Vectored Thrust


above image is of a Sprint F3 boat from HobbyKing (link)

Rover-3.3.1 (and higher) supports “vectored thrust” which improves steering control for boats and hovercraft that use the steering servo to aim the motor. This feature should not be used on cars or boats with a rudder positioned away from the motors.

To enable this features set the MOT_VEC_THR_BASE parameter to a value between 10 and 30 (normally 20 works well). This parameter specifies:

  • the throttle level above which the steering servo will be scaled towards the center. I.e. if set to 20%, the steering response will be unrestricted between 0% and 20% throttle but above 20% throttle it will be scaled towards the center more and more as throttle increases.
  • the maximum steering response at full throttle expressed as a percentage. I.e. if set to 20%, at full throttle, full steering input will only result in the steering servo moving 20% of its full range.

The rough image below shows how the steering servo angle must be reduced as the throttle increases in order to achieve a desired steering response.


The graph below shows how the steering response is reduced as the throttle is increased when MOT_VEC_THR_BASE = 30.