Apparatus for detecting the pitch of a marine controllable pitch propeller

Apparatus for detecting the pitch of a marine controllable pitch propeller system that includes rotatable propeller shaft extending from within a vessel hull to a location outboard of the hull, a hub and blade assembly affixed to the shaft at said outboard location and having a plurality of blades mounted on a hub to pivot about axes disposed generally radially of the propeller shaft axis, and pitch-control means including a translating member located in the hub and coupled to the blades for changing the pitch settings of the blades in response to fore-and-aft movements of the translating member, comprising a stationary circuit in the vessel hull including means for generating a first AC signal, first rotary electrical transformer means in the vessel hull and including a stationary winding connected to the stationary circuit for receiving the first AC signal and a rotating winding rotatable with the propeller shaft for receiving the first AC signal from the rotating winding, thereby to transfer the first AC signal with no physical contact between relatively movable components, a first rotating circuit means rotatable with the propeller shaft for converting the first AC signal to a first DC signal, linear displacement transducer means received in the propeller hub and connected to the first rotating circuit for energization thereby for detecting the fore-and-aft position of the translating member without any physical contacts between relatively moving components of the transducing means and for converting the first DC signal to a second DC signal indicative of the position of the translating member, second rotating circuit means rotatable with the shaft and connected to the transducer means to receive the second DC signal for converting the second DC signal to a second AC signal, second rotary electrical transformer means within the vessel hull including a rotating winding rotatable with the propeller shaft and connected to the second rotating circuit means to receive the second AC signal and a stationary winding for receiving the second AC signal from the rotating winding without physical contacts of relatively moving components, and second stationary circuit means in the vessel hull connected to the stationary winding of the second transformer means to receive the second AC signal for processing the second AC signal and producing readout and control signals indicative of the pitch-setting of the hub and blade.