What are the dimentions of a bridge crane?

Giant cargo boat that is flat in the middle, often anchored near the Verrazano Bridge in Brooklyn.?

• I've noticed lately a boat anchored by the Verrazano Bridge in Brooklyn. The front and back ends of the boat looks just like any large cargo boat you would see, however the unique thing about this boat is that the middle of the boat is hollow and lays completely flat on top of the water ( \_|___________|_/ ) I hope this picture can help you visualize what I am describing. If you look at the boat from the highway the flat part appears to be only visible an inch or so above the water. There also appears to be a crane attached to one end of the ship. The description may not be the best but I really hope one of you out there can enlighten me on what type of boat this is and what its purpose is. Thanks in advance for any information you have to give!

• Answer:

  I believe the ship you are talking about is used to carry very tall cargo and still be able to pass under the bridge. I have seen a ship there that was carrying very tall cranes of the type used to unload ships. A normal height ship would not pass under the bridge with those cranes. Some of those ships can actually lower themselves deeper into the water by flooding and have floating cargo (other ships or oil rigs, etc) float over the cargo area into position and then the ship will pump out the water and rise under the cargo lifting it free of the water.