And herein lies the problem. Many things are carry-overs from a time when things were different, or simply not an apples to apples comparison. Storage tank material, internal coatings, fuel quality, fuel chemistry, the precision/requirements of the internal components of fuel systems, onboard filtration etc., have changed drastically over the years but the anachronisms linger.
If you want a fun topic to investigate, do a search on the whole theory about water getting into storage tanks or fuel tanks. Read some of the studies done on this and do some math and calculate the maximum amount of water vapor that's even possible in an empty 200 gallon tank let alone one that's 1/4, 1/2 or 3/4 full. There is so much mythology it's ridiculous. If you have water in your fuel storage tank it's not coming from air in the tank. This is why I've never subscribed to the theory that you should keep your fuel tanks close to full to avoid condensation. It's simply a myth that isn't supported by the math or physics.
I wonder what the filtration specs are on the Kubota fuel filters. I don't remember seeing a micron rating on the box or on the filter itself but that might just be my bad memory. My boat has a 10 micron fuel filter and water separator between the fuel tank and the engine, in addition to another fuel filter on the Yamaha engine itself.
