Propellor change or rip off yard

[SteveB_Sigma33]

To the great un-washed forumites

A friend of mine has a Sigma 33 the same as mine but is suffering from occasional bad vibration from something down below when the stinky is running.

Both boats are currently out of the water and I have checked her P bracket and propellor and both seem fine.

Both have twin bladed folding props.

She has had the local yard have a look and they have decreed the propellor is knackered - stating that one blade goes back further than the other. Well I'd expect that due to the teeth arrange ment and we're talking a few millimeters. Everything else seems exactly the same between the two props.

I've just replaced the cutlass bearing and suggested that maybe she should do the same as that removes another part of the equation.

Therefore what would the bearded and sandle types amongst you recommend for resolving this problem?

Oh by the way when she mentioned my prop is fine and looks exactly the same they stated that mine must be on the edge and need to be replaced too!!!!

This is also the same bunch who wanted to charge me £70 for drilling two holes into my shaft seal and tapping in two new threads for grub screws! Which I have found a company to do it for a £10 in Gosport

End of rant.


34 Going on 90 does that qualify me as a grumpy old man!

 

[cliff]

You don't mention which prop you have so check teh prop again and make sure the rubber "bump stops" are in place and in good condition, that is not missing or knackered on one blade. If they are either missing or knackered that would allow one blade to swing a little further forward resulting is a different angle of attack on that blade and could lead to vibration.

Check also for any damage to the blade especially where it stops against the hub.

If there is no real play in the cutlass bearing leave it alone but if it is well worn then do change it.

Check the alignment of the propshaft to the engine - really needs done when the boat is afloat unfortunately - although a check on the hard might indicate an alignment problem.

Did the boat suffer from vibration when going astern or only when going ahead?

70 beer tokens for drilling and tapping two holes does seem a little steep but there again 10 beer tokens does seem too cheap.
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“Artificial intelligence is no match for natural stupidity”
Skype id:cliffillupo

 

[SteveB_Sigma33]

bump stops, don't think I've ever seen anything like that on one of these props. Where/ how do they normally attach?

 

[cliff]

They should be on the hub where the blades would srtike the hub when open. They are to prevent shock loading of the blades / hub and prevent impact damage when the prop is engaged in ahead and the blades fly open.

Noticed them on several folding two bladers fitted on friends boats.
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“Artificial intelligence is no match for natural stupidity”
Skype id:cliffillupo

 

[SteveB_Sigma33]

Any idea where I can get any bumpers from?

 

[Sans Bateau]

Steve,

I agree with cliff, the only point I would add, I hope cliff agrees, if the cutlass bearing is worn replace it. However still align the gearbox to shaft. Because if this was the original cause of the vibration it will soon reappear. Also check engine mounts for oil damage or collapse.

 

[Sans Bateau]

cliff

I have a Volvo folding prop and years ago had a Gori version, neither had bump stops.

 

[SteveB_Sigma33]

Well its a Volvo penta 2002 that drives the boat so I'd guess it's probable that it's a Volvo prop.

 

[cliff]

Odd!!!! Little hard rubber button like thingies or a thin hard rubber pad. /forums/images/graemlins/crazy.gif
Maybe these are newish props I have seen or the owners retrofitted pads to prevent the "bang" on engaging ahead. I was down at a friends boat last week end - fitted with a Gori 2 blader It had a pad on one side on the hub but nothing on the other - had to make two new ones for him out of an old landrover bump stop.

Good point about checking the engine mounts as well as the alignment.
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“Artificial intelligence is no match for natural stupidity”
Skype id:cliffillupo

 

[adelaidem]

why dont u swap props and see if that solves his problem!

 

[Lakesailor]

Or creates one for you. Southace got there before me!

 

[SteveB_Sigma33]

Erm! I like mine where it is!