Eighteen gallons is the honest number for a weekend boat. It is two days of washing up, coffee, and rinsing salt off the crew without hauling around ballast you will never drink. The B192 gives you that capacity in a rotomolded marine fresh water tank that ships at just 30 lb, so getting it aboard and into the compartment is a one-person job rather than a crane appointment.
The shell is FDA-compliant polyethylene molded in one piece for potable service, and it arrives deliberately blank. Every fill, vent, and pickup is installed by Ronco to your order - spin-welded or threaded, located exactly where you mark them. Print the drawing below and pencil in your fitting positions, or drop them on the on-page fitting planner; either way the tank shows up ready to plumb into your system, not waiting for a drill you would rather not take to a new tank.
Full, it carries about 150 lb of water - 8.34 lb per gallon adds up faster than most owners expect - so give it a flat bearer and straps that pull down to structure. Ronco has been rotomolding these in Tustin, California since 1974, which is why the marine range covers so many small, odd, boat-shaped capacities like this one.
Weigh it against neighboring sizes in the boat tank category, or take in the full catalog on the Ronco Plastics hub. OneSource Plastics is an authorized Ronco Plastics dealer.
Technical drawing: download the Ronco Plastics B192 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.