I dont uses mixes, but do use exponential and rates (spektrum dx6i) with my twin screw brushless 4 foot fireboat. When at speed rates on, then it turns nicer, no roll, when going slow rates off so turns are sharper, if that makes sense.

Mixing the throttles.. interesting not thought of that, but it will lose power/speed. We use mixing on planes for taxiing, particularly on water, but once airborne its off. My avatar has this as the cheapo motors just wont balance so it compensates for this on the water. With the boat its easier to control with rudder input. I like the thinking though!😁

Thanks Jarvo

Hi Andy, I have 'twined both the 34" and the 48" Huntsman, i used 600 size motors in the 34, and 850 motors in the 48. Both were very quick, but, the run time was poor, about 10 mins.
With modern lipo's or big Nimh batteries they would be a lot longer especially if you used brushless motors. Props, on the 34, they were 35mm x 3 blade brass, on the 48, they were 45mm x 3 blade brass. Sad but i sold them some years ago but now have a 48" fireboat to play with.
Mark