katorpus wrote:I think you're on the right track with the idea of replacing the original Freedom water tank...mine are aluminum, built by Florida Tank and original to the boat (1981). One of the other drawbacks to "indiscriminate use of foam" in the original construction manifested before I bought the boat (when it was a "mere" 16 years old). That being, a relatively minor deck leak (in the area of the port scupper) resulted in unnoticed water intrusion that ran behind the batten "ceiling" on the hull of the boat in the aft cabin. It became "noticed" when I found rot in the plywood deck beneath the port berth cushion when inspecting the boat before purchase.
The water hadn't stopped there, of course...and it percolated down and soaked the foam in which the tank was bedded, causing it to corrode from the outside in. A considerable number of pinhole leaks developed. I discovered these when I filled the tanks (which the previous owner had "left empty") I drained that tank and left it empty. One possible solution would be to cut the top out, cut out the baffles, "pad" the inside walls of the tank to prevent chafe, and install a BIG Nauta bag that would be contained by the original tank. I haven't done that (yet), but it's "on the list" in case I ever go anywhere that requires that amount of water. I don't "top off" the starboard tank, and a couple of anchors and other heavy stuff in the port side lazarette mostly counteract the "lost trim" resulting from the absence of the weight of the water in the port tank.
I considered cutting the top off, cleaning the inside of the tank thoroughly and pouring in enough epoxy to seal the areas of leakage (sacrificing that amount of tank volume in the process), but I don't know what other areas on the (hidden) hull side are "thin" from the external corrosion, and I fear I'd just end up with more holes higher up once the water in the tank was restored. I can't really see any point in glassing in the entire inside of the tank, given that a bladder could easily be replaced if that time ever arose...
This is exactly my concern with the use of foam. It makes it very difficult and time consuming to access the hull wherever it is applied. In my case there was about a foot of foam completely filling a void in front of the tank. The area was more than a foot deep. Although unlikely, if one was holed or had leakage in that area one would play hell trying to get at the damage. Its true there are a number of areas in this category due to necessities of equipment installation but the gratuitous addition of foam was wrong IMO. It's a bit surprising because elsewhere Freedom obviously took pains to make obscure areas accessible for repairs. The hull deck joint bolts come to mind. One can get at them fairly easily around the full circumference of the joint. Removable panels have been incorporated as necessary to provide access. I would have thought there would be better ways to secure a tank, but water is awfully heavy and moves a lot so it would have been a tough problem to solve.
In any event I am going to think hard about the flex tank install into the current tank via cutouts, that really sounds like a simple and effective approach. I would be inclined to try to minimize the cutout(s) size to maintain the basic structural integrity of the original tank.