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Author Topic: Handing props  (Read 4071 times)

maninthestreet

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Handing props
« on: June 03, 2006, 10:38:02 AM »

Can someone please remind me of the way to determine whether a prop is LH or RH. Also, which way should a prop rotate, once you know whether it's LH or RH.

Thanks.
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boatmadman

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Re: Handing props
« Reply #1 on: June 03, 2006, 01:53:11 PM »

Hi,
Look along the line of the prop shaft from aft to forward. if the blades are angled so that the edge of the blades closest to the bow is on the right hand side of each blade, it is a right handed prop and should rotate clockwise for forward motion. Vice versa for left handed.

Just got up from nightshift so if my left and rights are crossed.......... ;D
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maninthestreet

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Re: Handing props
« Reply #2 on: June 03, 2006, 09:07:50 PM »

'bow' meaning the front end of the boat, I assume?
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meechingman

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Re: Handing props
« Reply #3 on: June 03, 2006, 09:54:09 PM »

Yup, the 'pointy' end!  ;D

OUt of interest, on a twin screw vessel, should the props turn inwards or outwards? My late father's tug (a real one!) had screws that turned outwards - ie right handed screw on the starboard side, but I've seen ships and models that do the opposite. Is there any advantage to one or the other?

Andy G
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boatmadman

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Re: Handing props
« Reply #4 on: June 04, 2006, 02:13:23 AM »

its something to do with manouverability versus speed...but dont ask me which!!!!
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John R Haynes

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Re: Handing props
« Reply #5 on: June 04, 2006, 10:29:59 AM »

They generally turn outwards, creates less turbulance
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towboatjoe

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Re: Handing props
« Reply #6 on: June 04, 2006, 06:38:39 PM »

I've noticed that a lot of ocean vessels have right hand screws on the starboard and most river vessels have right handed screws on the port. Some companies will reverse the order declaring better manuverability. Also I've notice vessels with kort nozzles have the right hand screw on the port to where most vessels without korts have them on the starboard.

So really it's up to you, or you need to find a prototype vessel and observe how it's set up. With my experience with river vessels, nine times out of ten it's short words go together. port, left, clockwise and longer words go together Starboard, right, counter-clockwise.

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Shipmate60

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Re: Handing props
« Reply #7 on: June 04, 2006, 07:21:02 PM »

Without Kort Nozzles, looking from the stern to a point above the propshaft.
If the props move from the point outboard for ahead movement they are outboard props or right handed on the stbd, left hand on port.
Outboard turning props give higher speed.
Inboard props have a propwash that comes together under the stern and goes over the rudder which assists in the rudder action and steering, but does increase the frictional drag therefore slightly less speed.

Bob
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maninthestreet

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Re: Handing props
« Reply #8 on: June 04, 2006, 10:09:27 PM »

Having bought a copy of the J Perkins catalogue this weekend, I'm still a little confused - it describes propellors as 'UK RH (Europe LH)' or vice versa - what are they trying to tell me?

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towboatjoe

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Re: Handing props
« Reply #9 on: June 05, 2006, 01:12:42 PM »

i've been told by an engineer, the reason most vessels with korts have the right hand wheel on the port shaft is so they'll draw more water from around the hull into the wheel. They said there had been times (in shallow water with the right hand wheel on the starboard shaft) that coming hard down on the throttles, the wheels couldn't get enough water flow and it caused a captivation action.
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malcolmfrary

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Re: Handing props
« Reply #10 on: June 06, 2006, 04:51:01 PM »

Having bought a copy of the J Perkins catalogue this weekend, I'm still a little confused - it describes propellors as 'UK RH (Europe LH)' or vice versa - what are they trying to tell me?



As I understand it, in the UK we look forward from the stern, the Europeans conventionally look at the props from where they are driven.  All adds to the interest.  I also noted from some Graupner instructions that a 4 function radio was required for a Pollux.  This turned out to be  forwards, backwards, left and right.  We tend to call that two channel.
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maninthestreet

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Re: Handing props
« Reply #11 on: June 06, 2006, 11:27:42 PM »

Malcolm,

Trhanks for this - I was thinking this must be explanation for the difference between UK LH/RH and European LH/RH


MITS

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Aage

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Re: Handing props
« Reply #12 on: June 09, 2006, 05:50:37 PM »

Isn't UK part of Europe?

Aage
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BobF

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Re: Handing props
« Reply #13 on: June 09, 2006, 07:00:17 PM »

Only at very low tides.

Bob ;D ;D ;D
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funtimefrankie

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Re: Handing props
« Reply #14 on: August 02, 2006, 07:35:49 PM »

So, is this left hand or right hand?
Bow, sharp end to the right of your screen.

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Shipmate60

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Re: Handing props
« Reply #15 on: August 02, 2006, 07:49:07 PM »

Left hand.

Bob
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funtimefrankie

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Re: Handing props
« Reply #16 on: August 02, 2006, 07:55:17 PM »

Thanks for the quick reply.
I thought it was a left hand.
I got this prop today from PropShop, I had ordered a right hand one.
Do you think it matters much?
 I have reversed the servo control in the Tx so I will still get forward for forward.
Or should I return the prop for exchange.
Thanks
Frank
A right handed one will tend to screw itself onto the propshaft???
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Tug

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Re: Handing props
« Reply #17 on: August 02, 2006, 09:15:23 PM »

Just a reminder here for those who like to be confussed even more,

Simon [prop shop] sells shafts as the length of the inner shaft threads included,

where as convention works to the length of the tube,

a 10 " ripmax propshaft will have an inner at 11" threads included. so are we European?
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malcolmfrary

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Re: Handing props
« Reply #18 on: August 03, 2006, 03:08:51 PM »

Throwing the servo reverse on the transmitter will work, but if you are using an ESC with a relay to do the reversing, you will be operating the relay all the time that you are going forward.  If you are also using a separate RX battery, it will drain at a surprisingly fast rate.
If you are using a BEC it is likely that you are informed that the battery is running down by the boat only going in reverse.  This can be embarrassing.
Better to reverse the motor connections.
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funtimefrankie

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Re: Handing props
« Reply #19 on: August 03, 2006, 07:29:42 PM »

It's an Mtroniks speedo without relay so that's not a problem.
The motor sounds to go quicker with the servo reversed than with the motor reversed. (Boat out of the water)
Frank
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malcolmfrary

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Re: Handing props
« Reply #20 on: August 06, 2006, 07:43:00 PM »

From observing the Mtroniks ESCs that I have in my boats, the power offered is the same both forward and reversed, so the only difference is how well the motor + drive train is handling it.  Someone is bound to say that motors are "handed", but unless talking about competition motors where the brushes are not "square" to the magnet poles, this is not the case.  Normal small electric motors are symetrical as regards forward/reverse performance.  However, this does not mean that performance will be identical, as production tolerances in the commutator etc could make a difference in the conversion efficiency depending on which way the motor is turning.  The brushes might get a rougher ride going one way than the other.
If just one motor is fitted it should not be a worry.
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tonyH

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Re: Handing props
« Reply #21 on: August 09, 2006, 05:03:56 PM »

Not adding anything, but an extension to the question.

What is the norm with twin outboards?

I've got a couple of Kyosho ones (with dog drives) that I was going to use on an Atlantic 21 but I've decided to build a USCG PB-S 25ft. See www.safeboat.com or www.uscg.mil - they look fun at 1:12
They need plenty of speed so would it look stupid to have contra-rotating outboards, because I presume Honda etc. do not produce matched pairs of motors, and if anyone has built anything similar with active, not dummy, outboards, how is the handling affected in terms of crabbing and torque roll.

Tony
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flag-d

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Re: Handing props
« Reply #22 on: August 10, 2006, 12:09:12 AM »

Going back to the start of this thread, I have a 4 shaft MTB with contra-rotating props in pairs, port and starboard.  I have tried both inboard (top of the prop turns towards the keel when going ahead) and outboard.  I have not noticed any difference in speed between the two, but inboard-turning props have given me a tighter turning capability, possibly because more of the prop wash is directed over the rudders.  Just my two penn'orth, from experience.

Mike
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tonyH

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Re: Handing props
« Reply #23 on: August 10, 2006, 09:43:30 AM »

Thanks Mike,

I don't know whether the situation is the same because with the screws well aft of the transom there is no hull or rudder to either flatten out or direct the water flow.
Any effect is going to be undiluted.

Tony
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