It's about a 10min. ride from the airport to the ferry terminal in Charlotte Amalie.
Out to Red Hook it could be 30mins to an hour as they
might drop at resorts b4 they get to the ferry port. And they'll wait to fill the van at the airport.
But you probably don't want to catch the ferry there. The fast ferry from Charlotte Amalie would get you there sooner than driving out to Red Hook, on any ferry it's an hour (or less) to the West End on Tortola, hour and 15mins. to Roadtown from the port downtown - Tortola'a a long island.
The ferries leave right on time also if that's something you need to plan for.
This is one of the better explanations of your options that I've seen:
British Virgin Islands Ferry
Smith's is one of the bigger ferry operators.
http://www.reservationsbvi.com/Ferries/smithsferry.html
Native Son is another.
http://www.wix.com/archiecoenterprise/nativeson