Carbon fiber prop shafts on yachts?
Installation of various carbon-fiber parts on a sailing vessel is increasingly common in yacht construction. Masts, booms, poles, and even rudders are being built of this ultra-lightweight, high-strength product on vessels that are built for speed and durability. Certain motor-driven vessels, including high-speed ferries and tugboats, have recently opted for installation of carbon-fiber propeller shafts over the industry standard, stainless steel. The latter, while strong and corrosive resistant, is exceedingly heavy in comparison. For example, a carbon-fiber prop shaft was installed on a brand-new tug now serving the Seattle waterfront for Western Towboat.
"The shafts are hollow and exceedingly light," said Jonathan Parrott, a designer who assisted with the tug project for Jensen Maritime in Seattle. "Another advantage is that they don't transmit as much vibration and noise.
Will carbon fiber soon be replacing steel in sailing vessels? Not likely, according to Steve Koopman, a naval architect with Langan Design Associates in Newport, R.I., which shapes some of today's most high-tech yachts. "Most of the yachts we see that are concerned about weight savings typically have a strut-drive [sail-drive] system, which means there isn't much of a shaft involved." Sailing vessels built for speed typically have small auxiliary engines that, by extension, require small shafts.
One of the drawbacks to carbon-fiber used for prop shafts is the need to make the shaft a larger diameter. While no motoryachts have been fitted with c/f shafts to date, according to a designer with the Sturgeon Bay, Wis., yard Palmer Johnson, the technology makes sense and might emerge on certain high-speed, high-horsepower craft-likely those capable of speeds more than 30 knots, according to Koopman.