The External Turret Mooring system comprises a steel box type structure that can be close or extended some distance from the bow or stern of the vessel, providing a foundation for a rotating bearing arrangement and a turret.

The bearing accommodates a fixed chaintable to which mooring chains and fluid transfer hoses are attached. The chain legs are anchored to the seabed either by anchors or piles. Product and utility connections are made between the facilities on the tanker and the seabed via a swivel stack in the turret, allowing the tanker to weather vane around the fixed part whilst continuing production.