[MHml] Synthetic Rigging

[Dan Frenette]

Weave has a lot to do with this as well. Spectra is slick. It's good for 
things like wiping, and connection points. I don't use it for halyards 
and stays.

Technora basically sister to Kevlar seems to be a bit better but the 
black coating turns to gold over time and at that point the UV has it's 
way. However with a 12 strand mono style creeps about 8 or 9" a year on 
my stay.

I tried to do my own prestretch but didn't seem to make any difference 
even with shrink tube put on under load. On it's third season it didn't 
seem to stretch more than about 6". It's time however to resplice it 
shorter.

The problems with going with straight line through the middle presents 
some huge problems splicing to a fitting. On stays I don't use knots. On 
halyards I don't have the windage problems so a bit thicker to allow for 
a knot isn't normally a problem.

For halyards parallel core may have a scaling problem. Those fibers may 
need some twist on very long halyards but this is pure speculation on my 
part. I haven't read anything to back that up.

Dan Frenette


Bill Gibbs wrote:
> Actually rope manufacturers do talk about creep.  And claim big improvements since 1988.  
> 
> http://www.thecortlandcompanies.com/psrope/SpectraandPlasmaRopesrev2.pdf
> 
> Describes a 3/8" spectra line loaded to 22% of published min breaking strength which showed no creep for the first 10 days of
> loading, that's 240 hours.  They continued the test for 3 years and creep did continue.  They also provide graphs of fiber tests
> showing the differences in modern spectra types and at different loading percentages.  Keeping sustained loading to 10% dramatically
> reduces creep, like 1/5 as much as at 20% loading.
> 
> Does spectra creep?  Yes.  "Inches" in "minutes"?  Doesn't seem like it.  Seems like it should be a small percentage of elastic
> stretch for the time periods that most of us sail.
> 
> Disclaimer - I don't currently have spectra halyards on commonly used sails.  Main halyard is galvanized wire w/ a mast head lock.
> #1 jib & screacher is Samson Validator SKB, Dyneema/Vectran blend, same as Lightning single braid.  
> 
> Bill
> Afterburner
> 
> 
>  Bill Gibbs wrote:
>>  > On the other hand, what's the big deal with creep?  As the wind
>> strength increases, I have to adjust halyard tension anyway.  How do
>>> I tell whether this is from elastic stretch in the sail and halyard, or 
>>> from creep?  Why should I care?
>> ------------------------------------
> snip
> 
> Spectra has no place as a halyard.  (My opinion)  I mistakenly used a 
> Dyneema halyard (similar to Spectra, but slightly less creep) and it drove 
> me nuts.  I'd tension the halyard and in 10 minutes my beautiful Calvert 
> Main's luff would look like the gathering on a curtain. 
> 
> Snip
> 
> CS 
> 
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