[Public-List] Hemp vs polyester

[R Kirk]

Michael... I'm curious why your boat chose dacron vs nylon for tow line. Cost? The fact that the line spends a lot of time in the water? Stretch? 
Bob Kirkex Isobar 181


-----Original Message-----
From: Michael Grosh via Public-List <public-list at lists.alberg30.org>
To: Alberg 30 Public List -- open to all <public-list at lists.alberg30.org>
Cc: Michael Grosh <dickdurk at gmail.com>
Sent: Thu, Mar 12, 2020 11:51 pm
Subject: Re: [Public-List] Hemp vs polyester

To add to Gord's great breaking strength story:  knot or splice...
A boat I worked on years ago was having issues with lines parting
prematurely, and the manufacturer wanted sample lengths to test to
destruction. We made up about 4 6' lengths and off they went. 3 of those
lengths were 2 tapered eye splices each end (a real pain in the neck to put
together) and one was the way we always spliced them-3 tucks. I have never
seen 3 tucks pull out, btw. Yes, I know the Coast Guard wants 4.
Anyway, bottom line is, there was no difference in the parting strength of
the samples, and all up to spec, the line parting issue was elsewhere.
I have always wondered what that test machine looked like, this was 9" 3
strand polyester (dacron).
I would say about 75% of the time, assuming no cuts or chafe, lines wanted
to part within 6" or so of the end of the splice. I always figured that had
something to do with the strain of opening up the lay for splicing-which
would be the arguement for tapering, but, testing, inconclusive.
Michael Grosh
#220

On Thu, Mar 12, 2020, 21:09 Gordon Laco via Public-List <
public-list at lists.alberg30.org> wrote:

> Good morning Stephen -
>
> The figure you quote is for flax, not hemp… and added to the disparity is
> that braided rope is generally stronger by diameter than twisted.
>
> Gordon Laco
> www.gordonlaco.com
>
>
>
>
> > On Mar 12, 2020, at 1:44 AM, Stephen Gwyn via Public-List <
> public-list at lists.alberg30.org> wrote:
> >
> > A quick bit of Googling suggests that 10mm hemp rope has a breaking
> > strength of 760kg vs 2600 kg for 10mm Marlowbraid polyester.
> >
> > SG
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