Hi, I think the most difficult thing about foiling is keeping the right height from the water. When it is a little too dark or the water is super clear, the distance can be almost impossible to judge.
When I get too far above the water, I always plunge forward.
I recently watched this video. Do you think this could work for e-foil?
Hard to say, I haven’t seen anyone trying. If you add air, you loose thrust. The question is wheter you can get enought air down to the propeller.
I chose a different aproach for this problem, see here: Daniels (un)geared inflatable (slowly built) - #87 by sat_be
instead of visually indicating height did you consider a haptic indicator?
It would be sooo nice if someone could opensource a simple ios watch app that talks to ESP32 so we could send bluetooth packet to trigger haptics to a watch.
If you are building for your self and will use the device lots, then those types of things are solutions looking for a problem.
Get a decent learner foil wing and spend sometime in the water.
Could be useful for rental situations where you want people to have maximum enjoyment in an hour or so, but for your own foil that you will be using multiple times it is not needed.
I have been foiling for about a year, as long as the water has some texture I can relax on the board, no problem.
But sometimes the water is totally flat, and all I can see is the reflection of the sky. Maybe I just have bad depth vision, but I think it would be a great feature for me.
Maybe the suction of the water around the outlet could pull the air down with no needs for a pump, no moving parts could make a reliable system
Definitely an interesting problem. An idea could be a few led’s to indicate distance. Not sure how they would handle salt water or water in general but maybe a cheap acoustic distance sensor or even a pressure sensor might work in the mast. Just brainstorming but maybe a accelerometer+gyro could calculate how much it has moved vertically?
What about a water pick up on the foil, like that is used for water cooling and then spray the water in front of you for some texture.
I know what you mean about when it is perfectly glassy, it’s almost impossible to tell how high you are on the foil, or even if you are moving. Such an eerie feeling.
I’ve been foiling for over 10 years and still get it, especially in low light on glass waves at sunset of early in the morning.
Yes, I did consider indicating it with a haptic signal on the remote. Th edvantage of the LED display is you can show the height before breaching and touch down in different levels and use colors. Not easy to implement a haptic pattern for that. It would be possible to give a warning before you reach max height though.
The whole system needs to be fast, measure, communicate, react, otherwise you are too late and breach.
Simplest solution I can think of would be to mechanically provocate a certain sound or vibration when a part of the mast rises above the surface. Have something flapper, whistle, or spin
I have had that on my mast, by accident😄
The old inlet to my motor wires was taped over when i moved motor further down and it acted as a drum skin, creating a slurping sound when it came above the surface, then it was 20cm left until breaching. Worked well, i miss it.
Now don’t go patenting this folks. I’m disclosing it freely here for everyone to use🫵
I was also considering acoustic sound with increasing frequency and peep length. Like it is done with paraglider variometers. Abandoned the idea because I think it is just too annoying and disturbes the silence on the water as it would have to be rather loud to hear it under the helment with ear drum protecting pads.
This is an interesting idea!
I wonder if an external tube would do the same. Anyone tried that?
(I mean sucking air to the prop when passing certain ride height)
Apparently, this Anti Breach System (ABS) slot is only fitted on the shorter mast version (60cm long for beginners) of the inflatable AirFly eFoil from Aerofoils.
Nerf plastic rifles for kids and teens use this principle. Nerf have developped a whistling dart head based on a whistle without pea principle.
The challenge would be to 3d print a head that could be screwed in / stuck or ajusted to the mast at the desired height. The hole would be facing downwards to let the water go. Sticking an existing Nerf whistling head to the mast could work as Nerf darts start whistling from 2 m/s (7 km/h). The head should be silent once submerged in water (most of the time) … and whistles on the way up. Will the sound be audible enough in the air, in the wind, with a helmet, … ?
When you activate the wireframe view in the above 3D viewer, you can see that the head is completely hollow. The sound depends on the dimensions of the opening and on the volume of the cylindrical cavity.
Reference: How do Nerf Whistler Darts work?
That would be super annoying though 
The slurp i had was actually kind of nice.
Just a question of settings, a bird whistle if you like 
This is a chickadee caller - Imitates the song of the chickadee to perfection:
I tried a plastic tube (id 6 mm). Not a game changer but it gave a warning when I was flying too high.
Sort of an anti breach system I stumbled upon on YouTube a few weeks ago. Really more of a simple height control system for this “boat”. I find the box shape of his craft kind of amusing, basically the worst possible shape.
Seems like this injects air along the wing surface to reduce lift when an air inlet breaches the surface and prevents the boat from lifting too high.
An ESP32 or Arduino with progressive water sensor + buzzer or loudspeaker, just behind the trailing edge of the mast in a NACA airfoil hollow section like the mantafoil Take-Off does for the supply of their motor
Have a reference for that?
