Adds massive cargo ships to the game, that function similarly to trains. Also adds deep sea oil, oil platforms, tanker ships, train bridges and other water based content.
Make sure you can select the ship engine at the back (and open the fuel/schedule dialog). If this doesn't work, then the ship was placed incorrectly. You have to pick it up and put it back down on a longer section of waterway.
Move the inserters closer to the ship. They need to be the same distance from the waterway as they would be to a train rail (this is a game engine limitation unfortunately).