Gotta' train!
I know this is easy to say, not to do, but you've got to convince your dog to do it himself. Otherwise you will forever be having to carry and handle long boards and such for his convenience, or, as you say, carry him, which is a pain.We also have a 50 lb. dog and she did not want to do it af first, but she now does it regularly, although I wouldn't say happily. And she is not the brightest of dogs. We have an H37.5 with steps about 4" wide, I assume your steps are similar width.What worked for us:1) Going up is easier for a dog than going down. So start with that. Wait till he is "desperate" and I don't know for what in your case, but in our case, it was to go out for a pee. Perhaps just having someone he adores stand at the top of the companionway would do it. Use treats. Now, as the dog begins to scrabble up the steps to reach his goal, just firmly guide his body/paws and help lift him. Repeat many times! Like all dog training, he will eventually get the hang of it.2) Once he's mastered going up the companionway, he'll be more inclined to try the difficult descent. And training for that obviously is similar. In the end, we still often just guide our dog on the way down, "spotting" her in effect, like a gymnast, in case of mishap, but it still beats carrying all her weight each time. Occasionally, she'll attempt it without our knowing but we usually hear about it because of the minor crashing noise at the bottom.Good luck!