St. John National Park Tour from St. Thoma

Carnival does not offer St. John National Park Tour in January 2015 from St. Thomas. We are only in port from 12pm until 8pm. Can I just get on the Island Girl without reservations or any other way I can get to St. John would be appreciated.

There are thousands of posts with recommendations on how to get to St John. Do a St John search in this forum.

I am pretty sure that the Island Girl ferry is only booked through cruise ships. There is a thread here about getting to St John with complete instructions.:D