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Brushless Motor for a Boat!!

Old 02-07-2008, 02:05 AM
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mumblinaviator
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Default Brushless Motor for a Boat!!

I know it's not Aviation related, but since there are so many knowledgable minds here, I figured I'd ask.
I'm looking to put a brushless sytem in a Reef Racer 2. It's a small (15 inch) lightweight hull with a mount for a 380 sized motor that will only accept an Inrunner.



Can you guys recommend a Torquey 380 sized Brushless that could work well? Thanks!!
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Old 02-07-2008, 02:09 AM
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Bub Steve
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Inrunners a better choice as it runs a higher RPM than outies (spins a smaller prop) but some of my bub's might have a way to do it , lets hope they chime it , your bub, steve
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Old 02-07-2008, 03:50 AM
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Larry3215
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The key here is the diameter and length of the mount - what size is it dsigned for?

You want that water cooling jacket to fit properly or you'll toast your new motor

Then you can see whats available.

Larry
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Old 02-07-2008, 04:08 AM
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The mount is made for a 380 sized motor:

Length: 1.7" (43mm) not including shaft
Length: 2.2" (56.4mm) including shaft
Diameter: 1.1" (29mm)
Shaft Diameter: .079" (2mm)

The water cooling jacket is very flexible and can be molded around a slightly larger can (if necessary). I've already played around with using a Super Cobalt 400. I'm hoping I can find a brushless that'll give me more get up n' go.
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Old 02-07-2008, 04:45 AM
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Ok, couple more questions.

Are you stuck with needing a 2mm shaft? Can you use a larger shaft diameter?

What battery packs are you going to be using?

Any idea what the full throttle rpm was on the original setup? What rpm would you want on the prop?

Need to know those things to select a good kv.

larry
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Old 02-07-2008, 05:10 AM
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-The Super Cobalt 400 that I'm using is rated at 2395KV
-I'm using an Octura 427 = 27mm 1.49 Pitch prop
-I was using the stock battery packs... 2/3A 7.2V
It was faster than stock but of course I still want more...

-I bought a Walkera 3000KV motor that I haven't been able to use yet because I don't yet have an ESC.
-Same Prop
-This time I'll be using 3S packs 1200/1800mah.

I'm just not sure if the Walkera was a good choice, or if there's better out there. Thanks!
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Old 02-07-2008, 05:58 AM
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Ok, that helps a lot.

Ive never used a Walkera motor so I dont have any idea how good/bad it is.

Most any of the name brand motors will perform similarly. I doubt you could tell the difference without using meters.

The key factor is going to be the battery packs voltage, current capability and the motors Kv.

Lets make some wild guess on losses etc.

Your current set up has a Kv of 2395 and your running it at probably 6 volts under load = 14300 rpm in theory. That brushed set up is probably only 50% efficient at getting the rpm to the prop so lets say your getting 7000 rpm at the prop.

If you go with a brushless motor that has 3000 kv and run it on 3S lipos thats going to hold closer to 10.5 volts under load = 31,500 rpm. Its also going to be a lot more efficient at getting rpm to the prop - probably in the 70-80% range so that gets you maybe 20-25,000 rpm at the prop.

Thats 3 times the rpm you were getting

I suspect that your packs will NOT be able to handle the amp load.

The power required goes up by the cube of the change in rpm more or less. So to tripple the rpm means you need 9 times as much power as you were using before. Not quite as much as that because your increasing your efficiency, but you see my point? Can your packs handle 9 times the load?

If your going to go with a 3S pack and increase the voltage that much you need to reduce the Kv on the motor.

Your still going to need more powerfull batteries to get more power out of the system.

Thats the key thing most guys forget - your motor cant put out more power than the batteries can deliver. The batteries have to come first and be able to deliver what is asked of them.

Any idea how many amps your drawing now?

Lets say you only change the motor - go with the 3000 kv walkera and keep your existing pack. 6x3000 = 18000 rpm but now you have a much better efficiency at close to 80% so you'll see 14,400 rpm at the prop.

Thats still double what you had before. You'll still need going on 4 times the power from the batteries to do that. Actually, with the increased efficiency maybe 3 times the power.

If it was me, Id go with the 3S packs and size them so that they can put out 2 to 3 times what your drawing now from that 2/3A pack.

Id pick a motor with a Kv in the 1300-1400 range. That should give you roughly a 50% increase in rpm at the prop which should be a big increase in power and speed. You'll only need about 2 to 3 times the power from the packs to do that.

Himax has a 28mm motor that can handle 275 watts (no idea how much you will actually need) at a reasonable cost. Its a decent motor but it has a 4mm shaft.

Off the top of my head I dont know of any 28mm motors that have 2mm shafts. You'd need to search on that.

Larry

http://www.maxxprod.com/pdf/HB2815-xx00.pdf
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Old 02-07-2008, 06:08 AM
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Hi Thats not a very big boat to work with here is a suggestion that I would pass this by larry first, as he is the motor expert here, and a smaller pitch prop,

a 3600kv water cooled motor
http://www.hobbycity.com/hobbycity/s...idProduct=5145

1450mah lipo 25 to 35c ,11.1v lipo
http://www.hobbycity.com/hobbycity/s...idProduct=6304

40 amp esc
http://www.hobbycity.com/hobbycity/s...idProduct=3729

prop. 1.2 pitch, not sure if this will work on your boat

http://www.funrcboats.com/ProductInf...uctid=OC1250PL








Last edited by CHELLIE; 02-07-2008 at 06:29 AM.
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Old 02-07-2008, 06:28 AM
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LOL - I should post a disclaimer - I am NOT a boat person so keep that in mind

Larry
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Old 02-07-2008, 06:42 AM
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CHELLIE
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Originally Posted by Larry3215 View Post
LOL - I should post a disclaimer - I am NOT a boat person so keep that in mind

Larry
Capricorn - the ultimate flying boat By Larry




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Old 02-07-2008, 07:29 AM
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LOL

Chellie you got me there!

I should have said I wasnt a normal boat person - just a flying boat person

Larry
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Old 02-07-2008, 07:33 AM
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Originally Posted by Larry3215 View Post
LOL

Chellie you got me there!

I should have said I wasnt a normal boat person - just a flying boat person

Larry
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Old 07-07-2010, 04:14 AM
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Hi there,

I am also hoping to upgrade this BABY. Hoping to land a brushless motor powered by NiMh.

Any suggestions for batteries, esc, and motor. I like the motor Chellie linked, but is it just a little too big for the boat. (diameter (28mm stock vs 35mm linked motor)).

Heres what i want: (all compared to stock set up)

- a little more speed. this thing wasn't made to go 35mph, so i wont even try. But i would like to see a bit more speed out of it. maybe 1.5 times as fast, or even 2 times as fast.

- a little longer run time. not 10 minutes longer or anything, just maybe a few minutes. lets just say i don't want to give up any run time.

- I don't want to be abusing/pushing-things-to-the-max. I want to be going fairly easy on the set up. because i want it to last.

- looking to keep stock prop, but i will upgrade if needed.

- i will buy a 2ch radio and receiver.

- want to keep stock servo, drive shaft, coupler (i know i will have to drill it out a bit to fit new motor shaft.), and drive system (rudder-prop set up (not looking to do a surface setup))

let me know if these requirements/goals are ridiculous.
Thanks guys!

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Last edited by superd333; 07-07-2010 at 04:56 AM.
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Old 07-07-2010, 06:48 AM
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You will have much better luck and get much better advice if you post that question in the Boat Forum somewhere. I dont know if WattFlyer has a boat forum even?

However, I am willing to make a wild guess as to what might possibly work for you - maybe

IF the original posters info was correct, then I would try this for starters.

You need to find a brushless motor with a 28mm outside diameter AND a 2mm shaft that is about 43mm long. Look for a kV in the 2000-2500 range.

Id use any brushless boat esc in the 25 to 35 amp range.

the esc is easy to find but I havent found any motors in a quick search that fit the bill. The trick is the 2mm shaft. So far everything Ive found has 3mm shaft or larger.

If you could make a custom coupler you would have lots of choices.

Himax, Hacker and Mega all make good 28mm inrunners that would work great - if you can make a shaft adaptor to go from the motor diameter down to 2mm.

if you are wanting to stick with round cells, then Id go with an 8 cell pack to start with. If thats too much, drop a cell. If its not enough, try a 9 cell pack.
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Old 07-07-2010, 07:01 AM
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Just re-read your post and see you can make an adaptor!

Here is a Mega motor that would work great. The 16-15-4 will be a little hot so you may end up going with fewer cells than I suggested.
http://www.espritmodel.com/index.asp...OD&ProdID=3191

For a Himax try the 2815-2000. This is a coller kV so you may end up going to 9 cells with it.

http://www.maxxprod.com/mpi/mpi-262.html

The Hacker Id start with is the B40-13L. Its kind of pricey but the best quality.
http://www.aero-model.com/Hacker-Brushless-B40-13L.aspx

There should be other choices out there as well.

For the controller Im not sure what to recomend. All the boat controllers I know of are pricey water cooled models costing $150 plus. Way more horsepower than you are needing. The problem is you have no cooling in that hull. You might get away with an over sized air controller if you water proof it but Im out of my "depth" on this one
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Old 07-07-2010, 04:24 PM
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Originally Posted by Larry3215 View Post
You will have much better luck and get much better advice if you post that question in the Boat Forum somewhere. I dont know if WattFlyer has a boat forum even?

However, I am willing to make a wild guess as to what might possibly work for you - maybe

IF the original posters info was correct, then I would try this for starters.

You need to find a brushless motor with a 28mm outside diameter AND a 2mm shaft that is about 43mm long. Look for a kV in the 2000-2500 range.

Id use any brushless boat esc in the 25 to 35 amp range.

the esc is easy to find but I havent found any motors in a quick search that fit the bill. The trick is the 2mm shaft. So far everything Ive found has 3mm shaft or larger.

If you could make a custom coupler you would have lots of choices.

Himax, Hacker and Mega all make good 28mm inrunners that would work great - if you can make a shaft adaptor to go from the motor diameter down to 2mm.

if you are wanting to stick with round cells, then Id go with an 8 cell pack to start with. If thats too much, drop a cell. If its not enough, try a 9 cell pack.
Hi, thanks for the advice... I will just drill the 2mm coupler hole on the motor side with a 3mm drill bit....

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Old 07-07-2010, 04:52 PM
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hey Larry,

What about this esc? it is what is in the widowmaker rc boat. or this esc

With this motor or this motor

What would be a decent NiMh batt to throw in this thing. i would get 3-4 for sure!

thanks

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Old 07-08-2010, 02:38 AM
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Im still guessing here but Id say the first esc - with reverse - would be the better choice.

The first motor listed is the wrong diameter - its only 20mm - and the kV is way too hi.

The second one might work ok - it the correct diameter and the kV is within range - but it is a bit short so the water jacket may not fit well. If they have a longer version of that E-Flight motor it would probably work better.
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Old 07-08-2010, 02:40 AM
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On the battery - Id wait untill you have a motor selection finalized - then order just one to start with. Get the motor in and run some tests to be sure it performs the way you want it to. You may need to go with fewer or more cells to adjust the performance and amp draw.
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Old 07-08-2010, 03:21 PM
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Ok, if i can't find a decent brushless motor. I may stay stock.

What do you think the biggest battery i could put in the stock set up would be?

Thanks so much.....,

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Old 07-08-2010, 03:36 PM
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Larry,

What is reverse?

also, the second motor has a max current at 32A, but the first esc is a 30A. would this work? would this one work better? but with that one, i don't see 3 battery leads, only two?

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Old 07-09-2010, 04:11 AM
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Default Another Choice?

Hello Mumblinaviator,
To get back to your original question, I was also looking for an inexpensive inrunner with (about) 2000Kv recently. I needed to fit a small-diameter motor into a pylon racer. The nose is too small for an outrunner.
And I found this;
http://www.headsuprc.com/servlet/the...s-Motor/Detail
Kv 2200
Weight 3.0 ounces
Diameter 28mm
Length 36mm
Shaft Diameter 3.17mm (1.8")
Voltage 7-17 (2s to 4s LiPo)
Max Current 28 amps
Price $ 23.95.
The shaft size is larger than you have, but an adaptor shouldn't be hard to find.
My tests with a small airplane prop showed plenty of power at a reasonable amp draw. 225 Watts with a 6.5 x 5 carbon, here's a wattmeter photo during that test;
Another choice for you!
Ron
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Old 07-13-2010, 12:25 AM
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Originally Posted by Sky Sharkster View Post
Hello Mumblinaviator,
To get back to your original question, I was also looking for an inexpensive inrunner with (about) 2000Kv recently. I needed to fit a small-diameter motor into a pylon racer. The nose is too small for an outrunner.
And I found this;
http://www.headsuprc.com/servlet/the...s-Motor/Detail
Kv 2200
Weight 3.0 ounces
Diameter 28mm
Length 36mm
Shaft Diameter 3.17mm (1.8")
Voltage 7-17 (2s to 4s LiPo)
Max Current 28 amps
Price $ 23.95.
The shaft size is larger than you have, but an adaptor shouldn't be hard to find.
My tests with a small airplane prop showed plenty of power at a reasonable amp draw. 225 Watts with a 6.5 x 5 carbon, here's a wattmeter photo during that test;
Another choice for you!
Ron
he posted in 2008, i would think this project would be long gone for him...
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Old 07-13-2010, 12:28 AM
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hi,

anyone have a response to my questions?

Thanks

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Old 08-04-2010, 07:56 PM
  #25  
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The motor that boat use is a speed-400 type, about 29mm OD and with a 2.3mm shaft. I once modified a Zig-Zag with a 20X40mm brushless on 2 cells:
http://www.hobbycity.com/hobbycity/s...hless_Inrunner
a surface piercing drive and Octura X-427 prop. It was very fast but also unstable because the hull was just not designed for that kind of power
Had to replace all the electronic because the original wasn't compatible with brushless esc and regular servo. Better running with a normal hull. Same power on 3 1800 mA Lipo.Click image for larger version

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