Do Halyards Shrink ?

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Jim@sea

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The boat I am improving (23'6 Colvic Watson) has a Kemp Mast and whilst the mast is on the floor I want to renew the Halyards.
I took the old ones out and threaded a temporary rope through.
Using a Vernier Gauge shows that the old ones are 8mm in places and 9mm in other places. But as the boat is 30 years old it would have been an Imperial measurement.
But at a chandlers today I saw some 10mm rope which looked better and with a Vernier Gauge measures out at 9.5mm
And the cheap (Builders Merchant Polypropylene) which I threaded through measures 10mm and it goes through the block things at the top.
Some of the original Halyard is worn and perhaps stretched
So the question is, A.
Can I go to 10mm or should I order 8mm as it appears that you cant buy 9mm
Should I ring Kemp Masts and ask them what size rope to use.
 
8mm is more than enough for the halyards. You don't handle them as much as sheets so there is no point in going bigger . Check the sheaves while you have the mast down, particularly for wear or seizing of the pins.
 
VicS said:
Kemp masts are now Selden

ITYWF that prestreched rope is in fact a little smaller than the nominal size. So prestretched 10mm is probably nearer to 9mm.

8mm polyester will be adequate for a boat that size.
http://www.jimmygreen.co.uk/p/techn...ical-articles-/sheets-and-halyards-size-guide

Whatever you buy be sure that it is not too large for the sheaves, turning blocks etc
Click to expand...

to add to VicS's comment.
The smaller the rope diameter the easier it runs - all my halyards are now UHMWPE - 2mm smaller than the originals - except for the main which is 12mm just like the original, frangible Kevlar.
 
I go with thicker ropes these days. They are kinder on the hands and arthritis is very unforgiving. Even my reefing pennant on the headsail is 12mm (the core has been removed from the length that wraps round the drum).
 
The heading "do halyards shrink" is very debateable. It will depend of course on the material that the halyard is made of. generally Halyards do not shrink however over a period of time they can and usually STRETCH. Hope that this may be of some help to you.
 
Hi Jim,

In answer to your original question, halyards can shrink. I have exoerience of this on my daughters 29er skiff where a new main halyard shrunk by about 25mm in the space of about 6 months, the rope was/is Excel D12 which you would not see on most crusing boats. We think the problem is UV light.The other problem I have experienced of some ropes going oval or even flat under heavy load whih can cause prolems passing though blocks etc.

The big question on size is related to strenth, obviously a thinner rope wil not be as strong as a thicker one of the same material but if you compare rope of different materials you will find or example that, say 8mm polyester has a breaking load of about 1.4 tonnes whilst a racing dyneema of the same size will be nearly 4 tonnes! I can't imagine you woud get close to even the lowest of these figures on a boat twice the size of yours. Polyster will stretch considerably under load so if you don't want a sagging jib luff I would go for something with a dyneema core and 8mm will be fine. If you are on a budget you might be abl to go thiner than that, often you can find bargins at boat jumbes and if pushed you woud be fine with a non-dyneema cre on the main halyard.

Give Jimmy Green Marine a call. I have found them full of useful advice, they have bee in tis businessfor a long time and they often have end-of-reel discounts too (no, I don't have any connection/interest).

Cheers, Dave
 
Most often halyards stretch along it's length, but when they stretch the diameter will decrease (shrink).
But ropes can also increase in diameter because the material get more "fluffy" when exposed to sun and weather.

Getting a reliable sizing of a new halyard by measuring the old rope is not easy.
As others here have already written, look at the sheaves and other related hardware and size based on that (and size of boat).
Type of fiber in the new rope will also be a part of that decision.
 
Jim@sea said:
The boat I am improving (23'6 Colvic Watson) has a Kemp Mast and whilst the mast is on the floor I want to renew the Halyards.
I took the old ones out and threaded a temporary rope through.
Using a Vernier Gauge shows that the old ones are 8mm in places and 9mm in other places. But as the boat is 30 years old it would have been an Imperial measurement.
But at a chandlers today I saw some 10mm rope which looked better and with a Vernier Gauge measures out at 9.5mm
And the cheap (Builders Merchant Polypropylene) which I threaded through measures 10mm and it goes through the block things at the top.
Some of the original Halyard is worn and perhaps stretched
So the question is, A.
Can I go to 10mm or should I order 8mm as it appears that you cant buy 9mm
Should I ring Kemp Masts and ask them what size rope to use.
Click to expand...

Hi Jim

I use 10mm briad on braid on my CW 23'-6" and my best advice is do not buy from a builders merchant, buy the right halyard (and get an eye put in the end) (to attach to the sail ) as that's one rope you do not want to break !

Mike
 
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