We are on our third boat dog. All started out as puppies with us. We always slowly introduced them as puppies to our boat at a slip. We would let them romp around on board and then rock the boat which would certainly get their attention. After their initial fright, as the boat settled down, so did they. Soon their fear was gone and they would feel at home on board. I usually had them on board for spring dockside preparations. After several days of becoming accustomed to the boat they all took to sailing happily. Whatever you do, do not frighten them too far beyond their comfort level until they have become familiar with the boat. I have seen lots of German Shepard boat dogs out there. The most important thing to a dog is being wherever you are. Our dog's biggest fear in life was getting groomed and certainly not sailing.