Water tanks

[pwl]

As part of her referb its time to paint the water tank which is a traditional, unlined tank. The boat is over 20 years old and I don't think it was done since she was built! Assuming I can get the bolts out of the access hatch, has anyone done this and any advice appreciated.I am assuming first clean up but do you rust treat or is that possibly too great a toxicity risk? Finally how many coats of tank paint and how long does it last? Thanks for any advice.

 

 

P

 

 

[blackrose]

As part of her referb its time to paint the water tank which is a traditional, unlined tank. The boat is over 20 years old and I don't think it was done since she was built! Assuming I can get the bolts out of the access hatch, has anyone done this and any advice appreciated.I am assuming first clean up but do you rust treat or is that possibly too great a toxicity risk? Finally how many coats of tank paint and how long does it last? Thanks for any advice.

 

 

P

 

After drying out the tank, scurf off the loose rust and paint with a wire wheel on a drill or mini-angle grinder (wear eye protection), or just use a hand held wire brush and some elbow grease! Clean the tank out (either soft brush or rinse with a hose), but don't worry about a little moisture and then treat the remaining rust with Vactan http://www.paco-systems.co.uk/vactan.html

 

It's suitable for water tanks and I would give the whole tank a coat even if you can't see rust. 1 litre is supposed to cover 8m2.

 

Vactan only takes a couple of hours to dry (but in corners where it goes on a bit thick it may take longer), after which you can paint over with a couple of coats of bitumen. There are certain brands of bitumen which state that they are water potable and suitable for water tanks, but basically it's the same stuff as used for blacking. The reason it's more expensive is that they've paid for the tests and certification and they're passing on that cost to you.

 

I guess it should last 4 or perhaps 5 years.

 

Seal the hatch and screws with an exterior silicone when you put it back on.

Edited February 24, 2011 by blackrose

[Québec]

As part of her referb its time to paint the water tank which is a traditional, unlined tank. The boat is over 20 years old and I don't think it was done since she was built! Assuming I can get the bolts out of the access hatch, has anyone done this and any advice appreciated.I am assuming first clean up but do you rust treat or is that possibly too great a toxicity risk? Finally how many coats of tank paint and how long does it last? Thanks for any advice.

 

P

 

Did exactly that a year ago, on a boat of similar age. Don't know what your access is like, but ours is a large hatch in the cratch. I'm small so relatively easy to get inside to de-rust and paint.

 

Used eye-protection and mask, and one of those white paper 'safety' suits, as it's obviously dirty work.

 

Used Vactan - which has been tested as suitable for potable water systems. So, as far as I understand it (and stand to be corrected) blacking isn't essential. There was a thread on this way back, and some people Vactanned and blacked, others just Vactanned.

 

The only downside as far as I can see with just using Vactan is that you have to redo it at least once a year, while with blacking you may get 3- 4 years. The advantage is that Vactan is relatively clean, and you don't end up picking bits of blacking out of hair and various body parts over the next few months

[blackrose]

Used Vactan - which has been tested as suitable for potable water systems. So, as far as I understand it (and stand to be corrected) blacking isn't essential. There was a thread on this way back, and some people Vactanned and blacked, others just Vactanned.

 

The only downside as far as I can see with just using Vactan is that you have to redo it at least once a year, while with blacking you may get 3- 4 years. The advantage is that Vactan is relatively clean, and you don't end up picking bits of blacking out of hair and various body parts over the next few months

 

The Vactan website actually recommends a topcoat and if you let the bitumen go off properly (24 hours), then it will not come off and into your freshwater system (or was that just a joke?)

[Iain_S]

(snip)

The advantage is that Vactan is relatively clean, and you don't end up picking bits of blacking out of hair and various body parts over the next few months

The Vactan website actually recommends a topcoat and if you let the bitumen go off properly (24 hours), then it will not come off and into your freshwater system (or was that just a joke?)

I think Quebec got the blacking on his various body parts from the painting, not the bath/shower

 

Iain

[Québec]

I think Quebec got the blacking on his various body parts from the painting, not the bath/shower

 

Iain

 

Actually I didn't, but I know a man who did!

 

re: VACTAN advice.

 

Here's the actual blurb from their website. Note the 'it is advisable for long term protection' and the 'may be coated'.

 

VACTAN is a self priming rust converter but for long term protection it is advisable to overcoat with a suitable water or solvent base midcoat or topcoat.

 

VACTAN may be coated when cured with any conventional paint using brush, roller or spray.

 

VACTAN has been tested and certified as fit for use for the use for the carriage of grain and use in potable water systems. It may also be used in sensitive foodstuff areas.

 

VACTAN is non-flammable and can be regarded as essentially non-hazardous under normal use.

 

...so I reckon it's what I said.

Edited February 25, 2011 by Québec

[kendo]

9 months on, and everything appears fine with our vactanned tank. but i'm going to lift

the hatch to eyeball it when the warm weather comes. if i have to redo the vactan, it's

a couple of hours job.

 

i would rather do this every year, or every six months,

than have to clean out a bitumen tank ever again.

 

[RobinJ]

As part of her referb its time to paint the water tank which is a traditional, unlined tank. The boat is over 20 years old and I don't think it was done since she was built! Assuming I can get the bolts out of the access hatch, has anyone done this and any advice appreciated.I am assuming first clean up but do you rust treat or is that possibly too great a toxicity risk? Finally how many coats of tank paint and how long does it last? Thanks for any advice.

You will need an impact driver (in my case it was an allen type driver) as you will generally find they have used steel bolts (replaced mine with stainless at enormous expense!).

The rust was bad (about 7 years worth), it was cleaned off completely and treated finishing with radiator paint (do not recommend it), after 6 years the solvents are just dissapearing, however have to admit there has been no more rust!

One piece of advice, keep the area covered, use some sort of hot air dryer. The paint needs to harden as much as possible and it is generally below the water line so can take a long time to dry (cos' if your on dry land less of a problem).

[sueb]

We never see posts about the pros and cons of metal versus plastic water tanks, but more important in my opinion.

Sue

[blackrose]

9 months on, and everything appears fine with our vactanned tank. but i'm going to lift

the hatch to eyeball it when the warm weather comes. if i have to redo the vactan, it's

a couple of hours job.

 

i would rather do this every year, or every six months,

than have to clean out a bitumen tank ever again.

 

 

That's interesting. Mine is well-overdue for painting (coming up for 6 years this summer), but I'd never thought of using Vactan alone without overcoating it. Scraping old bitumen off isn't that difficult is it? Anything that doesn't come off with a wire wheel stays on when I paint. We remove blacking on the outside of our hulls, although I do realise that access may be rather limited inside a water tank, but won't you have to get the old Vactan off when you come to re-Vactan it?

 

I guess I'll see how difficult it is to get the old paint off before I decide.

[blackrose]

We never see posts about the pros and cons of metal versus plastic water tanks, but more important in my opinion.

Sue

 

Well, this thread is really about painting the inside of integral water tanks. If you have a plastic tank then like a stainless tank that's not something you ever need to do, which is a big advantage.

 

However, neither a plastic nor a stainless tank will hold as much water as an integral tank on a particular boat, and they usually need to be insulated to prevent condensation on the outside.

 

I know a guy who filled up the big stainless tank on his boat one winter and the vertical pipe under the deck leading to the breather froze solid. Not realising this he continued to use water creating a vacuum in the tank. A few days later during a thaw he heard a big bang from the tank. Fortunately everything was ok and the sound he heard were the top, bottom and sides of the tank which had been sucked in by the vacuum being released. Still I reckon he was lucky that something didn't rupture. Even if you fill an integral tank right to the top this can't happen because the bottom of the breather is the top of the tank which generally doesn't freeze because it's a large volume of water. If the breather on an integral tank is at the highest point you shouldn't be able to leave it filled.

Edited February 25, 2011 by blackrose

[RLWP]

We never see posts about the pros and cons of metal versus plastic water tanks, but more important in my opinion.

Sue

 

Ours is rubber

 

Richard

[kendo]

Hi Blackrose.

 

Scraping old bitumen off isn't that difficult is it?

no, it's not particularly difficult. we have good access to the tank.

but it's a foul dirty job, and the bitumen sticks to you for months.

 

We remove blacking on the outside of our hulls

the difference is, that is outside. it disperses and blows away. only my face got

covered when i did that. crawling around inside the tank, all of me got covered.

despite wearing white suit, goggles, facemask, gloves, etc.

 

won't you have to get the old Vactan off when you come to re-Vactan it?

worst case scenario, the whole tank will have to be redone. but i think that's unlikely.

even so, it's a quick whizz round with an angle grinder, hoover up, and slap on 3 coats

of vactan. on a hot day (or with air blower), each coat dries in 30 minutes.

 

our old bitumen *had* to come off.. so the job had to be done. but i won't be slapping any more

down there. if people want to bitumen inside their watertanks, that's fine by me. but i'm not

dead (from vactan poisoning) yet, and our water is still running clear.

 

good luck with it, whatever you decide to do.

[blackrose]

Hi Blackrose.

 

 

no, it's not particularly difficult. we have good access to the tank.

but it's a foul dirty job, and the bitumen sticks to you for months.

 

 

the difference is, that is outside. it disperses and blows away. only my face got

covered when i did that. crawling around inside the tank, all of me got covered.

despite wearing white suit, goggles, facemask, gloves, etc.

 

Thanks. I don't know what you were doing but I've recently been cleaning old bitumen from the bilges (inside) of an old steam launch and I had plenty of melted bitumen from the wire wheels all over my face and even around my eyes despite wearing goggles. But even though it doesn't all come off in the shower I found it only takes a day or so to wear off.

[Dekazer]

As part of her referb its time to paint the water tank which is a traditional, unlined tank. The boat is over 20 years old and I don't think it was done since she was built! Assuming I can get the bolts out of the access hatch, has anyone done this and any advice appreciated.I am assuming first clean up but do you rust treat or is that possibly too great a toxicity risk? Finally how many coats of tank paint and how long does it last? Thanks for any advice.

 

 

P

 

We did ours ourselves (having read up on various threads here first). We used a wire brush to remove the bitumen, then Vactanned, then used potable bitumen. I think we gave it 2 coats of bitumen, leaving several days in between each coat.

 

It was nowhere near as horrible as people will tell you (!) although it is tiresome and time consuming. It's the wriggling into and back out of the tank that gets really old really quickly And definitely cover every inch of yourself with something.

 

The results were good. We didn't seal the hatch down immediately because we wanted to check it a few times - there were no problems. After emptying and refilling a couple of times the slightly chemically smell/taste went too. I think we'll probably leave it a good few years before we bother again.

 

Go for it!

[MikeV]

Having spent the last 3 days de-rusting the inside of our tank, one, probably obvious piece of advice, in hindsight: keep all the doors and windows shut. I had the extension lead coming out through the front door and was merrily kicking up a dust storm of rust for a couple of hours. When I went back inside the boat there was rust dust everywhere! :-( I spent about an hour cleaning down all the surfaces. Good job SWMBO said she was going to wash the curtains before we start cruising this year!

 

I am fairly sure the tank had never been re-blacked since new - 11 years. I'm not having much problem with the previous coating and about 80% it is still firmly adhered to the steel. Where it had broken down there is quite severe pitting and the really grotty part is the amount of dust that gets everywhere. When I took of the facemask off yesterday I looked like some kind of tribal warrior!

 

I've bought a litre of Vactan and a litre of blacking. So far I've recoated the inspection hatch using both but had to stand the tin of blacking in a bucket of near boiling water to get it fluid enoough to brush on easily. I'm not sure how thick you can apply it and whether thicker is better? I like the idea of Vactan only, but not sure if it's proven for the long term. My experience on other parts of the boat is that steel just coated with Vactan starts to rust after about a year, but perhaps I just need to apply more of it to provide greater protection?

 

Finally, I'm going to refit the inspection hatch using stainless nut rivets and screws. Even though the screws last used were SS they were into mild steel and I couldn't shift any of them. I had to drill out all sixteen. I'm planning to used closed foam tape as my main sealant so I can easily get the cover off each year for inspection and then just run a bead of sealant around the edge of the hatch once bolted down as an insurance to prevent water ingress.

[Nickhlx]

Having spent the last 3 days de-rusting the inside of our tank, one, probably obvious piece of advice, in hindsight: keep all the doors and windows shut. I had the extension lead coming out through the front door and was merrily kicking up a dust storm of rust for a couple of hours. When I went back inside the boat there was rust dust everywhere! :-( I spent about an hour cleaning down all the surfaces. Good job SWMBO said she was going to wash the curtains before we start cruising this year!

 

I am fairly sure the tank had never been re-blacked since new - 11 years. I'm not having much problem with the previous coating and about 80% it is still firmly adhered to the steel. Where it had broken down there is quite severe pitting and the really grotty part is the amount of dust that gets everywhere. When I took of the facemask off yesterday I looked like some kind of tribal warrior!

 

I've bought a litre of Vactan and a litre of blacking. So far I've recoated the inspection hatch using both but had to stand the tin of blacking in a bucket of near boiling water to get it fluid enoough to brush on easily. I'm not sure how thick you can apply it and whether thicker is better? I like the idea of Vactan only, but not sure if it's proven for the long term. My experience on other parts of the boat is that steel just coated with Vactan starts to rust after about a year, but perhaps I just need to apply more of it to provide greater protection?

 

Finally, I'm going to refit the inspection hatch using stainless nut rivets and screws. Even though the screws last used were SS they were into mild steel and I couldn't shift any of them. I had to drill out all sixteen. I'm planning to used closed foam tape as my main sealant so I can easily get the cover off each year for inspection and then just run a bead of sealant around the edge of the hatch once bolted down as an insurance to prevent water ingress.

 

 

 

 

 

I use ACF-50 extensively at home to prevent rust - it's safe on electrics / connectors too, to stop corrosion. I wonder if anyone uses on their boat and can report similar success ?

 

It's not suitable on the inside of water tanks though - just for preventing rusting / corrosion - has a very good creep factor as well

 

 

Nick

 

 

 

 

 

 

Edited March 3, 2011 by Nickhlx

[Paul Evans]

You will need an impact driver (in my case it was an allen type driver) as you will generally find they have used steel bolts (replaced mine with stainless at enormous expense!).

 

When I did mine, a ring spanner and applied Burminum screwdriver did the trick when it came to removing the bolts. A gentle tap in the tightening direction cracked the rust and gentle taps in the loosening direction saw off the paint. The application of WD40 by SWMBO to the removed bolts, cleaned them up, made themn fit for reuse and avoided the expense of buying stainless steel.

Edited March 3, 2011 by Paul Evans

[paulcatchpole]

Ours is rubber

 

Richard

 

Yerrrrs, Unkie Richard. We know what you like, don't we.

 

One thing I discovered about vactan recently, is that it really doesn't like being used below the 5deg temperature on the label.

 

Mind you, it was about -8 the night after I applied it... I shouldn't be surprised it went a bit odd.

 

Now, cement washing, I know about that...

 

PC