Cruise control mode, go straight ahead

Hello all,

I use a baitboat with a fishfinder for carp fishing.
It uses the pixhawk flightcontroller and a Skydroid H12 as the transmitter.

Now my question is, if it is possible to activate some sort of cruise control so that the boat goes in the direction it is pointing, without me a applying throttle on the transmitter.
Is this maybe possible with a driving mode or maybe a script?

Thank you for your answers.

Kind regards,

Wouter