System for controlling marine craft with steerable drives

1. A system for a marine vessel, the marine vessel having a steering actuator coupled to a propulsion device and a trim actuator coupled to the propulsion device, the trim actuator having a trim actuator position, the system comprising:

at least one processor configured to be coupled to a trim position sensor, the at least one processor being configured to:

receive a steering angle command for the propulsion device;

receive a sensed trim actuator position from the trim position sensor; and

generate a steering actuator position command for the steering actuator based on the steering angle command and the sensed trim actuator position, wherein the at least one processor is configured to change a position of the steering actuator when the sensed trim actuator position changes in order to maintain a same steering angle for the propulsion device.

2. The system of claim 1 , wherein the at least one processor is further configured to cause the steering actuator to extend or retract based on the steering actuator position command.

3. The system of claim 1 , wherein the at least one processor is configured to generate the steering actuator position command by:

identifying, based on the sensed trim actuator position, a mapping encoding a determined relationship between steering angle commands and corresponding steering actuator position commands; and

using the identified mapping to generate the steering actuator position command from the steering angle command.

4. The system of claim 1 , further comprising:

a memory storing a plurality of mappings corresponding to a respective plurality of trim positions, each of the plurality of mappings encoding a determined relationship between steering angle commands and corresponding steering actuator position commands,

wherein the at least one processor is configured to generate the steering actuator position command by:

identifying, based on the sensed trim actuator position, a mapping in the plurality of mappings; and

using the identified mapping to generate the steering actuator position command from the steering angle command.

5. The system of claim 1 , wherein the at least one processor is configured to generate the steering actuator position command by calculating the steering actuator position command based on the steering angle command and the trim actuator position.

6. The system of claim 1 , wherein the steering actuator is attached to a transom of the marine vessel at a different height and/or fore-aft position from a trimming pivot point of the propulsion device.

7. A method for use in a marine vessel, the marine vessel having a steering actuator coupled to a propulsion device and a trim actuator coupled to the propulsion device, the trim actuator having a trim actuator position, the method comprising:

receiving a steering angle command for the propulsion device;

receiving a sensed trim actuator position from a trim position sensor; and

generating a steering actuator position command for the steering actuator based on the steering angle command and the sensed trim actuator position such that a position of the steering actuator changes when the sensed trim actuator position changes in order to maintain a same steering angle for the propulsion device.

8. The method of claim 7 , further comprising:

causing the steering actuator to extend or retract based on the steering actuator position command.

9. The method of claim 7 , wherein the generating comprises:

identifying, based on the trim actuator position, a mapping encoding a determined relationship between steering angle commands and corresponding steering actuator position commands; and

using the identified mapping to generate the steering actuator position command from the steering angle command.

10. The method of claim 7 , wherein the generating comprises:

calculating the steering actuator position command based on the steering angle command and the trim actuator position.