The SB600 is a great Strobe. I use the SB900, and I still have been known to use my very old Vivitar 283 combined with it.
Besides having and using the Strobe in the situation at the Beach you didn't really give us any information about what your shooting or how large the group will be. I would also use a reflector to bounce light back onto your subject especially under these extreme lighting conditions.
You could always look up some of the stuff on "Strobists" go here:
Strobist: Welcome to Strobist.