PVC Tender tanks

[Glenn Brooks]

Dave, I think you could slip a shell over a PVC tank, easy enuf. The only structural effort you might have to do is add stiffeners front and rear, on the bottom of shell, to impart rigidity to the frame. Or build a bottom lip 2” around the frame, similar to the pics below. Very sturdy this way. the tank(s) could be strapped down to the frame, with the shell sitting on top. One good thing about poly tanks is the openings and fittings can be added most anywhere, to suit your design needs.

My tender for my 12” ga Ottaway is sort of made this way. It sits on top of the frame, and is held in place by a 2” overlap around the edge, at the bottom. The lip slips over the frame edge, holding everything snug, never had a problem with it shifting around. And very easy to remove for servicing, as needed.

Now the key for rigidity, at least on my tender, is to make it out of heavy gauge sheet metal- mine is 1/8” thickness, tops, sides, and bottom. It’s all riveted together, solid as a rock.

Last year I needed to replace the bottom to my tank, and explored installing poly tanks. However, in the end, figured out a way to cut out the corroded portion of the bottom of the tank, and install a new piece. So didn’t need to go the poly tank route... but, certainly could have if the bottom replacement didn’t work out.


Glenn

[Andy R]

My mogul's tender had a lining failure, so don't consider a liquid lining. The PVC lining Jack describes seems to be the best, but if you are really concerned about strong enough bulkheads inside to support Gulliver sitting on the tank then make the bulkheads from steel and keep the inside of the tender dry. Consider instead of using the tender to hold water make a PVC water tank car behind the tender. A piece of PVC pipe from a waterworks pipe supplier would be the cat's meow. There are even dished PVC bulkheads available. Has anybody tried this?

[rkcarguy]

+1 Glenn. They can probably find what they need and not have to make it.
I got my grey water tank for my last boat from these guys:

https://www.tank-mart.com/plastic-tanks/

They have oodles of different shapes sizes and capacities to choose from, even PDF drawings attached to many of the items.
I got a plain rectangle tank and drilled and tapped it with NPT threads for the fittings I needed.

Another option, at least here in the PNW, is to use polyethelyne water tanks, purchased from a marine sanitation, or RV supplier. We have one such marine vendor locally who stocks 100’s of various sizes and shapes. Most are in the hundred dollar category. These are typically seamless, being “forged”in a press or CNC controlled machine, somehow. Very good quality. The only disadvantage is some are limited to maybe 30 gal capacity, or thereabouts. I think thickness of construction material limits the size. Many still in use after 25 years service.

My guess is, buying one or two of these likely is cheaper than purchasing materials and tools, if you are only looking for one tank.

Anyway, possibly A quick and viable option for placing a tank , or two, inside a tender shell.

Glenn