Doesn't something like this change everything?

[Phils]

https://boostsurfing.com/

Turn it on while surface paddling and then off once on foil.

[DavidJohn]

That's if you can get on the foil.. The drag must be horrendous.

[exiled]

It should get you enough speed to get up with some decent pump technique. I just wonder if having that weight under your board is going to unbalance it what your are up on foil. I think you would almost want to put a fin box in mid body and stick it there on a foil board.

[Phils]

If this type of thing works out as advertised, I can imagine boards being designed to get the location right and balanced properly. 

[blueplanetsurf]

I tried using the scubajet, which I'm sure is more powerful than the boost, and it was not enough push for me to get up on foil in flat water though it worked well for Zane who is much lighter, see video.
https://www.youtube.com/watch?v=zyHxnw3pyBc

[jondrums]

For me, its not about getting up in flat water - it would be about catching swell before it gets steep.  Either for open ocean riding, or getting into a wave way outside.  Or some of the long period super fast moving big wave stuff that I have found almost impossible to catch early.  Or to go to a smaller board and still get in early.  So many great reasons why a little extra boost would help.  I wouldn't mind paddling as hard as I can AND getting a bit more boost.  It wouldn't take that much - say 25-50% on top of paddling.

[PonoBill]

I depends on the design used. If someone designed a boost system from the start to be used to get up on a foil and then continue without assistance then it could be light enough to not be a PITA once you're up. But if it's designed to give an hour of runtime it's going to suck, and if it's designed to push you around at 3 MPH then it's not going to help you get up on a foil. Props drag like crazy, even while they are pushing you. The idea of lifting the prop completely out of the water has merit--as long as the prop actually gets you to the speed you need for liftoff. You are NOT going to paddle or pump the foil to a higher speed than the prop can push you--if it can't get you to speed then you might as well try to foil with a sea anchor. Thinking of it as a way to boost the power you already have is simply wrong--you won't be just pushing your board through the water, you'd need to push the prop and motor through the water. Even with 100 horsepower tandem outboard motors if you set one to go 10 mph and then try to use the other to go 20mph you'll need many times more power than you would need if you only had one motor and you can literally rip the idling motor off the transom by trying the experiment.

I've seen a jet pump built into a fuselage that could actually work, but jet pumps have a long list of design issues--if the water intake is big enough to deliver the thrust you want then the drag is almost as ugly as prop drag. The notion of effortlessly getting up on a foil and then continuing without a compromised system is not likely to happen. The most advanced approach to this is the Lift eFoil, and it's a toy--meaning after you've played with it a while and realize you aren't going to drop into a wave and shut it off then it goes to the bottom of the toybox. A $12,000 toy.

All the same I ordered one of these, but my intent is to hack the shit out of it. Make it deliver 40 pounds of thrust for a minute, perhaps ten times with a rest in between to let the overstressed parts cool down.

[jondrums]

You are NOT going to paddle or pump the foil to a higher speed than the prop can push you--if it can't get you to speed then you might as well try to foil with a sea anchor. Thinking of it as a way to boost the power you already have is simply wrong--you won't be just pushing your board through the water, you'd need to push the prop and motor through the water. Even with 100 horsepower tandem outboard motors if you set one to go 10 mph and then try to use the other to go 20mph you'll need many times more power than you would need if you only had one motor and you can literally rip the idling motor off the transom by trying the experiment.

I don't agree with that assessment at all.  If the controller is designed to operate in "constant power" mode, an electric motor driven prop can increase RPM as you add thrust from some other source - while continuing to add net thrust (not drag).  If a standard electric speed controller is used, it wouldn't work because that's trying to keep the RPM constant.  In that case, you're absolutely correct that it would be nearly impossible to exceed the design speed of the prop.

edited to add: I would hope the boost system is designed correctly, since its supposed to assist with prone paddling into a wave.  It would be crazy to think that it goes the same speed while catching a wave whether the rider is paddling or not paddling.

[SUPdad]

I’m with Ponobill. While it’s possible, I doubt an inexpensive product like that is doing anything other than turning the motor on/off at full speed. In that case, once you exceed the pitch speed of the prop (need to consider the rpm will increase as your speed increases), it’s all just drag. Sure, you could paddle faster than the pitch speed but the prop won’t be helping you.

Their promo video is horrible. It’s also hard to tell, but after the guy catches the wave, it sure looks like he’s going slower than he should be. 

[clay]

Here's the other thread on this boost fin:
https://www.standupzone.com/forum/index.php/topic,35751

When I miss catching a wave surf foiling, it's usually by the itsy bitsy tiny tiniest amount.  And wing foiling has taught me how once on the foil, and again after a touchdown, it only takes the slightest bit of pull/push to get flying again.

So I am optimistic that the boost fin will be that tiny little extra push to get up on the foil and catch non breaking swell.  If not hopefully the hackers will shorten the run time to 6-10 seconds and up the boost.

[jondrums]

I’m with Ponobill. While it’s possible, I doubt an inexpensive product like that is doing anything other than turning the motor on/off at full speed.

This isn't how simple electric motors work.  Hook up a brushed motor to 12V with no load and it'll spin up to its max speed.  Load it up with a torque load and it'll run slower.   This behavior would work just fine as you paddle and accelerate the rpm of the motor can increase (with a decrease in its torque output, but still positive torque = positive thrust).  If they put a propeller on with too low of a pitch such that at the no-load speed of the motor the pitch velocity is slower than we want to ride, well then we're out of luck.  Hopefully this kind of thing would be figured out in the development phase.

If they use a brushless motor (doubt it) with a controller that is controlling RPM that'd be a problem.  One would want to use a brushless motor controller that could control torque.

In summary, if they aren't stupid, this could work just fine as an augmentation of human powered paddling.  Once you're on the wave, that's another story - seems super draggy.  luckily not a problem for us foilers wanting to try this.

[PonoBill]

As I said, I ordered one when the campaign started, but I doubt it will work for boosting, And I assume the motor IS brushless--it almost certainly is. A brushed motor is a bitch to seal and you have to provide a way to exhaust air. You don't really need to worry much about brushless motors getting wet and the stator windings are the only thing you need to cool--they are in contact with the casing. No problem. The motors are slightly more expensive than brushed, but a brushed motor that's big enough to provide 25 pounds of thrust is the size and weight of a typical trolling motor. A Brushless motor that size will fit in your palm.

There are ways to make motor speed increase if torque load decreases, the microcontroller can sense the back EMF coming from the stator coils as a simplified torque sensor. The circuitry to do that is already present in sensorless controllers, but it would take a lot of hacking to get at that. And once you did it's a lot of fiddling to get that to work, and I doubt they've done that. Maybe in V 3.0 if this gets that far. 

It's trivial to control the speed of a brushless DC motor--you need a three-phase controller to begin with and they are controlled with PWM, which virtually any microcontroller can provide. If you're going to do wireless control there's no difference in cost between doing variable speed and on/off, and it's just a few lines of code in the software. But three-phase motors are synchronous, they don't change their RPM with torque unless the torque is high enough to make the motor "cog", which means slipping poles. That ain't happening. So the idea that the motor would speed up when you paddle is almost certainly wrong unless the people designing this are incredibly bad engineers--which isn't likely.

I know way more about this stuff than I have any need to. When I was working on flight control systems for drones, hacking into motor controllers was a big issue. Like much of the stuff I was working on the motor controller hacks were ditched long ago when more responsive and faster processors made it unimportant. When you're using single-core ARM processors running at 8MHz you need direct control. Today the cheapest toy drone makes the old Arduino-based stuff we used look like works of primitive man.

[jondrums]

It makes total sense that they would use a brushless motor for all the reasons you mentioned.  You might be right that they use a speed controller, but one can always hope that they implement the control loop as a torque controller rather than closing the loop on RPM.  That would be the right way to do it for a boost function.  For example the IMC099 chip is $1 in small quantities and does sensorless brushless control and has a torque control mode that is just as easy to enable as the speed control mode.  No firmware required. 

[PonoBill]

I'm not familiar with that chip. Most of the fiddling I've done with sensorless control was to try to get a clean start and accelerate the response to PID control changes for multicopter stability. Sounds like you know a lot about this. for those in the peanut gallery, sensorless motor control for brushless DC motors has a problem in that the system doesn't know how the rotor is situated when it first starts and has a relatively slow way of reading rotor position while it's running. this means the motor might run backward when it first starts. Once it starts to move the direction can be detected and rotation direction is corrected. If you're ever played with brushless motors you might have seen the motor quiver before it begins turning--that's the sensorless control figuring out where the rotor is. There also used to be challenges in quickly changing motor speed as needed to keep a drone stable. Delays in the controller caused mostly by the sensorless system didn't matter for most use, but it was a problem in multis. The current performance level of drones indicates the problems are fully solved.

My involvement in all this ended a number of years ago when all the drone development went pro--I'd say five but I'm generally wrong when I guess years.

It would be nice if the design team were implementing this as torque controlled. Yup, one can hope.

This, in a nutshell, is the wonderful/terrifying thing about tech. It moves so fast that even people interested in a tiny facet have to be fully immersed to keep up. It's kind of Moore's law writ much larger--it isn't just microchips that are doubling in component density and capability. It's everything.

[Califoilia]

When all else fails, just go with more power...

https://youtu.be/QBKDYsAhiuc?t=216