Science of Seamless
Since we opened our doors in 1980, there's been
only one way to do things at Hall Spars & Rigging
– the best way. Only the best people, the
best tools, best methods and the best materials
give you the best results.
Each Hall factory uses the identical Seamless process,
refined over our 30+ years in business. No one has
more experience with carbon than Hall. Experience
translates into ever-improved laminate quality as
well as continued innovation in engineering and
Expert engineering is the foundation of every Hall
project. Our Rig Calculation Program (RC Sheet),
Finite Element Analysis (FEA) and advanced solid
modeling tools allow accurate evaluations of designs
before they’re built. To create an expertly
engineered spar, we consider everything from the
mast/sail combination to the overall construction
of the yacht.
We work seamlessly with both yacht and sail designers
to ensure that the mast/rigging’s weight and
center of gravity are exactly right for the boat
and that the stiffness and bend characteristics
are correct for the sails.
Hall builds seamless tubes by laying up unidirectional
pre-preg carbon around a male mandrel. Each mandrel
is shape-optimized by Hall's engineers. Mandrel
molding requires exceptional composite skills. Hall’s
unique ability to apply unidirectional carbon fiber
under tension is the key to turning our complex
strength and bending performance predictions into
With mandrel molding all unidirectional pre-preg
material is applied continuously, without interruption
along the length of the tube, ensuring strength
continuity. Longitudinally applied material resists
compression and bending loads. Continuous “off-axis”
layers are applied in alternating directions resisting
twist while adding compression and bending strength.
To maintain mast section shape integrity (and again,
strength) 90-degree layers are wrapped continuously
around the circumference of the mast.
In Hall’s proprietary process, virtually
every layer of carbon is carefully compacted (“de-bulked”)
before the next layer is applied, ensuring wrinkle-free
laminates while minimizing voids even in thick-walled
Mandrel-molded, seamless masts have tooled, smooth
inside surfaces, providing highly accurate surfaces
for internal mounting of close-tolerance computer-machined
fittings. And halyards love the baby-bottom smoothness
of the inner tube surfaces.
Pre-preg materials promise very accurate laminate
thicknesses (many times within fractions of a millimeter)
and outside surfaces so smooth they can be clear-coated
without the need for weight-adding fairing. To optimize
overall bend characteristics, strategically applied
layers are placed exactly where needed, maximizing
tuning and performance potential.
Modulus describes the potential strength and stiffness
of carbon spar materials. The higher the carbon
modulus, the stiffer the tube, enabling reduction
in the size of the mast section and its overall
weight. There is a wide range of carbon fiber material
on the market today.
At Hall we work mainly with four specific classifications
of carbon modulus (stiffness): standard modulus,
intermediate modulus, high modulus, and ultra-high
modulus. As material modulus increases, performance
increases (more stiffness/less weight). Hall’s
mandrel molding process is ideal for all these materials,
even with the process-sensitive more brittle ultra-high
Hall Seamless masts are always cured in an Aerospace-grade
autoclave. Autoclaves cure laminates under elevated
temperatures and pressures. The reason for autoclave
curing is simple: it eliminates strength-sapping
tiny air pockets called voids. Curing with vacuum
(atmospheric) pressure alone yields laminates with
over 3% void content. Autoclave curing, at 6 times
atmospheric pressure, reduces the laminate void
content to less than ½%. The strength difference
is close to 20%.
An additional benefit with mandrel molding is that
when the mandrel expands as heat increases, fibers
are stretched straighter. In composites, fiber straightness
is key to strength and stiffness.
Refined Details and Aerodynamic Shape
The key element in rig/sail aerodynamics is the
mast’s ability to bend optimally for sail
design shape at minimum weight. The Hall Seamless
process maximizes mast stiffness-to-weight ratios.
At the same bending stiffness, female molded masts,
with the required baggage of two full-length lap
joints - with attendant glue, screws, and filler
- cannot match the minimum weight of Hall Seamless
masts. And as everyone knows, lighter is always
Our commitment to total performance extends well
beyond the mast tube to the smallest of details.
Knowing that a scant millimeter difference can mean
a speed gain, we work closely with the boat and
sail designers to optimize the relationship of mast,
sail, and boat.
Welcome to Seamless Performance
With Hall Spars, you always get the ultimate in
high performance. The mast fits your boat, your
sails, and your crew as soon as it's stepped. Our
commitment to total performance shows in the incredible
race record of our masts and in their record of
No matter where you travel, a Hall expert is nearby.
The most demanding sailors in the world put their
trust in Hall. Whether your goal is to be first
across the finish line or first into the best anchorage,
Hall has the high-performance products for you.
We invite you to visit any of our factories and
see for yourself the power of Seamless performance.