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Weak Link


eid

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37 minutes ago, blackrose said:

I've never had a problem with cable ties degrading (unlike string). But I use 10mm wide cable ties. 

Black cable ties are UV resistant, white ones are not!

 

 

I never used to use a bow fender when doing flights of locks,  the bow on its own was much better shape for riding gates. Oh,  and the bylaws just say fenders should be ready to be deployed not that they should be used ;)

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I also quite like the idea of a brass shackle,but what size of brass shackle? I did have a look for failure loadings on brass shackles on the www a while ago but found nothing.

 

I suspect a possible issue is that hanging up in a lock is a static load, but driving into a lock cill at low speed is a dynamic load and depending upon the exact shape of the nose of the boat can give a very high transient  load.

 

..............Dave

 

 

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12 hours ago, dmr said:

My concern about a half cut through shackle (or chain link) is that failure requires the steel to actually break under tension and steel is much much stronger in this mode.

 

Dead right.

 

I cut about 90% of the way through a link i my bow fender chain and the boat was about a foot under normal level when the link finally gave way, when I was gassing to BiL and it caught in the gate without me noticing. I know this from the wet water line on the hull, and the size of the wave that ran up and down the lock after. 

 

 

 

 

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We shared a few locks with a hire dayboat yesterday, and with a new boater the day before, and we have had a couple of potentially scary moments ourselves on the Rochdale. There is a lot of stuff that can go wrong in a lock so I would like to get the weak link really sorted out.  The gunnel under an overhanging stone lock wall is the really difficult one. I think continuous moorers probably have the best approach. :)

 

.................Dave

 

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Another point is when one breaks a weak link, there is an obvious and immediate need to re-make the link in order to continue with one's journey. This means one needs to carry some sort of repair kit too. This need doesn't become obvious until one actually breaks the link and the bow fender hangs down off to one side. You can guess what makes me say this...

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12 hours ago, Loddon said:

 

 

 

. Oh,  and the bylaws just say fenders should be ready to be deployed not that they should be used ;)

Sorry not quite true. This is the actual wording from the Bye Laws:-

 

Vessels to have fenders ready for use


6. Every vessel navigated on any canal shall have ready for
immediate use proper fenders of suitable material and in good
condition and the master of such vessel shall use such fenders
whenever there is a risk of the vessel striking against any other
vessel or against any wall, lockgate, bridge or other thing.

 

Shall use, not just deploy. (my bold)

 

Howard

 

 

 

Edited by howardang
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1 hour ago, Onewheeler said:

Empirically, a 25 mm brass shackle does the job. One can overanalyse a problem.

Thats a very big shackle :) I was thinking of about 5mm.

 

.............Dave

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3 minutes ago, Mike the Boilerman said:

 

Surely that would be ridiculous small.....

 

:giggles:

 

I was just making a silly smart-arse forum post. I believe shackles are specified by the thickness (diameter) of the steel in the arch of the shackle so a 5mm shackle is what most of us would call a 25mm shackle.  There are lots of cheap Chinese brass shackles on ebay so I will try some. The big attraction of the cut chain link is that it starts to open under  "almost accidents" of bigger impacts so you can see that its not to strong. A shackle deforms under stress but its not easy to see if its got close to actual failure.

 

................Dave

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1 hour ago, dmr said:

I was just making a silly smart-arse forum post. I believe shackles are specified by the thickness (diameter) of the steel in the arch of the shackle so a 5mm shackle is what most of us would call a 25mm shackle.  There are lots of cheap Chinese brass shackles on ebay so I will try some. The big attraction of the cut chain link is that it starts to open under  "almost accidents" of bigger impacts so you can see that its not to strong. A shackle deforms under stress but its not easy to see if its got close to actual failure.

 

................Dave

Is it the arch or the pin?

I always thought it was the diameter of the pin if you have to do it that way.

Proper shackles are specified by SWL ;)

 

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2 hours ago, Mike the Boilerman said:

Another point is when one breaks a weak link, there is an obvious and immediate need to re-make the link in order to continue with one's journey. This means one needs to carry some sort of repair kit too. This need doesn't become obvious until one actually breaks the link and the bow fender hangs down off to one side. You can guess what makes me say this...

This is where the various "come in handy" bits of rope "come in handy"!  :D

 

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4 hours ago, howardang said:

Sorry not quite true. This is the actual wording from the Bye Laws:-

 

Vessels to have fenders ready for use


6. Every vessel navigated on any canal shall have ready for
immediate use proper fenders of suitable material and in good
condition and the master of such vessel shall use such fenders
whenever there is a risk of the vessel striking against any other
vessel or against any wall, lockgate, bridge or other thing.

 

Shall use, not just deploy. (my bold)

 

Howard

 

 

 

Yes but you missed off the next bit - whenever there is a risk of the vessel striking.......  so ready to deploy when there is a risk.......   so touching gently onto (for example) a lock gate, then gently sliding up or down would probably not constitute ‘striking’ though one could argue that there was still a risk.

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11 minutes ago, Chewbacka said:

Yes but you missed off the next bit - whenever there is a risk of the vessel striking.......  so ready to deploy when there is a risk.......   so touching gently onto (for example) a lock gate, then gently sliding up or down would probably not constitute ‘striking’ though one could argue that there was still a risk.

Oh no I didn't.  I think if you look more closely you will see that I did quote the section in full, and didn't miss anything off.  If you want to make the rule say what you want it to say then please go ahead, it's your prerogative,  but don't try to split hairs, by misrepresenting what I said.  

 

Howard

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5 hours ago, howardang said:

Shall use, not just deploy.

Yes, but only...

5 hours ago, howardang said:

... whenever there is a risk of the vessel striking against any other vessel or against any wall, lockgate, bridge or other thing.

Does riding a lock gate constitute ‘striking’?

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22 minutes ago, WotEver said:

Yes, but only...

Does riding a lock gate constitute ‘striking’?

Not necessarily, but the rule says “risk of striking” and that of course relies on the judgement of the “master” at the time. I suggest that it will be up to him/her to justify any damage caused, especially if no fenders are used.

 

Howard

 

 

 

 

 

 

Edited by howardang
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