When we were there a few weeks ago, the schedule is basically OKW at the 1/2 hours and SSR as :15 and :45. The boat we took was right on time. To maintain this schedule, they have to have 2 boats running, and the ride took about 25 minutes total, putting us at DTD on the 1/2 hours as well.
Make sense?
When you are staying at OKW (and probably SSR), they give you a weekly schedule upon check in of all sorts of activities that are going on that week and the boat schedule is on there as well.