Fuel costs spark talk of kite power

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Developers in Hawaii say they’ve mastered the right wind technology to power the future

Developers in Hawaii say they’ve mastered the right wind technology to power the future

In Hawaii, where the seaways are interisland highways, Dan Tracy has found that kite-sails reduce the cost of running a boat so dramatically that he plans to fish commercially under kite power.

“We’ve got trade winds here 300 days out of the year,” says Tracy, 28, a co-founder of Kite for Sail LLC, a Maui company devoted to developing advanced wind propulsion technology.

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Hawaii’s fuel prices are fourth-highest in the nation, and with prices of more than $4 a gallon at the fuel dock, Tracy envisions the islands’ charter fishing boats, ferries, and tugs and barges — the workhorses of interisland commerce — operating under kite-sail one day.

Tracy and partner Ian Fisher started testing their kite-sail system on a Hobie 18 three years ago and since have retrofitted a Corsair 24 trimaran (sans mast) with an 18-square-meter kite-sail as its primary power source. The pair power up with the kite and troll for ono, mahi-mahi and tuna off Maui’s north shore, demonstrating to local charter captains how kite-sailing can work for them.

Tracy says the Corsair, dubbed Shark Pit, makes 7 to 10 knots without its engine in a 4- to 8-foot swell and 15- to 20-knot winds with four crewmembers aboard and two trolling lines in the water. A charter-fishing powerboat can suck up $100 to $500 of fuel a day. “We’re going out and not spending anything,” Tracy says. “The other day we caught a 20-pound wahoo.”

Shark Pit’s crew launch the kite when the wind breaks 10 knots. In light to moderate winds (10 to 18 knots), they can motorsail with kite and engine or use the kite alone at the high end of that wind range. In very light winds (5 to 10 knots), they reel the kite in to the bow — so it works like a headsail — and run the motor. Tracy says the kite-sail pulls the boat along at all points of sail, from downwind to 50 degrees into the wind. In a beat, “You either can retrieve the kite or keep it flying,” he says, though if it stays in the air it won’t give the boat any extra pull.

Tracy says the kite has some advantages over conventional sail, the chief ones being that it catches stronger, cleaner wind high up and lifts the boat, reducing drag. Also, “it can be retrofitted on an existing hull with minimal modification,” he says.

Shark Pit’s kite is a production model with inflatable bladders designed for kiteboarding. The launch gear consists of a seat for the kite operator, a large winch and an apparatus that looks like a big crossbow, which feeds five 100-meter control lines off the winch to the kite and keeps the lines from tangling. The system has an autopilot that can be used in wind speeds of more than 15 knots. The gear looks complicated, but “I’ve taken people out on the boat who have never flown a stunt kite before,” Tracy says. “They’ve picked it right up.”

Last fall, Shark Pit’s crew kite-sailed 32 miles from Molokai to Maui and back in a 10- to 20-knot crosswind, powered by an 18-square-meter kite-sail and 9.8-hp outboard. They burned just three gallons of fuel — less than half what they would have used without the kite, according to a report at the company Web site (www.kiteforsail.com). They plan to start selling a compact kite system for boats smaller than 50 feet later this year. They say it will be priced competitively with marine engines and that cost can be recouped from fuel savings.

Meanwhile, they plan to start a commercial fishing operation off Maui’s north shore this summer to sea-trial the compact kite system’s 20-square-meter kite, Tracy says. They’ll troll from Shark Pit and sell their catch to Mama’s Fish House, a local eatery. Tracy says they should be able to show significant fuel savings trolling at 7 to 11 knots across the 15- to 20-knot winds typically encountered on the north shore. He says they also plan to test the kite system on some other boats at ValleyIsleMarineCenter, a local dealership.

A native of Mount Desert Island, Maine, Tracy is a professional sailor, commercial fisherman and recreational hang-glider pilot who has designed and built hydrofoil prototypes and other kinds of “flying contraptions,” he says. He moved to Hawaii for the boardsailing and quickly took to kiteboarding — and now kite-boating. His partner, Fisher, is a Maui waterman who knows the islands’ coasts, winds and currents. Tracy’s twin brother Chris, a NASA mechanical engineer, has consulted with them on the system’s design and construction.

Commercial application of kite-sails is drawing a lot of interest. Skysails, of Hamburg, Germany, is developing kite-sails for megayachts and commercial shipping. Skysails says its kites can deliver fuel savings of 10 to 35 percent and as much as 50 percent when winds are ideal. The company envisions building megakites of 5,000 square feet or more.

Shippers are still casting a wary eye to see if kite-sails can keep them on tight schedules and if — with advanced electronics, computer software and lightweight materials — megakites can be practical, reliable and user-friendly. Skysails is offering parasail kites from 80 to 5,000 square meters for cargo ships, superyachts and fishing trawlers (www.skysails.info). Skysail kites are adjusted automatically using software that configures them based on wind direction, wind force, shipping route and ship speed. The kite’s launch and recovery is automatic and takes 10 to 20 minutes using a winch and telescopic mast that lifts the kite into and out of a storage container.

Tracy says their plans over the next five years are to kite-sail through the Hawaiian island chain, to mainland United States, and around the world to showcase the technology. “Our long-range goal is to set up a wind-powered shipping company in Hawaii because we have the trade winds,” he says. “It’s a sustainable technology. It’s the wave of the future.”