The 9KW generator used on the powercat burns .9 gallons an hour under full load. If you run it 10 hours a day you will burn 63 gallons on a 7 day trip. Main engine fuel burn is heavily dependent on cruising speed. Just going 2 knots faster can increase fuel burn 50%. Based on what I saw last trip most power cats were racing everywhere and the generators were running full time. It would take 150 gallons just for the generator running 24/7. By the way, I know this has been discussed before but if you want your generator to work the entire trip shut it down underway and during the day. Crank it up to sleep at night. Contrary to rumor sea air in the BVI won’t hurt you when the sun is up. It only becomes toxic at night!
G