This one is quite simple! You have one joystick for each waterjet, the left one for port side, the other for starboard side. You can use them each per each for manoeuvring or in combination whilst on journey. In real life, this one works another way. Both water jets are controlled electronical and you can change between manoeuvring and sea going mode. I prefer to cut them in twice by means of the precision steering. That allows me to use one of the water jet for steering and the other for reducing the speed when I berth the craft.
Cheers