Thanks man! I appreciate your kind words on the retro "feel" of the game, as that's kind of our jam, and seemed natural with the theme of gamejam.
As happens to us far too often in these game jams, 80% of the development happened in the last 12 hours. I absolutely missed all the edge cases you ran into! There were many more features that got cut in the interest of time, and the goal of the game actually changed in the last couple of hours to make it playable.
So as you say, the game doesn't explain super well, but if you couldn't pick up additional Crew, you probably had 12 crew already and they wouldn't fit. There should be a message or some way to notify the player, but there isn't.
All of your suggestions were super valid! There was a "How to Voyage" option in the title screen, but it got cut for time. We'll continue to develop a bit on the Android version after the competition, and it will absolutely go back in.
I've used Game Maker for ages :O I use Unity and XNA and other stuff as well, but I always find myself coming back to GM for gamejams for the ability to prototype super quickly.