There is 2 kind of ships on the image you are refering to. The first one is the improved version of the Oil Tanker. Goes faster and can take more oil than the original (the screen comes from an advanced game but I always switch to the new tanker when it become available. They take forever to go from one side of the map to another so speed is a huge factor. I think they have the same graphics tough) and the second ship is a cargo ship refitted for transporting Goods.
In that game the airport could not even manage to get all the goods away so I built other ships at the dock to transport some more goods to an ocean side city. It wasn't very efficient tough, would I have known better I would have done like I do right now and link the dock and the airport together. Way more efficient that way!
Of course the airships are refitted to transport goods too...
