Motors For Deans Marine Yarra

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Motors For Deans Marine Yarra

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27 August 2015 at 11:34 #59937
John Thornton 1
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@johnthornton1
Hi, Can anyone help me with the choice of motors for a Deans Marine Yarra? It's a twin-screw tug of 23" length and 7.25" beam. The props are 40mm, 4-bladed Kort types.

I called Deans and their rep. recommended their Kyte Standard. When I pointed out to him that their catalogue describes these motors as being best suited for use "in fast displacement type launches or the smaller warships," he said that the props in the kit had almost no pitch and needed to be run fast. When the kit arrived I found the props have a standard pitch, similar to those by Raboesch, etc. As a result, I don't have much confidence in Deans advice, and I'm hoping someone here can help.

The recommended batterty is a 5000mAH NiMh, so there isn't lots of room for high power consumption, and neither is there a lot of space in the model to fit a larger battery.

Would a pair of 385s be powerful enough? I think they'd be okay for 40mm 3-blade props, but I'm not sure about the 4-bladed Kort types.
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27 August 2015 at 11:34 #2498
John Thornton 1
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@johnthornton1
27 August 2015 at 12:25 #59938
Dave Milbourn
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@davemilbourn48782
John

The two rules of (brushed) motor choice are that the prop diameter mustn't exceed the motor case diameter, and the motor must have at least as many poles as the prop has blades (preferably more). I'd suggest two MFA 540 LN motors – **LINK** A tiny bit smaller on the diameter criteria but approx four times the torque of standard 385, the right speed range and very low current consumption. I have one for my Lord Nelson Victory tug and it's very good.

Dave M
27 August 2015 at 13:36 #59946
John Thornton 1
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@johnthornton1
That's the way I'll go then, thanks.

Can you advise a suitable ESC?
27 August 2015 at 13:56 #59947
Tony Hadley
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@tonyhadley
Posted by Dave Milbourn on 27/08/2015 12:25:04:.

I'd suggest two MFA 540 LN motors – **LINK** A tiny bit smaller on the diameter criteria but approx four times the torque of standard 385

Dave, do you mean four times the torque of a 540?

John, I fitted a 385LN to "Guardsman" recently on Dave's recommendation and the prop is very slightly larger in diameter than the motor case. The LN range of motors are a really superb & powerful and well worth the extra cost.
27 August 2015 at 13:58 #59948
Dave Milbourn
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@davemilbourn48782
No-brainer! ACTion P94 Lite. **LINK**

DM
27 August 2015 at 14:05 #59949
Dave Milbourn
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@davemilbourn48782
Dave, do you mean four times the torque of a 540?

No, m'duck. John's question was about fitting 385's, which have approx 65g.cm torque (in standard form). The 540LN has 240g.cm. There are full data sheets on all their motors on the MFA Como Drills website here

**LINK**

Dave M
27 August 2015 at 17:12 #59956
John Thornton 1
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@johnthornton1
One last question – is 6V / 5000mAH okay for power? I don't think I'd find room to fit a 12V pack.
27 August 2015 at 17:54 #59958
Dave Milbourn
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@davemilbourn48782
It'll be a bit slow. The closer to 12v you can get then the better the performance will be. With the current drawn by that motor you'll not need a 5AH Sub-C sized battery pack unless you want to sail all week at full throttle. Take a deep breath and think about fitting a 3S LiPo of around 2600mAH. Ignore all of the horror stories you've heard about them – those stories are all about idiots who think they know better than the folk who write instructions for batteries and chargers. I've been using LiPo's for about a year and I'm sold on them now.

These guys sell all manner of batteries and chargers, so have a good shufti. **LINK**

Dave M
27 August 2015 at 20:42 #59965
John Thornton 1
Participant
@johnthornton1
Thanks Dave.

How about this one: http://www.componentshop.co.uk/11-1v-2600mah-5c-transmitter-lipo-battery-square.html?___SID=U

or this one, which has a higher discharge rate but is more expensive: http://www.componentshop.co.uk/11-1v-2600mah-35c-continuous-discharge-lipo-battery.html?___SID=U
27 August 2015 at 20:51 #59966
Dave Milbourn
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@davemilbourn48782
John

I use the second type as it already has the thicker cabling and power connector needed for a motor circuit, but there is a slightly lower-capacity pack for less money here **LINK**

Dave
27 August 2015 at 21:23 #59967
John Thornton 1
Participant
@johnthornton1
Thanks for all the advice, Dave. I've placed my orders for the 540LN motors and 2200mAH battery. I won't need to buy a Lipo charger, as the Accucel I bought from you a little while back will do the trick nicely!
28 August 2015 at 09:51 #59970
Dave Milbourn
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@davemilbourn48782
John

You'll need a low-voltage alarm, too. I use this one **LINK** but there are several different types.

Dave M
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