Our first build has been in progress for around 18 months. Went through a few iterations of boards, motors, props, etc. Ended up coming in at around AU$2,500 all told.
- Board - second hand ~$500
- Battery - 13s9p (48V 20Ah) ~$500
- Foil - Aliexpress - $700
- Prop & motor mount - 3D printed
- Waterproof case $80
- Motor - 8384 120kV direct drive outrunner - $80
- ESC - 120A - $120
- Controller - $50
Went through quite a few iterations on the propulsion system. Ended up going with a 150mm diameter 3.5" pitch 3-blade prop printed in PLA. Design is custom and pitch of blades is defined parametrically. Use some filler to prime and sand to get a good smooth finish.
The battery we got from Ali Express was a bit dodgy (LiitoKalo brand). All the current is sinking out of the nickel strips which are only rated for around 10A. Ended up having to take it apart and rewire it after we noticed some heat damage. Also the battery was sold as 30Ah (ie 3.3Ah per cell) but actual capacity was 20Ah (ie each cell said 2.2Ah).
This is the controller and ESC - seems to be alright for the price. The controller in particular does not seem waterproof at first glance, however I took it apart and was impressed with the build: no mechanical switches or connectors (uses magnets and reed switches/hall effect sensors), wireless charging, and circuit covered in resin.
This shows arrangement of direct drive outrunner mounted to mast. The battery and ESC fit inside this waterproof yellow box which is strapped to the back of the board. It’s worked out quite well that the whole propulsion system is pretty much a bolt-on to any foil-board setup.
Still learning how to ride it, but seems to be pulling about 60A to get up to speed and 30A to keep going once foiling. Seems to get foiling at very slow speed around 15km/h; we do have quite a large foil on it.
Here it is in action