Controllable Pitch Propellers (CPP)

CPP for smaller ships and boats has been around for a century, but CPP for larger ships a few decades:

1935

Liaaen (later acquired by Ulstein) develops the first controllable pitch propeller. The Heliston propeller range is introduced with cavitation-reducing blade shapes. Ships include Aquitania, Mauretania, Queen Mary and Queen Elizabeth.

A.M.Liaaen patented their CPP for large ships in the US in 1972:
https://www.freepatentsonline.com/3640644.html
A.M.Liaaen CPPs were supplied to several US Navy and USCG vessels.

Here is some drawings of their propeller system:

Liaaen’s propeller division was sold to Ulstein in 1996, which became Rolls-Royce Marine and now Kongsberg Marine. Propeller production was moved to Ulsteinvik in 2003:
http://liaaen.no/index.php?sideID=172

Service and Spare parts are still available, even for very old models, through KM:
http://liaaen.no/index.php?sideID=135

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