Cable laying vessels are used for laying sub-sea cables. In addition to laying sub-sea cables, cable layers are also able to retrieve broken or damaged sub-sea cables and repair them on board. Depending on water depth and the risk of potential damage, sub-sea cables are buried in the sea floor by the cable layer using a special plough. A DP 2 system enables the vessel to remain in a precise position above the defined cable route, cable laying vessels are now equipped with powerful propulsion systems and a dynamic positioning system. The cable is usually stowed spirally in a cable carousel (horizontal rotating table) and unreeled according to the speed at which the cable laying takes place. Today, the largest cable layers can stow and lay up to 7,000 tonnes and more of cables on board.