Diesel is $6.50 a gallon as of the first week of june at the marina's so think twice about running the generator. Water like people said is free is you get a mooring at several places.

The new fuel dock at Cane Garden Bay charge $4.75 (June 15th)per gallon and the water was $ 0.15/gallon.
These prices were the same in Roadtown.

Spanish town was $6.75/gallon for fuel and $ 0.25/gallon for water.

Also keep in mind, that the Bobbys Marketplace store in Cane garden Bay is super. Their was a great selection of fresh produce and a Deli and small Bakery section.

Since most of the time people on cats motor sail I would plan on 1 gallon an hour for both engines( 1/2 gallon each) the generator probably burns 1 quart an hour. You should not have to motor more than 25 to 30 hours to go from e end of the BVI's to the other. If you sail when able or at least motor sail at a lower RPM you could cut the consumption dramatically. What ever it cost the vacation is worth it. You can more than make up for the high cost of fuel with the cheap cost of rum. If you use water wisely it should not be a problem, plus top off at Saba Rock or Leverick bay for free. The moorings at Saba are right in front and they are labeled.
Fair Winds