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Old 10 September 2006, 15:16   #1
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My poor prop

Folks,

just chipped one of the blades on my new honda engine whilst coming to.
Think it hit a still submerged metal post. (See attached pic)
Would you still continue to use it, as the engine was ok afterwards or do you think I should replace the prop right away?
Would it effect engine performance much?

cheers
Martin
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Old 10 September 2006, 15:34   #2
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I would have thought you may get a lot of turbulence off that?

I changed my prop for a new one and one of the things I noticed (apart from a better top speed which was the main point of the change) is that it seems to run noticeably smoother than before at a fast cruise. The old prop has some damage to the blade tips and leading edges that had been "cleaned up" by the previous owners using a file or something; whether it was putting the prop out of balance, whether it was tip turbulence, or whether the new one is just a better prop I don't know, but the damage was nowhere near as bad as that and I noticed a difference as soon as I opened it up above about half throttle for the first time.
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Old 10 September 2006, 15:44   #3
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I would send it off for a repair. I have recently damaged a prop and it was repaired within a week by steel developments for 50 including p and p. A new prop was 200. My engine manual says that if the prop is out of balance it could damage your engine/gearbox if used for extended periods.
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Old 10 September 2006, 17:03   #4
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I didin't run it long enough after the accident to notice any turbulence so quit possible.
Cheers Paul, looks like steel developments for me. Having paid out for a new engine, I don't think i'll take a chance doing any more damage!
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Old 11 September 2006, 03:11   #5
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That's going to put the prop pretty seriously out of balance. Lots of stress on the bearings and seals in the lower unit. Have it repaired.

jky
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Old 11 September 2006, 14:46   #6
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By the way the other thing that steel developments offered was a change of pitch by 1 inch for no extra cost so if you are unhappy with your maximum rpm maybe you should consider this.
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Old 12 September 2006, 03:29   #7
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Thanks paul, i've already sent it to them! But it revved up to honda's 6000rpm so I assume it's ok
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Old 12 September 2006, 04:35   #8
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Just a quick question about prop removal. After removing the cotter pin I was able to unscrew the nut holding the prop on by hand. Is this normal or should it have a torque rating?
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Old 12 September 2006, 05:26   #9
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It would have a torque value- it's a bad idea for a castle nut to be able to move against a split pin-the pin is there as a lock not a substitute for the right torque.

As to what the torque value IS, I don't know.
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Old 12 September 2006, 05:37   #10
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Quote:
Originally Posted by martx007
Just a quick question about prop removal. After removing the cotter pin I was able to unscrew the nut holding the prop on by hand. Is this normal or should it have a torque rating?
Don't know exactly what the mounting arrangement is on yours but on mine there is a metal thrust washer, then the prop, then a nylon washer, then the nut and split pin. The nut on the new prop was only supposed to go to 14nm on a Johnson which is not very tight, I would guess that if the nylon washer compressed over time (the old one on mine had started to split) you might find the nut would be loose enough to undo with fingers. Mine wasn't, but I think it was stuck on the shaft, it needed a few good smacks on the spanner to shift it as it was turning the engine over in gear.
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