Steel Boat Maintenance

[Microship]

Hiracer - thanks for the tip on Fertan; I'll try some!

David... thanks! What nudged me in that direction was grinding all night in a gale at a Cap Sante yard dock while awaiting a thruster quote (big dock gaposis ate one of my fenders), waking in the morning to find a 10 square-inch patch of bare metal, being very happy I have a steel boat, then getting a $1300 quote from them to make it purty as new with Awlgrip. "Umm, I'll make do with a DIY patch, thanks (oh, and please fix your dock!)"

[Boracay]

Tanic acid seems to work better than phosphoric. A little patience and elbow grease and all the rust comes off leaving nice bare metal.

Only problem is the time it takes and the purple colour stains everything.

If you wash it off quick it's not so bad, and the dark streaks do fade with time...

[straycurrent]

Originally Posted by Boracay

I have a brochure for a product called Penetrol CIP.

It is claimed that the Penetrol has a low surface tension and so can penetrate the rust through to the underlying metal. After it dries it can be overcoated with single pack or two pack paints.

Does anyone have any experience with this product?

The problem with steel is that any rust contains moisture and air. Painting over the top just seals in the moisture and air so rust continues, forcing the paint off the steel still further. Hard to get on top of it.

A freind of mine used penetrol on his rust after needlegunning,it did seem to soak in well.time will tell if it works!I`ve tried a lot of magic potions but rust always comes back in time.Then I bought a mini sandblaster ,it has a small sand tank on top works realy well and gives permanent results....so far.

[ianhef]

I'm on the steep learning curve with a steel boat, one small patch about 2 square inches removed and replaced but the rest seems fine. Couple of questions for those with more experience, knowledge and miles;
1) Is it acceptable to remove areas and simply replace them with new plating? Anything in particular to watch/avoid when doing this?
2) These small sandblasters people have mentioned, are they expensive?
3) Is there any simple or foolproof way of checking for stray currents on a steel boat (I have the books on corrosion ect just trying to read through them and extract the necessary information seems to be difficult)
Cheers

[neelie]

To answer (1) - This is a normal repair with steel - and that's the beauty of it. Only thing to watch for is that the heat of welding will have damaged a significant area of the protecting paint - you'll need to grind all the weakened paint to bare metal, prime and paint. Can't help you with brands or paint systems, its been too long. But I'm sure any of the modern paint systems will be excellent.

[ianhef]

Cheers Neelie, I made sure she was well coated just wanted to check that was the norm, more used to wood and plastic boats.

[chala]

Question 2
Pic 1. Cheap blasting pistol with spare nozzle, the nozzle does not last long. Cost around $30, and the abrasive material, (garnets, reusable many time)
Pic 2. More expensive blaster, aluminum body, 5mm professional nozzle, last for ever for small cleaning job, 70 to 100 dollars, air valve extra.
Pic 3. Protective gear, if you need to wear glasses, you can fit welder glasses inside this hood, modify the shade with replaceable plastic lens. The blasted garnets go everywhere, eyes, ears, nose, protect accordingly by wearing extra protective goggles, if you already have clean fingers, wear thick rubber gloves.
Pic 4. A 2 ½ hp compressor will do the job of Pic 5. This one did cost $80. Two of them in parallel will let you clean fittings more easily and 3 even better, keep between 80 to 120 psi. When blasting fittings, doing it in a small tent ($40) this will let you recover most of the garnets.
Pics 5. repair to the keel, mask area using ordinary masking tape. A 3 seconds blast (120 psi) cleaned the steel, the tie coat and feathered the 4 layers of Jotomastic 87. Then rebuild the paint layers, tie coat and antifouling.

Question 3
See CF thread Zincs and hot marinas.

[Hiracer]

Originally Posted by Boracay

Tanic acid seems to work better than phosphoric. A little patience and elbow grease and all the rust comes off leaving nice bare metal.

Only problem is the time it takes and the purple colour stains everything.

If you wash it off quick it's not so bad, and the dark streaks do fade with time...

Fertan is a collection of various tanic acids, among other acids such as phosphoric acid and ascorbic acid. It has something like 30 different acids to work at various depths. It streaks purple also.

My experience--so far (three years)-- is that the stuff works, only so long as you follow directions. You can't rush the stuff and you have to do the H2O mist or wash after application.

[Hiracer]

Originally Posted by chala

Question 2
Pic 1. Cheap blasting pistol with spare nozzle, the nozzle does not last long. Cost around $30, and the abrasive material, (garnets, reusable many time)
Pic 2. More expensive blaster, aluminum body, 5mm professional nozzle, last for ever for small cleaning job, 70 to 100 dollars, air valve extra.
Pic 3. Protective gear, if you need to wear glasses, you can fit welder glasses inside this hood, modify the shade with replaceable plastic lens. The blasted garnets go everywhere, eyes, ears, nose, protect accordingly by wearing extra protective goggles, if you already have clean fingers, wear thick rubber gloves.
Pic 4. A 2 ½ hp compressor will do the job of Pic 5. This one did cost $80. Two of them in parallel will let you clean fittings more easily and 3 even better, keep between 80 to 120 psi. When blasting fittings, doing it in a small tent ($40) this will let you recover most of the garnets.
Pics 5. repair to the keel, mask area using ordinary masking tape. A 3 seconds blast (120 psi) cleaned the steel, the tie coat and feathered the 4 layers of Jotomastic 87. Then rebuild the paint layers, tie coat and antifouling.

Question 3
See CF thread Zincs and hot marinas.

This is perfect. I have been thinking of springing for a pencil blaster.

[TOM]

We have very little problems with rust on our boat and when we do you can bet that it will be near wood. When we first purchased Byamee and found some rust {leaking water tank}we freaked out .I remember been too scared to scrape it back thinking i was going to penetrate the hull. Many nautical miles later i have learnt that there is more often then not more good metal left then you may first think.Also when metal rusts it exspands x8 so what appears as alot of rust is not that much.

My wife who does our rust patrol swears by "Metal Ready" exspensive but good.