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Author Topic: Left or Right Prop?  (Read 3556 times)

tizdaz

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Left or Right Prop?
« on: January 03, 2017, 01:05:39 AM »

Hi guys,


ok ive googled it etc but still not quite sure which to purchase as it seems 50/50 weather to use a LH or RH Prop for my Direct Drive single screw Tug, i read that using one or the other is better as it will not work lose (unwind) when going forward but i cant remember which, i think it was LH?


I want to get the correct one as the prop its quite pricey (about 75 posted) so dont want to get it wrong and end up costing double!


Cheers :)

RAAArtyGunner

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Re: Left or Right Prop?
« Reply #1 on: January 03, 2017, 02:50:25 AM »

There is lengthy discussion on this forum which fully answers your question, which is often asked, such as if you pick one that doesn't unwind forwards it will in reverse.
Should be something that tells you how to search the forum.
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derekwarner

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Re: Left or Right Prop?
« Reply #2 on: January 03, 2017, 03:59:47 AM »

Daz........

I understand you have chosen your electric motor .....and from memory it was from a mobility scooter??........if this is correct, the design of the machine [gearing??] would be for the motor to rotate in one or a 'preferred direction'

Would I be correct in thinking that model Tugboats would spend 80% of their time on the water going FWD?........and not actually manoeuvring astern?......

So if you plan a direct drive system, why not test the motor and current draw on the bench [preferably with an external power supply.....not a battery]........ let the motor run for 30 minutes....... thumb & forefinger will get hot :embarrassed: , try a wooden clothes peg pressed over the shaft as the load .....then 30 minutes in the opposite direction......

You may actually find  %) that the motor has a preferred direction of rotation.....[remembering the 80/20% estimate]

There may be 5000 pages of technical yes's or no's on propeller LH or RH........I haven't found any clear definitive proof of the advantage of a RH to LH single direct drive .....or LH to RH  {-) for Tugboats...& lets not further confuse any other Class of vessel

Derek
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malcolmfrary

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Re: Left or Right Prop?
« Reply #3 on: January 03, 2017, 09:12:26 AM »

Some prop manufacturers define LH and RH differently - either looking at the prop from the engine end or from behind.  Lots of threads on the subject. 
Either way, the "unwinding problem" is immaterial - the prop should be properly fixed so that is stays in place.  If it isn't, running one way it will try to wind itself up the shaft, tightening everything and stalling the motor.  Running the other way it will unwind and sooner or later (probably sooner) fall off.  A properly applied lock nut (NOT a self locking one) prevents this.  Applying thread locking compound helps more, and to be totally certain, drilling a hole and inserting a pin makes really sure.
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tizdaz

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Re: Left or Right Prop?
« Reply #4 on: January 03, 2017, 11:01:59 AM »

Thanks for replys guys ;)


aye i did read somewhere that there was a preferred direction for single prop with a reason (think it might have just been due to extra safety measure in terms of prop coming loose) but i cant remember where i read about it, my motor definately seems to run best with red wire to + and black wire to - ..vice versa the motor runs similar but not as smooth or as quiet

imsinking

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Re: Left or Right Prop?
« Reply #5 on: January 03, 2017, 11:36:49 AM »

Looking from the Com'(or unattached end) majority of motors run correctly clockwise , which is the direction it will 'lock' a thread into the prop when moving forward, you need a locknut to maintain the running clearance in the propshaft . . .
I use M3 S/Steel grub screws to further secure the prop to the thread , one is enough for standard rotation for forward (LH prop in Europe RH in the COLONIES  :P  ) motion , need two grubs if you want to run a RH prop on a screwed shaft , I'm not a fan of pinning props as when the thrust washer wears you need to adjust the locknut/prop to compensate & the hole will not line up , I don't 'dimple' the shaft for the same reason , the small amount of damage the grub does to the thread top is negligible , YOU DONT NEED TO HEAVE ON THE ALLEN KEY you'll twist out the hex' flats in the grubscrew THEN your in trouble . . .
If you do need to run anti clockwise consider grubing the coupling adapter to any threaded shaft also , vibration may shake the locknut loose .
Bill
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imsinking

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Re: Left or Right Prop?
« Reply #6 on: January 03, 2017, 11:49:29 AM »

How do you tell if a prop is left or right handed ?
I use an old  trick, screw a bolt into the prop, then just rotate the BOLT clockwise (in your left hand) & see which way the blades are going , you'll see if it's forward or backward (imagine the prop is a bolt & the water is the nut)
Most modern motors run happily in either direction, brushless included, the ESC usually controls percentages for forward / reverse speeds .
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rnli12

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Re: Left or Right Prop?
« Reply #7 on: January 03, 2017, 11:59:45 AM »

Hi,
Normally the straight edge from the centre is the leading edge (cutting edge) with the curved the trailing edge, although this is not always the case and depends on rotation  with some types of designs especially with models.
https://www.hhprop.com/how-boat-props-work.php
 
Rich
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Regards,

Rich

Martin [Admin]

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Re: Left or Right Prop?
« Reply #8 on: January 03, 2017, 12:39:49 PM »


"Usually" most modellers uses a ANTI-CLOCKWISE or LEFT HANDED props on single Right Handed thread shaft, with the motor spinning Anti-Clock when viewed from the back of the boat.









(  Please, please, please, have I've got that right?! )
                       
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morley bill 1

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Re: Left or Right Prop?
« Reply #9 on: January 03, 2017, 12:50:38 PM »

Hi for the best advice on props contact Simon Higgins at Protean Design I buy all my props from Simon never had any better advice or props from anywhere else hope this helps you  Bill..
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tizdaz

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Re: Left or Right Prop?
« Reply #10 on: January 03, 2017, 01:40:51 PM »

Thanks again guys :)


@ Martin
yup i thought i read somewhere that LH was the way to go so im guessing your right! :D


@ morley bill 1
is http://proteandg.com/ the website? if so it doesn't really give much info props etc :s ?



morley bill 1

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Re: Left or Right Prop?
« Reply #11 on: January 03, 2017, 03:27:45 PM »

Hi pm sent Bill..
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C-3PO

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Re: Left or Right Prop?
« Reply #12 on: January 03, 2017, 03:47:33 PM »

Protean Design
21 Victoria Cottages, Shipston
Road, Stratford On Avon, CV37 7LN
T: 01789 565228
E: simonhiggins181@btinternet.com
W: www.propman.uk.com
Precision cast and machined
model parts inc. propellers, shafts
and custom components.
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tizdaz

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Re: Left or Right Prop?
« Reply #13 on: January 03, 2017, 08:51:19 PM »

Cheers guys :-)

RAAArtyGunner

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Re: Left or Right Prop?
« Reply #14 on: January 04, 2017, 12:04:48 AM »

Protean Design
21 Victoria Cottages, Shipston
Road, Stratford On Avon, CV37 7LN
T: 01789 565228
E: simonhiggins181@btinternet.com
W: www.propman.uk.com
Precision cast and machined
model parts inc. propellers, shafts
and custom components.

Thank you  :-))
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