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Author Topic: Recommendations needed for suitable powerplant.  (Read 1137 times)

gregk9

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Recommendations needed for suitable powerplant.
« on: June 08, 2011, 11:23:58 PM »

Just aquired a "Cen Aqua Jet" power boat. 700 mm long, 225mm wide, fitted factory with a 42mm "dog drive" propeller, has a nice metal universal joint fitted ready for coupling to a motor [electric].
Now, question is, what would you guys recommend as a suitable powerplant.
kindly appreciate my pockets are not bottomless so dont quote silly telephone number long prices for motors and esc's.
Ive not used brushless kit yet, but not adverse to fitting a decent brushed motor.
there is loads of free space so can slot in twin battery packs, right down against the hull floor, so keeping "c of g" low.









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Steve. G.
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http://chasewatermbc.blogspot.com/

Roadrunner

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Re: Recommendations needed for suitable powerplant.
« Reply #1 on: June 08, 2011, 11:42:11 PM »

You can run a single brushless motor similar sizes to the DC 600-700's might be a good starting point, run them of lipos cells if you want to spend out for them, or stick with standard nihm packs, if you room for two run them in parallel, or you can stick with traditional DC motors and use a 600 or 700 there off nihm packs either way both setups should give you good speed, but brushless will be far better then DC.
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gregk9

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Re: Recommendations needed for suitable powerplant.
« Reply #2 on: June 10, 2011, 03:06:21 PM »

"IF" I were to go the brushless motor route, can you suggest a perticular one to opt for, suitable for this size of boat, with the "oe" fitted 42mm prop, so i dont have to go replacing the propshaft which is already in.
I have to admit |im not familiar with the brushless jargon, regarding capacity/size, speed so thats why I asked for help.


As far as batteries for the brushless, im looking to go "twin" setup, to keep the hull balanced, 11.1v each is an option for twin/ parallel  or can possibly go 7.4v  twin/series for slightly higher setup.

I do have a spare 700bb turbo motor, but to run this, I dare say it would take some battery backup to enable any decent running time.
But prefer to save the 700, for another heavier boat, thats will take the batteries it would need.
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Steve. G.
Treasurer & Membership Secretary:  Chasewater Model Boat Club
http://chasewatermbc.blogspot.com/

pompebled

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Re: Recommendations needed for suitable powerplant.
« Reply #3 on: June 24, 2011, 05:55:47 PM »

Hi Greg,

The Cen Aqua Jet was originally sold in two versions; one with a docile 600 motor 8,4V set-up and one with the 700 motor on 12- 14 cells NiMH.
The 700 motor version is the most exiting to run, but runtimes on 3300mAh NiMH were 8-10 minutes full throttle, depending on the propchoice.

The 'average' 700 motor used, turned about 1600 rpm/Volt, with brushless motors it's called KV, so to have a fitting replacement, look for a brushless motor with 1600 KV, which on a 4S lipo gives you about 21.000 rpm under load.

It doesn't necessarily have to be an inrunner, as an outrunner has more torque and in general is lighter.

As an example, my 65 cm long monohull runs over 30 mph on a 1700KV brushless outrunner on a 3S (11,1V) Lipo, which is close to the speeds this boat used to run on the much heavier combo of an 700 Neodym and 12 cells NiMH.
It's the white boat in the video:
http://www.youtube.com/watch?v=I2h1kWwaFCA
The conditions were rough, but you get an idea...

Runtimes are about 10 minutes, depending on propchoice and battery capacity.

Let me know if I have to get you some links on motor, ESC and Lipo for such a combo.

Regards, Jan.
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