Based on liveaboard
friend's recommendation (he did it on his boat) I'm planning to change to integral fiberglass tanks. What my friend did was as follows. He simply lifted the plywood
under the settees (its a long story but he converted a 46' IOR early 80s racer
into a liveaboard
cruiser and initially built her out inside himself, then as the time went by he changed this and that which was easy since all the inside furniture was built by him and can be moved/removed as needed, except the original bulkheads and floor stringers.
So basically he fiberglassed all that space under the settees and fiberglassed the under the settee plywood
to that (with 3 well spaced access hatches) and now he has 2 probably 150+gal (or larger) tanks next to the bilge
My original 2 aluminum
tanks were 55gal each, not bad but one got galvanically corroded here and there (making repair not feasible) from several pennies which gotten underneath it from one of the POs (one penny was dated after the date of manufacture so I know it was not them) so I replaced it, "temporarily", with a used 40gal plastic tank (as they say - nothing is more permanent that what is to be a temporary solution
). I expect to have at least 80gal capacity in each such built out tanks, if not more. Will depend on how low can I spread them out as I don't want to end up with too much water weight up high in the hull
. Probably will not attempt the job myself but will hire it out as a weekend moonlight job to one of the boatyard guys at my winter haul out
On the other hand I may decide to DIY since I previously did fiberglass repair on my very first boat (finishing up unfinished job by an absconded boat guy) and was able to avoid any grinding by doing wet on wet layers. I was pleasantly surprised that not only it came out nice and strong there was no need for any grinding as that area was covered by vinyl anyway. Same with the tanks as they will be covered by veneered plywood and cushions
above. Will probably need to use a longer setting hardener to allow for large area to be worked on.