Repowering: greater efficiency for difficult times

The down economy has everyone looking for ways to save money, and the maritime industry is no exception. Although repowering vessels with newer engines requires a significant capital expense, the improved technology can reduce operating and maintenance costs and increase reliability, saving money over time.

Technological improvements over the past decade have led to engines that are both more powerful and more efficient.

“Anytime you’re going to repower a boat with an engine that’s, say, 10 years old with a new engine, you’re going to see a lot of improvements in power and efficiency,†said Dave Flaherty, marine marketing and product manager for John Deere Power Systems. “And you want something that’s reliable. Commercial guys are making a living with their boats. They want something that’s not going to wear out.â€

Island Tug and Barge repowered its 33-year-old tug Island Defender with two 500-hp Cummins KT19s, resulting in higher speed and reduced fuel consumption. (Photo courtesy Island Tug and Barge)

The better fuel economy new engines provide is an indirect result of manufacturers redesigning engines to keep pace with changes in emissions requirements. Electronic fuel injection is the biggest improvement over older, mechanical engines, Flaherty said, but vessels also benefit from the increased displacement manufacturers create to counteract the loss of power that engines suffer as a result of the emissions-based changes.

“You typically lose some power because you have to reduce the amount of fuel you’re putting into the cylinder,†he said. “We’ve increased displacement and added technology for better cooling systems, improved power cylinder parts, and improvements to the oiling system to try and make parts last longer and get better oiling.â€

Flaherty said the majority of John Deere commercial marine business goes to repowered boats rather than new builds. Customers routinely see 30 to 40 percent reductions in annual fuel costs, even when moving up in horsepower. The technology is driven by the tractor market, he said, and then adapted for the marine environment.

“We get to take an engine that’s completely modern from a tractor and ‘marine-ize’ it,†he said.

New technologies have improved other manufacturers’ engines as well. On Yonges Island, S.C., Stevens Towing recently replaced the engines in six of its 10 tugs with environmentally friendly Volvo Penta diesels, reducing fuel consumption by 1,200 gallons per day across the fleet.

The change also increased the boats’ speed and reliability, and improved engine life from 8,500 hours to 35,000 hours per engine, all while cutting the company’s operating cost by measurable amounts — almost half a million dollars per year in fuel alone.

The process began a few years ago when the nearly 100-year-old family business decided to replace the aging two-cycle Detroit Diesel engines in its tugs. Evaluating options led Stevens to Volvo Penta’s four-cycle marine diesels — first the 510-hp TAMD 165, installed in the first three tugs it repowered, and then the 650-hp D16.

Two of the D16s were purchased with funds matched by Environmental Protection Agency grants through the state’s Port Authority.

Charlie Madsen’s Kodiak Diesel Service in Kodiak, Alaska, primarily serves crab boats up to 225 tons. “A typical crabber in this class burns 700 to 800 gallons a day,†he said. “We can cut that in half.â€

On a recent job, Madsen repowered two vessels, cutting their average fuel consumption in half. “Their initial investment in new engines was about $120,000,†he said. “They probably came pretty close to paying for them in the first season.â€

In August, Island Tug and Barge, based in Vancouver, British Columbia, relaunched its 33-year-old tug Island Defender, repowered and rebuilt with Cummins engines. The 69-foot steel tug Island Defender first hit the water in 1977. Island Tug and Barge bought the vessel after her first repower, but the hull was in good enough condition to make a second rebuild worthwhile.

Work began more than a year earlier with a life-cycle cost analysis performed by Todd Barber of Vancouver’s Robert Allan Ltd., a naval architect and marine engineer firm. To find the best repower solution, Barber ran numbers for three different engine manufacturers, considering capital and operating costs, and ultimately chose a pair of Cummins KT19s.

“The old engines they had … weren’t very economical to run,†said Paul Kruse, Island Tug’s fleet manager for tugs. “It was a fleetwide decision to go with Cummins product.â€

The complete rebuild package also included a Krill fuel management and monitoring system, new shafts and Kobelt shaft brakes, Rice nozzles and propellers, and a pair of John Deere generators.

“We redesigned the shafting propellers and nozzles to get the most effective thrust out of this thing for the fuel we’re using,†Kruse said.

In addition, galley and living quarters were gutted and refinished, the bridge and external controls were updated, and other equipment was improved throughout. Towing pins were refurbished and the tug’s original towing winch was rebuilt and updated. Though the horsepower was cut by more than half, the renovated vessel offers improved performance over the original setup, plus reduced fuel consumption. That means significant savings.

President Bob Shields said the renovations cost about 60 percent of what it would cost to replace the vessel.

The engine work was the heart of the rebuild. The two 1,100-hp engines were replaced with two 500-hp engines, which the cost analysis predicted would push the 5,500-gross-ton barge at 7 knots when loaded, or 9 empty — an increase in speed of 8 percent over the old engines.

The Cummins engines are mechanical, not electronic, Kruse said, but the Krill system lets the crew monitor everything from a flat screen in the wheelhouse, improving performance and efficiency. “We can also monitor it from the office, over the Internet,†he said. “These are four-stroke engines, and they’re quite efficient. The next move is to go fully electronic with the next set of engines.â€

Because Canadian crewing regulations mandate full-time engineers for tugs over 1,000 hp, Island Defender’s new engines mean she’s exempt. The smaller crew contributes to the cost efficiency of the rebuild.

“We’re going to run it for two or three weeks to break everything in properly, then run a bollard pull test,†Kruse said. “Initial testing looked really strong. There was a marked improvement in steering, and we did quite a bit with vessel noise reduction. The engines contributed to that, but basically all internal decking was renewed, and we did a lot of work on the exhaust.â€

In southern California, Crowley Maritime recently repowered four Harbor-class tugs in its ship-assist and tanker-escort fleet as part of a Port of Los Angeles emissions and air quality initiative. Crowley partnered with Alameda-based Bay Ship and Yacht Company to replace the Caterpillar 3516 main engines in all four vessels with the newer CAT 3512 engine.

The repower led to a significant reduction in emissions, said Crowley spokesman Mark Miller, which was the impetus for the repower, but the side effects were increased power — bollard pull jumped from 51 tons to 59 tons — and a nearly 5 percent improvement in fuel efficiency.

Jeff Sherman, commercial marine sales manager with MTU Detroit Diesel, said his company works with customers to understand their goals when considering a repower. “We try to look at overall repowers as not just an engine change-out but a solution system,†he said.

Customers often are concerned about fuel burn and overall maintenance over the life of an engine — and what that will reflect in their pockets. “Life cycle studies can be measured in many different ways,†he said. “Our intent is to deliver life cycle that they can measure going forward in cost vs. the unexpected.â€

Sherman said repowers can lead to fuel performance increases of 2 percent to more than 15 percent, depending on the vessel and other factors. As an example, he cited a current proposal to repower a 170-foot conventional ferry/freight vessel and satisfy three customer requirements: meet the latest emissions standards, increase speed by 2 knots, and reduce fuel consumption.

“We employed a full study, understood the requirements, verified the hp output of the older engines, and were able to come back with a program with a lower hp requirement than what … was on the boat,†he said. By replacing the existing engines with MTU 12V4000 M53R engines and designing a propeller to work with them, MTU was able to increase fuel efficiency by 14.5 percent, and increase speed by 3.5 knots.

“This is an extreme opportunity,†he said, “but it shows what we can do if we really spend the time to investigate it.â€

As manufacturers continue to chase the emissions standards requirements for the next five years, engines will continue to improve, said John Deere’s Flaherty. “The question is, what are we going to do after that?†he said. “I hope we’re able to go after the other improvements that customers want.â€

Even before the economy dropped, fuel prices were on the rise. Eleven years ago, when the emissions standards were signed, marine diesel averaged more than $2 less per gallon than today.

“Over the last few years, fuel economy’s been the driving force,†said Kodiak Diesel Service’s Madsen. “The new engines are just so much more fuel efficient than the old engines that it justifies changing them. The better fuel performance may not have been the intent (of manufacturers’ redesigns), but it was definitely a bonus.â€

By Professional Mariner Staff