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Old 27 September 2008, 08:48   #11
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Well it's my own stupid fault but I never expected this to happen.

Although the bow eye is seriously strong the hole is quite small. I had 4 ropes through it and another 2 old ones that I hadn't bothered removing when they had snapped.

I can only assume that the ropes expanded due to water absorbtion and caused the fracture. The forces must have been immense - I would guess at about 5 - 10 tons.

When I looked at the ropes the remains of the bow eye was still in the knots - it was so tight I could not pull it out - I had to cut each rope through to remove it.

Thanks God for a strong hull - I couldn't belive that it hadn't just pulled through. When I measured the thickness of the hull there it is well over an inch thick - prob about 35mm as you can see from the position of the nuts.
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Old 27 September 2008, 19:22   #12
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How is it moored now?
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Old 27 September 2008, 19:58   #13
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I bought one of the rubbish ones with 2 crimps - the washers/plate just pulled through but the load is outwards. I am looking for a decent quality one - most seem to have these crimped "ears" and they are useless - as least supply an extra 2 nuts but I would rather a proper shoulder/collar.
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Old 27 September 2008, 21:57   #14
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Quote:
Originally Posted by codprawn View Post
Well it's my own stupid fault but I never expected this to happen.

Although the bow eye is seriously strong the hole is quite small. I had 4 ropes through it and another 2 old ones that I hadn't bothered removing when they had snapped.

I can only assume that the ropes expanded due to water absorbtion and caused the fracture. The forces must have been immense - I would guess at about 5 - 10 tons.

When I looked at the ropes the remains of the bow eye was still in the knots - it was so tight I could not pull it out - I had to cut each rope through to remove it.

Thanks God for a strong hull - I couldn't belive that it hadn't just pulled through. When I measured the thickness of the hull there it is well over an inch thick - prob about 35mm as you can see from the position of the nuts.
I believe your diagnosis to be incorrect as usual. I think you are saying that the failure was due to tensile stress caused by expanding ropes. Assuming that your U bolt was at least 3/8in. dia. it has a tensile strength of at least 20+ tons.
So when are you going to start making Bio diesel as you committed to last Jan. or was this just more Codswallop.
We aere waiting for the results
Think again
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Old 28 September 2008, 02:11   #15
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Quote:
Originally Posted by codprawn View Post
I bought one of the rubbish ones with 2 crimps - the washers/plate just pulled through but the load is outwards. I am looking for a decent quality one - most seem to have these crimped "ears" and they are useless - as least supply an extra 2 nuts but I would rather a proper shoulder/collar.
I tried working out the dimensions from the photo, but the scale seems to be just out of shot.
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Old 28 September 2008, 02:12   #16
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crevice corrosion ( stainless steel's form of rusting) http://www.corrosionist.com/Pitting_..._Corrosion.htm
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Old 28 September 2008, 08:51   #17
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I believe your diagnosis to be incorrect as usual. I think you are saying that the failure was due to tensile stress caused by expanding ropes. Assuming that your U bolt was at least 3/8in. dia. it has a tensile strength of at least 20+ tons.
So when are you going to start making Bio diesel as you committed to last Jan. or was this just more Codswallop.
We aere waiting for the results
Think again
Yes I am saying the failiure was due to the expanding ropes.

I have seen enough snapped bolts in my time to know the difference. They look exactly like a bolt that has snapped from over tightening or stretching.

Sideways forces would not have acted there as the bolt was in a hole over 1" deep and was glassed in - I had to unscrew them all the way out.

As to the biodiesel I gave up on it when the price of cooking oil hit 1.20 a litre - diesel is 1.19 at the moment. Used oil is pretty hard to get as that sells for over 0.45 a litre now.

I have a great solution now - I run on 30% neat used cooking oil - and I get contaminated diesel cheap - stuff that has been drained from tanks where people have stuck in a bit of petrol as well. The 30% oil takes care of any lube problems the petrol may cause. It saves me about 50 a week on fuel costs.
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Old 28 September 2008, 08:52   #18
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crevice corrosion ( stainless steel's form of rusting) http://www.corrosionist.com/Pitting_..._Corrosion.htm
NOT!!!
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Old 28 September 2008, 08:53   #19
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I tried working out the dimensions from the photo, but the scale seems to be just out of shot.
I will get the calipers on it later!!!
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Old 28 September 2008, 09:24   #20
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from the pictures it looked around the 12mm x 150mm .....It seemed to fail at its weakest point ...just where the crimping hammer forces the lugs into it .....

if you can find 12mm stainless U bolts that arent crimped let me know cause i'm looking for another .......they seem to call them 'sealed' and offer them in 8 and 10mm sizes .....they do make them cause i already have 1 which i got from our local chandler ...but he only had one and it was old stock he got rid of and didnt know the maker


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