When is 12mm not 12mm?

Dazedkipper

Dazedkipper

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When it's rope and blocks it would appear.

Treat myself to some new Barton size 5 fiddle blocks a while ago for the mainsheet, rated to 12mm max line size. The other day I bought some new Liros 12mm 16 plait Matt rope, lovely until I tried to put the two together and found the rope too big for the blocks. Back to Foxes to double check, yes my rope was definitely off a reel marked 12mm and the blocks are definitely rated for 12mm. We then did some trials and found that my 12mm rope fits nicely in Barton's size 4 blocks which are also rated to 12mm, how odd? We then tried some 12mm braid on braid and found it just fitted my size 5 blocks, and I do mean just.
So I took it up with Barton who, in the past have been very helpful but this time fell short of expectations. They couldn't explain why one range of 12mm blocks were ok but another weren't, not until I pointed out they have different sheave sizes anyway. They obtained some braid on braid from a local chandler and sent me photos of it reeved through the size 5 blocks, also one showing it being measured by vernier at 12mm. At their request I then measured my new rope, it was dead on 14mm, ah they said you have the wrong rope, no I replied it's 12mm, and we went round in circles! To be fair they did offer to swap, plus cash adjust, my blocks for bigger ones to suit the rope but they would have looked silly on my 29 footer and anyway my blocks have been in the boot of the car for a while so no longer pristine.
I then took it up with Liros who couldn't have been more helpful, a phone call with their area sales mgr discussing how rope sizes vary between types as well as makes and the offer of a free replacement length of 10mm rope, which naturally I accepted.
So I'm a happy bunny, rope and blocks now fit together!
The lesson learned, well rope sizes do vary from stated and blocks, well I think they do too so when buying in future I'll fit the two together before making a decision.
Finally, a big thank you to Liros.
 
Some rope also flattens and gets wider as it goes around a block, under tension.
Can be a hard to find source of friction.
 
' I then measured my new rope, it was dead on 14mm, '

I think there's your answer; I have found Barton a very reliable company and they've been going for decades; hardware like blocks can't vary much, rope from cheap suppliers can...
 
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Seajet said:
' I then measured my new rope, it was dead on 14mm, '

I think there's your answer; I have found Barton a very reliable company and they've been going for decades; hardware like blocks can't vary much, rope from cheap suppliers can..and frequently does.
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there, fixed that for you - one reason I avoid cheap rope
 
Sorry, are you saying Liros is cheap rope?! Are you inferring that Foxes sell cheap products?

In my opinion Liros is on a par with Marlow and English Braids.

If I'd bought unbranded rope from a jumble I'd agree with you but not in this instance. I think your comments are unwarranted and rather insulting.
 
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I don't understand the bit where you measured your 12mm rope, and it measured 14mm, (not 12mm?). You then got some free 10mm rope, which went through your 12mm sheaves fine.

Wasn't the problem because your 12mm rope actually measured 14mm, or am I missing something?
 
Richard10002 said:
I don't understand the bit where you measured your 12mm rope, and it measured 14mm, (not 12mm?). You then got some free 10mm rope, which went through your 12mm sheaves fine.

Wasn't the problem because your 12mm rope actually measured 14mm, or am I missing something?
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In a nut shell yes.

My whole point is don't take the quoted sizes as being the actual physical size, rope manufacturers quote a rope size when it's under load, 30% IIRC, which can be less than it's unloaded size due to the tightening effect as it's loaded. Block manufacturers work on exact dimensions, although that doesn't explain why one 12mm block had more capacity than another.
 
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In answer to your title, when it's 14mm. You are complaint about a 14mm diameter rope not fitting a 12mm block and blaming the block? If a rope supplier marks 14mm dia rope as12mm as it shrinks 10% under load then how will it fit a 12mm block when not under load? I think the answer is buy rope 12mm when not under load or get bigger blocks to fit the rope you want...
 
Dazedkipper said:
In a nut shell yes.

My whole point is don't take the quoted sizes as being the actual physical size, rope manufacturers quote a rope size when it's under load, 30% IIRC, which can be less than it's unloaded size due to the tightening effect as it's loaded. Block manufacturers work on exact dimensions, although that doesn't explain why one 12mm block had more capacity than another.
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Aha! So the 10mm rope is actually 12mm when not loaded.

I would want my rope described as it is when coiled up. If it gets thinner under load, so be it.
 
neilf39 said:
In answer to your title, when it's 14mm. You are complaint about a 14mm diameter rope not fitting a 12mm block and blaming the block? If a rope supplier marks 14mm dia rope as12mm as it shrinks 10% under load then how will it fit a 12mm block when not under load? I think the answer is buy rope 12mm when not under load or get bigger blocks to fit the rope you want...
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No, I bought 12mm blocks and 12mm rope in good faith that the two would work together. Unfortunately the two manufacturers are working to different standards, I can't believe I'm the only person that this has happened to?
Liros explained the situation and offered a solution. Barton didn't even know ropes differ in size nor that they make blocks with supposedly the same capacity but are in fact different, that I found odd and surprising because I have always found them to be on the ball in the past.
 
12mm blocks with only 11.5mm clearance between becket and sheave, how does that one work then? Oh yes, under load of course, but then how does the rope run freely when not under load? It doesent!
 
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trapezeartist said:
This does seem a little unfair on Barton. They make 12mm blocks which are 12mm and they are criticised. Liros make 12mm rope which isn't, and they come out smelling of roses.

It's a funny old world.
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Actually they quote a maximum rope size, not a physical clearance. Therefore one would expect it to take a rope that is of that size, not smaller.
 
neilf39 said:
In answer to your title, when it's 14mm. You are complaint about a 14mm diameter rope not fitting a 12mm block and blaming the block? If a rope supplier marks 14mm dia rope as12mm as it shrinks 10% under load then how will it fit a 12mm block when not under load? I think the answer is buy rope 12mm when not under load or get bigger blocks to fit the rope you want...
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Indeed, but do you go to a chandlery armed with a vernier calliper or a gauge to measure rope diameter or do you just read the label on the reel, or even just ask for a particular size?
 
Much better to be at the bottom of the rope diameter for any given block. Less friction.
But then I only allow Harken onto the boat for any serious use.
 
Ropes, even hitech expensive stuff can differ slightly in size when new. Once it's been put under load for a bit it should all bed down to what it should be. One solution can be to only buy prestretched stuff, but that adds cost and is often a bugger to work with.
 
Woodlouse said:
Ropes, even hitech expensive stuff can differ slightly in size when new. Once it's been put under load for a bit it should all bed down to what it should be. One solution can be to only buy prestretched stuff, but that adds cost and is often a bugger to work with.
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Yes I can see that BUT how does one know what size rope to purchase in the first place? Taking my experience, if the "correct" size binds how does one overcome that until the size has been attained.

Incidentally, I always use pre-stretched, non is like using elastic bands!
 
Seajet said:
trapezeartist,

that's what I was getting at; having worked at a chandlery and been a consumer for over 4 decades, I have only good things to say about Barton !
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I think the fact that I've spent over £1000 on Barton deck gear in the last couple of months is a good indication as to what I think of their products, don't you?!
 
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