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Don't Neglect Your Integral Water Tank


matty40s

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A boat comes in for blacking, anodes and wants water tank looking at as the water is cloudy.

After drilling most of the bolts out as they were rusted in,pumping the water out, then came clearing the debris.

There were two bowls like this....plus more in the wet and dry vacs.

20170424_162252_zpsswo2nv7e.jpg

 

after leaving a hot air fan down there overnight, the scraping , grinding and wire brushing revealed lots of things like this.

 

20170425_090718_zpsw5rrbwc8.jpg

 

the deepest pit was over 6mm deep, there were lots more over 4mm.

We carried on grinding and scraping and then managed to get an inverter welder at arms length into the worst pits.

The boat is NEVER on a landline......probably luckily, as the exterior of the hull is in a fair condition for age. 

 

 

 

 

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Crikey, that's bad. We had an integral tank in the bow of our previous boat and every 4-5 years it would be re blacked, as most of the coating had disappeared by then. Is there such a thing as a potable anode, or low toxicity metal that could be thrown into the tank? 

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11 hours ago, matty40s said:

he deepest pit was over 6mm deep, there were lots more over 4mm.

We carried on grinding and scraping and then managed to get an inverter welder at arms length into the worst pits.

The boat is NEVER on a landline......probably luckily, as the exterior of the hull is in a fair condition for age. 

 

 

 

 

I would not expect a landline to be a factor in corrosion inside the water tank. When we looked inside ours it was in very good condition but the blacking had perforated in a couple of spots causing pits about 1.5mm deep. I have read that there are possibly some unique pitting mechanisms inside water tanks which can cause accelerated pitting on the bottom surface, so yes...look after your water tank.

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

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I suspect this is what awaits us when I finally have the nerve to have a look in ours...

However, I've no intention of trying to sort it out by keyhole surgery, the entire front deck is coming off.

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19 hours ago, matty40s said:

A boat comes in for blacking, anodes and wants water tank looking at as the water is cloudy.

After drilling most of the bolts out as they were rusted in,pumping the water out, then came clearing the debris.

There were two bowls like this....plus more in the wet and dry vacs.

20170424_162252_zpsswo2nv7e.jpg

 

after leaving a hot air fan down there overnight, the scraping , grinding and wire brushing revealed lots of things like this.

 

20170425_090718_zpsw5rrbwc8.jpg

 

the deepest pit was over 6mm deep, there were lots more over 4mm.

We carried on grinding and scraping and then managed to get an inverter welder at arms length into the worst pits.

The boat is NEVER on a landline......probably luckily, as the exterior of the hull is in a fair condition for age.

I fitted a purpose made bespoke plastic liner bag/tank. That cured my leak problems caused by serious rusting.

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5 hours ago, AllanC said:

So, how will this tank be treated so as to make it useable again Matty.

The tank base (the boat baseplate) was cleaned with an angle grinder with wire wheel. Severe pits were filled with weld. This was very difficult as it was impossible to get into the tank, so everything had to be done at arms length, sometimes blind, looking first and feeling where to go.

Two coats of Black Jack blacking now. Until recently, this was the standard tank paint, it has recently been deemed not suitable for potable water but this is what the customer wanted. Tank will be filled and emptied several times before it leaves, to ensure no chemical taste in water. 

The baseplate was only 8mm thick, so I believe the owner was quite close to having a self filling tank.

1 hour ago, Horace42 said:

I fitted a purpose made bespoke plastic liner bag/tank. That cured my leak problems caused by serious rusting.

The tank will still need to be derusted and protected, the liner will get condensation on its outer skin and this will continue to affect the steel.

Edited by matty40s
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19 minutes ago, matty40s said:

The tank will still need to be derusted and protected, the liner will get condensation on its outer skin and this will continue to affect the steel.

Yes, I can't remember what I did exactly, but mechanical derusting and treatment withrust proofing and paint is the sort of thing I would have done as a matter of routine. The tank is under the front deck and sealed and watertight to prevent ingress of water - overflowing filler pipe or rain or leaking lock walls - so in theory as the tank was completely dry when I installed the plastic liner and with a sealed cover - it should still be dry - even after 12 years of service.

But I will take the cover plate off to double check - just in case there are 'holes' in my theory.

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My tank was painted with Armourguard PW about a year ago.  Too early to give an indication of life, but so far the orange tinge in the water when the tank was almost empty has gone when repainted and not come back.  Next year I'll open the hatch and have a look in.  Fingers crossed.

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How easy is it to fit a bespoke flexible water tank. I have quite a large hatch cover in my front well deck but not big enough to get into the tank. How are the filler and supply connections made ? Any info', good suppliers of such tanks and approx costings. Have just researched Armourguard and find it will cost £50 plus postage for 1 litre of the primer and 1 of the actual coating. Any advice appreciated

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I investigated bespoke liners when I did my tank - cost was around the £700 mark. Went instead for Armourguard at £70 for 2.5 litres using Vactan as primer thereby avoiding the need to take bake to bare steel - just scrape and brush. I fill the tank through the hatch so it gets inspected regularly - still looking good and with crystal clear water after 3 years.

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7 hours ago, Señor Chris said:

Went instead for Armourguard at £70 for 2.5 litres using Vactan as primer thereby avoiding the need to take bake to bare steel - just scrape and brush. I fill the tank through the hatch so it gets inspected regularly - still looking good and with crystal clear water after 3 years.

Proof of the pudding I guess. Any dissenters to using Vactan instead of the pukka Armourguard primer?

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suggest to line the tank space with 50mm foam insulation to separate the liner from the steel.

the liner can easily be inserted through a small hatch, but you may want to suspend it at the upper corners, just to ensure it is in the right place when you fill it.  It should have connections for the filler pipe, the vent pipe and the outlet, which all need to be connected during the insertion process.  Not easy, but can be done.

http://www.duratank.com/

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That is just horrible. What is the stuff in the bowl?, it doesn't look like just rust and old paint. Many years ago I took our narrowboat down the Thames where it had a good bounce around and the water looked cloudy and unpleasant and even had a few wriggly things in it. It was not integral, was steel, was about 4 years old and we had very young children drinking the stuff. What happens inside tanks is some cause for concern. Our present boat has a window cleaners poly something tank with a big screw on lid, nothing in it except a bit of sand. If I had another boat built I would specify fuel tanks that had a proper lid after last years shenanigans trying to clean sludge out of ours and the water tank would not be steel and would have a big lid on it as well. Oh, the floor would lift up throughout the boat as well but that's another story. NOTHING on a boat should be 'Fit and forget' .

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This is a summertime job for me. Finally managed to get my cover off. I wouldn't imagine it's been done since new 03 boat. Judging by how hard the screws was to get out off the cover. 

Thinking about using armourguard pw.  How easy is it to use. Did you do sections at a time. Side, top, bottom etc. 

Is there other options I can use. 

IMG_3221.JPG

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3 hours ago, Bee said:

That is just horrible. What is the stuff in the bowl?, it doesn't look like just rust and old paint. Many years ago I took our narrowboat down the Thames where it had a good bounce around and the water looked cloudy and unpleasant and even had a few wriggly things in it. It was not integral, was steel, was about 4 years old and we had very young children drinking the stuff. What happens inside tanks is some cause for concern.

<Snip>

We have an integral water tank and do get rust in the drinking water when we are cack handed with the locks.  We were made aware by an article in WW years'n'years ago that while the water that fills your tank is adequately chlorinated over time the chlorine concentration will reduce.  The answer was to dose the tank with thin bleach.  We have a 900 litre tank.  When we dewinterised a few days ago I started filling the tank and opened the taps to do a bit of vague flushing out.  Once I was bored with that I turned off the taps and allowed the tank to start filling.   Next job to squirt 20ml bleach to the tap end of the hose (This keeps the hose sweet.).  I would usually add 15ml bleach but this was a first filling.

That was all about three days ago.  So far no stomach upsets and we do drink cold water straight from the tap. In the 910 days that we lived aboard (We stopped living aboard last autumn. :huh:) neither of us had stomach upsets so it appears not be be a health issue for us.  This would be quite different if we achieved a self filling tank, of course.

Is it not true that the usual hull survey will detect a serious problem?

Edited by Theo
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4 hours ago, Theo said:

<Snip>

We have an integral water tank and do get rust in the drinking water when we are cack handed with the locks.  We were made aware by an article in WW years'n'years ago that while the water that fills your tank is adequately chlorinated over time the chlorine concentration will reduce.  The answer was to dose the tank with thin bleach.  We have a 900 litre tank.  When we dewinterised a few days ago I started filling the tank and opened the taps to do a bit of vague flushing out.  Once I was bored with that I turned off the taps and allowed the tank to start filling.   Next job to squirt 20ml bleach to the tap end of the hose (This keeps the hose sweet.).  I would usually add 15ml bleach but this was a first filling.

That was all about three days ago.  So far no stomach upsets and we do drink cold water straight from the tap. In the 910 days that we lived aboard (We stopped living aboard last autumn. :huh:) neither of us had stomach upsets so it appears not be be a health issue for us.  This would be quite different if we achieved a self filling tank, of course.

Is it not true that the usual hull survey will detect a serious problem?

A boat owner might not think they need a hull survey if the exterior of the hull has no or little pitting. 

The boat in question was not 20 years old yet and very little exterior pitting.

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Oh, bleugh! I am a big fan of my plastic water tank for this reason, also that I can glance under a bed panel to see how full it is.

Other things to not neglect are blacking inside the weedhatch, and checking the integrity of the seals on a wet gas locker...

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On 03/05/2017 at 12:58, rustydiver said:

This is a summertime job for me. Finally managed to get my cover off. I wouldn't imagine it's been done since new 03 boat. Judging by how hard the screws was to get out off the cover. 

Thinking about using armourguard pw.  How easy is it to use. Did you do sections at a time. Side, top, bottom etc. 

Is there other options I can use. 

IMG_3221.JPG

Just looked in my tank which has a large lift up access top so easy to get into.  The sides look similar to this with brown slime but the water is clear and we've been drinking it with no issues for over a month.  So whats the best way to clean it - presumably empty it and then scrub it out (steam cleaner) and I note several products are metntioned here but I've also heard of 'bitumen' being used. Any advice gratefully received.

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52 minutes ago, larryjc said:

Just looked in my tank which has a large lift up access top so easy to get into.  The sides look similar to this with brown slime but the water is clear and we've been drinking it with no issues for over a month.  So whats the best way to clean it - presumably empty it and then scrub it out (steam cleaner) and I note several products are metntioned here but I've also heard of 'bitumen' being used. Any advice gratefully received.

To clean the tank, I climbed inside and scrubbed all the surfaces with a couple of stainless steel pan scourers in a weak sugar soap solution.  This helps to identify any areas of weakly adhered coatings as well as getting the muck off, being abrasive it also helps to key the surface.  Then a good hose down and bail out the water.

For rusty/peeling  patches I attacked them with a scrapper followed by a wire brush in an angle grinder and then a flap disk to polish off any remaining rust.   It is rather loud in the tank so I used foam ear plugs and ear defenders (like head phones) as well as a full face screen (protection against flying bits) and a decent dust mask.  Wear  a beanie hat - assuming you have hair.  Then a rub all over with 60 grit paper.

It took about a day to prep the tank.

As to applying the armourguard I used a 4" solvent resistant roller and working quickly I did one coat in one go.  A 2" brush for the corners where the roller doesn't fit.  Avoid sunny days as the side with the sun on will be so hot the paint cures very quickly, including the roller.  So a cool, dry, overcast day is by far the best weather.  I used a painters dust mask as it has a carbon filter and keeps the fumes from your lungs, from memory they cost something like £20 from screwfix.  Speed is much more important than beauty for the coating, so a few runs etc don't matter.   Remember the base of the tank is probably at canal water temperature and so a lot cooler than the sides and so will take a lot longer to cure.  There is no way of speeding this up.

As it is a very restricted space, don't use an angle grinder if you are not good with them.  Also it would help when painting to be physically small and flexible, but my good wife who is, refused point blank to climb in with a paint roller.  I could just about manage it.  If you are big or not very flexible, I would do the top and sides as one coat, and the tank base as another.  As to getting the pads, scrapper, solvent resistant rollers etc, they all came from toolstation.

  • Greenie 1
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