The B256 is a marine 40 with balanced proportions: 29.88 x 20.88 x 16.62 inches, neither slab nor tower. That middle-ground shape is the easiest 40 gallon tank to actually install - short enough for most lockers, low enough for most soles, wide enough to sit stable while you plumb it.
Forty gallons is the dual-role sweet spot, and this B-series blank swings either way: fresh-fitted, the food-grade polyethylene serves days of potable supply; waste-fitted, it is a serious gray or black holding tank between pump-outs. Ronco ships it bare. Print the drawing below, mark each fitting location, and use the on-page fitting planner to spec spin-weld or threaded fittings, installed per order at the plant.
The 35 lb empty weight makes for an easy dry-fit; the roughly 334 lb full weight makes the case for a flat supported platform and honest strapping, mounted low where a third of a ton of water helps stability instead of fighting it. Molded in Tustin, California since 1974. Weigh it against the tall and slab-shaped 40s in our boat tank category, or see the whole catalog at the Ronco Plastics hub. OneSource Plastics is an authorized Ronco Plastics dealer.
Technical drawing: download the Ronco Plastics B256 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.
