NOVEMBER 2017 http://www.yachtingmonthly.com 67The higher the average break
load of a rope is, the stronger
it is. Right? Not necessarily as
Graham Snook finds out.
I
t would seem common sense that a
Dyneema cored rope, with a break
load of 5.3 tonnes would always be
stronger than three-strand polyester
with a break load of 2.6 tonnes. But if you
were, for example, to tie a buntline hitch
in the end of both and destruction test,
the Dyneema cored rope would fail fi rst,before the rope with half of its break load.
Knots in ropes make them weaker.
How much weaker depends on the
material the rope is manufactured from,
the construction of the rope and the knot
tied in it. Of the four rope types tested,
taking the average loss of the nine knots
we tested, the rope with a 7mm Dyneemacore lost over 62% of it’s strength,
whereas the three-strand polyester
retained over 60% of it’s strength.
The strongest way of attaching a rope
to something is with a splice, however
splices aren’t always easy or possible in a
number of circumstances, so knowing the
best knot to use from a selection of easily
tied knots would be an advantage.
The purpose of this test was to fi nd out
how much strength a rope loses when a
certain knot is tied in it, and which knot
is strongest in which rope. There are
thousands of knots, many of which you’d
need a diagram to actually tie, so I set
out to fi nd easy-to-tie knots, or simple
variations, which may improve the knot.
Owing to the number of applications
ropes have on yachts, I reduced them
down to the three most common:
attaching a line closely to a shackle or
fi xed point, making a loop, and joining
two ropes together. I only tested joining
two ropes together with a style of rope
where this would actually happen: a
genoa sheet or halyard with a knot in the
middle is of little practical use.WHICH KNOT IS STRONGEST? TECHNICAL
All the knots were tested to failure on Marlow Ropes' test machine in HailshamHow much
strength do
knots take
from your rope?
ALL PHOTOS: GRAHAM-SNOOK.COM