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Corrosion in holding tank.


Tigerr

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I have a 1998 Reeves with a sewage holding tank built into the rear of the boat under the steps to the back cabin.

In the last couple of years I have noticed rust 'plates' in the pumpout 'observation window' when pumping out. They can be quite big and solid, like sheets that have broken off the inside of the tank. 

I knew of another Reeves owner whose tank rusted through and this was a nasty business. 

I suspect that welding onto the old tank is going to be a big job as it is behind much woodwork and cabinetry in the rear cabin. Anyine got experience of doing this? Is there a 'fix' with something that might 'seal' the inside of the tank?

Alternatively I am thinking maybe a new installation might be the way to go - put a new tank elsewhere (under a bed?) and relocate the pumpout skin fittings etc accordingly. I think there is space. Any experience/views?

Really hoping to avoid discussion of pros and cons of pumpout vs cassette - thanks.

 

 

 

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I encounter a continuous dribble of boat owners whose tanks have rusted though, so yours is not unusual in any way. 

An integrated pump out tank is the worst possible design to have for this reason. For a quality hull builder I’m surprised Reeves were capable of a basic design error like this. 

Fixing it properly will be as expensive and messy as you already realise, but there might possibly be some mileage in a water tank liner bodge.

 

 

There are several firms making liners for fresh water tanks. They must be familiar with this problem too. 

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39 minutes ago, Tigerr said:

I have a 1998 Reeves with a sewage holding tank built into the rear of the boat under the steps to the back cabin.

 

We had a 1998 Reeves, 45 foot, Trad.

The holding tank was originally under the bed,  but fortunately a  previous owner had sensibly had it removed and a cassette toilet installed.

Trying to avoid the cassette / pump-out debate but would suggest that the ’cleanest’ & most economic method of resolving your problem would be the fitting of a cassette, and the sealing up of the old tank.

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I suppose it's quite likely to be rust, but how do you know it's not crusty crap or perhaps bitumen or other paint? If and when it's definitely rusty sheets, take into account that 1mm of steel is said to produce 5-10mm of rust (iirc), so you may well have many, many years left before it becomes a genuine issue.  I'd have thought that more investigation is required, because you'll be going to a lot of trouble here and it would be a bummer to find you've fixed something that wasn't actually broken.

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Integrated tanks, i.e. ones that are made using the hull as part of the tank are not brilliant for any purpose really, fresh water, sewage, even diesel but that at least is less likely to corrode, not sure about keel cooling either, maybe external pipes are better but we are where we are. I think if I was the OP I think I might investigate a separate plastic holding tank and isolating the old one but its a bit of a sod whatever you do. I think I would investigate putting a window cleaners plastic tank under the bed. Think of it as a winter project. Good luck anyway.

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Thanks - I think the plastic tank under the bed with a gunnel fitting is where we are heading now. Simply isolate, clean & seal up the old system, relocate the vacuum unit to a better site adjacent to loo and reduce all the pipe runs - might be a better system in the end. 

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1 minute ago, Tony Brooks said:

I would be wary about any plastic tank not specifically sold for toilet holding use. Some plastics are permeable for odours and the last thing one needs is a smelly plastic tank under the bed.

Although, you could get a 20 litre 'tank' and just empty it every few days, replace it if it became smelly.

In fact, if you take a plastic tank, add a 'flap' and put a toilet on top of it ...............

Great idea, I might try and patent that.

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I too have a stupid very posh looking macerator toilet on this boat. There is nothing to debate re cassettes any one with any sense knows cassettes make absolute sense. However as I am fed up of removing stupid poo tanks I have left this one in and am using it. The owner/builder had the sense to put a pukka purpose built plastic tank easily accessible under the bed which I check  about 4 times a year. There is zero smell anywhere so I suppose this is the best of a silly idea. I do know that Oxfordshire narrowboats however always use mild steel tanks but they are not integral, bloomin heavy but can be got out.

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4 hours ago, Sea Dog said:

I suppose it's quite likely to be rust, but how do you know it's not crusty crap or perhaps bitumen or other paint? If and when it's definitely rusty sheets, take into account that 1mm of steel is said to produce 5-10mm of rust (iirc), so you may well have many, many years left before it becomes a genuine issue.  I'd have thought that more investigation is required, because you'll be going to a lot of trouble here and it would be a bummer to find you've fixed something that wasn't actually broken.

I would agree with Sea Dog. You may have years left in the original tank. Why not try and do some thickness  tests on the metal tank? I am not familiar how these tanks fail, ie is it on welds, is it where there is usually air present ( ie not at the base of the tank)? If it is about to die, then make sure as Tony says above, to get a proper waste holding tank. They are usually rotomoulded polyethylene and you should be looking for a good thickness ie 9mm at least to reduce odour - especially as it is under the bed.

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I've had two fail on two boats, both on the top surface. First one rusted through where the base of the Mansfield was, started to get rocky then came away in my hands.  Luckilly not an integral tank so flushed it out as best I could, dismantled the bathroom, removed the tank and took it to metal recycling at the council tip. Second one we discovered leaking from the top surface when we left PO an extra couple of days and what I thought was liquid rust turned out not to be. Again flushed the tank well, covered the pin hole with gaffa tape and sealed the inlet with a chapagne cork, this one had to be left in situ as it would have meant destroying hald the boat to get it out. One day I wilk cut a hole in the top pressure wash the inside and fill it with expanding foam..........

So far on all the boats I've owned with tanks they have all been removed or taken out of use............

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Thanks all - I am pretty sure about it being rust, and the problem only manifested after a negative pressurisation to clear a line a couple of years ago. Can't check tank due to access issues. So, yes a nice thick purpose made plastic underbed tank is going to be the way. 

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Do you eat Ryvita and not chew it enough???

A rubber liner would probably not be a good idea for a pumpout, when you suck the tank out with the pumpout machine the whole liner might sort of turn inside out and get sucked out along with the contents.

This will sound daft, but can you (or a competent metalworker) cut the entire back deck/counter off to get access, rebuild or remove the tank, and then put the deck back on. It sounds drastic, but in skilled hands an angle grinder and a welding set are quick and effective tools. In the kit car/classic restoration world people routinely "cut and shut" to get better access to difficult to reach places. 

Turn the back into storage and get a nice new plastic tank under the bed or somewhere convenient.

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

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I've just cut up the mild steel tank on our mainland share boat. 3 mm steel and I guess it had lasted for rather less than 30 years (not being sure when it was installed or when it rusted through). It was well-knackered with several imminent failure points as well as the bit that had failed. There were also large sheets of spalled oxide in the bottom (thankfully dry when I took the machine tools to it!)

If anyone needs a good quality Leesan plastic tank, there's a spare one one in my garage - 900 x 600 x 400(h). It came out of the UK boat when we moved to using a Portapotti. Open to offers, fittings thrown in!

Martin/

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The advantage of a sailaway. 20 minutes with a battery drill. 8 jubilee clips -two on each pipe. ( twin vents, plus one pump out and one in pipe) remove stuck on Gobius sonic level sensors and I can lift my tank out (Tec-Tanks black water tank in poly). Holding tank located in the lounge area under L shaped seating which also converts to a third double. So easy might consider just automatically changing it every few years if cost effective.

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1 hour ago, Onewheeler said:

3 mm steel and I guess it had lasted for rather less than 30 years

So, if the OP's tank is like many and therefore 6mm sides on a 10mm baseplate, that's (potentially) "rather less than" 60 years and 90 years respectively.  Not bad, and it'll see most of us out - surely worth a check before assuming the worst?

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  • 1 year later...

well the old Reeves integrated steel poo tank problem. there is one fix that is fairly quick and less obtrusive, basically the boat is lifted out of the water and supported about a foot for and aft of the poo tank, the connections are undone and the whole tank is cut out from the bottom of the boat that section is then lowered with a fork lift and moved for carefull measuring. the new section of hull is then welded and a stainless steel tank is made to match the height and connection configuration the whole lot is then treated/ painted and lifted into position the hull is then re welded and blacked and the tank connected. 

This solution minimised the ripping out of internal structures etc.

i know of two Reeves boats who have used this solution, one was only 9 years old and a 57x10 widebeam.

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4 minutes ago, bobabout said:

well the old Reeves integrated steel poo tank problem. there is one fix that is fairly quick and less obtrusive, basically the boat is lifted out of the water and supported about a foot for and aft of the poo tank, the connections are undone and the whole tank is cut out from the bottom of the boat that section is then lowered with a fork lift and moved for carefull measuring. the new section of hull is then welded and a stainless steel tank is made to match the height and connection configuration the whole lot is then treated/ painted and lifted into position the hull is then re welded and blacked and the tank connected. 

This solution minimised the ripping out of internal structures etc.

i know of two Reeves boats who have used this solution, one was only 9 years old and a 57x10 widebeam.

My Reeves had the holding tank cut up and removed and a proper system installed instead.

 

 

IMG_1531.JPG

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Phew! Kelpie is a Reeves shell about the age of the boats mentioned on here with rusting loo tanks and I have just checked with the skipper who assures me that our tank is plastic. It is a very large tank and it was probably installed when the previous owner gave the boat a make over. Thank goodness!

 

haggis

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13 hours ago, haggis said:

Phew! Kelpie is a Reeves shell about the age of the boats mentioned on here with rusting loo tanks and I have just checked with the skipper who assures me that our tank is plastic. It is a very large tank and it was probably installed when the previous owner gave the boat a make over. Thank goodness!

 

haggis

All cassettes are plastic :cheers:

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