Having searching ultimate motors and ESC setups I always come to widely used skateboard motor setups, which become common and low price.
There are also very cheap and nice setups having motors within a wheel being installed on fixed shaft. They are commonly couple of motors and ESC is also supporting two motors inherently:
Below are examples of it:
Looking into it I got in mind the two prop contra rotating setup (as it shown in the link below):
Before brushless motor came up such setups where very complicated and costly to build but now with motors are installed iwthin the prop having single fixed shaft, might be very efficient setup, reducing current by at least twice for each motor (30-40A) and improve the efficiency (I hope)
I will be happy, guys, to see your comments and thoughts keeping two contra-rotating props, with smaller diameter (80-90) in the same duct having two waterproofed outrunner motors, whithin the prop.
Again direct drive
Simple and hopefully efficient
Please your comments and ideas!