Hmm, I suppose. I'll do it for sure, just to have another piece of cool looking paper to show the harbor master. It's just that I can go for helmsman over there in about 4-5 years. That'll let me do even more, and then the rank of sea captain and icebreaker captain.
As for the question of the tanker, yes, I can. It says any boat with or without mechanical propulsion inland. That includes supertankers.
-Penguin