In most of the aeromodelos you have the inclination of the motor for the right to compensate for the sense of the rotation of the motor.
I read what the aquacraft also adjusts the motor for the right in 3 °, and he would like knowing if the airboat with the rudder out of the water it has the problem not to walk in straight line without using the right thrust.

look for page 7/15 http://manuals.hobbico.com/aqu/aqub2...anual-v1_1.pdf