Auxiliary marine vessel propulsion system

Abstract

The main propulsion and drive system of a merchant vessel such as a freighter or tank vessel, or a military vessel is supplemented by an auxiliary propulsion and drive system that includes at least one, but preferably a pair of auxiliary propellers that flank the main propeller at port and starboard positions and each of which are attached via a drive shaft through a gear train, which can optionally include a clutch mechanism, to an auxiliary motor or motors. In order to reduce the drag when the main propeller is disabled, segments of a wake field modifying propeller duct are mounted for repositioning to form at least a partial housing or cowling that diverts the water over the exterior surface of the duct and minimizes contact with the stationary blades of the main propeller as the vessel moves through the sea when powered by the auxiliary propulsion system.

1 . A marine vessel propulsion system for a marine vessel comprising:
 a. a main propulsion drive subsystem that includes a main propeller and a main engine, the main propulsion drive subsystem including
 a propulsion mode in which the main propeller is operably connected to the main engine, and 
 a disengaged mode in which the main propeller is disengaged from the main engine; and 
   b. an auxiliary propulsion drive subsystem that includes at least one auxiliary propeller and at least one auxiliary motor, the auxiliary propulsion drive subsystem including
 a disengaged mode, coincident with the propulsion mode of the main propulsion drive subsystem, in which the auxiliary propeller is disengaged from the auxiliary motor; and 
 a propulsion mode coincident with the disengaged mode of the main propulsion drive subsystem in which the least one auxiliary propeller is operably connected to at least one auxiliary motor. 
   
     
     
         2 . The marine vessel propulsion system of  claim 1  in which the main propulsion drive subsystem includes a drive shaft in selective mechanical cooperation with the engine and with the propeller, and a clutch for engaging and disengaging the main engine from the propeller to effectuate selective mechanical cooperation to permit free rotation of the main propeller under the influence of applied hydrodynamic force whereby the overall hydrodynamic drag on the moving vessel is minimized in the disengaged mode of the main propulsion drive subsystem. 
     
     
         3 . The marine propulsion system of  claim 1 , wherein the auxiliary propulsion drive subsystem further includes a mechanical subsystem for feathering the at least one auxiliary propeller when the auxiliary propulsion drive subsystem is in the disengaged mode. 
     
     
         4 . The marine propulsion system of  claim 3 , wherein the mechanical subsystem for feathering the at least one propeller operates to turn the blades from a position that is generally transverse to the drive shaft to a position that is generally aligned with the drive shaft. 
     
     
         5 . The marine propulsion system of  claim 1 , wherein the auxiliary propulsion drive subsystem further includes a generator that is selectively coupled to the at least one auxiliary propeller for operation in a power-generating mode while the vessel is moving. 
     
     
         6 . The marine propulsion system of  claim 1 , wherein at least one motor of the auxiliary propulsion drive subsystem is an electric motor that is powered by the vessel's electrical generation system and/or electrical storage batteries. 
     
     
         7 . The marine propulsion system of  claim 1  that includes two propellers that flank the main propeller, each of which auxiliary propellers is associated with an independently controlled auxiliary motor. 
     
     
         8 . The marine propulsion system of  claim 2  that includes a wake field modifying apparatus comprising a two-part duct that is mounted coaxially with the main drive shaft and is movable from a first position in which opposing arcuate members define an open cylindrical form to a second position defining an open-ended truncated conical form. 
     
     
         9 . The system of  claim 8  in which the opposing arcuate members are mounted for pivotal rotation about an axis that is transverse to the drive shaft. 
     
     
         10 . The system of  claim 8  in which the aft end portions of the opposing arcuate members define a generally circular opening that has a diameter that is at least as great as the diameter of the main propeller. 
     
     
         11 . An auxiliary propulsion apparatus for a marine vessel having a main propeller mounted on a drive shaft that is operatively connected to the vessel's main engine, the auxiliary propeller apparatus comprising:
 a pair of auxiliary propellers flanking the main propeller, each auxiliary propeller being operatively linked to an auxiliary motor through a clutch mechanism operatively positioned between the main engine and the main propeller driveshaft, whereby the main propeller can be disengaged when the main engine is stopped.   
     
     
         12 . The apparatus of  claim 11  in which the blades of the auxiliary propellers are moveable from one or more operable drive positions to a feathered position. 
     
     
         13 . The apparatus of  claim 11  in which the blades of the main propeller are moveable from one or more drive positions to a feathered position. 
     
     
         14 . The apparatus of  claim 11  which further includes an electrical generator that is configured to selectively engage the drive shaft of an auxiliary propeller. 
     
     
         15 . The apparatus of  claim 11  in which each auxiliary propeller is linked to a separate motor. 
     
     
         16 . The apparatus of  claim 11  which also includes a variable gear mechanism operatively attached to each of the auxiliary propeller drive shafts. 
     
     
         17 . The apparatus of  claim 11  which includes a wake field modifying apparatus comprising a two-part duct that is mounted coaxially with the main drive shaft and is movable from a first position in which opposing arcuate members define an open cylindrical form to a second position defining an open-ended truncated conical form.