Chester the wonderdog, half English spaniel and half lab. He's 40 pounds. He's a velcro dog. He loves to sail, but absolutely hates to motor, hey I have a YSM8 single so I hate it too :-). My boat is a center cockpit with a steep ladder companionway, so navigating dog from below to topsides gets a little tiresome. and yes when things get to popping in the cockpit, he can get in the way (velcro dog ya see).
Still, on a light heel and fair wind, having him up top is a real treat. I think having a dog along changes the way you look at the world. I think, in general, smaller is simpler with dogs and boats. If Chester was 30 or less pounds he'd be no problem at all. But I'dnever trade him in, we are pals for life.
A ship in harbor is safe, but that is not what ships are built for.