The rules state you have to use all waterway and lock movements that you have picked on your turn. Even if that means moving other ships. Does this mean you can move another ship that is partially loaded in the waiting zone even though you are not the owner or have any cargo on that ship?
As a side note, even if you could move your ship, could you choose to move another players ship anyway (in same partially loaded state) as long as it met the minimum move criteria? I was wondering if this would be a strategy to minimize the cargo that player could move if it looked obvious they were going to load it again next turn and you could not?
Any ship can be moved, regardless of player ownership.
You must use all movement points if possible, this means any valid ship so either military or ship that the total of the dice on the ship are in that's ships range (as printed on the ship, 2 to 5 for a 1 slot ship) or for the passenger ships the black slots are covered by dice.
Hope this helps