Can't yaw or thrust in manual mode using rc overrides

ArduRover Rover 4.3
1

Application: use a companion compute to send mavlink commands in order to pilot an autonomous boat.

Goal: be able to use manual mode and then be able to switch to automodes such as loiter and RTL

Approach: arm the vehicle, put it in manual mode and then use RC_OVERRIDE commands like this:
data[3] = 1500+yaw_delta yaw pos
master.mav.rc_channels_override_send(master.target_system, master.target_component, *data)

Issue: can’t yaw or thrust in manual mode using rc overrides.

I have set the following parameters for skid steering:
SERVO5_FUNCTION, 74
SERVO3_FUNCTION, 73

Any help much appreciated!

2

The solution is to use channel 0 (roll channel) for steering and not the yaw channel 3:

data[0] = 1300 yaw neg
master.mav.rc_channels_override_send(master.target_system, master.target_component, *data)

Note that throttle is still channel 2.

3

Better to use guided mode and send position or velocity vector updates.

Manually controlling a vehicle with RC overrides is hacky at best.