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Old 09-08-2013, 15:32   #1
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Metal Boat Rebuild - Painting and Coating Advice Needed

Hi All,

I bought a 53' Steel Hulled, Bruce Roberts as a project boat. I had it trucked to my hometown (Bolton, Ontario) where I have leased a corner of a truck-container yard.

I have pretty much stripped most of the inside getting ready for welding repairs. As I was hunting around for a welder I decided to go ahead and get the bottom sandblasted (in order to facilitate the welding work and to point out other issues). Looking around I ended up deciding to rent the equipment and do the sandblasting myself. (It is definitely taking me longer and probably costing me more...but in the long run I am enjoying that the effort I am putting into the boat).

Sandblasting is just about completed on the bottom (now thinking of doing above the waterline as there looks to be several "patch jobs" that I don't know what is under...and since I have come this far...

Welding is about to start...expected to take about 2 weeks. So...I am thinking about the next step and have some questions:

I suspect that I will have to do another sandblast once the welding is done to get rid of the surface rust that will have formed.

I believe that I then put on a sealer coat of something. Can someone point me in the right direction here?
- I have heard terms like "2-part epoxy" or "zinc based epoxy"
- I understand that the paint needs to be put on within 4 hours of people do part of the hull, paint, wait for paint to dry, do next part, etc? As I don't know how I could sandblast the entire hull and paint the entire hull within 4 hours
- I understand that I have to be concerned about electrolysis and the metals in the paint. What advice do people have on this?
- Do I put the through-hulls in before I do any bottom painting...or do I wait for all the painting to be done before I install the through-hulls? (I am going to use the black plastic type unless someone suggests something else)
- Can this initial coat be sprayed on (rent a spray painting system from home depot or somewhere?)
- Is it one coat or multiple coats? (I am sure that it says on the manufacturers instructions...but I have read things like "6 mil" thickness...and it baffles me how you would be able to measure the thickness of the paint when it is on the boat)

After this initial coat, I understand that I would then use some sort of fairing compound to fix all the imperfections.
- I am assuming this is like drywall mud (put it on...feather it in...wait for it to dry...sand smooth...add additional coats to blend it all to a nice smooth surface)
- Is there a concern when sanding that the original epoxy paint gets sanded (do you just touch this up again?)

After the fairing I understand that you would coat the hull with a primer

After the primer I would imagine that you would then
1. paint below the water line with some sort of anti-fouling
2. paint above the water line with some sort of finish, glossy coat.

Seems like a lot of work. However, up in Ontario it doesn't appear obvious that there are companies that would come out and do a hull "paint-job" so I might be stuck doing it myself.

Any advice would be helpful...and any contacts for anyone that would take on a hull painting job like this would be greatly appreciated.



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Old 09-08-2013, 17:55   #2
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Re: Metal Boat Rebuild - Painting and Coating Advice Needed

Since you are still in welding phase (pre basting) on the inside the most important action you can take right now is to make sure that no water can ever pool anywhere inside your boat.

Combine this with a totally watertight deck and it is technically possible that blasting and painting the inside is not totally necessary.

I would really love to have a bilge lined with stainless steel sheet. This place is practically impossible to get to after the engine is in place.

Of course we live in a real world so I'd recommend considering the following:-
1) Any place that water can possibly pool (and it's probably not practicable to get them all) fill with thickened epoxy resin after blasting.
2) The are several brands of high build epoxy paints used industrially. Check with the companies that make them as to their suitability for inside the boat. You'll be needing quite a bit so they should be very friendly.
3) You may be able to use the same paint inside and outside. Again check with the manufacturer as to whether their paint "blushes" and the best way to manage it. I try to use an alkaline wash (cloudy ammonia!) every time I'm top coating cured epoxy.
4) I'm not a big fan of two pack hull finishes. One scratch and it's never going to be the same again. If you can find a good single pack enamel then future repairs are going to be that much easier, and they are much safer to use.
4) If you can prime while the epoxy paint is "cheesy" (highly technical term) so much the better. Otherwise check with the manufacturer.
5) Below the water line I'd check what aluminium filled vinyl primers (Primocon is a common brand) are available. Again apply while the epoxy undercoat is "cheesy" and the antifoul may be able to wait till just before you go in the water.
6) Others may have different experience but I've found that Propspeed on the propeller give a slight increase in rpm and hull speed. It could be my imagination but the stuff also seems to reduce the rate at which my anodes "evaporate".

This is also a good time to put in electrical and plumbing conduits. I'd suggest considering running most electrical wiring (don't forget antenna wiring - radar, VHF, AM/FM, SSB, AIS etc!). I'm seeing bundles of wiring an inch in diameter so some really generous sized conduit is going to make life much easier. I've run my plumbing under the floor but even a few 1" water pipes mount up. Having big holes and even channels (to hold pipe) in place is going to make life much easier later.

And again in this unfortunate real world some decent sized holding tanks are very useful. If you want to stay more than a couple of weeks in a sensitive area a couple of 200 litre polyethylene tanks (one under the sole, one just under the deck, connect with a diaphragm pump) is going to help keep officialdom happier.

Don't forget a couple of decent sized water tanks either.

My experience has been that what totally stuffs paint under the waterline is electrolytic action. Drags big patches right off. On Boracay bitter experience has two huge anodes ether side of the bottom of the keel, two smaller ones halfway up, two on the prop shaft, and two on the skeg and two on the rudder. The ones on the skeg/rudder seem to vanish before my eyes but I don't like to go too big on control surfaces.

I've heard anecdotal evidence of skeg failure on steel skeg/rudder boats and in my opinion these always need to have anode protection.

I've started using survey rated plastic through hulls after an unfortunate experience with a stainless steel one. I've heard some builder use thick stainless pipe welded the the hull with the other end threaded to accept a ball valve but your designer would be the best person to ask about this.

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Old 09-08-2013, 18:35   #3
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Download this ........

Or have a browse first
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Old 09-08-2013, 20:59   #4
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Try the "Metal boat society"
That derelict boat was another dream for somebody else, don't let it be your nightmare and a waste of your life.
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Old 12-08-2013, 05:30   #5
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Re: Metal Boat Rebuild - Painting and Coating Advice Needed

Thanks all for the advice...
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paint, rebuild

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