Water tanks, why not GRP?

[Dylan]

First post on this forum, so be nice

 

I have often wondered why there are not more water tanks made from GRP. If the correct resin is used (water potable), and the correct matting I can think of no reason why they are unsuitable. Another advantage is that such tanks can be constructed by a DIY type using simple mould material such as timber/plywood/MDF. Does anybody have any experience of GRP tanks on boats?

[onthecut]

Hi Dylan.

 

I have two GRP water tanks going begging, but they are quite deep and distinctly second hand. Whoever had them previously only removed them on refit, so must have been happy enough with them up to that point. If you wind up fabricating some, don't forget the outlet pipe, filler, breather and inspection hatch.

 

Mike.

[blackrose]

First post on this forum, so be nice

 

I have often wondered why there are not more water tanks made from GRP. If the correct resin is used (water potable), and the correct matting I can think of no reason why they are unsuitable. Another advantage is that such tanks can be constructed by a DIY type using simple mould material such as timber/plywood/MDF. Does anybody have any experience of GRP tanks on boats?

 

I think it might just boil down to the fact that there are better materials available for this application - it's as simple as that. Unless of course DIY water tank construction is your thing.

[pwl]

Could you use GRP to line an existing old style tank, i.e. when the tank wa just the hull, not stainless liner? If not, what can you line it with (other than tank black).

 

p

[magnetman]

Could you use GRP to line an existing old style tank, i.e. when the tank wa just the hull, not stainless liner? If not, what can you line it with (other than tank black).

 

p

You can get 'bladder type' tanks I think.

[ChrisPy]

Could you use GRP to line an existing old style tank, i.e. when the tank wa just the hull, not stainless liner? If not, what can you line it with (other than tank black).

 

p

Why would you want to 'line' the inside of a steel tank?

 

This has been discussed many times before on this forum. All types of steel vessels have incorporated integral steel tanks which are simply painted (not 'lined') for a century or more.

 

You could line it, but it is likely that there is an underlying problem if an existing tank formed by the hull shell needs lining. Sheathing it with GRP may not cure the problem, but may just hide it from view. And if the GRP cracks or deteriorates such that water gets between the lining and the steel, then the problem is hugely complicated.

 

Fact is that you can paint the inside of tanks with various coatings that are approved for potable water. I have used Vactan which is a rust converter, and is approved by some authorities for water and food storage (i.e. it is non-toxic).

 

Tanks need disinfection, drinking water may need filtering, regardless of the structure of the tank or the lining or coating material.

[blackrose]

Fact is that you can paint the inside of tanks with various coatings that are approved for potable water. I have used Vactan which is a rust converter, and is approved by some authorities for water and food storage (i.e. it is non-toxic).

 

Did you paint the tank after using Vactan Chris?

[David Schweizer]

Did you paint the tank after using Vactan Chris?

Yes, was going to ask that as well. How many coats would you use?

[ChrisPy]

I don't think there is any need to paint over it.

 

Vactan, unlike Fertan for example, is held in an acrylic type medium and can provide a semi-permanent finish if it is not worn off.

 

The beauty of these systems is that you can scrub the rusty surface of the tank with a brush, moving the Vactan around into the corners and crevices, without needing to dry and clean the tank surface fully. Further rusting should be prevented for a year or two.

 

Only one coat is normally necessary to achieve the rust-proofing.

Edited December 28, 2007 by chris polley

[Yoda]

There is no problem using GRP tanks but it depends where they are fitted. If you put one into the bow, and you hit something, the steel will bend and spring back but the tank would be crushed and collapse.

[Broughton 2]

Why would you want to 'line' the inside of a steel tank?

 

This has been discussed many times before on this forum. All types of steel vessels have incorporated integral steel tanks which are simply painted (not 'lined') for a century or more.

 

You could line it, but it is likely that there is an underlying problem if an existing tank formed by the hull shell needs lining. Sheathing it with GRP may not cure the problem, but may just hide it from view. And if the GRP cracks or deteriorates such that water gets between the lining and the steel, then the problem is hugely complicated.

 

Fact is that you can paint the inside of tanks with various coatings that are approved for potable water. I have used Vactan which is a rust converter, and is approved by some authorities for water and food storage (i.e. it is non-toxic).

 

Tanks need disinfection, drinking water may need filtering, regardless of the structure of the tank or the lining or coating material.

 

 

"Tanks need disinfection". I picked up on that comment as I have a stainless tank that hasn't been disinfected for over 12 months and am considiering doing so (still fitting-out the boat and though the tank is full of water it is not in use). A search on this site was interesting and the merits of using chlorine, Milton or bleach to disinfect have been discussed. One discussion seemed to come to an end when it was pointed out that our tap water anyway is already generally chlorinated, the inference being that there is possibly no need to add further disinfectant. If that is the case then for how long would chlorinated tap water be effective in preventing nasty things growing in the tank? Any ideas?

[Yoda]

Chlorination at the pumping works fizzizs off when the pressure is released ie when filling the tank. It's to keep the mains clean. There is some residiule but if the tank is clean there's nothing to do.

[ChrisPy]

you should disinfect your tank before first use, and occasionally after that, possibly after each time you take the inspection cover off.

[Broughton 2]

you should disinfect your tank before first use, and occasionally after that, possibly after each time you take the inspection cover off.

 

Thanks Chris but "Inspection cover", I wish! Just 'cos it's stainless the maker deemed inspection cover not necessary. If I were having a new tank made I'd spend the extra shilling and definitely have one.