I do understand StormJibs point, however, Since first night (before charter starts) is at the marina, I would not worry to much about others being delayed. With mobile phones/texts, they let me know what ferry they are ON and I let them know where I will pick them up. It may cost them an extra taxi ride to Trellis bay, etc.
1 way ticket..Agree.

Ferry trip to Tortola is not bad... Starts Vacation. Coming Back is worse (ends vacation)