Remove/replace water tank - Islander 37

[island37]

I want to remove and/or replace the water tank in my Islander 37. leaks badly.
It is under the cabin sole which I have removed. See pic. attached

One corner of the tank is under the settee, which do not want to remove, so removal is problematic. I am considering 2 approaches:
1. Somehow cut up the tank and remove in pieces. Add new tank and replumb
2. Leave the tank, cut off the top, and place a bladder inside the old tank
and replumb thru old tank.
All opinions and ideas on how to proceed gratefully solicited.

[turbulicity]

If you could cut the thing out in pieces, you could have a polyethylene tank custom made for the space. That would be the ideal solution but I don't see how you can cut it in place without damaging anything else. So, probably either you will remove the settee or you will go with your Option 2.

[chef2sail]

Cut the top....get a vetus bladder or cmbo of them. The old tank will help give you the rigidity, but you may have to strap the new bladder down somehwat


Dave

[Minnewaska]

I agree, cut the top off (clean and smooth the cut metal) and insert whatever you may want to use inside the old tank. That could be a new, presumably smaller tank.

However, I would be highly inclined to doing this right and removing the settee.

[CaptainForce]

I'm in a somewhat similar position. My starboard 50 gallon polypropylene tank is leaky and with limited access. I considered cutting it out and putting in a series of smaller tanks plumbed together, but my final plan is to insert a bladder into the old tank. I have a 6" diameter side access cut out and a square foot out of the top to insert the bladder and the fill tube. I shopped for the Vetus bladder first, but a Nauta tank turned out to be my best dimensional match. I was advised to bring the fill tube accross the top of the tank to a 90 degree fitting to facilitate the tank expansion instead of a straight down fill tube. I'm losing 14 gallons of capacity, but I'll still be able to carry about 200 gallons with my total tankage. The plan is looking good, but I'm still awaiting delivery of my new bladder tank. Take care and joy, Aythya crew

[island37]

Thanks to all who've replied. My main issue with removing the settee is time.
I want to get the boat back in the water before summer so I'm afraid of the time to remove/redo the settee as well as get a custom tank replacement.
I'm considering leaving my future options open by putting back the floor in a temporary manner with a temporary finish floor so that I can revisit the whole
installation at the end of the season/next year.

About installing a bladder. I agree with rounding the cut edges. How do I keep the bladder from sloshing around inside the old tank?
I'd also like to put in a reasonably sized access hatch in the floor so I can
remove the bladder later for cleaning/future replacement. This hatch will also
allow access to the bilge and the auto pump switch. I expect to size the opening to the size of the bladder.

comments?

[SJ34]

As for getting the old tank out, once the top is cut away the tank will lose most of it's structural rigidity and you can simply bend the corners down and pull it out. Having a sawzall or nibbler on hand to make strategic cuts as it's coming out will help also.

I had a similar problem with an aluminum tank several years ago. My tank was in a place where it was not practical to replace it. I could get it out but the only options for replacement would have me wasting space and losing quite a bit of capacity.

My solution was to install an access hatch in the top, repair the leaks with epoxy then epoxy line the entire tank. I'm 3 years into the repair and it's working perfectly. An unexpected benefit is that my water stays cleaner and fresher much longer than before.

[Minnewaska]

Once the top is cut off, it just might be bendable to get out. If not, you don't necessarily have to put a bladder inside. You could simply put a smaller tank inside.