Great info Tankbuilder, thanks!
I'm running three brushless on three separate ESCs and batteries. My thought was that if I hit LVC while on the water, I could use the at least one motor to get back if necessary. When you run your PTs, do you have the center prop runnng at all?
Originally I was thinking that having the center mixed in at 125% it would provide some stabilzing thrust, but maybe the best way is to drop it to less than the wing motors or cut it out altogether and just use it for a boost of speed.
Right now I have the Left motor on throttle, the right on elevator and the center on the rudder channel with the actual rudder as aileron. I mixed the center motor into both wings, so it goes equal with the fastest movng motor. But if it doesn't pose a drag risk, keeping it slow (or idle) until a burst is needed might work best for everything.