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Jools_of_Top_Cat
New member
Re: Bent Propshaft
Maybe they actually mean 'off true' rather than bent which conjures up an image of a shaft changing direction visibly along its length.
A few mm will be bent, roll it on a flat and it will rise and fall. Might have been 'off true' from manufacture, maybe it has been knocked, maybe your engine mounts are shot and causing too much vibration.
I don't know, I wouldn't be overly surprised if my stbd shaft was off true as it keeps shaking the screws out of the cutlass bearing assy.
<hr width=100% size=1>Julian
<A target="_blank" HREF=http://www.topcatsail.co.uk>
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Maybe they actually mean 'off true' rather than bent which conjures up an image of a shaft changing direction visibly along its length.
A few mm will be bent, roll it on a flat and it will rise and fall. Might have been 'off true' from manufacture, maybe it has been knocked, maybe your engine mounts are shot and causing too much vibration.
I don't know, I wouldn't be overly surprised if my stbd shaft was off true as it keeps shaking the screws out of the cutlass bearing assy.
<hr width=100% size=1>Julian
<A target="_blank" HREF=http://www.topcatsail.co.uk>
Sunnyseeker
New member
Re: Bent Propshaft
I am aware of it happening to power boats when they've caught something tough round the prop, as well as P brackets bent, and gear boxes pulled off! If it was my boat I'd want to check, should be easy to see. did they say by how much.
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I am aware of it happening to power boats when they've caught something tough round the prop, as well as P brackets bent, and gear boxes pulled off! If it was my boat I'd want to check, should be easy to see. did they say by how much.
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Strathglass
New member
Re: Bent Propshaft
Yes.
It is possible for a shaft to be bent, seen it more than once on hire cruisers. ( once on a 1 3/8" shaft)
It may be possible to have it trued by a good propeller engineering shop.
Iain
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Yes.
It is possible for a shaft to be bent, seen it more than once on hire cruisers. ( once on a 1 3/8" shaft)
It may be possible to have it trued by a good propeller engineering shop.
Iain
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steve28
Active member
Re: Bent Propshaft
Most definatley possible to bend them, mostly if the ropecutter hits something big at high revs or of the prop itself has hit something.
Also as others have said it may have been due to an initial weakness.
most of the time though they are only out by a few thou.
steve
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Most definatley possible to bend them, mostly if the ropecutter hits something big at high revs or of the prop itself has hit something.
Also as others have said it may have been due to an initial weakness.
most of the time though they are only out by a few thou.
steve
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FinesseChris
Active member
Re: Bent Propshaft
I bent ours reversing into a submerged slipway at Bosham. It lasted the rest of the season, vibrating a fair bit, and caused much mirth when lifted oput as the prop was at a very odd angle.
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I bent ours reversing into a submerged slipway at Bosham. It lasted the rest of the season, vibrating a fair bit, and caused much mirth when lifted oput as the prop was at a very odd angle.
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Sunnyseeker
New member
Re: Bent Propshaft
But only if it was a scissor cutter...not a shaver cutter, which has no shock loads when cutting!
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But only if it was a scissor cutter...not a shaver cutter, which has no shock loads when cutting!
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Oldhand
New member
Re: Bent Propshaft
Replacement shouldn't be that difficult. You need to source a suitable length of 318 stainless bar of the correct diameter. This has to be chosen carefully, roll what is offered by the metal supplier on a flat surface and check it is straight. Once a suitable bar is purchased get a machine shop to match the taper for the prop from the old shaft onto the new bar, cut the keyway and cut to length. Apart from installing it, check the part of the shaft that is going to run inside the stuffing box/seal for smoothness, rub with1000 wet & dry if necessary. Latter may also be a good idea for the part of the shaft that will run in the cutlass bearing.
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Replacement shouldn't be that difficult. You need to source a suitable length of 318 stainless bar of the correct diameter. This has to be chosen carefully, roll what is offered by the metal supplier on a flat surface and check it is straight. Once a suitable bar is purchased get a machine shop to match the taper for the prop from the old shaft onto the new bar, cut the keyway and cut to length. Apart from installing it, check the part of the shaft that is going to run inside the stuffing box/seal for smoothness, rub with1000 wet & dry if necessary. Latter may also be a good idea for the part of the shaft that will run in the cutlass bearing.
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supermalc
New member
Re: Bent Propshaft
The 1" shaft on my 20ft clinker was bent when I got it. I found out when first changing the prop to a left hand one, from the incorrect right hand prop that was fitted. I've since assumed the engine, a YSE12 was fitted, then not used.
Not the most precision job, but taking my boat out on a trailer, I removed the bronze shaft, and straightened it, using a portapower (tool used by car bodyshops). The shaft is worn, and the low revving shaft is good enough for the few miles I will do up and down the river. I hope to get a new shaft at a later date.
I believe my shaft may have been bent, due to the boat on a tidal mooring previous to my getting it. Sitting in the mud with the prop in the same position twice a day for years could have caused this.
<hr width=100% size=1>Malcolm.
<A target="_blank" HREF=http://geocities.com/malcsworld/>http://geocities.com/malcsworld/</A>
Take a look at my boating pages.
The 1" shaft on my 20ft clinker was bent when I got it. I found out when first changing the prop to a left hand one, from the incorrect right hand prop that was fitted. I've since assumed the engine, a YSE12 was fitted, then not used.
Not the most precision job, but taking my boat out on a trailer, I removed the bronze shaft, and straightened it, using a portapower (tool used by car bodyshops). The shaft is worn, and the low revving shaft is good enough for the few miles I will do up and down the river. I hope to get a new shaft at a later date.
I believe my shaft may have been bent, due to the boat on a tidal mooring previous to my getting it. Sitting in the mud with the prop in the same position twice a day for years could have caused this.
<hr width=100% size=1>Malcolm.
<A target="_blank" HREF=http://geocities.com/malcsworld/>http://geocities.com/malcsworld/</A>
Take a look at my boating pages.
charles_reed
Active member
I suspect
you intended to type 316.
318 is great for producing wire.
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you intended to type 316.
318 is great for producing wire.
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charles_reed
Active member
Unfortunately
all too likely - in most cases trying to straighten it is unlikely to work.
If it's less than 1.5m long far cheaper to have a new one machined.
Get a check-price off Les Hill of Lake Engineering on 01202 621631.
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all too likely - in most cases trying to straighten it is unlikely to work.
If it's less than 1.5m long far cheaper to have a new one machined.
Get a check-price off Les Hill of Lake Engineering on 01202 621631.
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