Scientific Sailmaking
This article was provided by Jim Frisinger of Bluffton Bay Sails, a North Sails dealer. Jim recommends the article for people who are thinking of buying new sails.
SCIENTIFIC SAILMAKING
Peter Mahr, President, North Cloth
Without a doubt, the number one feature cruising sailors look forin sails is durability. Yet durability is one of the least quantified elements in sail performance. Predicting durability is a tough challenge because sails are subjected to so many different forms of abuse, from mother nature and from their owners. Nonetheless, the most common question we hear from recreational sailors is “How long will my sails last?” Here, we’ll try to provide some answers.
Perhaps the most significant contributor to the lifespan of a sail is sailcloth. In racing sails it can mean the difference between winning and losing. In cruising sails it can mean as much or more.
While racing sailcloth has undergone a revolution over the last 10 - 15 years, cruising sailcloth has as well; taking the best ideas developed for racing and adapting them for a different task. Not only are today’s woven polyester fabrics more stable and stretch resistant than ever, cruisers can also choose from lighter, stronger polyester/mylar laminates and ultra durable high performance Spectra laminates that combine superior performance and long sail life. Today’s cruising sail has a lot more racing heritage than most sailors realize!
Whether it’s a traditional woven polyester, polyester/Mylar laminate or high-performance Spectra laminate, quality counts in any discussion of durability. Well engineered, well made sail fabrics last far longer than bargain brands. For that reason, the most economical sails to own are most often those made with “the good stuff.” Before your choose your next cruising sail, look closely at the cloth.
The longevity question
The best way to measure sail longevity is not in years of ownership, but in hours of use. Racers log hours on their sails to track the aerodynamic life of their sails (how long the designed shape will last)… recreational sailors should do the same. How many hours should you expect out of a cruising sail? Here are some clues:
Most charter fleets expect 2 - 3 years of use from basic woven polyester sails, which translates to about 1500 - 2500 hours of varied duty, typically including a high flogging quotient. Charter sails used 2,000 hours or more are typically considered “shot.”
The best way to measure sail longevity is not in years of ownership, but in hours of use. Racers log hours on their sails to track the aerodynamic life of their sails (how long the designed shape will last)… recreational sailors should do the same.
An important point: There is a big difference between a sail’s “ultimate life” — when it starts to fall apart — and its “performance life”— when it loses its shape to a point that it could benefit from recutting or replacement for optimum performance. Performance life is always shorter than ultimate life.
The record-setting ocean multihull Commodore Explorer used her FULLBATTEN
Spectra/Dyneema mainsail for 80 days, 24 hours a day, for 1,920 hard hours of use, and the sail still had performance life left.
If you assume a typical sailing season might be 30 days sailing 5 hours per day for a total of 150 hours, you might calculate that an average cruising sailor can expect 10+ years of use out of a premium polyester cruising sail.
From here, there are other factors to take into account:
Quality. We’ve all seen sails with 50 - 100 hours of use that are a mass of wrinkles, even with careful use. Low quality cloth may look comparable to “the good stuff” at first, but will break down much faster. Seams stitched properly with UV resistant thread, well designed patches and batten pockets, chafe protection, leech and foot cords all affect sail longevity.
A look at the cost/useful life of various types of sail cloth
Maintenance. Small problems left unattended become big ones later. Regular service helps sails last longer, just as it does with your automobile’s engine. Unusual conditions. If you sail in southern latitudes and don’t cover your sails, UV degradation can be significantly accelerated. Leaving a sail up and flogging in a squall for 30 minutes can equal 50 hours of “normal” sailing. Consistently flying a sail over its designed wind range can also age a sail well before its time. The life expectancy of a well-maintained airplane engine is about 1,800 hours. For an automobile engine…2,000+ hours. Many cruising sailors will probably be surprised to know that the life expectancy of their “wind
engine” is in the same range.
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