I've taken Cookie out on our boat many times and everytime she has a lot of fun. We planned on getting her out on the water before we even got her fromt he breeder, when she was only eight weeks old we already had a life jacket for her, the funny thing was that it was so big and she was so small that when we put it on her she fell over!
From what I've seen Yorkies really do like going out on the water, it's like riding in a car for them only they can just run around on dock instead of simply sticking their head out the window.