Carl Stahl: Stainless steel is not on the ropes
ZAANDAM _ The carbon-and-synthetic-fibers revolution is taking no hostages as it replaces traditional rope, sail and spar materials fore and aft. Dyneema _ an Ultra-high Molecular Weight Polyethylene (Gesundheit!) _ has lately set its sights on standing rigging with a strong-as-steel synthetic wire developed for permanent, deep-water moorings. Is stainless steel on the ropes in yachting?
Not at all, says Merijn Ruiters, Product Manager Water Sports at Carl Stahl Benelux B.V. “The vast majority of recreational sailors opts for steel wire rigging,” Ruiters tells the trade magazine Jachtbouw Nederland. “It’s far cheaper than synthetic versions. We’ll always have steel.”
Ruiters sees carbon and synthetic being of interest to only a small market segment. Stainless steel has been around for a century and continues to be developed into high-end variants. A wire is typically made of 19 strands. A more expensive ‘compacted strand’ version has a higher breaking strength and less stretch and weight.
Stainless steel is not totally immune to corrosion or magnetism. Its molybdenum content determines the extent to which it oxidizes. The alloy is very lightly magnetic and attracts air-borne dirt particles that can settle at the collar of the terminal. In rigging of 16-mm and up, the terminal may get a silicon collar to ward off water running down the strands. Ruiter advises not to polish stainless steel with scrub side of a sponge and to treat it with a Teflon spray to protect the surface. Carl Stahl gets its cables from South Korea. It carries out quality checks in a climate chamber into which salt water is misted.
How long does steel rigging last? “If you put a load on a cable exceeding 50% of the breaking strength, the material will age quickly which makes the wire more susceptible to corrosion.” Says Carl Stahl Benelux Managing Director Danny Hol. “Exposure to salt, sun and high temperatures accelerates aging as can particulate airborne matter _ from a rust source next to a boat’s berth, for instance. The naked eye cannot see if the terminal connection is still good. An X-ray survey can, but that’s expensive and only done on big ships with stays that can each cost several thousand euros.”