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configurations. Initially, link plates
remained in the system, but refinements
for racing boats have eliminated
these. All the rigging components are
incorporated into a single assembly,
with the verticals and diagonals in one
piece, achieving significant weight
reductions. One company has devised
a pinned link ferrule within the fiber
bundle that separates the diagonals
from the verticals and increases weight
somewhat, but has easier replacement
methods for attached components.
New fiber rigging materials began
by replacing metal stays and now can
actually do away with other conventional
rigging hardware. Replacing
metal turnbuckles, terminal lashing
through simple open thimbles or deadeyes
is common on today’s competitive
raceboats. The technology is
visually and functionally similar
to
18th-, 19th-, and early-20th-century
rigging practices, where fiber (often
hemp) lanyards rove through hardwood
deadeyes and blocks were the
mechanism to tension fiber or wire
rope standing rigging. With both
historical and modern fiber rigging,
connections are easily adjusted and
revolution is slowly displacing more
metal components from sailboat rigs.
Modern Rigging Fiber
Let’s look at today’s major fiber
types of standing rigging, their trade
names, and trademark holders.
PBO, or poly(p-phenylene benzobisoxazole):
Zylon (Toyobo)
Sling-wound PBO stays from Navtec with
two different terminations: the top stay
has a uniball end fitting for conventional
clevis pin attachments; the lower unit is
a more modern smooth eye for tensioning
with rope strops and lashings.
repaired, but their vulnerability to
chafe requires them to be regularly
maintained and monitored. Now, even
shackles are being replaced by loops
of high-performance fiber line with a
button-and-loop end connection for
easy removal. Instructive online videos
illustrate how anyone can make these
functional and easily replaceable rigging
elements. With every additional
new application, the modern fiber
C
The New Continuous
onventional continuous rigging comprises simple individual shrouds—
uppers, intermediates, and lowers—that run from a mast fitting to the
deck, often leading over, but not fixed to, a spreader tip. Discon tinuous rigging
is a more complex system of straight cable elements with connective
fittings at each junction. As shown at right, they run from deck to spreader
tip (V1), deck to mast (D1), spreader tip to mast (D2), and tip to tip or tip to
mast (V2, V3). At each junction is a link plate that accommodates terminal
pins for attachment. In a discontinuous rig, each element is analyzed for the
calculated load and sized accordingly, which allows for smaller-diameter,
lighter-weight wire to be applied higher above the deck. This system to
minimize weight aloft is common to modern wire and rod rigging.
Sophisticated synthetic rigging has led to the creation of a new generation
of continuous rigging that includes the significant advantages of discontinuous
rigging. It combines all the standing rigging fibers into a single
shroud loom for each side of the mast, eliminating the link plates, terminals,
and pins at spreader tips. The entire shroud assembly is one piece with
multiple attachment points on the mast and one on deck. Engineering and
construction are complex, but as with any rigging, it all starts with calculated
loads and appropriate sizing of the fiber bundle to resist them. Each
piece is attached at the mast and led over an appropriate spreader tip,
where it is joined into a single larger fiber bundle that terminates at the
deck. The rig is tuned through tensioning devices at each mast terminal.
This approach has achieved significant weight reduction aloft by eliminating
much of the hardware of a conventional discontinuous rig, and reduced
windage by combining the multiple stays of conventional continuous rigging
in one element. The downsides to this system are initial cost, and if
damaged anywhere, the entire expensive assembly must be replaced.
These terms seem to be acceptable to racing-yacht owners who want the
maximum benefit of synthetic fiber rigging at any cost.
—John Marples
April/MAy 2015 49
V3
Link
Upper
Intermediate
plate
Lower
D1 V1
D2
V2
Aramid: Kevlar (Dupont), Technora
(Teijin)
Carbon: carbon fiber pultruded matrix
rods
HMPE (high-modulus polyethylene):
Spectra (Honeywell), Dyneema
(DSM Dyneema)
Heat-treated SK75 Dyneema: Dynex
Dux (Hampidjan)
Heat-treated HMPE: STS (New
England Ropes/Teufelberger Corp.)
PBO polymers, developed in the
late 1980s by the U.S. Air Force, were
employed in yacht rigging shortly
thereafter. The fibers are gold colored
and tough enough to require special
cutting tools. The cable system manufacturer
buys the fiber either consolidated
to a given size within a
continuous
rigging
New
Continuous
Discontinuous
COURTESy NAvTEC
jOHN MARPLES
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