I have friends who have successfully converted their pooch into a boat dog, and others who were not as successful. The worst story I have seen was a Golden Retriever that would throw up (and it was a lot!) every time they would set sail. He was fine if the boat was upright, but he would hurl the moment the boat started to heel. Aside from the sea sickness, he was a great boat dog! He would stay on board and resisted chasing ducks and going swimming.
Most of the horror stories I have heard involved converting a dog from land-based life to life aboard. On the flip side, most of the success stories I have heard involved dogs that were raised as puppies aboard and that was all they knew!
Going the puppy route is not a guarantee of success, but it seems to improve the chances of a positive outcome.
I had my selection criteria:
Shorter than the lifelines to avoid falling overboard
No tail to get ripped off in a winch
Good with birds
This pretty much narrowed my choice of breeds down to the Corgi. They have stubby legs, no tail, and are used to herd sheep, cows, and chickens! Just be sure to get the most calm puppy in the litter.
Potty training was rather easy to accomplish. Since it's a small space, I was always there with him. If we were watching a movie and he got up, it probably meant that it was time to go outside. Also, if he were thinking about doing something inside, I would see him getting ready and be able to take him out before the accident occurred.
He became boat broken right away, but since we were rarely inside a building, it took a while to get him house broken. My most embarrassing moment was when he peed and then pooped in a West Marine. He was completely boat broken by around 4 months, and house broken by 2 years.
When he was a tiny puppy, he would lay at my feet with his life jacket tied to the binnacle.
Now that he's older, we let him roam the deck by tying his life jacket to the jacklines, but he usually just finds a comfy place to sit and relax while we are out.
He even stays calm in rough weather. When we had to broad reach off of a lee shore while a few miles off the coast of North Carolina, he was calm as can be (and stayed in the cockpit with us instead of walking all over the deck like he usually does).
He is now 2.5 years old and we can't imagine life without him! There are disadvantages to having a dog on board, such as dog hair everywhere, needing to take him to shore to go to the bathroom, needing to carry extra food on board for him to eat, going to the bathroom inside out of protest, and dog hair getting in the bilge pump intakes. Despite the downsides of a dog on board, he is an awesome crew member and we love having him around!