Some suggestions.
I assume you are charting with TMM. They used to offer a one-way drop off in Placencia. Not sure if they still do, but this eliminates the need for you just to hump the boat back up to San Pedro (against prevailing winds and currents), keeps your
route downwind and down
current, and lets you see more of
Belize.
Some family
charter activity suggestions:
Ambergris Caye: Hol Chan snorkel tour, popular site, guide required, but great snorkeling.
Caye Caulker: fun family activities: Shark Ray Alley snorkel tour, Ras Creek rastaman nature tour,...
St. Georges Caye: Walk to the N end of the caye and ask about the aquarium tour.
Swallow Caye (just across the cut from Drowned Cayes): The
ranger there offer Manatee watching tours...he knows where they like to hang out so can take you right to them.
Re
provisioning:
The are loads of good
provisioning and dining options in both San Pedro and on Caye Caulker (just south), but it starts getting pretty sparse as you
work your way south from there.
You can duck into Cucumber Beach Marina (near Belize City) for fuel/water/bar/restaurant/zip lining...
You can sometimes take on
fuel &
water at Southwater Caye (depends on their supply levels at the time). Good bar/restaurant there too.
....currently in Placencia delivering a boat up from the Rio Dulce...