Electric Surf Board
- Thread starter Matthias_S
- Start date
dirkdiggler
10 kW
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Yeah, I bench tested it for about 10 minutes with the torqeedo prop. It ran great - blew everything off the table. At the lake I would hold the board out of the water and spin up the motor. The minute I dropped it into the water the motor stopped. I switched over to a turnigy HV 100 ESC for this test, but was still trying it out on 6s. I had been attempting to use a 120a HK boat esc, it had some issues with sync when bench testing with the prop so thought the HV esc would work better in the water. Now I'm thinking maybe I should have tried out the motor on 12s - maybe that would have worked better. I was stoked to finally get this going.
If this does require total water proofing of the motor - the options aren't great for a half-assed attempt like mine. I think you need to either do a shaft drive drive with the motor in the board or find a way to fully enclose the motor. Enclosure wouldn't be a problem for an inrunner, but the outrunner with a stationary part and a spinning part adds to the complexity. Need to find an easier way to do this.
If this does require total water proofing of the motor - the options aren't great for a half-assed attempt like mine. I think you need to either do a shaft drive drive with the motor in the board or find a way to fully enclose the motor. Enclosure wouldn't be a problem for an inrunner, but the outrunner with a stationary part and a spinning part adds to the complexity. Need to find an easier way to do this.
Bazaki
10 kW
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Maybe test it with motor out of the water and prop in the water, just for testing, but probably it will suck air from above......
I didn't dare to epoxy my motor since that can't be removed, but the plastidip is too thick and soft so I will epoxy my turnigy. The magnets are scraping the plastidip from the stator because there is very little space between them.
Did you measure resistance (Ohms) between a phase wire and the water?
I didn't dare to epoxy my motor since that can't be removed, but the plastidip is too thick and soft so I will epoxy my turnigy. The magnets are scraping the plastidip from the stator because there is very little space between them.
Did you measure resistance (Ohms) between a phase wire and the water?
Honk
100 W
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- Oct 10, 2011
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A water prop in air does not give any resistance. Air is to thin for this!
You need a much heavier load, it should actually load the
motor just as hard as the prop would do submerged in water....meaning
lots of amps drawn from the battery.
Hook up another motor to the shaft as generator and load its output hard.
Or brake the shaft mechanically until you see heavy amps flowing.
You need a much heavier load, it should actually load the
motor just as hard as the prop would do submerged in water....meaning
lots of amps drawn from the battery.
Hook up another motor to the shaft as generator and load its output hard.
Or brake the shaft mechanically until you see heavy amps flowing.
John in CR
100 TW
I think the primary problem is way too big a prop. The torqueedo has a gear reduction.
2nd for having the motor directly in the water you want an inrunner. Then the windings will be connected by metal to the water. Sealing will be a relatively simple matter at the axle. The next step would be cooling with a water jacket and bring the motor in the board. Unless you go to something like an RC size prop, then an RC motor isn't going to work.
I remember at least one of the geared hubbies has a little inrunner that may have an appropriate Kv, and with the far superior cooling than sealed in a hubbie you may be able to get a couple or few KW into it. Gotta walk before you can run, and sealing an outrunner well enough to run salt water through it with any reliability sounds like an uphill battle, and plasti dip is way way too thick to be in the magnetic gap.
If you want to stay the course, then pick up a few cheap trolling motor props and cut one down to a significantly smaller size and see if you can get that working with thrust in the water. If it works then you know it's a prop size issue, and you can cut the next one down in smaller increments until you dial it in.
2nd for having the motor directly in the water you want an inrunner. Then the windings will be connected by metal to the water. Sealing will be a relatively simple matter at the axle. The next step would be cooling with a water jacket and bring the motor in the board. Unless you go to something like an RC size prop, then an RC motor isn't going to work.
I remember at least one of the geared hubbies has a little inrunner that may have an appropriate Kv, and with the far superior cooling than sealed in a hubbie you may be able to get a couple or few KW into it. Gotta walk before you can run, and sealing an outrunner well enough to run salt water through it with any reliability sounds like an uphill battle, and plasti dip is way way too thick to be in the magnetic gap.
If you want to stay the course, then pick up a few cheap trolling motor props and cut one down to a significantly smaller size and see if you can get that working with thrust in the water. If it works then you know it's a prop size issue, and you can cut the next one down in smaller increments until you dial it in.
dirkdiggler
10 kW
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Did some testing on it today. Here are some videos:
6364
[youtube]EexxJcjbGak[/youtube]
c80100
[youtube]D-zdHYI_ZkI[/youtube]
Both were using 6s battery and Turnigy hv100 esc. The c80100 had some real power to it. Couldn't hold on to it very well. I know that would push me on a board. How fast is the question?
Does seem more of a lack of power than anything. I would imagine the 6364 would work if you could get it waterproofed. I'm going to try out the c80100 this weekend onboard and hope for better results than I've had with the 6364. I wish I had the patience to run it through a full battery in the water bucket before I take it to the lake.
There are issues with using an inrunner also. You would definitely need gearing reduction as the lowest kv inrunner is 540. If I can get everything to work now with the 80100 and it provides enough speed, I will spend some money and put the electronics in the board with a direct drive shaft. Also add a prop guard for protection. I do still have a jet drive unit that I'd like to try out. Got a bit sidetracked with the prop version after I saw the waterwolf build. Using a jet drive has its own issues too. Aquilla might have there board out by then though and I'd rather just suck it up and pay for it. Their pricing seems pretty reasonable for what you get. I hate being an early adopter of things like that. Half the entertainment for me is in building things.
6364
[youtube]EexxJcjbGak[/youtube]
c80100
[youtube]D-zdHYI_ZkI[/youtube]
Both were using 6s battery and Turnigy hv100 esc. The c80100 had some real power to it. Couldn't hold on to it very well. I know that would push me on a board. How fast is the question?
Does seem more of a lack of power than anything. I would imagine the 6364 would work if you could get it waterproofed. I'm going to try out the c80100 this weekend onboard and hope for better results than I've had with the 6364. I wish I had the patience to run it through a full battery in the water bucket before I take it to the lake.
There are issues with using an inrunner also. You would definitely need gearing reduction as the lowest kv inrunner is 540. If I can get everything to work now with the 80100 and it provides enough speed, I will spend some money and put the electronics in the board with a direct drive shaft. Also add a prop guard for protection. I do still have a jet drive unit that I'd like to try out. Got a bit sidetracked with the prop version after I saw the waterwolf build. Using a jet drive has its own issues too. Aquilla might have there board out by then though and I'd rather just suck it up and pay for it. Their pricing seems pretty reasonable for what you get. I hate being an early adopter of things like that. Half the entertainment for me is in building things.
Matthias_S
10 mW
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- Jul 22, 2012
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- 22
when i started this project i also made some tests whit direct drive propulsion. i mounted a standard trolling propeller to the 80-100, sealed everything in a aluminum tube and taped it on a surfboard. the result was 3 burned turnigy 150A HV controller. But also whit my kelly controller the trust was not enough because of sync lose at high rpm. So I started to rethink the whole project and ended whit a propulsion system which can be mounted on every surfboard whit powerbox fin system. I`m using the turnigy 80-100 connected to a neugard planetary gear an the torquedo prop. Here are some pictures 
Attachments
John in CR
100 TW
Dirk,
You absolutely have way too much prop. You'd need pretty high hp to turn that rpm. Think small blade and a shorter trolling motor prop type pitch. I think cutting down a cheap trolling motor prop is worth a try. Matthias's approach with the gearbox will tell you alot.
Matthias,
What amount of gear reduction do you have? I look forward to your results. I see you standing in the water with it, so how did it go other than to tell you it's no something you can hold onto? FWIW, I think you'll need a really soft start, and even then a surfboard keel mount is unlikely to be strong enough for either the trust or especially the twisting torque of the prop loaded with water.
Open props are scary on a board. My son and I did up a proof of concept by making a standup paddleboard size board and drove it with a trolling motor and larger homemade prop. It worked great out past the break, and proved the thrust would really help catch waves early. Our thought that the small skeg on the motor and the motor itself would act as enough of a keel was sorely mistaken, and we both quickly went sideways due to a lack of fin on our few attempts before the controller got drops of seawater. Tumbling in a wave with an exposed metal motor and prop nearby isn't something I'll intentionally repeat.
You absolutely have way too much prop. You'd need pretty high hp to turn that rpm. Think small blade and a shorter trolling motor prop type pitch. I think cutting down a cheap trolling motor prop is worth a try. Matthias's approach with the gearbox will tell you alot.
Matthias,
What amount of gear reduction do you have? I look forward to your results. I see you standing in the water with it, so how did it go other than to tell you it's no something you can hold onto? FWIW, I think you'll need a really soft start, and even then a surfboard keel mount is unlikely to be strong enough for either the trust or especially the twisting torque of the prop loaded with water.
Open props are scary on a board. My son and I did up a proof of concept by making a standup paddleboard size board and drove it with a trolling motor and larger homemade prop. It worked great out past the break, and proved the thrust would really help catch waves early. Our thought that the small skeg on the motor and the motor itself would act as enough of a keel was sorely mistaken, and we both quickly went sideways due to a lack of fin on our few attempts before the controller got drops of seawater. Tumbling in a wave with an exposed metal motor and prop nearby isn't something I'll intentionally repeat.
Matthias_S
10 mW
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- Jul 22, 2012
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- 22
The torqeedo prop is desingned to work at 1300rpm most efficient so i choose the gear reduction a little higher to get around 1500rpm. I'm not sure what the trust is but it feels like 30 kg. i dont know why i cant get more trust at full speed the multimeter shows me 4kw of power consumption. I don't think the open prop concept is the best solution for wave surfing, the resistance of the whole motor housing will make it impossible to get good performance when the motor is shut off. But to have fun on flat water this is perfect. I made a lot of test rides on different surfboards an had no problems whit the force on the keel mount, but I'm sure if you hit the ground or something it would definitely break of. I know its dangerous with the open propeller but I'm working on a protection ring around the prop.
at full speed the multimeter shows me 4kw of power consumption. I don't think the open prop concept is the best solution for wave surfing, the resistance of the whole motor housing will make it impossible to get good performance when the motor is shut off. But to have fun on flat water this is perfect. I made a lot of test rides on different surfboards an had no problems whit the force on the keel mount, but I'm sure if you hit the ground or something it would definitely break of. I know its dangerous with the open propeller but I'm working on a protection ring around the prop.
Bazaki
10 kW
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- Dec 25, 2009
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Very nice Matthias and thank you for sharing the details !
At the pictures it looks like you have also a rewinded motor, about 50kv ?
I wonder why you, me and others have out of sync problems when the motor needs more rpm. At an Ebike it should be the same, but on an Ebike I don't read about these out of sync problems.
About what speed do you get at 4 kw input ?
At the pictures it looks like you have also a rewinded motor, about 50kv ?
I wonder why you, me and others have out of sync problems when the motor needs more rpm. At an Ebike it should be the same, but on an Ebike I don't read about these out of sync problems.
About what speed do you get at 4 kw input ?
John in CR
100 TW
Matthias_S said:The torqeedo prop is desingned to work at 1300rpm most efficient so i choose the gear reduction a little higher to get around 1500rpm. I'm not sure what the trust is but it feels like 30 kg. i dont know why i cant get more trust
For flat water I wouldn't have an issue with an open prop. If you do a ring around the prop, then the way to go is to make it a Kort nozzle. That will give you maximum thrust (though you'll need to go to a different prop), and it won't provide net drag in excess of benefit until somewhere in the 15-20mph range if done right. Here's a very interesting discussion about using cheap RC props and ducted fans on ROV's http://openrov.com/forum/topics/usi...-water?id=6365107:Topic:13402&page=1#comments. The HK mentioned in one reply http://www.hobbyking.com/hobbyking/...EDF_Ducted_Fan_Unit_3Blade_2_75inch_70mm.html wasn't too far from what you need based on the 1/15th ratio for air vs water rpm. It seems to need around 2500rpm, but may give you an idea of sizing, as well as show the guys without gear reductions the direction they need to head, because they're trying to swing props that are drastically over-sized.
Your perceived thrust issue is likely a combination of controller and the fact that the prop is designed for speed, efficiency, and quite likely visual aesthetics, since they do look cool and futuristic but we see no similar powerboat props. That combines to tell me to expect higher than typical slippage getting out of the hole and up on plane.
Good to hear the mounts are working out for you, since that makes things easier. Can't wait to see some video of you zipping around. Then imagine what small kid could do.
They're the ones we can much more easily design outstanding performance for. With the current state of batteries, small light people enjoy a tremendous advantage.John in CR
100 TW
An outrunner running inside an aluminum case is a guaranteed fail. The magnets moving next to the aluminum turn it into an eddy current heating element.
I don't get wanting to put any outrunner sealed in a tube. Outrunners need air flow to cool. Yes the tube is water cooled, but the air between the case and the motor is insulation to prevent rapid heat transfer from the motor. Plus their diameter is so much bigger.
An inrunner seems the better choice due to smaller diameter, and the stator (where most of the heat is generated) is connected directly to the non-spinning outer shell, which can be directly connected to the outer casing for a much better heat path to the cool water. I'd think you could even seal thing well and have much of the motor housing in direct contact with the water...like water jacket cooling, but much better because no losses to pumping and the water temp in contact is lower. It seems much more simple and better.
I don't get wanting to put any outrunner sealed in a tube. Outrunners need air flow to cool. Yes the tube is water cooled, but the air between the case and the motor is insulation to prevent rapid heat transfer from the motor. Plus their diameter is so much bigger.
An inrunner seems the better choice due to smaller diameter, and the stator (where most of the heat is generated) is connected directly to the non-spinning outer shell, which can be directly connected to the outer casing for a much better heat path to the cool water. I'd think you could even seal thing well and have much of the motor housing in direct contact with the water...like water jacket cooling, but much better because no losses to pumping and the water temp in contact is lower. It seems much more simple and better.
Lebowski
10 MW
i would also not be too worried about eddy current, IF a will-it-stick-test with something iron on the outside of the motor turns op negative.
is the controller sensorless ? if sensored, are you sure the hall combo is good ? have you measured the full throttle no load battery current ?
cool project by the way, would love to have something like this
is the controller sensorless ? if sensored, are you sure the hall combo is good ? have you measured the full throttle no load battery current ?
cool project by the way, would love to have something like this
John in CR
100 TW
Louiss, I'm just trying to help you avoid a different motor same problem issue. Though I find it baffling, Torqeedo uses an outrunner, at least in their smaller models. What is their shell made of? Maybe I'm just way off base, but I don't think so, and I'll have to test some inrunners myself.
nechaus
100 kW
Have you tried esc's that support a hi pole count and low RPM?
I have ran into this issue with large multirotors using cheap ESC's..
I am assuming you have tried Hi timing and LOW as well as the auto mode?
I have ran into this issue with large multirotors using cheap ESC's..
I am assuming you have tried Hi timing and LOW as well as the auto mode?
Bazaki
10 kW
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- Dec 25, 2009
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- 639
[youtube]4FsDdojTUeA[/youtube]
Well today I have my Revolt RV 100 45kv motor with epoxied stator and winding, ceramic bearings to a new Torqeedo 10 or 12 pitch prop with 18 fet sensorless controller at 44v
Same as with the turnigy 45kv motor, out of sync
As you can hear, it spins nice at very low rpm and at some higher rpm it goes out of sync.
I still measure resistance between the water and all phase wires, so probably it is still not 100% waterproof what I hoped for. So now I still wonder if the out sync issue is because of the water of something else. I get stuck now
tdonnelley
1 µW
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- Jun 7, 2014
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what do you guys think about using an engine like this:
http://whobbies.com/product.php?id=342
wouldn't have to buy expensive batteries and is very powerful.
http://whobbies.com/product.php?id=342
wouldn't have to buy expensive batteries and is very powerful.
dirkdiggler
10 kW
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- Oct 17, 2012
- Messages
- 641
Great that we are getting some new attempts at this. I will finally have a chance to try out the 80-100 motor today. We'll see how it goes. I'll post later.
Bazaki-
What controller are you using with that motor? What voltage? Do you have the 12 pitch prop? It looks like it is mounted backwards in the photo, but that is likely the photo.
Louiss-
Your board looks great. I don't know about your motor size though. That is small. My 6364 lost sync, but I'm not running any reduction. Keep us updated on how it works.
Matthias-
Thanks for finally giving us some help. Are you planning on selling the kit?
tdonnelly-
The gassers are using an 80cc motor, but I'd think that would work. The nice thing about electronics is they are easier DIY. Maybe not in this case though.
Bazaki-
What controller are you using with that motor? What voltage? Do you have the 12 pitch prop? It looks like it is mounted backwards in the photo, but that is likely the photo.
Louiss-
Your board looks great. I don't know about your motor size though. That is small. My 6364 lost sync, but I'm not running any reduction. Keep us updated on how it works.
Matthias-
Thanks for finally giving us some help. Are you planning on selling the kit?
tdonnelly-
The gassers are using an 80cc motor, but I'd think that would work. The nice thing about electronics is they are easier DIY. Maybe not in this case though.
tdonnelley
1 µW
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- Jun 7, 2014
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- 3
dirkdiggler
do you by any chance have an idea what the name of the engine(s) that gasser are looking at?
do you by any chance have an idea what the name of the engine(s) that gasser are looking at?
nechaus
100 kW
the out of sync issues, i hate them, hi pole count low rpm rc motors can be difficult
I have these troubles when using RC motors lower than 500kv pretty much need to buy expensive controllers to make it work.
I find mine have behaved like this...
Slow throttle, you are able to get the motor to spin, but its not really that smooth... if you hit wot, it just loose's sync, stop stalls ect.
Have you tired lower RPM by reducing the voltage? I found this to improve it but not fix the issue.
It's a real asshole to deal with when you got all the parts and expect them to work...
You might need to rig up a gearbox to make this work, Id give a belt drive a go.
I have these troubles when using RC motors lower than 500kv pretty much need to buy expensive controllers to make it work.
I find mine have behaved like this...
Slow throttle, you are able to get the motor to spin, but its not really that smooth... if you hit wot, it just loose's sync, stop stalls ect.
Have you tired lower RPM by reducing the voltage? I found this to improve it but not fix the issue.
It's a real asshole to deal with when you got all the parts and expect them to work...
You might need to rig up a gearbox to make this work, Id give a belt drive a go.
dirkdiggler
10 kW
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- Oct 17, 2012
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Well, didn't go much better with the 80100 motor. Ran for a bit then started to cut out. Sync issues again. The disappointing thing was I grabbed all my stuff before work and forgot a serial cable to run it on 12s. It keeps me thinking that it might have worked. I think enclosure or like nechaus said using a pulley system is the next step for me. Don't want to bag the project yet. On paper it seems to work. Should just spend the money and enjoy the ride time instead of tinkering in the garage. Matthias got it to work, so its an obtainable goal. Maybe using some reduction would be better than waterproofing - but I'm still in test mode on this and figured lower voltage would keep the rpms down. All it did was heat up the esc. I know the torqeedo prop I have is meant for 1300 rpms. Their website mentions that at 4000w you will have a comparable thrust to 10 hp. That should be plenty to get a paddleboard moving!
Here is the link to the gasser. Can't recall the pricing, but it was more than I could justify. Instead I waste hours of time trying to build my own, which will never be as nice as their's. They use a custom built motor, which I don't think they'd sell individually. I asked last year about selling just the board and they declined, but you never know.
http://www.jet-surf.com
Also an interesting video about the design and company from their website:
[youtube]g7wZfxyTz5M[/youtube]
Here is the link to the gasser. Can't recall the pricing, but it was more than I could justify. Instead I waste hours of time trying to build my own, which will never be as nice as their's. They use a custom built motor, which I don't think they'd sell individually. I asked last year about selling just the board and they declined, but you never know.
http://www.jet-surf.com
Also an interesting video about the design and company from their website:
[youtube]g7wZfxyTz5M[/youtube]
nechaus
100 kW
its gonna be sweet when it's running dont bin it, you can see she just wants to take off
Honk
100 W
- Joined
- Oct 10, 2011
- Messages
- 230
Sorry to disappoint you but the thrust statement from Torqeedo is entirely false marketing.dirkdiggler said:
They compare their motors to old 70's outboards when motor power was measured at the flywheel.
All outboards after 1985 is thrust measured at the prop shaft where each hp equals 746W.
That menas Torqeedo's 4000W = 5.36hp when correctly compared and it's certainly not 10hp.
10hp at the prop equals 7460W.
nechaus
100 kW
I don't think it will be disappointing as long as he can get it working .
If he can solve these sync issues he will be able to upgrade the power later. Its a common kind of issue really, just a real pain in the ass
If he can solve these sync issues he will be able to upgrade the power later. Its a common kind of issue really, just a real pain in the ass
