The B530 is the big one: 98 gallons, 44 x 25 x 23 inches, the largest marine molding on this page of Ronco's book. This is passagemaker and live-aboard capacity - or, run as a holding tank, the difference between pumping out weekly and pumping out when convenient. Very few compartments accept a tank this size, but the compartments that do usually exist because the builder intended tankage there.
It is molded as a dual-role B-series blank. In fresh service the polyethylene is FDA approved for potable water and the tank plumbs as primary supply; in waste service the same molding becomes a holding tank of genuinely unusual capacity. Fittings decide the role, and Ronco installs them per order - spin-welded or threaded, at the exact locations you mark. On a tank this large, take the layout seriously: print the drawing below, walk the actual compartment with a tape, and enter the final port positions in the fitting planner on this page.
The controlling number is 817 - the approximate pounds of water aboard when it is full. That is dense cargo, and it belongs low, centered, and on structure designed to carry it, with chocks that stop it surging in a seaway. The tank itself ships at 115 lb. Molded in Tustin, California by a shop doing marine rotomolding since 1974.
Freight on a molding this size is worth checking early - the freight estimator quotes it to your ZIP. The rest of the large-capacity range is in boat tanks and on the Ronco Plastics hub. OneSource Plastics is an authorized Ronco Plastics dealer.
Technical drawing: download the Ronco Plastics B530 dimensional drawing - print it to plan your install and mark exactly where you want fittings located; Ronco installs spin-weld or threaded fittings to your marked spec.
