Dacron sleeving

Dacron sleeving

Post by Andrew Beatt » Wed, 04 Aug 1993 16:58:42


Quote:

>The only thing I use dacron for is [...] sleeving Spectra..

I've stopped using it even for this.  I broke a 275lb line at the weekend
that was sleeved in Dacron.  The lines were quite new and they broke on
the knot inside the sleeving at much less than 275lb.  I would guess that
they broke at about 50lb.  I strongly suspect that the dacron sleeving
abraided the Spectra, leading to the breakage at such a low strain.  I am
now using softer, less abrasive and thicker sleeving (I'm not sure what it
is, it is just the thickest line that my kite store has, with the centre
removed).

A while ago, I reported that I once dropped my 6 flexies on a stunt
kite flying on Dacron line.  The flexies were bridled with 4mm diameter
rope (from a boat shop).  We didn't fight, the stack just fell on the line
and the 80lb dacron slid to the bridle point and then cut through the rope
till it was stopped by the metal O-ring.

Andrew
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Dacron sleeving

Post by Marty Sasa » Wed, 11 Aug 1993 01:40:44

Quote:

>I've stopped using it even for this.  I broke a 275lb line at the weekend
>that was sleeved in Dacron.  The lines were quite new and they broke on
>the knot inside the sleeving at much less than 275lb.  I would guess that
>they broke at about 50lb.  I strongly suspect that the dacron sleeving
>abraided the Spectra, leading to the breakage at such a low strain.  I am
>now using softer, less abrasive and thicker sleeving (I'm not sure what it
>is, it is just the thickest line that my kite store has, with the centre
>removed).

Abrasion may play a part, but there would not be abrasion if the knot
was tied properly. The folks that study these things, say that a line
breaks at the knot only after the line has slipped first. Spectra has
a low enough melting point that the heat from line slipping may be
enough to weaken the line significantly.

The solution is to be sure and tighten knots snugly. Since I started
being extra careful with my knots I have had no lines break at the
knot.
--
Marty Sasaki            Harvard University           Sasaki Kite Fabrications

617-496-4320            10 Ware Street               Jamaica Plain, MA 02130
                        Cambridge, MA 02138-4002     phone/fax: 617-522-8546