How can I tell if I've a spun prop?

Ross Young

Ross Young

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Joined
8 Jul 2012
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24
Location
Southsea
www.greekprincess310.blogspot.com
To day when returning from Bembridge to Langstone I was uable to get our Bayliner 245 to get on plane, the revs just rose to 4000 revs plus and the leg sounded like it was cavitating, reducing to 8 kts we limped across to home.

Some one on the dock said perhaps the prop was spun, meaning the rubber bush might be demaged, obviously I can remove the prop but will it be obvious visually?

If I need to test a good prop on our alpha one leg where might I loan one from for such a test...?:confused:
 
Make a mark or check the alignment of the prop to the nut or pin (take a photo as well for reference).. The go out and get it to "spin" as you experienced.. Then come back and see if the marks still line up or if they have moved..
 
Just to clarify: Mark the prop position relative to the prop shaft (paint, scratch, file). If shaft and prop does not follow each other, the marks will tell after a swift test run.

The Alpha One does not have any sort of clutch, so no issues in that.

When looking for a prop you need to know the specs on the current prop (stamped on hub between blades and/or on hub end). If any issues with it even when it worked (not within recommended rpm range at WOT, ventilate in turns at speed, doesn't grip properly during acceleration etc.) now is the time to get things sorted.

What engine is the Alpha mated to?

Edit:
If your prop has a replaceable hub (designed to allow same prop to fit various sterndrive makes), it might be just the hub carrier. Merc's solution is called FloTorq, usually holds up for years and years. Others have taken up the idea, not all with brilliant results.

TP-Prop-Hub-Example.png
 
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Ross Young said:
To day when returning from Bembridge to Langstone I was uable to get our Bayliner 245 to get on plane, the revs just rose to 4000 revs plus and the leg sounded like it was cavitating, reducing to 8 kts we limped across to home.

Some one on the dock said perhaps the prop was spun, meaning the rubber bush might be demaged, obviously I can remove the prop but will it be obvious visually?

If I need to test a good prop on our alpha one leg where might I loan one from for such a test...?:confused:
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Check that you haven't lost a peace of metal (a cylinder that attaches at the end called a diffuser ring) off the end of your prop. When mine went the difference in performance was striking. If that is your problem then at least it will be a cheap fix.
 
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Had this happen to me on a Monterey. BII leg on a Yanmar diesel. Got another prop from streamline props and put it on. Then got the old one repaired as a spare, which I never needed! The small rubber particles were visible on the very edge of the bush where it had spun and torn away - but only truly visible once the prop was off.
 
Ross Young said:
To day when returning from Bembridge to Langstone I was uable to get our Bayliner 245 to get on plane, the revs just rose to 4000 revs plus and the leg sounded like it was cavitating, reducing to 8 kts we limped across to home.

Some one on the dock said perhaps the prop was spun, meaning the rubber bush might be demaged, obviously I can remove the prop but will it be obvious visually?

If I need to test a good prop on our alpha one leg where might I loan one from for such a test...?:confused:
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Had this very problem recently. When engine revs got to 2000 rpm , no drive and engine revs increased. Drop engine revs back but dont put into neutral and it starts driving again. If this sounds like it , then its the bush. Took props off and bush was destroyed. New pros and problem solved.

If you need to put it into neutral and then back into drive before it starts driving , its something more serious like the clutch cone.
 
Ross Young said:
I will try the marker advice and test it this week but having read the replies and sort more advice it seems more than likley the hub is gone. Thak you all for this feedback I will post result of the tests in a few days
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On our previous boat we had a prop shift on the hub. As recommended by others we had it 're-hubbed' by steel developments. Very quick service which was brilliant - all worked fine - if I remember correctly they offered a guarantee on the work as well.
No connection with the company just a happy customer.
 
mparrish said:
On our previous boat we had a prop shift on the hub. As recommended by others we had it 're-hubbed' by steel developments. Very quick service which was brilliant - all worked fine - if I remember correctly they offered a guarantee on the work as well.
No connection with the company just a happy customer.
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I contacted steel developments today and they say 3/4 day turn round once received which would be great, thanks for the valued advice..
 
Ross Young said:
I contacted steel developments today and they say 3/4 day turn round once received which would be great, thanks for the valued advice..
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Would you really consider sending a prop away for this work? You have to do 75% of the work in taking the prop off and putting it back on on to send it away, you might as well push the hub centre in yourself. Tap the old one out (if its really spun then it could well fall out) put the new one in and tighten up by refitting onto drive. 30 minutes top.


http://www.sportsboat.org.uk/index.php/our-boat/10-service-and-modifications/8-13-08-2010-hub-repair
 
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mlines said:
Would you really consider sending a prop away for this work? You have to do 75% of the work in taking the prop off and putting it back on on to send it away, you might as well push the hub centre in yourself. Tap the old one out (if its really spun then it could well fall out) put the new one in and tighten up by refitting onto drive. 30 minutes top.


http://www.sportsboat.org.uk/index.php/our-boat/10-service-and-modifications/8-13-08-2010-hub-repair
Click to expand...

That's assuming it's a replaceable type hub in the first place.. It maybe a prop with a fixed hub.. Guess that will only be know once it is removed and the manufacturer/model of the prop is known..
 
Its an Alpha One drive in the Bayliner, at that age they were supplied with Flo Torque hubs as standard. It would need to have a really old Quicksilver prop or an aftermarket one to still have a rubber bush.

As mlines says, changing a flo torque hub is very simple, it will take longer to find the right sized socket than it will to change the hub.

If you are changing it in the water I would get a full kit (includes nut, washer etc), sods law you will drop something when you are swapping it !
 
landlockedpirate said:
If you are changing it in the water I would get a full kit (includes nut, washer etc), sods law you will drop something when you are swapping it !
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Use a bucket or upturned umbrella hanging below the drive to catch tools and fittings. As Landlocked says, you will prob drop something! good luck with it.
 
All fixed...Yes it was the hub, I had a Power Tech Prop and I drove to Wimbourne this morning to Propellor Solutions not knowing they dealt with Powertech Props, Thomas the owner repaired it in 10 minutes while I waited. The hub was infact shot......so well worth the drive with the right tools and a nifty press it was all back together in very quick time, not sure I would have wanted to try putting all those strips of rubber & nylon back in with a lump of wood and a hammer!

It has a cushion lock hub in Powertech Props

Can't thank you all enough for the help and advice, it was indeed the hub so next time you cant get on plane and the engine racing and the boats frothing at the rear look no further than the prop hub.....lesson learned!

Just need to re-essemble on to the shaft and I will be back on the water!

Can I highly recommend Propellor Solutions at Wimbourne, Thomas was great, thank you!

Here's the link http://www.propellersolutions.co.uk/ should you need it.

Regards Ross
 
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Just a quick foot note, run the boat today on test, ran like a dream.

Reach 30 knots no problem and on plane in seconds, clearly the prop hub has been on it way out for sometime, all back and running sweatly thank you to all who assisted with sound advice, hope this thread may help someone else in due time.
 
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