Hello Atreius ,
Modern electronics produce effective results, but if you are having problems have you thought of the old method where moving the rudder would activate a micro-switch which would reverse the power to a motor? If you are interested let me know and I'll find a circuit diagram.
Good luck
Tim

I have found my previous explanation to mix three channels so that 1 stick controls both motors and the rudder stick controls the rudder and each motor when turning.
Please see the attached pdf file for details. This was for a FlySky Fs i6 but the principle is the same for all sets with mixing functions.
dave976

Hi Atreius models, I Did have an Aziz tug with twin 600 motors controlled by 2 Mtronics 20amp esc's with a 12v system to power the motors. Also had a voltage reducer, (got through any of the electronics companies)12v to 6v to power rudder servo/nav lnav lightning and 10 channel 2.4ghz flysky rec. Using the flysky system and programming the transmitter on two channel, right stick ch1, right motor, left stick ch3, gave me independant control of left/right motors to help with steering. But having also a bow thruster in the tug on ch2 with a mix to ch4 rudder gave me infinite steering control in steering competitions. But everyone has their own rweeks.
Hopethis helps.😎

Thank you for the helpful replies everyone, @dave976 I believe both my transmitters are capable of that though I must admit I am not familiar with the method. I have a Turnigy 9x and a RadioLink AT10.

Hi Dave I have to honest I mist your explanation first time round so I would be grateful if you could post it again.
I have 3 FlySky Fs16x sets but at present only 1 twin screw that would benefit from your input
Many thanks

Hi AtreiusModels
If you have a programmable Tx with a mixer function you can use two ESC's and a rudder servo and set up the mixing on the Tx. This is possible with the FlySky Fs16x sets and I have posted details of how to do the programming in the past. I have used this on several twin screw models and find the Tx route to be far more configurable and easy to adjust and use. Please say if you have a programmable Tx and I will re post the details
dave976

Hi AtreliusModels
I have used the P94 and the Mtroniks wtail, the wtail went into the bin alone with the esc's, as for the P94 I do like, as I have been unable to get a new one I have gone for a Forge Electronics rudder mixer at £30.00, only thing wrong with it is it takes a bit of time to set it up correctly, when it is set up it works fine, Mtroniks esc do not like it so I have used the Hobbywing 1060 esc and they work fine.
Fred

The mtroniks unit is the one I use in my pilot boat. Twin motors and rudder control using two mtroniks speed controllers.
It is easy to set up and appears to work well.
Must admit to not having a great deal of time on the water with the boat as it shipped rather a lot of water on its test run. It was very controllable before it developed a worrying list😁