Tom Campbell and Beth Davidow have spent the past year cruising, diving and filming on their Maritimo 51 in Mexico, primarily in the Sea of Cortez. Now, the couple (he’s 80 and a wildlife and underwater cinematographer, she’s a scientist and documentary filmmaker) are heading north, up the Pacific side of the Baja Peninsula, ready to pursue the next stage in their five-year cruising adventure. Campbell and Davidow bought their new Maritimo, named Tangaroa, last February from Bill King of Maritimo Yacht Sales in Newport Harbor, California. They decided to live aboard full time, cruising and producing documentaries, starting in…