My son has a nice big dog, a boxer/shepard mix. Great dog, really good personality (brings me my newspaper every day). He came and visited the boat. We're talking small boat here... big dog, get the picture?
At any rate, he had no problem getting on the boat, or moving about where he wanted... up and down the companionway, etc. Love the main Settee... it was his bed. (my bed really, but we still haven't worked that issue out)
The only problem was when it came time to go ashore... he would not jump the same distance he had previously gone to get on board. Didn't like the dock or really loved the boat... not sure which.
I used the teak grate that forms the floor of the cockpit to make a "gangway" for the big guy. Worked just fine. Just set it in place and he scrambled down no problem. Funny dog.