Hi tica,
Thanks for the interest.
I changed the props to contra rotating which are slightly over-scale (Pic 6). Due to the slight increase in size I had to remove the rudders which were redundant anyway.
I use a Heng Long 1/16 tank 2.4Ghz RX18 receiver/controller unit and transmitter. Using this set up :- No servo. No linkages. No rudder/s. No speed controller. No visible antenna. Just two motors each operating independently with variable speed control. Power is a Lipo 40C-450mAh-7.4v battery. I have not installed an off on switch. I switch on transmitter then plug in battery to control unit and slip battery and unit under the deck (which is permanently glued on) as pictures 5,4,3,2. The white plastic pieces in the hull act as guides and hold the control unit in position. The tape covering the control unit is simply protection against splash and electrical contact with brass prop shafts. It was necessary to remove the unit casing to enable it to fit in (casing simply unclips). I pretreated the unit to water proof it. It takes a few seconds for the unit to bind with the transmitter. You then use the right hand stick to control the motors.
Your question was "How does it perform on the water?"
I tested the unit on my garden pond which is not overly large. The model floats slightly bow down when stationary but trims up with any forward way on. The speed is variable from a creep to well over scale speed. The steering is good and the model will turn in its own length if required. It will easily climb onto the plane and looks very good in my opinion. I plan to post some videos in the future.
Regards
Steve.