Yea, I'm pretty sure boats don't use breaks. Just forward-reverse. They wouldn't really do anything except slow the prop down which reverse would do the same thing and wouldn't hurt it since its only in water and theres not 12lb's slaming into reverse (like an MT)... If you understand what I'm saying let me know, cause I kinda confused myself, I think...
There is another way to do it if you have a 3 channel radio with channel mixing.You have the brake servo on the 3rd channel and you mix the brake side of the throttle channel with channel 3 100%,then you turn the EPA of the brake side of the throttle channel to zero,that will give you no controller brakes.You still have EPA adjustment of the brake servo on the 3rd channel.
That's what i do on controllers which you can't switch the brakes off.It's actually better because you don't have the brake servo moving in the throttle direction since it's only mixed to the brake side of the throttle channel.