North Sails tests the capabilities of every fabric or laminate style we use on an ongoing basis. Tests include stretch, breaking strength, tear strength, measurement of the adhesive bond in laminates, evaluation of peel strength in fasteners and the breaking strength of seam stitching and bonding techniques.

All cloth lots produced by North Cloth are tested and graded prior to placement in inventory, ensuring North Cloth styles meet our stated specifications. Developmental materials are likewise tested allowing objective comparison to established products.

Cloth stretch testing has always been the key to sailcloth understanding and quality control. When Lowell North started the company in 1957 he soon figured this out and bought a stretch tester called a “Scott Machine”. Primitive by today’s standards, it was replaced in the late 1980s by a second generation of cloth tester designed and produced for North Cloth by Princeton Engineering Professor Bill Putnam. The Putnam cloth tester was the industry standard for many years. Today, North uses two sophisticated computer driven systems for cloth stretch testing.

© North Sails 1) The Instron is the industry standard, and measures elongation and loads up to ten times more accurately than the Putnam Tester. The Instron computer is programmed to eliminate error induced by chart alignment and data reading. The program also corrects for the elongation of the testing apparatus, an increasingly significant factor when testing ultra-low-stretch sailcloth or laminate samples. The speed of the Instron is remarkable, allowing us to test many more samples in a shorter period of time.

© North Sails 2) A United Calibration SSTM-2000 tester is used for 3DL laminates, performing stretch and strength testing on a regular basis. The United is a high capacity device particularly appropriate for measuring dense 3DL laminates. It is also able to isolate specific regions of a laminate for strain measurement.

© North Sails 3) United Calibration stretch tester delivers high load capacity beneficial for testing 3DL laminates, whose thickness constantly varies.

© North Sails 4) 3DL engineers have also developed a new testing device that is advancing our understanding of long term fatigue of sail cloth and laminates. The North Fatigue Simulator bends strips of test cloth or laminate over and under a series of rollers in an oscillating carriage to simulate real world luffing and flogging in sails. The Fatigue Simulator is enhancing our understanding of the gradual breakdown of sail fabrics. 

North also uses a custom hydraulic powered test setup for high-load stretch and breaking strength testing of hardware, fittings and webbing and a custom “peel” tester for measuring bonding strength of laminates.