[Public-List] Hemp vs polyester

[Gordon Laco]

Stretch can be extremely dangerous in tow lines, particularly larger ones.  We supply amsteel or spectra for commercial tow lines…

Gordon Laco
www.gordonlaco.com




> On Mar 13, 2020, at 10:17 AM, R Kirk via Public-List <public-list at lists.alberg30.org> wrote:
> 
> 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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