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) was to be based on the CH-47B but the order was cancelled in a review of defence spending in November 1967. UK Chinook procurement ambitions were revived in 1978 with an announced requirement for a new heavy-lift helicopter to replace the Westland Wessex. Thirty Chinooks were ordered at a price of US$200 million. These helicopters, comparable to the CH-47C with Lycoming T55-L-11E engines, were again designated Chinook HC Mk1, and entered service in December 1980. Eight more Mk1s were delivered from 1984 to 1986 with the CH-47D's Lycoming T55-L-712 turboshafts. The replacement of the Mk1's metal rotor blades with aluminium