Hello,
First off, thank you to the admins who are hosting this site and everyone who’s contributed to this community.
Opinions?
Thanks!
Sanj!
It will be very interesting to see the results of this setup… The part that concerns me is that its direct drive, 20,000 RPM, and its a 130mm prop. I cant see it only drawing 180A, but you never know until someone tries it 
This kayak is moving at a decent speed with a trolling motor. I can only imagine if there was less drag with a foil it could go even faster.
The motor has 55lbs of thrust.
i´m sorry to tell you that i really dont think this will work. these motors have normally about 1-2kw power. These SSS motors got about 15kw peak power. i think you will need at least 7-8kw start power and if your weight is more than lets say 80kg you should need even more… i tried a 5,5kw motor with my 60kg weight but it didnt work.
The next point is that these dc motors are very heavy, big and got a low power density, i think brushless is and will be the way to go here…
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Hello to everybody,
I am just starting to build Electrical Hydrofoil with surfboard and I am reading your discussion about motors.
I asked two manufacturers of the brushless motor ( http://alienpowersystem.com/product-category/brushless-motors/58mm/ and http://www.tppower.com/ ) If they can make inrunner diameter 58 with 100kv, 7000W and max voltage 18s.
Alien power system said that they will have this kind of motor in 5-6 weeks for aprox 180 GBP and tppower said that they already made this kind of motor for some Denmark company (custom-made) but the price is 399 USD.
Just for an idea, maybe you can instal outrunner (alien power system) with less kv which is water cooled, so that it will not overheat but the diameter of motor is minimum 80mm for 6000 or 7000W.
I hope this info is helpful
outrunners are good in torque and performance but as you said the diameter is quiet high and they are difficult to cool because the rotor on the outside spins and the stator surface for cooling is very small…its hard to get the heat out of your waterproof housing i guess…
I like your point.
Thank you for the advice!
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There is one other version of the SSS motor which is rated at 360KV. It’s 10mm longer but should allow for a 3:1 gearbox and thus lower input speed. It’s available here: SSS 56114/360KV. Anyone tried this?
Has anyone used this 7kw 130KV water cooled motor. It seems to be advertised as being for electric surfboards:
It seems like it could be used for direct drive.
Hi Yannick,
I think that, in quadcopters, outrunners are cooled by running air through the motor. Would you think it is possible to make a conformal coating of the wiring and let water flow through the motor itself? That could take care of the cooling.
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Hello,
You can buy outrunner with instaled system for water cooling (http://alienpowersystem.com/shop/brushless-motors/wc80100-outrunner-brushless-motor-180kv-7000w-watercooled/), you just need to instal tube for water (one more thing that can go wrong ) 
The problem with outrunner is big diameter and also weight (almost 2 kg).
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Hi Everyone. First of all HUGE thanks to pacificmeister for opening this forum and sharing his research!
What do you think about the Idea to go back to 8-10S battery system with the sss 360KV motor and the the kort available in aliexpress, as below:
https://www.aliexpress.com/item/Duct-Propeller-Assembly-Diameter-80mm-ADP8012-4-L-R-D-4-Blades-used-in-RC-boats/32272783458.html?spm=2114.search0104.3.2.eKkVNe&ws_ab_test=searchweb0_0,searchweb201602_4_10152_10065_10151_10068_10344_10345_10342_10343_10340_10341_10540_10307_5640015_10060_10155_10154_10056_10055_10054_10539_10538_5370015_10537_10059_10536_10534_10533_100031_10099_10338_10103_10102_10052_10053_10107_10050_10142_10051_10172_10084_10083_10080_10082_10081_10110_5590015_10111_10112_10113_10114_5610015_10312_10313_10314_10078_10079_10073-10050,searchweb201603_17,ppcSwitch_0&btsid=f436c2f8-51d2-49b8-a1c1-a8741a9a1b90&algo_expid=20e2f250-26bb-4df9-8131-fcd4aa7862fd-0&algo_pvid=20e2f250-26bb-4df9-8131-fcd4aa7862fd
As per thrust measurements (available in the page) it provides 27Kg of thrust with 7k RPM and with 2500wt of power needed (as below):
Im thinking to buy it and try as direct drive with 360kv sss motor and 8S-10S power system.
Advantages (as per my vision):
- Low cost
- Direct drive (less complexity an better reliability)
- Simplicity
- Possibly more speed (less drug in high speed)
Open questions:
- Pick current at 0 speed (100-120A)?
- Max speed and power estimations with 10S (37V)
- efficiency in mid-range speed point
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The following ESC might be good second option to try:
- It is rated up to 120A cont. 150A burst
- Up to 12S battery
- different programming options, such as soft acceleration start ups ( make the motors run smoothly) - It is very important to keep gearbox happy!
- Price - 80USD
Negative: doesn’t have water cooling, but it can be cooled by attaching it to the metal plate under the board, so both will have a permanent contact with the water beneath the board.
What Kind of batterysystem could Support a current this high?
But i Like your find a lot.
basically any Lipo having 10000mah/h capacity with c rating of 10 or higher (10Ax10c=100A current)
Hello,
You can buy outrunner with instaled system for water cooling
The problem with outrunner is big diameter and also weight (almost 2 kg).
Hello to everybody,
I am writing this again because they blocked my text.
I am just starting to build Electrical Hydrofoil with surfboard and I am reading your discussion about motors.
I asked two manufacturers of the brushless motor If they can make inrunner diameter 58 with 100kv, 7000W and max voltage 18s.
First one said that they will have this kind of motor in 5-6 weeks for aprox 180 GBP and second said that they already made this kind of motor for some Denmark company (custom-made) but the price is 399 USD. If anybody is interested about any of this motors just tell me and I will send contact.
Just for an idea, maybe you can instal outrunner (alien power system) with less kv which is water cooled, so that it will not overheat but the diameter of motor is minimum 80mm for 6000 or 7000W.
I hope this info is helpful
2 Likes
Hello
The problem is that when you know how to ride with electrical kitefoil you are more or less out of the water and then nothing will cool down your ESC. The best solution is to drive water through ESC with water pump (through the must), maybe it would be even enough If you just instal input area in direction of driving and water would come through the tube to ESC and then back.
Another option is to install the ESC within the foil body attached to it (usually heavy metal construction). Do you think it is possible? (I haven’t bought mine yet)
Has anyone looked into the geared Neu motors? There are a couple different models ranging up to 10kW with a built in 6.7:1 gear head. They are pricy but this might solve a lot of the issues with using gear boxed under rated for this application
http://www.espritmodel.com/neu-2230g-super-hd-series-motors.aspx