Measuring rope diameter on old sheets

Ruffles

Ruffles

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Boat: Portsmouth, Us: Stewkley
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I'm hoping to replace my genoa sheets at the show tomorrow. The diameter of the old ones seem to be 13mm. Not 12mm or 14mm which appears to be the sizes it comes in.

Does rope get thicker or thinner over the years as it wears? I'd like to replace with the same stuff.

Also, is braid on braid the usual choice? There appears to be Matt braid and halyard braid as well. What's the difference?
 
I use 12mm which has slightly reduced in diameter over the years. Matt braid is easier on the hands but does not wear as well as the 'shiny' braid on braid. Use whichever you and your budget are happy with, they both have about the same stretch - 6% from memory. Unless you are very keen on racing you don't need to use high tech 'no stretch' rope. On the other hand I've just fitted 14mm to my mainsheet which is a bit OTT, but it's nice to handle and I got it at a very good price!
 
I was thinking they'd get thicker as the outer gets fluffier. Climbing ropes certainly do!

I might take along a sample to compare. Chances are I'll go for 12mm.

I've just discovered that the clutches I'm using for halyards should only take up to 10mm. I've got a 14mm spinnaker halyard stuffed in one of these!

Rob.
 
"I've just discovered that the clutches I'm using for halyards should only take up to 10mm. I've got a 14mm spinnaker halyard stuffed in one of these!"

Discovered similar with a genny halyard. Wondered why it was such a struggle to hoist it. Problem solved when the old clutch fell apart. Oversized halyard was probably the reason why.
 
They may get fluffier when they age, but slide a rope gauge on and maybe like mine they show about 1mm smaller than original.
Also note that prestretched is actually slightly smaller than quoted size. Size quoted is as per before pre-stretching.
 
Mattbraid is less likely to slip through wet hands but it has a slightly lower breaking point than braid on braid.

A rope diameter selection guide can be found here
 
Depending on age, they could apparently be imperial - or at least imperial equivalent.

I am too young to have experience of this change in rope size, but was told this by a local chandler when going through the same process. Others (older than me) hopefully may be able to confirm or deny this theory!
 
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The diameter of the old ones seem to be 13mm. Not 12mm or 14mm which appears to be the sizes it comes in.

Does rope get thicker or thinner over the years as it wears?

Also, is braid on braid the usual choice? There appears to be Matt braid and halyard braid as well. What's the difference?

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General ropes like polyester halyards gets thinner after they've been used due to the fibres bedding down as they stretch. So I would expect your 13mm halyard was originally 14mm.

One thing to be aware of here. If your 'halyard' was bought at a boat jumble, or an event like that it could quite easily be a climbing or abseiling rope. These ropes come in un-usual diameters eg 9.5mm, 11mm etc. All marine ropes are generally even numbers going up in twos (6mm, 8mm, 10mm, 12mm, 14mm, etc).

Don't get confused with all the braided rope trade names used in the marine leisure industry like Mattbraid, yacht braid, halyard braid, marlowbraid, Ebraid etc. Unless you're racing and want the fancy Dyneema halyards, then there are only 3 general halyard types you need to look out for if cruising. A chandlery should have them labeled up, but if they don't then ask to see the product book so you can determine the core construction.

1 Polyester braid on braid AKA double braid. As it says it is a polyester braided cover on a polyester braided core. Cheapest and most widely used cruising halyard, and easiest to splice.

2 Polyester braid cover on polyester twisted 3 strand core.

3 Polyester braided cover on polyester parallel filament core.

2 and 3 perform better than number 1 (i.e. less stretch), but cost more.

As mentioned earlier. If buying braided 'Halyards' from a boat jumble, unless you're in the know it's very difficult for the average person to tell a marine rope from a climbing / abseiling rope. I have known a few people who have bought a dynamic (stretchy) climbing rope for use as a halyard! A lot of climbing ropes have 7 small individually twisted ropes inside the cover.

The only real way of finding out what you have purchased at a boat jumble (unless you can tell by refering to a brochure, the manufacturers flecked yarns and rogue yard on the cover), is to cut the heat sealed end off, pull out the core to see what is it's construction. Then do a burn test and a specific gravity test on the core material and maybe the cover material as well.
I can't see the stall owner letting you do this, so it's a case of buyer beware at jumbles.
 
Genoa sheets are as much down to handling/fitting your winches (if S/Tailing) rather than strength, 12 mm more than adequate for 31' boat.

Look at rope-celler stand at the show; lots of offers there.
 
for some reason I went off on a tangent about halyards instead of sheets but most of it still applied.

And yes you're also right about feel, grip and fitting the self tailer.
 
When buying rope for halyards / sheets it's IMHO advisable to only buy Pre-Stretched - which is generally 0.5mm less actual size than quoted due to the stretching.

I have been on boats that people have bought "off-peg" unstretched rope and I have known immediately when having to sweat up halyard later after setting.
So you can even check if Pre-Stretched or not ... go to good chandlers with reasonable rope shack. Run your rope gauge around stock and see if you can ID which. Look for rope that is slightly ... 0.5 - 1mm is average reduction ... below stated.
 
I think I would differentiate between sheets and halyards. I've no quarrel with pre-stretched for halyards. Sheets, however, particularly genoa sheets, are a bit different: ease of handling matters, and matt braid is more easily gripped than pre-stretched. Similarly, for handling comfort, the genoa sheet diameter is likely to be greater than that required simply to handle the load.
 
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I think I would differentiate between sheets and halyards. I've no quarrel with pre-stretched for halyards. Sheets, however, particularly genoa sheets, are a bit different: ease of handling matters, and matt braid is more easily gripped than pre-stretched. Similarly, for handling comfort, the genoa sheet diameter is likely to be greater than that required simply to handle the load.

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You can have pre-stretched in any construction rope you want. Sounds like you consider the PS is only in some forms ?
 
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