The dinghy's name is Scout. Scout's original fuel tank was pretty beat up.
The tank was ancient — came with Red Ranger almost a decade ago — which means some of the plastic had started to crack. And other bits and pieces were starting to fall apart.
The gasket around the filler, for example, was a right awful mess, and if you moved the tank around at all, fuel worked its way out the top.
We have a nice, new Scepter brand underseat tank. It has a gauge to show how much fuel is in it.
The old tank's gauge had crazed to the point where you couldn't even see the little indicator.
Here's the other problem we had.
The tank connector is a Nissan/Tohatsu "quick disconnect" style. It had developed a bit of a leak. It started as a slowish dribble. When it was hot, it became an alarming flow into the dinghy.
I took the female piece apart to see if I could clean it or maybe replace the little ball-bearings inside it.
No dice. Cleaning the metal parts didn't help. I'm now thinking the rubber parts may have degraded over the last decade or so.
I kind of like the idea of a quick disconnect and multiple tanks. I could swap tanks: when one goes empty, switch to the other and refill the empty one.
But.
Because the ancient, original equipment tank was leaky and I couldn't judge the level of fuel well, I only used it for storage. I would siphon fuel from old to the new tank. Eventually, when the old tank was empty, I'd take it ashore and refill it.
In spite of my imagined tank-swapping use case. I wasn't actually switching tanks. I wasn't maximizing use of those quick-disconnect fittings. I can simplify my life by permanently mounting a fuel line on one fuel tank. This means replacing the original tank with a (new) Attwood tank (without a gauge) that I can use for storage.
Since we have a two-stroke engine, we need to mix oil into the fuel at a 50:1 ratio. In real units, we have a 12 liter tank which requires 240 milliliters of oil. If you follow the Old Religion, the 3g tank holds 384oz, which means 7.68oz. of oil. Call it 8oz and be done with it using round, simple numbers.