System for controlling marine craft with steerable propellers

Abstract

An apparatus and method for use with a marine vessel having a first steerable propeller and a second steerable propeller is disclosed. The apparatus and method providing for movement of the first and second steerable propellers relative to each other and also maintains a minimum distance between the first and second steerable propellers so as to prevent the first and second steerable from contacting each other. Also disclosed is a control system and method to control the first steerable propeller and the second steerable propeller to provide the fixed distance between the first and second steerable propellers and so as to individually control the first steerable propeller and the second steerable propellers to allow the first steerable propeller and the second steerable propeller to move relative to each other.

What is claimed is: 
     
         1 .- 50 . (canceled) 
     
     
         51 . An apparatus, comprising:
 a control system configured to control a first drive of a watercraft to be positioned at a first steering angle and a second drive of the watercraft to be positioned at a second steering angle; and   an actuating tie-bar operable to generate a force that causes the actuating tie-bar to modify a length of the actuating tie-bar based on the first and second steering angles.   
     
     
         52 . The apparatus of  claim 51 , wherein the actuating tie-bar is configured to prevent the first drive from contacting the second drive. 
     
     
         53 . The apparatus of  claim 51 , wherein the actuating tie-bar holds the first and second drives a fixed distance apart when the actuating tie-bar is locked. 
     
     
         54 . The apparatus of  claim 51 , wherein the actuating tie-bar is operable to adjustably hold the first and second drives apart by a distance in a range of distances. 
     
     
         55 . The apparatus of  claim 51 , wherein the actuating tie-bar is external to a hull of the watercraft. 
     
     
         56 . The apparatus of  claim 51 , wherein the actuating tie-bar is controlled by a valve, wherein fluid is driven through the valve by a pump. 
     
     
         57 . The apparatus of  claim 51 , wherein the actuating tie-bar is operable to generate a force that causes the actuating tie-bar to extend the length of the actuating tie-bar. 
     
     
         58 . The apparatus of  claim 51 , wherein the actuating tie-bar is operable to generate a force that causes the actuating tie-bar to retract the length of the actuating tie-bar. 
     
     
         59 . The apparatus of  claim 51 , wherein the actuating tie-bar is operable to generate forces that cause the actuating tie-bar to extend and/or retract the length of the actuating tie-bar. 
     
     
         60 . The apparatus of  claim 51 , wherein the actuating tie-bar is coupled to a hydraulic circuit that fluidically actuates the actuating tie-bar to modify the length of the actuating tie-bar. 
     
     
         61 . The apparatus of  claim 60 , wherein the hydraulic circuit comprises at least one valve fluidically coupled to the actuating tie-bar and a pump that drives fluid through the at least one valve. 
     
     
         62 . An apparatus, comprising:
 a control system configured to receive at least one command of a rotational movement command and a translational movement command for a watercraft and control, based on the at least one command, a first drive of the watercraft to be positioned at a first steering angle and a second drive of the watercraft to be positioned at a second steering angle; and   an actuating tie-bar operable to generate a force that causes the actuating tie-bar to modify a length of the actuating tie-bar based on the at least one command.   
     
     
         63 . The apparatus of  claim 62 , wherein the actuating tie-bar is configured to prevent the first drive from contacting the second drive. 
     
     
         64 . The apparatus of  claim 62 , wherein the actuating tie-bar holds the first and second drives a fixed distance apart when the actuating tie-bar is locked. 
     
     
         65 . The apparatus of  claim 62 , wherein the actuating tie-bar is external to a hull of the watercraft. 
     
     
         66 . The apparatus of  claim 62 , wherein the actuating tie-bar is operable to generate a force that causes the actuating tie-bar to extend the length of the actuating tie-bar. 
     
     
         67 . The apparatus of  claim 62 , wherein the actuating tie-bar is operable to generate a force that causes the actuating tie-bar to retract the length of the actuating tie-bar. 
     
     
         68 . The apparatus of  claim 62 , wherein the actuating tie-bar is coupled to a hydraulic circuit that fluidically actuates the actuating tie-bar to modify a length of the actuating tie-bar. 
     
     
         69 . The apparatus of  claim 68 , wherein the hydraulic circuit comprises at least one valve fluidically coupled to the actuating tie-bar and a pump that drives fluid through the at least one valve. 
     
     
         70 . An apparatus, comprising:
 a control system configured to control a first drive of a watercraft to be positioned at a first steering angle and a second drive of the watercraft to be positioned at a second steering angle; and   a tie-bar operable to unlock to allow at least one drive of the first and second drives to move and operable to lock to hold the first drive and the second drive a fixed distance apart at the first and second steering angles, respectively.