After almost 15 years of playing around with electric outboards, jetsurfboards, winches, electric surfboards, fast Ebikes and other projects, reading and posting for years at the endless sphere forum I today had my best ride ever on my homemade electric hydrofoil
No leaks, no burning stuff, nothing broken, no slow riding with 10kw input power but playing around for a long time with just 1300 watt.
I did cut a surfboard in a 165cm piece at the almost no rocker area.
A boat hatch with the sealing replaced by alieexpress silicone tube, works great, no leaks. Inside the board, so not on top, so the board is almost flat at the surface.
LG Chem 15ah lion pouch battery from opel ampera ( chevy volt ) in 11s 30ah pack.
Gong Pro L wing 65cm mast.
65161 flipsky 100kv motor, filled with Corrosion X
Flier 500A esc. Firmware boat 24s v31a with starting power at 95%. Timing at 5
Starting is a bit up and down I hope we can solve this.
Prop, standard cheap aluminium prop from alieexpress, 7/12 diameter with 7 pitch
Bad weather filmed with bad camera:
Top speed was about 25 kmh non foiling. and 1300 watt flying cruising speed at about 20 kmh.
Build inside the board a display, alieexpress waterproof encloser, with Big screen GPS 2x temp reading, Battery level indicator, and a meter for Watt hour, powerconsumption Voltage etc.
I was suprised today to see that it only took 1300 watt for cruising in rough conditions. Maybe I try an 8 pitch prop later and I wonder what a flying rodeo prop would do, they are also 7 pitch I think and they say they are even more efficient compared to the cheap chinese alu props.
I think lower rpm with high pitch prop is more efficient then low pitch with high rpm. Maybe I am wrong about this?
When accelerating I see about 3000 watt. I did not use the watercooling, the 500A has a big alu plate and keeps cool. The motor is very silent and is really powerful. Accelerating is real fun !
No load amp is now only 3.3a at 42v with full throttle with the big alu prop mounted blowing some wind.
I think the sealings, bearings and corrosion x is now all in place and the motor runs really smooth.
For safety reason I wanted to make sure that I have a good deadman switch, in other projects I used a magnet switch at the ESC powerline, or at the ESC signal line, but in those cases the motor kept on running for about a second. And a second of power can be dangerous, the board can ride away fast or you hit a running prop.
So what I did is installing a 80v to 12v converter parallel with the main power wires, from there is a magnetic switch at the surfboard that will switch on 2 x small relay, and they will power the GPS Speedometer, Battery level indicator, the watt data meter a 12v to 5v converter as a BEC for the receiver, and it will power the 12v waterpump, it will power it will power the 500A Esc by the precharge resistor and it will power a time delayed relay which is set at 2 seconds, ( bought for a buck at alieexpress ) after these 2 seconds the Capacitors of the Esc are charged and it will turn on a heavy 200A relay that will power the big 500A esc by the main power wires, so now there is no spark seen in the 200A relay and can not be welded together inside the relay.
Long story, but I just want to share it with you, I did not see a more simple solution for a 100% sure all power is OFF.
When I fall of my board there is no power anywhere, only at the small 80v to 12v converter that will almost drain nothing from the battery. It works really good.
Ofcourse I want to do things like a good paint job with rubber deck etc.
But I also wonder why it is so hard to ride, last summer I efoiled with an F one 850cm wing, that was to unstable, now I have this Gong Pro L with 1350cm2 and it is much better but not like cruising along in corners, maybe need more practice or bigger wing ?
I have noticed when kitesurfing with Fone Ic6 foil 850cm2 compared to the Fone ic6 foil 850cm2 version 2 that the version 2 has a longer fuselage and I think therefore much more stable. I hope Gong will provide a longe fusulage too.
Also, when foiling the board will fall over, the board is so heavy like it is top heavy and wants to fall over.
When kitefoiling you have lighter board and a kite to hold on.
I mounted my foil mast 33cm ( middel foil ) from the back, If I would mount it more to the back does this have effect in stability or does it only change the position of standing ?