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| Crowley installed new Rolls-Royce 132-inch five-blade propellers on Sentry, one of a class of 20-year-old tugs. Lower cavitation, combined with fuel monitoring, resulted in a fuel savings of 4 percent. |
A vessel operator’s fuel cost burden is proportional to the size of the ships and the length of their routes, but for operators both large and small, the fuel savings approaches are similar.
At the larger end of the maritime scale, Koji Miyahara, president of NYK Group, which operates containerships worldwide, noted that the bunker-oil prices rose from $164 per ton in 2003 to $500 for the second half of 2007. To save fuel, he called for NYK’s ships to slow down, since “a 10 percent slowdown of voyage speed will produce more than a 25 percent saving of fuel oil and reduction of CO2 emissions.”
At the smaller end of the scale, Dana L. Brodie, manager of marine engineering with Hawaiian Tug & Barge/Young Brothers in Honolulu, Hawaii, noted in March 2008 that No. 2 diesel in Hawaii “had just hit $3.17 per gallon.” Crude oil hit $110 the same day. His response to rising prices: “Every gallon you can reduce in consumption is savings to the bottom line.”
With the ever-higher fuel prices, vessel operators are reviewing their vessel propulsion, onboard energy-consuming systems, methods of operation, hull structures and fuel-control systems to reduce fuel waste.
Brodie cited an operating example of the FloScan Instrument Interface Systems: “We monitor our speed through the GPS once we get strung out on the towline and then start backing off the throttles until we see a two-tenths drop in our speed and leave it there. That last 10 or 15 percent of throttle on most tugs is wasted fuel that gives you no greater hull speed and also decreases the life cycle of the engine components, such as liners, rings and pistons.”
A multiple approach to achieving greater fuel economies and environmental compliance is underway at Crowley Maritime Corp. Jim Gillen, director of marine operations, used the 14 tugs operating on the Puerto Rico-Caribbean liner service and Trailer Bridge’s Puerto Rico barge service as an example. The tugs were built 20 years ago but were refurbished as recently as seven years ago. A series of recently completed major upgrades included changeovers to four-pass aftercoolers, installation of optimized General Electric turbochargers and improved engine-room ventilation.
Direct fuel savings of 3 percent were achieved by the installation of Interstate Diesel’s Ecotip injectors in the EMD engines. Upgrading the end of the propulsion system was a major undertaking.
Gillen explained, “We went to Rolls-Royce and they designed New Generation Workwheels to improve cavitation aspects. One tug was outfitted with fuel meters before installation of the new Workwheels and by comparing before-and-after data we are seeing a minimum fuel savings of 4 percent.”
Another propeller improvement approach by Hawaiian Tug & Barge/Young Brothers was fitting three ocean towing tugs with high-performance propeller systems from Nautican. Brodie explained, “They are a three-blade high-performance wheel in a Kort nozzle. It raises the pounds of thrust per horsepower from an open wheel design of 23 pounds on a average to just over 30 pounds.”
As an example he cited a 3,000-hp tug with the Nautican performance package. That tug, he said, “has the thrust of a 4,000-hp open-wheel tug, but we burn the fuel of a 3,000-hp tug. This is a huge fuel savings per trip.”
The Cape May-Lewes Ferry, which operates four boats between New Jersey and Delaware, has decided to reduce engine rpms from 600 to 575. “That is giving us some measure of savings,” said Heath Gehrke, director of ferry operations.
The ferries carry between 800 to 1,000 passengers and 100 regular-sized vehicles on the 80-minute crossing. On average the boats had used about 110 gallons of fuel per hour and the speed reduction cut fuel use by 10 percent. However, the recent switchover to low-sulfur marine diesel to meet environmental restrictions added 15 cents per gallon to fuel costs so the savings achieved by running slower “have been largely offset,” he noted.
The ferry company’s port engineer, Jim Gillespie, explained that several upgrading projects performed while the ferries were in the shipyard helped to reduce fuel costs. Those projects included correcting propulsion shaft misalignments caused by normal hogging and sagging of the hulls as well as rebuilding the reduction gearing. That work “has saved around 6 percent in fuel costs and that’s on top of the rpm savings,” Gillespie said.
Fine-tuning performance
Fuel-flow meters offer operators a tool to precisely monitor fuel use and engine performance. Gehrke at Cape May-Lewes Ferry noted fuel meters are especially useful because “we can see fuel consumption changes as rpms change and maybe there is a sweet spot we didn’t know about.”
The four ferries are each powered by two vintage 12-cylinder, 2,000-hp Fairbanks Morse engines. Gillespie said the flow meters permit engine performance and efficiency to be closely monitored. “It allows us to dial in each cylinder’s fuel injector, giving us the most fuel efficient operation for the engine as a whole.”
Brodie at Hawaiian Tug & Barge agreed, noting the FloScan Interface systems are “reliable and a great tool to use troubleshooting performance problems related to a main engine or propeller issue.”
Reducing electric generator loads from the motors running numerous pumps is also on Gillespie’s list of priorities. He said a process by Belzona Inc. in Miami applies a coating to the interior surfaces of the pumps to reduce fluid friction, thereby reducing electric motor power demands by 2 to 4 percent.
Reducing generator loads to reduce fuel use at Crowley Maritime included conversion to florescent lighting fixtures and LED running lights. In port, the tugs use shore electrical power whenever possible, saving fuel by shutting down engines and generators.
Reducing underwater hull friction is an important factor and the latest underwater paints offer new long-term benefits. One example is Intersleek 900 that the manufacturer, International Paint, said can offer fuel savings of 6 percent in comparison to self-polishing copolymer (SPC) antifoulings. “The potential exists for even greater savings in comparison to controlled depletion antifoulings,” according to International Paint.
The PPG-SigmaKalon foul-release SigmaGlide coatings can offer fuel savings between 3 and 8 percent and satisfactory organism release rates at vessel speeds as low as 5 knots.
Gehrke at Cape May-Lewes Ferry said coatings with the ability to shed attaching organisms on vessels sailing at slower speeds are of interest. “We normally do 12 to 13 knots, so it would be good for us.”
Fuel-saving approaches are varied and environmentally friendly. Common-rail and electronic-controls technology found on larger engines optimize engine performance across the engine’s complete load range. Gillen, of Crowley, expects electronic ignition technologies on the tugs within two years. Other small changes have big benefits long term.
Crowley’s approach is typical of the marine industry, Gillen said. Crowley is “doing everything we can to make the engines as efficient as possible while being as green as possible.”
| Sails provide an innovative way to cut fuel use and emissions |
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| MV Beluga SkySails uses kite-like sails for supplementary power. The sails reduce fuel usage by as much as 15 percent. Beluga Shipping believes that savings of up to 30 percent are possible with larger sails. |
Could this vessel usher in a new era of sail?
The unique MV Beluga SkySails cast off on its maiden voyage in January 2008. The ship’s creators say its kite-like supplemental propulsion system, which harnesses wind power, reduces bunker-fuel consumption by as much as 15 percent.
The 459-foot cargo ship’s use of wind to supplement conventional power cuts emissions, while it harkens back to the technological future. The developers are hoping the industry embraces the vessel as a solution to a pair of major problems: soaring fuel costs and stiffer environmental regulation.
“You have to have the courage to try something new,” said Niels Stolberg, chief executive of Beluga Shipping GmbH in Bremen, Germany.
The high-flying auxiliary wind propulsion system installed on the newbuild MV Beluga SkySails has a 175-square-yard towing kite attached to the ship with a high-strength synthetic rope controlled by a winch in the ship’s forecastle. Automatic deployment and recovery operations are manipulated from the bridge, as are the kite’s flight maneuvers — such as a figure eight — to maximize the effect of the wind.
During operation, the kite is deployed to an altitude between 325 and 985 feet, where winds are as much as 20 percent stronger and are more stable than near the surface. The new ship’s sail-like system reduces bunker-fuel consumption by an estimated 10 to 15 percent — while lowering air-pollution emissions proportionally.
Based on testing, larger kites size may be used to achieve fuel savings of 30 percent or more, the company said.
MV Beluga SkySails is the newest addition to Beluga Shipping’s fleet of multipurpose heavy-lift project carriers. The SkySails equipment will supplement the single Caterpillar MaK 8M32 diesel propulsion engine rated at 3,400 kw that drives a four-blade variable-pitch propeller.
The first voyage departed Bremerhaven, Germany, on Jan. 22, 2008, en route to Venezuela, using a westbound course south of the Azores favored by 19th century windjammers. The return to Europe included one U.S. port call in Davant, La. The ship then continued eastbound to Norway.
“The kite was launched several times, mainly for practical and testing reasons including calibrating, adjusting and setting up the system for safe and regular usage,” said Timo Cyriacks, spokesman at Beluga Shipping. “That was the main goal at the first stage of the commercial voyages of MV Beluga SkySails.”
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