Electric Surf Board

Sorry misspelled Radinn. Check Radinn.com To call it a wakeboard is probably a stretch. More like a large skurfer.

Try your kiteboard out at a cable park or behind a boat. They don't work so well. Or try and kite with your wakeboard. I tried to learn to kite that way - didn't work so well, but maybe helped in the long run.

Haven't gotten to try the board yet due to the wind finally picking up around here. Nice to get under the kite. It had been a while. My brother once said that he thought it would be great to have fans on your kite. I thought he was stupid at the time, but I bet you could stick some huge EDFs on lines and get pulled around, like using a big RC plane to tow you. Someone try that out.
 
I really wonder IF it is possible to run 5kw direct drive at 2500 rpm. without problems.

Today I learned this :
[youtube]9X44zHyAuME[/youtube]

my 10kw motor running hot even at low speeds.

So my Revolt RV 100 motor with 45kv goes out of sync, but even if I install hall sensors and the motor can indeed run under water at 2500 rpm at 60v with 5kw = about 100A. Maybe it would spin also at 50% efficiency ?

If we look at torqeedo with a high speed brushless motor, it probably is always in a 85 % to 95% efficiency range.......

So getting planing speeds with a boat or surfboard always needs a high rpm motor and a gear reduction. My outboard is only 1:1.73 ratio.

What about those jet drives ? how much rpm will those make ? Maybe than direct drive is possible ?
 
I've gone thru a lot of equipment, and can list some failures to help others from repeating:

Chinese controllers for 6374 outrunners often require Halls sensors. I just could not get a pair of them to work. Tested the Halls. Could get 3300 rpm, never 6000rpm, under load they lost sync.

Off with the Halls, over to 120 amp hv ESC's: torched two of them. Meter was reading 40 amps when one lit up. Motors and esc's were both cooled with ducted fans. Noisy.

Out with the outrunner, installed a 4 pole PM DC motor, as in scooter size, with a pwm speed control. Got sustained operability, but ops were only like 3 knots. Still, better than any outrunner ops.

I've used Torqeedo before, an 801, and finished first in a 25 mile endurance race. 5 knots. I'm trying a Torqeedo now, a Cruise 4. Worth noting their manual does claim 56% efficiency. No more.

Torqeedo does use 2.2Kw on the Cruise 4, I assume that's at max throttle, 1300 rpm. The 4 is quieter than the 801, and in both cases immersing both the outrunner and the electronics into the water is a huge cooling feature, foolproof and Quiet. Gas power is noisy, is the chief reason I play with electrics: quiet. Steam is also quiet, but then you need cooling for the captain and crew....

To the ES readership, here's what I think would be ideal: foremost, surface piercing props providing thrust with NO underwater appendages that might create drag. No gearboxes, straight shafts running ceramic bearings. Two props, reversing, perhaps also articulated for steering. Motors and esc's with water cooling, no fans. That might mean inrunners, where a waterjacket can be incorporated.

Finding the surface piercing props, and the best configuration, is the greatest challenge in that picture.
 
Thanks for sharing details, I can use that to prevent making same mistakes.

Guys what about this ?

[youtube]HT6r1NWS-qI[/youtube]

Expensive but looks solid, I wonder how much rpm I will need to get about 40 kmh at a surfboard.
 
Had a go with the solas prop. Still had sync issues, but had a few minutes before they started showing. I guess it's a water problem. Next attempt is waterproofing or going back to the jet. The great thing about the small prop is it isn't as much of a danger. I looked into rc boat props and they might be a good idea. They have 82mm props for 80cc twin motors for three foot boats. They have potential. Would have to do a surface drive.
Aquilla will beat me to this. The weather is cooling off.
 
Picture this.....

A surf location which offers good break... but a very tough paddle.
Meaning... for whatever reason there is no "channel" to take you back out

(Most surfers wont tell you that in nearly every location there is a "channel" that offers the path out of least resistance. BUT - due to geographical details... some places are better than others. I have been in channels that literally "take you out to see" and I have surfed at spots where no matter how hard you paddle you cant get out)

So...
(and this is pure fantasy so bear with me)

We have probably all seen videos where the big dogs get towed into big surf by big Jet Ski's right?

Dude...

What if some nerd (like me) went out to "da spot" with a powerful electric RC boat and offered "tows" to surfers. :p Starting with a tow out... but... once things got more advanced... a good rigging could allow a "pull" onto a wave.

The best surfers (NurdSurfers) could actually go out on a board
With a waterproof TX
With a boat in the water
And... tow themselves

Yep
Yep... I get that people have built this into surfboards... but that is a big barrier to jump.

This way - with a thousand bucks and some time on Craigs List you could be up and running with almost no custom work.
Hrmmmmm...

You could then fund the project by charging other surfers $5/day of "tow service" :mrgreen:

-methods
 
@dirkdiggler maybe this is an interesting solution for the solas prop http://www.rcgroups.com/forums/showthread.php?t=1649299#post21671080 and the motor is also water-cooled. This is the solution that I would like to take my kayak, with two double lip seals and two bearings for the motor shaft.
However, I remember the video in this post by mikebikerad http://endless-sphere.com/forums/viewtopic.php?f=39&t=33877&p=600127&hilit=rotomax#p600127 a Turnigy Rotomax with a trolling motor prop, fully submerged, go without problem. Why? What is the solution?
 
nanni,
I looked at that build a while back. I'm going to try something similar just to check if water is the problem. I wish people would at least update their project pages. Would have been nice to see if he ever got it working right. The tough thing with a drive like that is you really need to put it in the board - that requires some fiberglass skills and a board. That is a bunch of work and skill I don't have. Plus you need a surfboard and I don't know what size would be best. I'd hate to have to do two or three boards.
I'm going to flip my mount and place it on the top of the board and angle it to get the prop in the water. You really need a pillow block to support one end of the prop shaft. Especially on the outrunner, where you have 100mm of motor. The guy's build on RCgroups has the whole shaft changed which would be even better. My rig has too much wobble in the shaft without support, but it should help me rule out if water is the issue. I'll try this and if it doesn't work, I'll go back to tearing up the jetski. Or use a plastic mayonnaise jar and enclose the motor. :lol:

Methods,
Your idea would have been a better approach to this. I already have a decent RC boat and could have switched out parts, to see what was needed to get me planning. Should of at least looked at what is out there for RC boats prop wise. I imagine those props are better suited for higher RPMs than the trolling motors and such I've attempted. I remember seeing a small gas boat that was remote controlled which allowed you to water ski behind it. If I was smarter I would have focused on that first, but I already have a real boat to ski behind and don't want to hold onto a rope to get where I want to go.
1_manned_skiing.jpeg

The price tag is $17k - has a 80hp three cylinder engine with jet drive. It would take a bunch of $5 lifts to pay that off. I wonder how bad the surfers who paid up for a ride would get hounded!
 
Got another go at the board using direct drive. Finally got something that seems to work. My mount made the motor do more egg beating than propulsion, but still gave decent speeds. I imagine that the Solas prop should work great on 48v if it was in the correct position to provide max thrust. Just happy to not have sync issues. Now I need to get some sort of pod built up that will be waterproof and attach to the underside of the board. How do I get that done in a few weeks? Something like this:
esurfboard.png
Or just cut up a board and build that inside? I wish I would have gotten to this point a few months back.
Wattmeter showed only 2500w. Thought it would be much higher. Esc did get a bit warm, but manageable, motor showed no issues.
 
Stock winding at 150kv ? At 48v that would mean 7200 rpm at the prop. Than the solas prop must have a very low pitch.
I hope you can do more testing soon.
 
The KV is 130, and the prop is a 6" pitch. With 100% efficiency at 6200rpm that would be around 36mph at top speed. I'd imagine 20mph or more as a top speed depending on the board. I couldn't tell how fast with the mount I was using as the prop and motor would start hopping around before I got to full throttle.
 
Yeah that is the prop I'm trying. 7 1/4" diameter and 6" pitch. It has a 1/2 inner diameter with a closed end. I had to saw the end off to put a nut on the back to hold it on the drive shaft.
 
Matthias listed most of the stuff a page or so back. C80100 motor Neugart 5:1 reduction and Torqeedo prop. I think he was using a Turnigy ESC, but don't remember off the top of my head.

I got around to doing some testing on a kayak using a direct drive. I found it easier to do than the whole surfboard at this point in the season. The Solas prop pushed me at a decent clip for a bit likely over 10mph, but the way the prop spins, it would loosen up the drive shaft from the motor. I actually lost a prop on my first attempt - didn't want to have to admit that - stupid mistake. (BTW - I drove my RC boat after that 40sec fiasco and it did the same thing - lost a prop and motor shaft. Good thing I had a kayak with me to go get it. Never had that happen before. The Solas prop is cheaper than the Revolt prop. I do think this project is cursed!) I loctited everything this time to keep it together, but it still spun loose. This time I had a nut on the drive shaft to keep it from falling into the water. My watts were around 1500 or so with the Solas prop. It was fun, but the kayak doesn't have great turning. I was controlling the speed with an RC remote and using a paddle as the rudder to steer. If you hooked up a rudder system, that would be a nice way to go if you are into kayaking. You could easily add a foot pedal for your throttle and have a handle to control the rudder. I also don't know how well those kayaks are designed for speed. When I'd get it going it seemed to push water instead of cut through it. My top speed could have been much higher with a better boat. I'm hoping a surfboard will plane quicker and not plow water like the kayak did. Just need to figure out a better way to attach the prop to the motor. Might have to solder it on there. I was using a 1/2" threaded rod and a coupler that attached to the motor shaft.

Since the prop shaft kept coming unscrewed - I decided to try out the machete prop again, which turns the opposite way of the Solas and Torqeedo. The thing drew around 2500w on 60amps. Similar speeds, but obviously not nearly as efficient as the Solas. Esc got pretty hot after a few minutes of that. It was overworked.

I might have to get out there again if it stays warm. Like I said the steering was a big issue, but I'd still like to see what the top speed is with GPS.

Too bad I couldn't have gotten to this point at the start of the summer. The big decision is whether to design a board around the Solas prop, or suck it up and pay money for one those commercial boards. Tough to pay when you know what you are paying for, but I'd rather be out playing in the water. Hope that the Aquila or Radinn come in at good prices or don't end up being vaporware.

Another bad thing was I recently saw an ad on our local classifieds for the gas powered surfboard from the 80's. It had a 255cc motor and was in running condition. Guy was selling it for $300. The seller sold it a few hours before I called on it. I'm still mad about that! I considered calling him back and asking who bought it off him so I could offer him double. Sucks.
 
That could/should have been me...
That is the exact board with the 255cc engine.
I like the pic of Hobie Alter on the motorized board from your blog. And I thought the electric prop attempt was dangerous.
hobie%2Balter%2Bmoto%2Bsurfboard.jpg

That weird Chula guy from here would have a hayday with that.
 
Here's another board to add to the list:
[youtube]mFBwh4226Hk[/youtube]
Not much info on the website. Says it uses a 15hp motor. Google translate doesn't work well for me and I only know Ciao in Italian.

Time to get this thread going, summer is around the corner. Recumpence said he was working on a board. I'd like to see some others with working boards. I'm still waiting to find a good deal on a Neugart pLE60 5:1 or 4:1 to add to my list of purchases. I'm still quite a bit under the 10k they want for working models. Aquila mentioned they wouldn't be releasing their board until next year, so I have some time.
 
Good work! What did you end up using to get it to work? Is that a jetski jet or something from Hobbyking? I almost, just almost think you should add a rudder and keep it as a RC boat! :lol: You would blow everyone away with it. That's fast!
I checked some of your other videos - do you have a thread or specs on your electric winch? I was going to make one a while back, but bought a boat instead. Are you still into using it? There are times where it would still be a lot of fun just to mess around with it on the beach. I saw some guys in Cali towing into waves, which looked awesome.
 
I found out that the board in the video above is actually just the Lampuga, just being sold from someone else. I did find another board listed from Lampuga though:
[youtube]RDD6dEuAVbs[/youtube]
 
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