out of it,also the tar has seeped under the rivets.I'm pretty sure that hidden tar would ruin any paint I would put on it.I heard about coal tar epoxy and thought maybe it would be compatible.

Here is an example of the corrosion.That area was fairly clean but leached tar out from under the rivets and the corrosion when heated.

Johnny · Jul 30, 2015

eeewwww I am very sorry to inform you that your boat has Leprosy.

wow, without seeing more of the bottom, it is hard to tell if that scale
is the tar or the actual metal.

You may have to go to a more aggressive solvent such as xylene, lacquer thinner, naptha, acetone, etc.
when you get to the point that little to no tar leaches out of the cracks and crevices,
and you just simply give up and don't want to waste any more of your time.
dry it well IN THE SUN for a full day, cover up at night with a blanket then plastic tarp over the blanket.
then, next day, paint with an EXTERIOR OIL BASED PRIMER/STAIN BLOCKER such as Zinsser, Kilz, Rust-Oleum, etc.
the petroleum base will dissolve and absorb the tar making it chemically the same.
LOL that is the plan, anyway. It may take a couple of coats. Let dry thoroughly 24 hours between coats.
Try not to puddle the primer in the low spots. Nice even thin coats all over.
again, cover with a blanket and plastic over the blanket at night.
Reason? because if the plastic touches the boat, moisture could form and ruin your paint project.

after the primer is applied, report back with your results . . . . . more PHOTOS will help us help you.

DaleH · Jul 30, 2015

Is/was that a saltwater boat? Looking at that corrosion ... I don't see it stopping. If in indeed is a chloride attack that is now within the aluminum, it is self-perpetuating and you can't stop it ....

Johnny · Jul 30, 2015

I have never seen or used Coal Tar Epoxy. A quick search on the web turned up this.
But like Dale said, what you have is a cancer. You can cover it up but it is still there.
We can not suggest that you cut your losses and get another boat. That is your call.

• Heavy Duty High Build Epoxy Primer - 4:1 Mix
• Prevents Rust and Corrosion
• Excellent Adhesion & Abrasion Resistance
• Heavy Duty 4:1 Mix
• Recommended for Saltwater Immersion Service
• Conforms with U.S. Corp of Engineer - C-200 specification
• Perfect for Commercial Marine, Yacht & Industrial Use

Coal Tar Epoxy Primer is a heavy duty high build epoxy primer. Prevents rust and corrosion, has excellent adhesion & abrasion resistance, and Is recommended for saltwater immersion service. Conforms with U.S. Corp of Engineer - C-200 specification. • Perfect for commercial marine, yacht & industrial use.

john.0 · Jul 30, 2015

Barefoot_Johnny said:
eeewwww I am very sorry to inform you that your boat has Leprosy.

It sure looks that way doesn't it.

That is the scale in the photo.It was clean untill I put a bit of heat to it then the tar boiled out.
Rust-Oleum self etching appears to be oil based so I might give it a try.I would just hate to waste the time and money on primer and paint only for it to fail.

Since it is so pitted I'm leaning towards the coal tar epoxy now because from what I understand it can be applied with some thickness to it.

john.0 · Jul 30, 2015

DaleH said:
Is/was that a saltwater boat? Looking at that corrosion ... I don't see it stopping. If in indeed is a chloride attack that is now within the aluminum, it is self-perpetuating and you can't stop it ....

I'm in Missouri so as far as I know its not been in salt water.
It was heavily coated with what I think was a copper paint though.

john.0 · Jul 30, 2015

I wouldn't be losing much.I paid $150 for it and was most interested in the trailer it came on.

I have also never seen or used coal tar epoxy before and was hoping to find somebody who has.I just figured it probably mesh with what was left behind.I'll likely end up trying the coal tar epoxy and see if it sticks.

richg99 · Jul 30, 2015

Coating an aluminum boat with copper paint is most likely the culprit. Way worse than using copper impregnated treated lumber IMHO.

Better see if there is enough aluminum left to hold up to pounding, waves etc.

I would take my $150.00 loss and move on. You can get a bit back by selling it for scrap aluminum.

richg99

john.0 · Jul 30, 2015

richg99 said:
Coating an aluminum boat with copper paint is most likely the culprit. Way worse than using copper impregnated treated lumber IMHO.

Better see if there is enough aluminum left to hold up to pounding, waves etc.

I would take my $150.00 loss and move on. You can get a bit back by selling it for scrap aluminum.

richg99

I think it's because of the paint also.It appears to still be structurally sound and there aren't too many waves around these creeks here.
I wouldn't be losing anything,I got a trailer with a title out of it.Around here any kind of trailer with a title is a steal for $150.

Shoedawg · Jul 30, 2015

+1 for Rich on selling it for scrap.

From the picture, it looks like the battle is over and the tar+corrosion won. BJ made some really good recommendations, by suggesting to use more aggressive solvents. If you wanna try those, I buy them in the smallest sizes you can find, to save money, and use it in small test areas. You can also try Zip Strip, Aircraft Remover or something similar.

I ran into tar on my hull, and found that the only way to remove it was a heavy duty Rust/Paint Stripper pad made by 3M and the occasional use of a brass wire cup using Aircraft Remover. I didnt have all that pitting like you are facing, though. I would keep the trailer, scrap the boat and use the money for another tin.

john.0 · Jul 31, 2015

Shoedawg said:
+1 for Rich on selling it for scrap.

From the picture, it looks like the battle is over and the tar+corrosion won. BJ made some really good recommendations, by suggesting to use more aggressive solvents. If you wanna try those, I buy them in the smallest sizes you can find, to save money, and use it in small test areas. You can also try Zip Strip, Aircraft Remover or something similar.

I ran into tar on my hull, and found that the only way to remove it was a heavy duty Rust/Paint Stripper pad made by 3M and the occasional use of a brass wire cup using Aircraft Remover. I didnt have all that pitting like you are facing, though. I would keep the trailer, scrap the boat and use the money for another tin.

I used diesel and rags to remove the tar and it worked quite well.I sprayed it and let it sit in the sun and the tar liquified it.

My concern is not with the pitting but getting a base coat to properly adhere with what little tar that's left in the nooks and crannies.Scrapping it for $40 or $50 dollars would be such a waste.It is structurally sound and other than the pitting it's a useable boat.

Globbing soft roofing tar or whatever tar it was on it was a horribly silly thing for someone to do.

richg99 · Jul 31, 2015

If she is structurally sound, why do you think you must coat it with anything? My 1648 Lowe is bare aluminum. ????

richg99

Shoedawg · Jul 31, 2015

Yes, why paint it then? Just keep it bare aluminum, unless you really want to paint.

Have your tried a Pressure Washer to help get some of the tar out of the nooks and crannies? If you dont have one, you can take the boat to one of those car washes that have a PW. I'd find one that has a heated pressure washer. That may help loosen and break the crap out of there. Or try some some local mechanics and see if they have a heated PW you could use. You be surprised most would be willing to help.

Shoe

john.0 · Aug 1, 2015

I took it out to the car wash this afternoon and it helped a little bit but it's still not how I would like it to be.

I want to coat it because it looks like crap and it's obviously got a few leaks.I was looking into Gluvit but for $107 a gallon I would hate for it to not properly adhere.I also considered Steel-Flex but again I would hate for it to not properly take hold.

Skiffing · Aug 1, 2015

John -

Cut your losses, man.

It is too far gone.

AND there is now crevice corrosion and you will not be able to stop that.

I was reading a story a while ago about a ~ 30 foot pilot house in the northwest that some yard put copper paint on.

The owner didn't realize it until the corrosion started to flower through the paint.

The hull is GONE. Not repairable.

Don't throw money at this.

mirroman · Aug 1, 2015

I'm not what you would call and authority but, I have been restoring alum boats for a long time and would not even attempt to restore that one. I agree with those that recommend finding another tinny to restore.

Johnny · Aug 1, 2015

.

Think about this . . . when you said . . .
"I wouldn't be losing much.I paid $150 for it and was most interested in the trailer it came on".

so, if you can clean it up a bit more, maybe you can sell it for $50-100 and you get a free trailer out of the deal.
if you spend a hundred bucks on primers and coatings, you are going back into the hole.

Just take a breath, back up, and start over in your thought process

and this is my last Dos Centavos

.

john.0 · Aug 1, 2015

My intent is not to do a full restoration of this boat and pass it down the family for generations to come.It's an old boat that would be used on local creeks for a couple of years and likely never see anything other than a 40 pound thrust trolling motor.

I have a 12 foot jon aswell (which I bought the trailer for)but cannot take my wife and child on it with me.I don't see that spending something around $100 to seal up the bottom and make it look nice to get out on the water with my wife and kid is such a horrible idea.The boat is not crumbling apart,it has a couple of small leaks but in no way is dangerous or going to spontaneously fall apart or dissolve while on the water.
Around here a boat this size with a title would be $400-$500,that also is not possible for me at this time.

Anyways I got at it with a stainless cup brush on a grinder this evening and it seemed to get in there and clean things out pretty good.
I do appreciate the advice,just maybe don't agree with all if it.

Coating hull after removing roofing tar.

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