How should I protect my steel hull from rust?

[s/v Jedi]

The use of the steel brush in wet paint or epoxy for adhesion to metal is to create contact between the resin and clean, bare metal that has absolutely no corrosion because below the resin, oxygen cannot get to the metal.

POR15 works differently, I almost think there may be a rust converter in it, but then again they sell it with separate cleaner and converter so who knows. The thing is that I see it bond much better than something like a good epoxy primer after doing all the same prep.

[RaymondR]

My 30 year experience with a steel boat is that unless you can blast and immediately apply a low viscosity epoxy primer, the result will not last more than a few years.

Internally in non traffic areas I used a cement render formulated from linseed oil that I boiled and white cement. This provided a basic environment to any areas wetted and also showed up any areas rust had commenced.

I tried wax oil in lower bilge areas without a good result.

The boat had a number of bad, inaccessible water traps built in the worst of which was at the stem where a stem bar and the converging hull plating created a deep crevice either side of the stem bar. After the original coating with Hempel's vinyle tar paint I ran hot pitch down the crevice using a heat gun to preheat the metal. During adjacent hull repairs about twenty five years later I found the pitch coating still in perfect condition and wetting the steel with no underlying corrosion.

[Jimbo2010]

I restored an Airstream years ago, used por15 on the steel chassis, just loosened the the rust with wire brush, was told at the time not to clean it all off, as in shiny!

Looked great after 2nd coat and years later.

you must wear a respirator mask, it can knock u on your ass.

[Oceanride007]

I,ve been battling corrosion for years on my corten round bilge, still trying to up my percentage of success. Outside hull generally good.
In short this is what I know: Trouble spots are generally in hard to access places like under caprails, in inadequate limber holes, in areas that occasionally get wet, like under windlass, any wet area, and longitudinals that don't drain.
Often I find myself using shot glass as small containers to mix up my paints, volume is tiny perhaps my measurements have been inaccurate, as I do spots, bonding with adjacent paint could be a problem, generally I use Ultralock 576 for first coat, unlikely to use rust converter as bonding to older paint would be issue. Would not use POR15 as paint instructions quite strict about using 2 pack system, yes agree polishing with wire brush not a good idea but sometimes need to use rotating wire brush to seriously wash area with Oxylic acid, needs roughening after. Not had desired results using grit blast and do not use inside hull, its messy. Next time intend using a Zinc rich epoxy as a first coat (inside), finish with High build epoxy and Polyerethane.
Sometimes I wish I had tried test strips years ago.

[hpeer]

I also have had problems where water is trapped. And sometimes you just need replace some steel. The good news is the repairs are relatively easy PROVIDED you can get to the inside.

Our big boat is hard chined and was constructed without stringers. The plates were welded to 1” bar. This allows any water to shed off the interior hull.

At times I have resorted to gooping an area with grease until I can get to it.

At 73 I am gaging my repairs for a 10 year service life. LOL!

Merry Christmas.

[Mick of 42]

Originally Posted by hpeer

I also have had problems where water is trapped. And sometimes you just need replace some steel. The good news is the repairs are relatively easy PROVIDED you can get to the inside.

Our big boat is hard chined and was constructed without stringers. The plates were welded to 1” bar. This allows any water to shed off the interior hull.

At times I have resorted to gooping an area with grease until I can get to it.

At 73 I am gaging my repairs for a 10 year service life. LOL!

Merry Christmas.

Thanks.
The grease sounds like a good idea as a holding action.
cheers

[Mick of 42]

Originally Posted by Oceanride007

I,ve been battling corrosion for years on my corten round bilge, still trying to up my percentage of success. Outside hull generally good.
In short this is what I know: Trouble spots are generally in hard to access places like under caprails, in inadequate limber holes, in areas that occasionally get wet, like under windlass, any wet area, and longitudinals that don't drain.
Often I find myself using shot glass as small containers to mix up my paints, volume is tiny perhaps my measurements have been inaccurate, as I do spots, bonding with adjacent paint could be a problem, generally I use Ultralock 576 for first coat, unlikely to use rust converter as bonding to older paint would be issue. Would not use POR15 as paint instructions quite strict about using 2 pack system, yes agree polishing with wire brush not a good idea but sometimes need to use rotating wire brush to seriously wash area with Oxylic acid, needs roughening after. Not had desired results using grit blast and do not use inside hull, its messy. Next time intend using a Zinc rich epoxy as a first coat (inside), finish with High build epoxy and Polyerethane.
Sometimes I wish I had tried test strips years ago.

I have purchased a Terrcoo Blaster wheel to remove whatever rust scale I can access which will be limited but grit blasting sounds way to messy inside.
A Dremel/die grinder will help in confined areas. With rust converter before using a Altra-lock equivalent.


Thanks for your help.

[Mick of 42]

Originally Posted by RaymondR

My 30 year experience with a steel boat is that unless you can blast and immediately apply a low viscosity epoxy primer, the result will not last more than a few years.

Internally in non traffic areas I used a cement render formulated from linseed oil that I boiled and white cement. This provided a basic environment to any areas wetted and also showed up any areas rust had commenced.

I tried wax oil in lower bilge areas without a good result.

The boat had a number of bad, inaccessible water traps built in the worst of which was at the stem where a stem bar and the converging hull plating created a deep crevice either side of the stem bar. After the original coating with Hempel's vinyle tar paint I ran hot pitch down the crevice using a heat gun to preheat the metal. During adjacent hull repairs about twenty five years later I found the pitch coating still in perfect condition and wetting the steel with no underlying corrosion.

The use of pitch sounds good in hard to get at places.

[MicHughV]

I built my steel boat back in the late 70's....launched 1980.

I had the inside sand blasted and painted with a two-part cold-tar epoxy. It goes on real thick and took 11 gallons to paint the inside.

There were some areas I missed under the cockpit seats and didn't discover this until several weeks later, giving the steel some time to build surface rust. I simply painted right over it with the two-part coal tar epoxy.

I had that boat for around 15 years or so, and never had the slightest issue with rust anywhere on the inside.

That boat is now on it's third owner, who stripped the interior down to the hull, wanting to built a new layout. After 40 some years, the inside of the hull is still like the day I painted it.

Coal-tar epoxy hardens like steel after curing. There were areas along the inside of the keel which I couldn't reach with a brush, so simply poured the paint down the sides.

Coat-tar epoxy comes in both one part and two part epoxy. and I have found both types excellent, with the two part being slightly harder when cured. It is incredible tenacious paint and will adhere to most anything.

If I had to do it all over again, I'd opt for the coal-tar epoxy again. I especially liked it in areas between hull plating and frames where I could not see, so simply slathered it on really thick to ensure, the back of frames was coated.

I know folk that cleaned the metal with wire brush, etc, applied various anti-rust products and painted it with various coats of urethane, but the finished product was simply not up the strenght of C-T epoxy.

The only issue I had w.ith C-T paint is that it does smell just like tar and the smell takes a while to disappear

[Mick of 42]

Originally Posted by MicHughV

I built my steel boat back in the late 70's....launched 1980.

I had the inside sand blasted and painted with a two-part cold-tar epoxy. It goes on real thick and took 11 gallons to paint the inside.

There were some areas I missed under the cockpit seats and didn't discover this until several weeks later, giving the steel some time to build surface rust. I simply painted right over it with the two-part coal tar epoxy.

I had that boat for around 15 years or so, and never had the slightest issue with rust anywhere on the inside.

That boat is now on it's third owner, who stripped the interior down to the hull, wanting to built a new layout. After 40 some years, the inside of the hull is still like the day I painted it.

Coal-tar epoxy hardens like steel after curing. There were areas along the inside of the keel which I couldn't reach with a brush, so simply poured the paint down the sides.

Coat-tar epoxy comes in both one part and two part epoxy. and I have found both types excellent, with the two part being slightly harder when cured. It is incredible tenacious paint and will adhere to most anything.

If I had to do it all over again, I'd opt for the coal-tar epoxy again. I especially liked it in areas between hull plating and frames where I could not see, so simply slathered it on really thick to ensure, the back of frames was coated.

I know folk that cleaned the metal with wire brush, etc, applied various anti-rust products and painted it with various coats of urethane, but the finished product was simply not up the strenght of C-T epoxy.

The only issue I had w.ith C-T paint is that it does smell just like tar and the smell takes a while to disappear

The 'coal tar epoxy' sounds like the winner.
Was the smell bad? As I live aboard.

Thanks for your time and suggestion.

[barcoMeCasa]

Well worth a few dollars imho >
https://www.amazon.com/Metal-boat-ma.../dp/B0070QRME4

Had great results from amerlock sealer if you can find any.

[hpeer]

I had chronic spots, like around the water fill and fuel fill, that had rusted pretty badly. Welded over with a SS disk and redrill the hole. Done forever.

I have done this in a number of areas, around the rudder post coming through the coach roof. The entire pulpit was mild steel with a singular pinhole. I redid the entire pulpit in SS and made it work with new gen roll bar anchors.

More work up front, less work and worry later.

[MicHughV]

The coal-tar smell goes away after a while.....maybe a week or so....it's much like any fresh paint.
I used coal-tar on the inside, but the outside was done with a system.
First coat was a zinc heavy base coat. Then followed some " build up" coats (2), quite thick paint, which was sanded smooth. My boat had the hard chines, so this was great for filling in the weld dimples, etc. Then (2) coats of finish color.
The exterior paint was also an epoxy base, but after a few years it tended to " chalk" so I repainted the hull with a two-part urethane. Ironically, the older epoxy finish paint made for the perfect primer for the urethane paint.
Never had any issues with this. On occasion, I dropped something on deck, which caused a blemish on the paint, but I'd patch this up with some one part polyurethane paint.
Some years later I covered the decks in " deck tread", which was glued on. Besides improving grip while walking on deck, it also provided a barrier against further " whoops" moments as it was quite thick, 1/8" or so. It comes in various colors. Was a bit pricey, but I grew to love the stuff.

[hpeer]

Terrco Blaster is good.
Dremel is good.

I also use a vibratory tool, low speed. Use yp your old blades or get cheap ones. I often use it as a one needle needle gun. It can get in tight places like interior corners others can not. Can make a hell of a racket. Leaves a good rough surface. Just one more tool in the belt.

[MicHughV]

Yep, also used a dremel tool for the odd touch up job.....can buy bits about the size of a match head.....and poke it most anywhere...

On some rare occasions after I'd been at sea for several weeks, pounding to weather, I'd get some rust " weeping" from the bottom of the bow pulpit railing posts. I suspect it was some minuscule welding residue that I missed. Nonetheless it cleaned up right quick once I stopped somewhere.