Cheers ... with "returning to map mode" you mnean returning to world map?
Ok .. It's been a while since I last was there ... but I underszand you were able to sail out of that narrow bay directly, right?
But you get back into the bay when going to world map?
If that's the problem, then I suggest just not to go back to world map.
In any game mode - arcade, realistic and iron man - direct sail is enabled, means, yo can sail completely directly from one island to the next. You don't need the world map at all.
This may not become your favorite playing style, but it shall solve your actual problem.
So - sail out of that bay, point your ship towards the next island, should be Cuba or Eleuthera whatever you choose - and then sail strait there. Whith sextant and chronometer you will see your position on the map (I mean the map at M, not the world map used fort traveling). If you don't have a chronometer, just head roughly Northeast for Cuba or southeast for Eleuthere. Sail straight until you get a "land ho" loadscreen. Save the game. Then try your short travel and see if it leads to new targets now. Or hit worlf map, I think it will place you near your new island rather than back to cozumel.
Hope this helps.