I don't know if you have any book with a Shaman class or if you are just going to use the Druid class with modifications (I just realised that I know next to noting about druids in D&D), but a book that I could recommend as interesting reading is 'Skull & Bones' from Green Ronin Publication. It has rules for sailing and ship and Voodoo with two Voodoo priest character classes that probably could be used as Shaman.