By the way, here is a semi-related interesting quote from the designers notes that clarifies an aspect of moving your ships:
Before a ship starts its sail action or after it ends its sail action, you are allowed to rearrange what is in its hold provided the ship is at land (not out in the open sea). For example, you could sail back to your home harbor and unload your goods to your warehouse. Or you could move goods between your ships if they are at the same island. One trick is to buy goods on two different islands, then move your first ship to your second ship, transfer the good to the second ship, and then sail the second ship home with both goods. This chaining of sail actions allows a good to go twice as far in one turn than keeping them on their original ships.