Helicopter deck the submarine, but brushes the officer charged with trying to hook him who receives a minor injury. Coaxial rotor helicopters in flight are highly resistant to side-winds, which makes them suitable for shipboard use, even without a rope-pulley landing system. Marine and offshore helicopter decks on board offshore oil platforms and ships are typically regulated by the rules defined within CAP 437, which defines standards for the design, marking, and lighting of marine/offshore helicopter decks, and is produced by the Civil Aviation Authority. The largest marine heli decks will accommodate the Boeing CH-47 Chinook, which requires a D value of
Boeing Chinook (UK variants) such as the AgustaWestland Merlin HC.3 of the Royal Navy's Commando Helicopter Force and the RAF's Westland Puma HC.2, based at RNAS Yeovilton and RAF Benson. The RAF has a total of 60 active Chinooks in inventory as of 2015. In 2018 the UK issued a request to the United States to purchase 16 additional aircraft. The Chinook is expected to remain in RAF service until the 2040s. In March 1967 an order was placed for fifteen Chinook HC Mk1s, standing for "Helicopter, Cargo Mark 1", for the Royal Air Force to replace the Bristol Belvedere. This original MK1 variant