Want to paint inaccessible area can I.....

[rubblequeen]

I have plastic water tank under the front decking in a well which fills with water in a good downpour. Obviously I pump the water out but doubt if it is ever fully dry. My concern is that this area is probably rusting badly. Can I just pour some sort of metal paint down the side of the tank and hope for the best that it spreads out over the bottom. The sides I can paint with a small roller.

Do you think this would work? If so what product do you recommend?

Thanks for any help

[by'eck]

If the floor is rusted, pouring paint down the sides will, at best, just dry to a finish that isn't bonded and will simply trap water causing it to linger and likely accelerate the rusting.

 

You will have to find a way to remove the tank and be free to treat the area properly by removing all loose rust, applying an inhibitor, applying suitable undercoat's (Primocon, Red oxide) followed by top coat's, Hammerite etc.

[dmr]

Painting without some preparation is a waste of good paint and as Byeck says can be destructive.

Last year I "bare metalled" both front lockers. On one side the paint had lifted and the water was trapped underneath, the rusting below this was significant, much worse than in areas were the paint had totally gone away.

 

An old friend used to pour light oil into inaccessible places, that might be better way to go if you are sure it wont end up in the canal etc. He reckoned that something like "3 in 1" (purchased in big quantities) was much better than stuff like Waxoyl.

 

.............Dave

[PaddingtonBear]

Cure the leak first

[Chewbacka]

Trapping oil between to your plastic tank and the rusty steel hull is a bad idea as the oil may - depending upon the plastic :-

1) weaken the plastic tank - solvent crazing and swelling

2) diffuse through the plastic wall into the tank

3) float on top of the water at the bottom preventing the water from evaporating.

 

Whist in the real world these are all low risk, there is some risk, so I would not do it.

Best fix the leak and dry out the hull and corrosion will if lucky stop or depending upon how much condensation there is be slower.

Even better, repaint after fixing the leaks

[system 4-50]

and 3 in 1 stinks as it gets old!

[blackrose]

Sounds like a job for summer. In an ideal world you'd stop water getting down there in the first place, but you'll still need to treat the area.

 

Empty the plastic tank, get it out, relocate and connect it temporarily to your water pump so you've still got water while you're doing the job (assuming you're living aboard). This means you don't need to rush and can take your time - spend the whole summer doing the job if you want. If the tank is too big to put inside the boat then find a smaller tank. I used a half size garden water butt in the bedroom as a water tank when I repainted my integral tank.

 

Get the entire area back to bare metal with an angle grinder and wire wheels. Wear the appropriate PPE. You can get into the corners with old chisels, a welding hammer and wire brushes. You'll have to tarp the area over if it looks like rain. I'm sure you can rig up some sort of tent arrangement with a rope, a tarp and some weights (plastic bottles filled with water and tied onto the eyelets) to keep the sides of the tarp down. You can get into the corners with chisels and wire brushes. It's hard, dirty work but satisfying when you get it all done.

 

Once you're satisfied with your prep, having done all that hard work you'll never want to do it again, so I'd recommend using something much more permanent than Vactan and single-part primers/paints. Unless you manage to completely seal the area from rainwater then you've got to assume it's going to be a wet bilge. If you correctly apply 3 or 4 coats of a good two part epoxy such as Jotamastic 87 it will be at least 10 years before you even need to look at it again.

 

You'll pay about £50 for a 4 litre can including the hardener - definitely use winter grade hardener if the boat is in the water and the area is below the water level on the other side of the steel. Stir part A well in the can before you take any out of the can to mix with part B and only mix (by volume) as much as you can use within the pot life. I have a stack of those plastic fresh soup containers from the supermarket as I used to buy quite a lot of them for lunch at work. They're perfect as they're transparent and you can fill them with water from a measurement jug and mark a line with a marker pen at various levels for paint and hardener, then just dry them out before use. http://www.jotun.com/Datasheets/Download?url=%2FTDS%2FTDS__515__Jotamastic+87__Euk__GB.pdf

 

However, if you know you're not keeping the boat that long then perhaps you don't need to do such a good job.

 

As Chewy says, before chucking any kind of oil down there (including waxoyl) check the compatibility with your plastic tank.

Edited November 19, 2016 by blackrose

[rubblequeen]

OK guys thanks for all the advice and I have taken on board to remove the tank and do it right as described above. I don't have a leak, the rain gets in when the cratch cover is off and we are cruising. Tried all ways to minimise it but doesn't seem to take much before the area is full despite pumping it out all the time with a small hand drill pump attachment. There are no drain holes as the decking is below the water line and no room for a bilge pump.

Early spring job me thinks.

[Neil2]

Funnily enough I heard of someone with a boat very similar to mine where the front well was constructed like this, and surface water had to be pumped out periodically, a strange arrangement I thought.

 

If you want a sort of quick fix until you can tackle the job properly Owatrol oil will do a very good job of purging moisture and stop the rust in its tracks. IMHO it's a better product than Waxoyl because Owatrol is runny and will flow into areas you can't easily reach. It is expensive though.

Edited November 19, 2016 by Neil2