I haven't made a dugout, but I have seen Natives here on the Pacific coast make cedar dugouts. Natives used alaskan yellow cedar, and western red, I think. Big trees, split, then char/burn out the middle core, then carve out. I have seen one, was offered a ride. It was 40 ft. long?
I saw one made once by an amateur. He left the bottom round and darn near killed himself. It would roll every time he tried to get inside. I think the wood was Tammarac.... not certain. It was in MN, so Tammarac makes sense.
In the construction he made liberal use of a chain saw. It was probably a little over 20 ft. Anyway, I never did see it used successfully.
Good decisions come from experience. Experience comes from making bad decisions. Mark Twain