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Old 19 July 2014, 03:17   #1
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High speed prop wrap!

A customer of ours hit a pot marker as speed this week. He was able to recover the prop which was knotted in the rope.
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Old 19 July 2014, 04:26   #2
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Sheared the prop shaft? That's impressive.

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Old 19 July 2014, 07:07   #3
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Ouch!! On the plus side the prop doesn't look too damaged.
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Old 19 July 2014, 07:54   #4
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Shouldn't the rubber' in the hub have sheared and the shaft left intact.

Why did the shaft snap?
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Old 19 July 2014, 11:55   #5
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I would have expected the bush to break not the shaft to break.
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Old 19 July 2014, 13:10   #6
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It wouldn't have been a sudden impact type force but a more gradual force as the rope tightened it's grip thus sealing the prop shaft's fate. Was there any sign on the fail point of a previous damage/fracture Jim.

I once had a crankshaft break on an old Evinrude 40 twin off of Bembridge. It had been failing for quite some time until it met it's end. I offered it to my local technical college who showed it to their students as an example of metal fatigue brought about by vibration.
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Old 19 July 2014, 13:33   #7
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Looks like it has sheared on a joint. I think the spline is friction welded to the main shaft at that point. The pattern of the rope is imprinted in the paint of the prop.
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Old 19 July 2014, 13:38   #8
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All of the shafts that I have held in my hand, mostly from outdrives, are one piece, that the splines are cut into.

You wouldn't happen to have a close up picture of the end of the shaft would you? Looks almost like it was failing previous to this event, but the photo is not very good on my computer.
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Old 19 July 2014, 15:59   #9
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Yep would agree with you peter, but it is such a clean shear like a knife cut
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Old 19 July 2014, 16:11   #10
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Didn't a similar thing happen to a members Verado? Looked identical.
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Old 19 July 2014, 17:15   #11
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If you need to know for sure, Send it to Materials Technology in Totton.
They can have a proper look at it.

Fast fracture - probably caused by the rope.
Fatigue failure - possibly initiated by out of balance / damaged propeller over time.
Friction weld failure - maybe down to manufacturing defect.
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Old 20 July 2014, 13:13   #12
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Hard to believe,something way wrong their?
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Old 20 July 2014, 16:44   #13
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Bit better picture of the break.
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Old 20 July 2014, 17:37   #14
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Another high speed prop wrap.

This was on one of the Thames Clippers!!

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Old 20 July 2014, 18:50   #15
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Quote:
Originally Posted by Jim Robinson View Post
Bit better picture of the break.
From my perspective the rusty middle part had been severed before this event. Maybe this is not the first prop strike, or maybe it is just a failure of the metal? Doesn't really matter it just needs a new shaft installed. To a pro it shouldn't be too bad of a job, unless there is a lot of corrosion in which case it could get ugly.
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Old 21 July 2014, 15:34   #16
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It a year old so off for inspection by the warranty team. Love the tyre picture.
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Old 22 July 2014, 13:57   #17
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Quote:
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Bit better picture of the break.
Is that 'old' corrosion in the centre, or corrosion that occurred between the time the shaft broke and the picture was take?
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