We just returned from a STT/St John charter a few weeks ago. We had no trouble getting a mooring ball at Francis and Waterlemon Bays. There was plenty of room to anchor in Coral Bay the night we were there. However, we did snag the last mooring ball in Salt Pond and Caneel Bay each of the nights we stopped there. I think the key is to get going pretty early so that if your intended destination is full, you have secondary options before it gets too late. I hope you have an excellent trip!