Ship collision is the structural impact between two ships or one ship and a floating or still object such as an iceberg

Iceberg

An iceberg is a large piece of ice from freshwater that has broken off from a snow-formed glacier or ice shelf and is floating in open water. It may subsequently become frozen into pack ice...

. Ship collisions are of particular importance in marine accidents. Some reasons for the latter are:

• The loss of human life.
• The environmental impact of oil spill
  Oil spill
  An oil spill is the release of a liquid petroleum hydrocarbon into the environment, especially marine areas, due to human activity, and is a form of pollution. The term is mostly used to describe marine oil spills, where oil is released into the ocean or coastal waters...
  
  s, especially where large tanker ships
  Oil tanker
  An oil tanker, also known as a petroleum tanker, is a merchant ship designed for the bulk transport of oil. There are two basic types of oil tankers: the crude tanker and the product tanker. Crude tankers move large quantities of unrefined crude oil from its point of extraction to refineries...
  
   are involved.
• Financial consequences to local communities close to the accident.
• The financial consequences to shipowners, due to ship loss or penalties.
• Damage to coastal or off-shore infrastructure, for example collision with bridge
  Bridge
  A bridge is a structure built to span physical obstacles such as a body of water, valley, or road, for the purpose of providing passage over the obstacle...
  
  s.

As sea lane

Sea lane

A sea lane or shipping lane is a regularly used route for ocean-going and Great Lakes vessels. In the time of sailing ships they were not only determined by the distribution of land masses but also the prevailing winds, whose discovery was crucial for the success of long voyages...

s are getting more congested and ship speeds higher, there is a good possibility that a ship may experience an important accident during her lifetime. Higher speeds may cause larger operational loads, like slamming

Slamming

Slamming is the impact of the bottom structure of a ship onto the sea surface. It is mainly observed while sailing in waves, when the bow raises from the water and subsequently impacts on it. Slamming induces extremely high loads to ship structures and is taken under consideration when designing...

, or excessively severe loads, for example during a collision. Denser sea routes increase the probability of an accident – in particular a collision – involving ships or ships and shore or offshore structures.

Due to extremely large masses and relatively high velocities the energy involved in such an accident is astonishing: the collision energy of a 10,000 tonne RoRo

RORO

Roll-on/roll-off ships are vessels designed to carry wheeled cargo such as automobiles, trucks, semi-trailer trucks, trailers or railroad cars that are driven on and off the ship on their own wheels...

 passenger at a speed of 30kn, is equivalent to 10,000 cars of approximately 1 tonne each, impacting a small area with a speed of approximately 55km/h (slightly higher than the speed used in Euro NCAP side impact tests for cars).