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The 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 process.

Expert Engineering
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 reality.

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 tubes.

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.

Carbon Modulus
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 modulus materials.

Autoclave Curing
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 faster.

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 longevity.

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.


Hall US
33 Broadcommon Road, Bristol, RI 02809 USA
+1 401 253 4858 // infonz@hallspars.com
Hall BV
Deltahoek 42, 4511 PA Breskens, Holland
+31 117 381397 // infobv@hallspars.com
Hall NZ
100 Foundry Road
Silverdale 0932 Auckland, New Zealand
+64 9 427 5472 // infonz@hallspars.com

NORTH AMERICA +1 401 253 4858
EUROPE +31 117 381397
PACIFIC RIM +64 9 4275472
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