That was my first choice but there is not enough clearance inbetween the motor and drive shafts and the motor to hull in the aft half area ,only a very tiny 1/8 aluminum tube coil would fit and it would take to mush water pressure to operate,also the instalation would be very dificult as there is no top acsses in the aft motor bay for lines to the exterior.
A ram water system would have been nice but it could not be done.[]

The large area of the coolling fins disapate the heat very well as I tested it in and out of the water,a noticable amount of warmth is present after about 5 minutes of running at medium speed outside of the water.The distance the heat has to travel is only about  2cm to 3.5 cm,also the cold water temperature migrates into the sink as well.

I have been running it every day now for fast long runs and have noticed less internal pressure when I unscrew the top acsses screw,before alot more pressure with even a his could be heard,so i think its working pritty well.

Dave