My new Electric Outboard Motor ( hub motor ) Silent and Fast

In the past I have made an electric outboardmotor that was able to go a planing speeds which is my goal, planing at about 25 km/h. But the Agni 95 r at 4000 RPM is making too much noise for me. In fact I think every motor that spins over 4000 Rpm is making to much noise, even good brushless motors. Not only the motor , but gears or toothed belts will make noise too. Even the original torqeedo 4.0r motor is making a high pitching noise. Because of the standard gear ration of 1:2.33 at most common outboards you need a shaft speed of about 6000 RPM that always will make some noise I think.

So I have done something totally new and it is almost working perfect. It is a belt driving prop, with a toothed belt all the way down through the shaft to the prop.


It is really silent and powerfull, but for planing speeds I need a stronger motor, this motor was smoked after a few attempts ( Crystalyte HT3525 )

I think to get at planing speeds I need a few seconds at 7000 Watts, and at a Ebike the motor can make more rpm and will survive, at the boat the rpm is too low.
I had a 90V 80A = 7Kw setup.




And a video :

[youtube]QYR_sgHDU-4[/youtube]


Next step is to mount a motor like this:
http://image.made-in-china.com/2f0j00QMOadtVArczw/3000W-5000w-Brushless-Hub-Motor-for-Electric-Scooter.jpg

Or maybe a Cro motor, I don't know if a Cro motor is strong enough.

How creative fugly as hell though

Isnt it possible to rewind a decent big outrunner to star configuration and reduce the windings for outboard usage? So with the reduced kV you shouldnt need gears to lower the rpm. This way the noise should be way less as you use the motor as direct drive on the shaft.

I'm thinking about doing this, i just need a decent cheap 2nd hand outboard leg.

Bazaki:
I truly admire your efforts!
But may I suggest a simpler method? Those conversions from the lower end of an ICE outboard can be pretty awkward in gear choices.
The advent of the purpose built "Surface Drive Mudmotor" in the USA has really advanced the old motor-to-prop powertrain (via belt drive)
EX: Typical example of an ICE surface drive, Gatortail brand >>>>


AND , the proven antique Caille Liberty, and latter Thailand Longtail Mudmotors direct drive coupling to PTO have a lot to offer in a simple motor-to-prop design.{1895 electric Allen Type ---http://www.caille.8m.com/rowboat/Allen/index.html }


{This video is likely ICE 2 stroke gas/petrol, but an electric motor should be a good choice for experimentation on that style planing hull design??}
http://youtu.be/S2hzVpGiB58

Nice, I never heard of this mud drive motor. Looks good but a prop at the surface is probably also not very silent. But now I also see a lot of mud drives with a prop below surface on youtube.

This can be a very good idea, I will look into this.

On the other hand my new outboard as seen above is the same idea.

My belt is going all the way down, direct to the prop shaft

So my motor spins only 400 RPM ( low noise ) and the prop is going 2000 RPM



I have a C80100 Turnigy motor at 75 rpm/v, and maybe I do something with it, but for planing speeds I need about 7000 Watt for a while, probably that won't work.

Nice but still a bit noisy :wink:

My five cents!
Have a look at Miles motor design thread and learn to build a heavy duty inrunner at 93-95% efficiency at low Kv for direct prop drive.
This means no noisy gearbox. Then watertighten and submerge the whole motor and voilá, you got yourself an uber silent outboard capable of planning speeds.

NOT a "mud drive motor", but a mud motor . Just a slang word used to describe the general purpose and intent of that style marine motor.
It is called a "mud motor" because many other traditional outboard motors have suction tubes (water pick-ups often near the prop) to intake their cooling water.
In shallow, or muddy water, this "water cooled" motor can get clogged cooling passages, and then ruin the motor by overheating .... so mud motors are often air cooled.

The Surface Drive mudmotor is another slang term to distinguish it from the Long Tail mudmotors . Surface Drives' have more of the "Z shaped" configuration of powertrain to propeller, and they also can benefit from a "gearing" of the final motor-to-prop ratio.
The Long Tail mudmotors are usually straight direct/drive coupled to the motor in a long drive shaft out to the water. Long Tails operate at the same prop RPM as the motor output shaft (usually about 3600-4600 RPM's at the prop)

Prop noise in a Long Tail (and some Surface Drives) is often cured by an anti-cavitation plate OR by making the driveshaft longer .(sometimes about 2-3 meters long ) to get the prop further from the driver, AND its length changes its angle-of-attack relative to the water .Prop depth, and the angle at which it operates in the water is usually adjustable , and can be made very silent.
Mudmotor types often have a "plate" installed above the prop (a.k.a. an anti-cavitation plate) that cures both excessive prop noise AND helps increase the props job to get the boat "on plane". In summary: both methods make the prop noise-reduced and also can make the boat faster at top rpm's.

Some general tips:
1) inflatable , or soft pliable boats, can be difficult to get up on plane simply because of the flexing of the hull (and drag) relative to the water surface.
2) to silence an electric motors' noise that close to the driver often requires a shroud , or case, to muffle the noise of the motor or belts/gears. Shrouds hold heat, and then you have to cool the motor better.
3) Props are the final "screw" (almost akin to a gear). They must withstand strikes of a large fish, rocks, vegetation, bottom of river/lake. That's why the boat prop blades are relatively small and robust. Big, thin, long bladed airplane style props flex too much in water and can shatter underwater at higher rpm strikes. Keep your prop small, robust, and try and not "over or under prop" the propellor size/pitch relative to your boats load and its planing rpm speed. That is usually done by switching props a lot to get the right size for your boat. The props will have also some "slippage". If you know how your boat performs with an internal combustion outboard, then it may be easier to guess the right prop size and pitch from that experience.

Best of luck in your efforts. I truly appreciate your designs and your actual application!
{PS -- Honks' idea is great BUT it has proven very difficult historically to effectively seal the underwater electric motor and its output shaft from water intrusion. Underwater electric outboard motors have been used for almost a century, BUT they have a notorious problem with water intrusion on the shafts and the case seals --> example of early 1936 Bendix Aviation submerged electric boat motor http://home.comcast.net/~bendix/manuals/bendix_electric_manual_1.jpg ) }

Thank you. Mud motor indeed

This latest project as seen above at the video is pretty close for what I want, except burning crystalyte motors
It is really silent, with my phone very close to make a video it sounds louder than it is.

http://continuouswave.com/cgi-bin/propcalc.pl

I use this alot and for this latest outboard I have 90V at a Crystalyte HT3525 5,5 rpm/Volt = 495 rpm with a belt drive ratio to the prop of 1:5 os the prop spins about 2500 RPM.
At the above calc you can see that with a 9 pitch prop at 15% slip I should reach 29 km/h

But to get the boat in plane it will take a lot of power while the motor is at low RPM, so that's why it will get overheated.

A 8 kw scooter hub of 22 kg should bring the boat to planing speeds, but should have a lower gearing since the motor is 15 rpm/volt. and therefore it will spin faster and make more ( too much ) noise.
My inflatable boat has a V shaped solid bottom, so when planing it should be a good boat for this project.

I have a rewinded C80100 motor at 75 rpm/v and have mounted it inside the stock housing of a trolling motor with original sealings etc. So it is waterproof, also the tube casing around the motor is made of nylon to
avoid eddy currents.

But to have 5 Kw of power at 2500 RPM it will need 33V at 150A the motor will probably run hot in a few seconds.

Maybe put this thing under water with a prop straigth to the shaft ?
http://alienpowersystem.com/shop/120mm/120100-outrunner-brushless-motor-50kv-25000w-2/

Or put a Goldenmotor 5kw or 10kw completely under water.

Yes there are more ways to get this project further, I still just am not sure what the best way is.
For low sound and stealthy looks a complete under water motor seems the best solution.

Golden motor 20KW is 17 kg....17 kg underwater :?
But at about 75 rpm/v it also need 33V for 2500 rpm prop speed which is 150A. This Golden motor with it's liquid cooling should not run hot.

http://www.goldenmotor.com/eCar/HPM48-10000.pdf

Hi Bazaki,

Please provide a little more information on how you put a brushless motor in a trolling motor casing...
I really like the idea... apart from the fact that you can't put a big motor in, it is ideal as a remedy for the noise and cooling issues.

- Did you break out the original stator magnets from the brushed dc motor?
- How did u mount the new brushless in the casing?

I found the biggest trolling motor i could find, it was cheap sinces it was melted so the motor was destroyed anyway.
I removed the magnets and I had a tubed of about 110mm ? the c80-100 turnigy fits inside. But to avoid eddy currents I had the outer casing made of nylon/plastic.
I send my 150kv motor to Thud and he rewinded it to 55 rpm/volt and install hall sensors.

So I can't provide pictures because someone else is making the last part for me.

Also I have a new shaft, complete with rear end that fits inside the original bearing of the trolling motor, than through the turnigy and then thicker so it fits the original sealings and bearings, than at the end thread for a normal boat prop.

The idea is to run it at 44v x 5 rpm is 2400 rpm which is perfect boat prop rpm.

So it will stay dry since the original sealings are used and that is working really well.

Now run it with a 24 fet sensored or 18 fet sensorless controller, did not test this yet.

My concern is how to cool it, it is under water but runs dry. Maybe I will blow cold air through the bracket shaft.


My other outboard motor.
Here is a video of yesterday, only 1500 Watts, full throttle is 4000 Watts and will burn the motor.
So I go slow.
http://www.youtube.com/watch?v=34v3UZ94Zr0

Bazaki;
I can not dispute your prior success!
BUT , IMHO, that "propellor calculator" you linked to is frankly not practical. It even warns that it is "no Greek Oracle". That prop calculator does NOT even consider your hull configuration, nor you essential load information. Those final numbers it spits out are "ballpark". They are just a guess.


The first thing I noticed when I saw your video was the way your hull was "dragging" its' side pontoons at low speed (the wake). Thus it looks to me like it takes a higher prop RPM to get up on plane OR it even may possibly benefit by running twin motors?

The BIGGEST problem I have in getting up on plane is getting RPMs from a prop. The only way I have had success with choosing the best prop is by actually switching out different props to see which one truly works best with each engine power. The cheap aluminum props are very economical, but somewhat fragile .They are limited by their internal taper and keyway, but great for experiments --- if you can get them to fit, here's an example:http://www.ebay.com/itm/Mud-skipper..._Accessories_Gear&hash=item2eca71e30f&vxp=mtr

Do you have a tachometer effectively sensing driveshaft/prop RPM's? Tachs are essential.

On the topic of using an outrunner as a powerhead for direct drive ... well the first virtue of using an electric motor over a ICE is the ability to get a reverse . Direct drive 4-Stroke ICE normally do not provide a reverse for the boat, and can thus be difficult to stop swiftly, or dock easily. Some 2-Stroke ICE can be reversed if stopped and then restarted in the opposite direction .
An electric outrunner may be a good choice for direct drive experiments, especially IF it is capable of reversing shaft output direction.

Also note that when an internal combustion motor is used, that type ICE motor has a flywheel to help carry the propellor momentum. Most electric motors outrunners that I have seen used as direct drive do not have any form of weighted flywheel (they don't need one for the motor) BUT it theoretically could help on the prop momentum? The simplest form of cooling an outrunner in that direct drive application could be like an R/C version of a coil of open-circuit copper tubing wrapped around the motor to carry lake water that has been "rammed" into its' intake (and drained out an exit). A small air "bladed fan" in front of motor may help too (it will drag some efficiency).

I'm sure you know the old axiom of cooling an electric motor.
1) reduce the load
2) ventilate or cool thru casing.

Bazaki: I think your electric motor propulsion experiments are great , your application and actual build is super, but I feel you are limiting yourself with your commitment to your boats hull design. (see my video in the first post and note those little Thai boat designs ... and how fast they get on plane with those tiny motors!} .

----- As a general audience side note: IMHO Boat motors that are called "trolling motors" are just a marketing name. The electric versions are, and have always effectively been, electric boat motors. When submerged and running they get hot, when they stop (and especially are still submerged), they rapidly cool. That heat expansion and rapid cooling underwater can lead to "sucking" water past a hot shaft seal. The seals are vulnerable to snagged fishing line, and even tough aquatic vegetation, and thus drive shaft seal-to-prop can be ripped. I get this information from USA (and International) Patent filings. Patent info on submerged electric motors in the "trolling motor" industry can be very useful as their design is usually explained , diagramed and already tested!! Searching Google "Patents" and keywording things such a Minn Kota seals , Torqeedo etc . Example:
http://patentimages.storage.googleapis.com/pages/US3814961-1.png

Finally: "My concern is how to cool it, it is under water but runs dry. Maybe I will blow cold air through the bracket shaft" . Perhaps measure the casing temperature after it has run? Maybe use a non-contact thermometer to detect the hot-spots. The wide skeg on the case can act as a "heat sink". Fins make good ways to bleed off heat ....

Hi,

The C80100 55 rpm/volt motor inside the casing of a "trolling motor " is an idea of a few years ago. After all I think it can not get a boat in plane for a longer period. But for an electric surfboard it might work, needs less power to get in plane. Have to finish this project later.

Yes I know a hull is an important factor, but I see small 3,40meter inflatable getting in plane with 5 hp ICE outboards.

So my choice was this inflatable with polyester hard bottom V shape


I also want to sit dry and do some shopping at the local super market

Thanks for the link of that prop, it's really cheap compared to boat normall boat props.

A few years ago I made this:
[youtube]rb2FkCF-e58[/youtube]

But too noise, a big agni and 400A kelly controller.
Due to imbalance it made even more noise.

First I told I don't want a 6000 rpm E motor to the driveshaft because it makes noise, see other projects at youtube too.
But now I thought of this, get a Golden motor liquid cooled at the drive shaft at 6000rpm

http://www.goldenmotor.com/ check Electric boat kit incl video.

Now it is still noisy, but a few months ago I had another e-outboard, I drilled a hole in the hollow bracket and put lot's of expendable foam inside, this stuff:
http://bouwwereld.nl/wp-content/uploads/2010/08/10784_pur-schuim.jpg

It expended and I cut it off where it came out. The result was, 50% less sound.

Now get this golden motor on top of where the ICE was, cool it liquid and fill it up with this expendable foam. It should reduce lot's of noise, dus to liquid cooling the foam should not give problems.

A Torqeedo 4.0 can also get an inflatable in plane at 5 kw, ( 3500 usd ) A liquid cooled 10Kw golden motor should run 5 kw without problems I think.

What batteri type are you using? Lead Acid, NiMH or Lithium?
If you don't mind me asking

At the pic is a Chevy Volt / Opel Ampera pack 16 kwh

As for my project I now have a 10KW Golden motor liquid cooled, let's see how that goes

You should try a better controller that makes true sinewave. Saves a ton of engine noise, and i guess that's exactly what you're looking for.

Thanks for the feedback.
I googled the pack it was lithium-ion.
What is the spec if I may ask another question, Voltage, Ah, Weight?

[youtube]64gpEKM5rQk[/youtube]


Another attempt, this should work fine after some improvements.

Great speed, how fast was it?
What was the power consumption?

20 kmh at GPS at 8kw.

Need better prop and other things, but now we are getting somewhere

About the battery, LG Chem cells 360v at 45ah

About 200kg but that is including all casings and mounting plates, so the cells itself are about 150 kg? same density as HK RC lipo's I think.

At the boat project I use a small module of 96v 45ah. So If I can get into planing speeds with 5 kw ( should be doable ) I can plane almost one hour.

Hehe, 8KW minus the electrical inefficiency of the controller and motor comes to approx 9.9hp shaft power.
What size prop is you using, diameter and pitch? With the right prop you should be to hit 30km/h if the hull allows it.

Regarding the battery I was curious because I'm working on an 10KW outboard project myself.
I will use a lower voltage battery made from 2.2Ah NMC cells 110p12s. That comes to 43.2V 242Ah 10.5KWh.
It's pretty lightweight, 57kg casing and BMS included. The motor will have very high efficiency, targeted to 98% peak.

I'm impressed by the fast advances of your builds.
You must have a lot of spare time to spend. Or perhaps your project is a full time occupation.
Anyway, keep up your good work. I'll keep on reading.

When my project is finished I use a A123 28s 60Ah pack 5.5kwh of 50kg
I build things in my head, then the only thing I have to do is installing the components, and stuff I don't have I have to order.

8 kw in is about 8 hp out I think, but my cycle analyst was maybe set a bit wrong, so maybe it is 7 kw instead of 8 kw.

Prop is a 8 pitch and 8 diameter. I need more pitch I know. Also the motor rpm is now about 4400 rpm, stock ice was about 5800 rpm. So I will increase motor rpm.

I hope to get on planing speed with about 20 km/h with only 5 kw.

I also installed smart tabs, now the boat planes at low speeds like 14 km/h, but at the same 8 kw my max speed is 16 km/h instead of 20 km/h

What setup will you use, motor and controller ?

I already have an aluminum motorboat, Linder Sportsman 400, pretty lightweight at 125kg. Speed test in knots at different loads
As you can see it can reach 17.5knots (32km/h) at 9.9hp with two persons. My own electrical outboard is aimed for 13.5hp (10KW)
At the moment I use an old two-stroke 8hp Yamaha outboard. It's OK but very noisy and fumy.

The electrical motor is completely a design by my own using exotic materials...built from scratch.
Predicted efficiency 97-98% peak at 2KW, 94% at 10KW. It will be submerged for most silent operation possible.
No problem with the seals. I have made another small outboard back in 2006 that has no problems with water leakiness.

The controller is also a design by my own. A three-fase sinusoidal output for high efficiency and silent operation.

The Battery charger is yet another of my designs. It has 20 channels for separate cell charge and equalisation.
I only need 12 channels for the NMC battpack but I'll prepare it for future LiSP (Lithium Sulphur) with a lower cell voltage.
Using LiSP at 2.1V nominal, it takes 20 cells serial to build a 42V pack.

As you do I also work out the details in my mind & make all drawings in my CAD system, then I build and perform real world tests on scale models.
All good ideas or great results is always written down for safe keeping. All progress is focused on high efficiency.

All of this combined with work-hrs and familytime makes the project take several years before finished.
Perhaps I can finish it all sometimes 2016-2017. If I was paid to do it all during daytime work-hrs it would be finished spring last year.

Ok I see, that is a whole different story.

If I have a project then I can't stop working on it and just continue untill it works...or not, than I start over again.
85% or 95% efficiency is not a big deal too me. If I can get good speeds like 30 km/h with 8500w or 9500w is not important. As long as the motor/controller don't run hot ofcourse.

Why do you ( and many others ) want such a high efficient setup ? Because you can ? Probably not for run time, than you always can add 10% more batteries.
I can imagine that it is some part of the goal to reach.

I believe the Torqeedo 4.0 peaks about 5.0 kw and get's an inflatable around 30 km/h so that is a really efficient setup I believe.

Well, my story is simple. :wink:

My whole working career as an electronic development engineer have been focused on efficiency, the higher the better.
During my fishing trips I realised I wanted the best electric outboard possible without drawbacks.
Most folks uses a secondary silent trolling motor besides their noisy ICE outboard. I wanted both in the same package.
And yes, it's just a goal for me or I wouldn't be committed starting such a big task.

1) It must have the best efficiency possible at the right RPM for a prop direct drive.
2) It should be as silent as possible = no gearbox, smooth bearings and sinusoidal phase control.
3) It will be waterproof and submerged, muffling residue sound and cooling the motor.
4) The controller must be 3-phase sinusoidal for full wave smooth torque.
5) The batteripack should have good energy storage to save weight. Present affordable NMC chemistry is 183Wh/kg.
6) Lightweight compared to equivalent ICE motors. At present it's calculated to 13.5kg, all included except batteries.

5KW is enough for an inflatable but not good enough for my needs. 8)
The Torqeedo 4.0 is powerful but not very efficient, neither is it silent due to the noisy gearbox.
It's actually using the Torcman 685 motor and waste a lot of energy.

Regarding pitch, if you use a prop with more pitch you will get less planning thrust unless perfectly adapted to the motor.
The final prop selection for my project is still an open issue. I have actually designed my own prop using Javaprop
calculations at 74% efficiency if I cannot find a suitable one for my needs. Perhaps I'll build that one later on once the project is finished.

I hope you will succeed with this outboard motor.
So it will be a direct drive without gearing and motor below surface ?

What prop will you use ? I see the torqeedo has a big prop 12 x 12 with only 1300 rpm, I wonder why beauce most prop will run at about 2500 rpm. that is about the most efficient prop rpm with lowest slip I believe ?

You will build a 50 kv motor ? at 42v it will spin about fast enough, but at 10 kw it will take about 240 A.
You will watercool the motor ? Will it be an outrunner ?

I still have my 50 rpm/v Turnigy, maybe I can do some testing.

What about this:

My 50 kv Turnigy outrunner c80-100 motor, epoxy the windings to make it waterproof, use ceramic bearings and run the whole thing IN the water.
So it will never heat up and no worries about a waterproof casing. Maybe a 36 Fet sensorless controller to drive this thing.

The final prop is still an open question, but initially I will use the Motorguide MGA087M, at 9.76" x 4.2".
I expect to hit approx 22km/h at very good thrust, meaning I can get into plan fully loaded with people and gear.
Later I will experiment with different props. My goal is 32km/h with 2 persons and fishing gear.

Planning high speed is a combo of prop dimensions and enough rpm. But tip speed should never
go faster than 12000ft/min to avoid cavitation, as a thumb of rule. 12000ft/min = 3658meter/min.
The torqeedo is strong but not as fast as it could have been. A low speed prop is efficient but
lack higher speeds as the pitch is to low, while increasing the pitch further reduces thrust.
Calculations show a 12" pitch prop at 1300 rpm and 8% slip is only capable of 22km/h maximum.

My motor is targeted to 91KV = 3900rpm at 43V.
It's an inrunner with outer windings and being easily cooled by the passing waterflow.
Due to its high efficiency only 600W has to be carried off at 10KW output and my real world measurements
show 1.14W per cm2 surface area being dissipated, this comes to 70C hot windings.
As I intend using N50M magnets that withstand 100C I don't fear overheating. The motor windings is also monitored
by an internal temp sensor so I can keep track of the heat build-up. If dangerously high I just throttle down.

Yes, perhaps your idea with the Turnigy outrunner is a good idea, at least it will not overheat.
Make sure everything with iron is well coated or you will face rust problems. I belive stagnant laquer is better than epoxy.