I'll ad my peso.
I would agree about the fuel polishing. But if it were mine I'd pump out all the fuel and do an inspection
of the bottom of the tank(s).
And depending on the material of the tanks
is how I'd follow up. If they are steel
and the tanks looks black on the bottom, I'd be concerned. If water had been sitting in there a long time it could have developed some erosion causing pin holes.
tanks would have the same problem but it would take much longer to eat thru.
Plastic tanks would most likely be OK but being 1800 ltr (480 gl.) I'd think they would be metal.
All fuel tanks have a vent line which can draw in moisture. If the boat were stored in a hot dry climate the chances of moisture is slim............_/)