Okay, I'm doing pretty well as Portugal, but now I've run into an inexplicable.
I took the "New World" idea, eager to conquer new lands and enslave new peoples. And with my handy Conquistador I took the islands near me; the Azores, Canaries, etc. But now I want to explore the sea, so I recruit an Explorer, but I cannot attach him to any of my fleets.
I looked at the ship descriptions and saw that carracks are able to handle the Atlantic, so I tried to put him in charge of a carrack-only fleet. No dice. Then I tried to put him on my cogs. Nuh-uh. Now I see Castille sending colonists hither thither and yon, and I can't join in the fun. What am I missing?