[Public-List] Hemp vs polyester

[Mike Meinhold]

When we practice towing the 130 ton ship we designed, those aboard hide
behind the deckhouse . A snapped hawser has more than enough energy to kill
a sailor .

Mike
#272

On Fri, Mar 13, 2020 at 10:50 Gordon Laco via Public-List <
public-list at lists.alberg30.org> wrote:

> 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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