There are two main dangers if the cargo is not properly balanced. If
the heaviest load on the ship is at either end then there will be a lot
of stress on the middle of the ship when it is hit by waves. Over time,
this can crack the middle of a large ship. If the weight of cargo is
not evenly distributed on both sides of a ship, it can easily topple
over or lean to one side.
Cargo ships including container ships have a cargo plan. The plan shows
the location on the ship of every bit of cargo and every container as
well as the port where it will be unloaded. The plan is very
complicated and is usually worked out using computer programs.
Container ships in port will often exchange some but not all of their
containers. Some containers will remain and new containers will be
loaded. To work out the cargo plan the cargo planners must make sure of
the following things.
A container ship needs to remain balanced in the water. At times
ships will be hit by large waves and strong winds. If the cargo
containers are not evenly stacked on a ship, this can change the
balance of the ship.