Replacement of rear water tank in a Bavaria 44

[REGNIER]

The 210 liters rear water tank of my Bavaria 44 has two long cracks (between 5 and 8 cm), therefore the tank is leaking. Professional workers went twice to weld the cracks (150 ? each time), but after a short time, the cracks reappeared. As it is possible to buy a new one (about 450 ?), I would like to change it.
Have you ever done this operation ? How could  I get information on the procedures and the difficulties?
Thank you in advance.
Bests, Gilles

[IslandAlchemy]

My fuel tank let go a few years ago.  Replacement isn't too difficult, but you'll have to completely dismantle the aft cabin bed base (which means using an exakt saw and cutting big chunks out of it, then glassing/epoxying it back together afterwards.  It's a couple days work.

[nornie lees]

We had simular problem in forward tank Bav42, tried lots various repairs, none satisfactory.  Then just put a flexible bag type in, the bladder just collapses as you use the contents, they are double skinned so last a good few years, ours lasted 6years. The replacement again was around £50. The plumbing in is straight forward and nothing a teenager couldn't handle! Only thing I would recommend you do is keep it topped up as much as possible to reduce and movement, use the largest size you can squeeze in. Make sure the inside of the existing tank is clear of anything that might damage the flex/bladder tank.
We did have to cut a fairly large opening in top to put the flex tank in the original tank, so once started there's no going back.

Ray

[Spirit of Mary]

I thought I had a leak in my rear water tank, but couldn't find it. As a preparation measurement for removing the tank I made a bigger cover in the rear cabin bed layer with a saw. By doing this by accident I also cut the tank by a cut of at least 10 cm. Then it proved not the tank was leaking but the calorifier, so I had to repair the tank. Because the tank is made from PE it cannot be glued. The only way to repair is welding with the same material.
I used a professional plastic welding pistol and found some PE donation material. I could as an inexperienced welder repair the cut and till today (after 7 years) it is still 100% tight. So to my opinion when you can reach it with a welding pistol a crack of the size you mention is repairable.
I am happy that I didn't need to remove the tank, because what I found it is almost impossible. The rear water tanks are fitted during boat fabrication when nothing is fitted yet in the hull.
Ger