Not to hijack this thread, but rather than start another so closely aligned...
Our 1998 Jeanneau SO45.2 has two 50-gal holding tanks, one under the aft port berth, anothe under the forward berth. They are plumbed for dual outlets; a deck pumpout and (decommissioned) overboard offshore discharge, so the tanks each have one inlet, one vent, and two outlets. The heads always flush into the tanks, and each has a Whale diaphragm pump (currently missing several 4' sections of hose) to discharge 'overboard.
Last summer I noticed a blue stain in the bilge coming from the aft tank and tracked it down to a quantity of pinholes in the lowest forward-inboard corner. Attempts by a local shop to weld the pinholes did not go well; they kept burning through the thin metal. As I was in mid-cruise, we coated the affected part of the tank with JBWeld and reinstalled it. So far so good, but... this time were were lucky in that I discovered the leak a few miles from a good shop.
I am wondering... how long the epoxy will hold out. How long the rest of the tank will hold out. How long the forward tank will hold out.
I wrote Jeanneau America asking how long stainless holding tanks normally last, and was told that given the varied use, they can't say. Likewise, I can't say whether it was the PO's first 5 years that started the process, or something we've done since we've owned the boat - though for us it's the "guest head" and generally gets less use than the fwd one.
Part of me just wants to never deal with a sewage-in-bilge affair again (this "blue stain" was nothing, I've had a few experiences I prefer not to recount, ever), and simply replace both tanks, especially before taking the boat south in two years.
Because of the odd shape, dropping in the OEM original tank would be the simplest approach, though surely the most expensive (about USD 880 PLUS
TBD shipping from France).
I plan to ask for local quotes to either replace the tank, or if practical, weld on a new bottom (keeping the complicated plumbing in the top half).
A plastic tank might be an option, though I had that on my previous C&C... and until recently thought stainless was superior.
All of this to say - comments, ideas? Stick with stainless, or not? Anyone know a good tank fabricator in upstate VT/NY?