Replace Water Tank with Stainless Steel?

[Hippy Steve]

Toying with the idea of fitting a stainless steel water tank inside the existing mild steel tank.  Am weighing up the cost against the benefits, are there any disadvantages that I need to be aware of?

[blackrose]

The relative advantages and disadvantages might be related to the condition of your existing integral tank and also how you'd plan to fit a new stainless tank. Assuming it's in the bow it would either involve cutting away the rear bulkhead of the existing tank to get the new one in place, or cutting out the well deck and then welding in supports underneath the rim for the deck to rest on once the new tank is in there. Either way it's not something to be undertaken lightly.

 

Why do you want to do it anyway? What's wrong with the existing integral tank?

Edited June 28, 2021 by blackrose

[OldGoat]

When my hull was built xx years ago - I sugessted SS to the builder. Much sucking of teeth - and he said 'galvanised' - to which I replied OK, but only if it electro galvanised - not of the hot dipped rubbish... Still in use some 30 years later.

 

SS might be good but it needs specialist skills / good quality welding and (IMO) needs support etc to stop fractures.

 

[Hippy Steve]

Existing tank is in need of refurbishment (no need to start the debate on the best method for that!)  I have been trying to get that done but everybody seems very busy...

Looking at options - it's either repaint, fit a flexible tank (though I haven't seen any of a suitable size) or fit a stainless / plastic tank.  One of the benefits of stainless steel is that, once done, we don't have to worry again...

 

[blackrose]

Despite it being a horrible job, de-rusting, cleaning out and repainting the existing tank is going to be a LOT less work than cutting out the deck for example, to fit a new tank. The other thing is that whatever option you choose, the old rusty tank will still need refurbishing before you do it, so you're not saving that bit of work this time, but you wouldn't need to do it again in the future. 

 

If you use few coats of a good water-potable epoxy paint on top of several coats of standard epoxy you might get 8-10 years out of it before it needed doing again and it would likely just be sanding and the water potable coats that needed re-doing.

 

On the other hand, unless you're doing the job yourself, it's very hard to find someone good who's going to prep and repaint the tank properly.

Edited June 28, 2021 by blackrose

[Hippy Steve]

19 minutes ago, blackrose said:

 The other thing is that whatever option you choose, the old rusty tank will still need refurbishing before you do it, so you're not saving that bit of work this time, but you wouldn't need to do it again in the future. 

 

 

 

Very good point!

[Stilllearning]

1 hour ago, Hippy Steve said:

 

Very good point!

The existing tank must have (I hope) an access hatch. Getting in and cleaning and painting it is a pain, but not impossible, just don’t do it on a hot day, or in the winter. Hot because it will bake you and be horrid, and the winter because there will be condensation and the new paint won’t stick. The likely reason you can’t find anyone to do it is because it’s a nasty messy job, so I suggest a gullible family member.

I have had boats with integral steel and with stainless tanks, and the advantage of a steel tank tends to be its bigger, so you need to refill it less often.

As most others have said, bite the bullet and stick with the tank you have got: imagine how many steps it will take to get access, fabricate, fit, weld, then refit the boat round a new stainless tank....while you try to live onboard. A couple of days getting dirty and rusty will seem as nothing, believe me, once you have finished.

[Chewbacka]

2 hours ago, Stilllearning said:

The existing tank must have (I hope) an access hatch. Getting in and cleaning and painting it is a pain, but not impossible, just don’t do it on a hot day, or in the winter. Hot because it will bake you and be horrid, and the winter because there will be condensation and the new paint won’t stick. The likely reason you can’t find anyone to do it is because it’s a nasty messy job, so I suggest a gullible family member.

I have had boats with integral steel and with stainless tanks, and the advantage of a steel tank tends to be its bigger, so you need to refill it less often.

As most others have said, bite the bullet and stick with the tank you have got: imagine how many steps it will take to get access, fabricate, fit, weld, then refit the boat round a new stainless tank....while you try to live onboard. A couple of days getting dirty and rusty will seem as nothing, believe me, once you have finished.

Not a job a tall fat person, needs a good level of flexibility if you are going to get into the pointy corner of the boat.  

[Bee]

Depends on the boat. Is this a narrowboat? Got any spare space? Our water tank is under the bed and its a window cleaners plastic tank. The last narrowboat had a tank under the bath (yea really) and the one before that had a tank under the front deck that was just slid in from the cabin. If at all possible I would shove it under the bed and if you wanted a bit extra put a long, narrow roof tank on the roof as well. Wyvern Shipping used to have roof tanks on their boats a long time ago.

[Alan de Enfield]

38 minutes ago, Bee said:

and if you wanted a bit extra put a long, narrow roof tank on the roof as well.

 

But remember that "a tonne" of water on the roof will have a huge affect on the boat stability and roll, and as the tank empties will the water will surge (ala Herald of Free Enterprise) and, if it is a post 1998 boat will require a PCA as the original stability calculations will no longer be valid.

 

If the owner decides not to have a PCA undertaken. that is, of course, their choice, but they will at least be aware of the legal requirement and the likelihood of invalidating their insurance. They can at least make an informed decision and 'weigh up' the risks. 

[Bee]

3 minutes ago, Alan de Enfield said:

 

But remember that "a tonne" of water on the roof will have a huge affect on the boat stability and roll, and as the tank empties will the water will surge (ala Herald of Free Enterprise) and, if it is a post 1998 boat will require a PCA as the original stability calculations will no longer be valid.

 

If the owner decides not to have a PCA undertaken. that is, of course, their choice, but they will at least be aware of the legal requirement and the likelihood of invalidating their insurance. They can at least make an informed decision and 'weigh up' the risks. 

A friend had an ex Wyvern Shipping tank on his boat and it did make the boat roll a little bit more. but he used to reckon that it was well offset by the full tank in the boat (They were interlinked so the top tank emptied first)  There is certainly a limit though to the amount of weight that is sensible to shove on the roof. Now as for firewood, bits of engine, turf and chickens on the roof ....

[ditchcrawler]

6 hours ago, Bee said:

 There is certainly a limit though to the amount of weight that is sensible to shove on the roof. Now as for firewood, bits of engine, turf and chickens on the roof ....

And the odd half tone of coal, 6 people drinking beer etc