I have a Takuma eFoil board that I’m modifying to use as a tow-in for foil surfing. Right now I’m just paddling back out to find the thing, but I plan to have it navigate back to me once I call it. So far the modifications are simple–a PVC pipe attached to the deck with a flag pole grafted in so I can find the thing. the first time I tried it I had a heck of a time finding it.
the pipe extends three feet past the end of the deck to provide leverage to steer, help keep the nose down, and keep the tow line out of the prop. Steering works surprisingly well. the BB Bluetooth controller has a range os about 100 feet, so no issues there. I take the foil off completely when I use it as a tow. Now I’m working on having it come find me.
I’ve ordered two sets of two versions of the ESP32-based T-Beam LilyGO version V1.1 development module to base my “return to me” tech on. These are LoRa radio chips with ESP32 controllers that can be programmed with C++ (Arduino IDE) and includes a GPS, one of the versions has an OLED screen.
I don’t foresee a huge amount of difficulty in writing the software, or adding a rudder mod to the eFoil so it can drive back to me, but it’s not going to be a trivial project.
Is anyone else working on something like this? It would be handy to share effort with other builders.
Until they can go as fast as a foiler on a DW run you can’t crack that. It won’t surf with you. You’re gonna have to just buy a wing and take your lickings Hdip. But I do like the “go to a neutral corner” idea for sure.
Pono, good to see you tackle this. You’ve got the chops. I’ll let the tow boogie guys I know chime in. That’s where we will see this shine. But your converted efoil is a great way to prototype without having to invent the wheel and fix other stuff.
Would totally love a return function. I’ve been surfing with the boogie. Either I leave it before the break or it surfs next to me on the wave. It tracks surprisingly well on the wave so I let it do its thing while I focus on the wave.
I’ll have to try that. I’ve been just releasing the deadman switch as soon as I let go of the tow rope. I never thought of letting it run and see what happens. If it gets more than about 150 feet away it drops out of Bluetooth range and stops anyway.
I’ve half convinced myself to build a tow-specific boat rather than further modifying the Avante/Takuma eFoil. A blank slate means fewer compromises. If nothing else the Efoil is very heavy. I could build a smaller, lighter tow craft and have easy access to the controller instead of having to screw around with something someone else engineered. I don’t really expect fiddling with the existing controller to be to be a huge undertaking, it’s just a speed control for the drive motor.
You refer to a boogie–is that a tow that you built?
I read through some of your posts, Valhalla. Is your Boogie the one that Mark Ribcoff was playing with? Mark is a good Hood River friend. It looked from the video that you are located someplace in SoCal. I’m renting a house in La Jolla Shores, hiding out from the cold in Hood River without getting on a plane to Maui. My wife has Diabetes, so until we get vaccinated we’re stuck. The downside is that I don’t have my shop available to do serious work, so I’ll just work on the code and electronics for the “come get me” feature. I have a great shop in Hood River, I can build about anything there.
I’ve been screwing around with somewhat related stuff a long time. This is a video I posted in 2013 of a remote controlled rudder I installed on a SIC (mark Raaphorst’s company before he sold it) F16 to enable steering and basic autopilot functions, replacing the standard foot steering. It worked well but i lost interest in the project (I am the poster boy for ADHD).
this video is a bit more recent, using ESP32 wireless control for my motor home restomod. A seriously stupid project that is still underway.
Yeah that was the one mark was trying out. That auto pilot is really neat stuff. I never delved that far into building my own boards but now that I have a reason to I just might. I’m in the Long Beach area.
Fiasco!! My new flag/rope extension screwed up everything. Not only does it not turn better, it also picks the nose up easier, which is completely the opposite of what I expected. In my usual stupidly optimistic way I switched from my 1150/440 combo to a 860/340 that needs a lot more speed. It seems that I was getting away with a lot of mediocre choices by simply going slower which the 1150 permits.
Once the nose comes up enough it starts torque steering and wants to go left. the longer extension out the back somehow makes the steering substantially worse and does nothing to combat the nose lifting. I’m starting to understand why (I forget the guy’s name) that turned the foil around backward did so. I also understand why he connects the tow to the mast. I was getting away with towing from the deck because A. I was going slow. And B. I have a short mast (40cm) to begin with. Even with the extension shoved as far forward as it would go the steering was much harder and required slower speeds to work. Like kneeling on the board, not foiling slower speeds.
Oh well, back to the drawing board. A learning experience, yeah that’s what it was… A learning experience. I put the foil back on the Takuma, did a consolation lap around the bay, and went home to drown my sorrows in Spaghetti and kale-stuffed meatballs (way, way better than it sounds) and a nice glass of Bastide Miraflores.
I never thought to look at that. I used to contribute to the open source efforts for drones in the early days. all the guys that did that are long gone–hired by DJI mostly. Even I got a recruitment call though my code sucked. I explained that I was 70+ years old and had no interest in working and they STILL wanted to hire me. Thanks much for the reminder–at the very least I’ll look at whatever code there is on Github.
Damn, I have a big box full of pixhawk stuff at my shop in Hood River. Left over from some waterproof drones I built. Of course it’s probably a zillion revs ago, but the OLED, GPS, and other ancillary stuff is probably still usable. I haven’t thought about 3DR since they quit making consumer drones.
I’m trying to follow Valhalla’s build. I ordered a 3d printer, a 65161 motor and the 75/300 Vesc. I have no idea what I’m doing so I have been reading as much as possible on this forum. My problem is the batteries . It seems everywhere I look the 6s 22ah lipo is out of stock except on Chinese websites.
-Are sites like Alibaba reliable?
Can I get away with a lipo that is less than 22ah? I have seen 12000 Turnigy batteries in stock.
Is a 25c rating required or will 10c work?
Last dumb question-what kind of plug do I select for the pos/neg cables coming out of the battery?
I’m sure it will take forever for everything to arrive so I will keep reading!
Cheers!
I’m attempting a tow board too. Decided to go with a 20Ah LiFePO4 battery 16S since I’m not used to lipo. We’ll see if I have enough power to get up on foil. The continuous discharge is 50A and the max is 100A.
Should be more than plenty. The biggest thing that’ll hinder the tow device is poorly managed weight distribution and how the user decides to counteract the torque twist. At least that was my issue. I have way more than enough power and only keep throttle at most at about 70-80% due to oscillation of the hull. I’m mostly cruising at about 50-60% throttle
That’s one of the reasons I plan to use a catamaran, I think I can control the torque twist and nose-up attitude. The main reason is how easy it is to build low-drag catamaran hulls. This is a good video to watch anyway. the drag explanation is excellent. the only problem with watching Tech Ingedients videos is that you can piss away a tremendous amount of time watching them all, and you’ll want to build twenty projects instead of just one.
A slightly scaled up version of the prototype shown in the video is what I have in mind. If theres’s a easier way to build an accurate and strong hull I don’t know what it would be.
20ah should be fine. You need a decent BMS even if it’s LiFe, and DON’T solder the cells. Get a spot welder, you can build a cheap one that works fine with a kit from Bangood. I can’t understand why all the DIY powerwall guys persist in doing that. It’s moronic. Make sure the BMS is for LiFe Chemistry, you need to cut off the charge at 3.6V or somewhat less (unless you get some exotic LiFe battery that has Yttrium in the mix). If you use a LiPo BMS with max charged voltage at 4.15 your LiFePO4 batteries are now dead or dying. If you’re buying the pack instead of building and the charger is supplied, then you’re probably fine.
I assume you’re talking about 24V. If that’s so then 50Amps is 1200 watts assuming no loss. That’s about 1.6hp and it’s a bit light, though once you’re up on foil it should be fine. Obviously 100 A is 3.2hp which should be plenty to get you up. the critical element will be the prop and the RPM the motor spins it at.
