Cruise -> Sea Trek -> Maho Beach?

[ScubaDuck]

My wife and I will be travelling to St Maarten via Carnival on May 14. We expect to be in port from 9am to 6pm, and have signed up for a Sea Trek excursion that has an estimated time of 11:30a to 2pm. According to our calculations that leaves about 5-6 hours of time to do other things, and so she suggested we go to Maho too. Looking at the map it looks like the excursion and ship are pretty close with Maho 22 mins (drive) to the West. Reading other posts I see it could be dicey getting back to the ship in time to leave, so I want to ask who else has left in the afternoon for Maho and then gotten back to boat? And if you did, how much time to leave to get there?

 

Thanks in advance!!!