The North Carolina Department of Transportation (NCDOT) operates the second largest stateowned ferry system in the United States. Within the short choppy winds of this natural phenomenon known as the Outer Banks, its 32 ferry vessels serve seven routes, operate over 200 sailings daily, and transport more than 1.1 million vehicles and 2.5 million passengers annually across five bodies of water. Residents of North Carolina’s coastal communities depend on the Ferry System for transportation to work, school and as a means of emergency evacuation. Regularly traversing ocean waters on ferries, Outer Banks residents have a unique tie to nature. The North Carolina Department of Transportation honors the costal area’s values by ensuring new additions to their fleet are cleanrunning and abide by the Environmental Protection Agency’s marine emission requirements.
In 2010, NCDOT replaced two 20-year-old ferries in its fleet with newer, larger and cleaner-running vessels named Sea Level and Swan Quarter. In NCDOT’s search for EPA Tier 2 compliant diesel engines, mtu triumphed over other marine power industry heavyweights and won the bid to power the new vessels. mtu outfitted the new ferries with two mtu 8V 4000 M60 engines. mtu engines were selected for their competitive price point, reliability and low lifecycle costs, which make them the ideal fuel-efficient passengerfriendly marine propulsion system. The 1,000-ton ferries are 43 percent larger than the retired ferries and can carry 50 cars—or four tour buses—at a time.
The new ferries, each with capacity for 300 passengers, have been well received by tourists and operators alike. Sea Level and Swan Quarter carry day-tripping tourists across the Pamlico Sound to and from Ocracoke Island, an Outer Banks gem that boasts 16 miles of pristine wild beaches. And, thanks to the 250-foot increase in passenger-friendly space, tourists are able to explore the vessel’s passenger lounge and front and back decks while enjoying the picturesque Outer Banks scenery en route. Running from North Carolina’s Cedar Island and Swan Quarter ports, the vessels complete four, two-hour runs per day through the open water, where they can experience waves up to seven feet high.
Power and control
The upgrade to mtu Series 4000 M60 engines has offered operators more power and control, giving them more confidence maneuvering in close quarters. With 700-800 horsepower at 1400 RPM, the turbocharged engines are powered to run at speeds faster than 14 knots.
According to Joe Waldrep, marine design engineer for the NCDOT Ferry project, the second turbo only kicks in when the vessels are approaching 12 knots. Once the vessels hit 12 knots, operators are able to back off the throttle and continue the voyage at one turbo. This increase in power capacity allows the vessels to run at 60 percent of their power, which saves fuel and reduces wear and tear on the engine. Since the ferries run at a fraction of their power, they’re able to use the ferry’s reserve power to catch up to schedule or power through inclement weather. “We could leave five to 20 minutes late and still get passengers there on time,” said Waldrep.
Though the vessels are dramatically larger than the ferries they replaced, they burn the same amount of fuel due to their efficient, yet powerful mtu diesel engines. The Series 4000 engine’s common rail fuel system, coupled with turbocharging, leads to a drop in fuel burn and a leap in efficiency and performance.
“Everyone was concerned that the new ships would burn a lot of fuel because of the size increase, but we’re not. We’re pushing a lot more boat through the water and still not burning more fuel,” said Waldrep.
According to Jeff Sherman, mtu Marine Sales Manager, 95 percent of an engine’s overall cost is fuel and any fuel savings an engine can achieve translates into major cost savings.
Standard mtu practices elevate customer satisfaction
With mtu’s reduced maintenance schedule, including extended oil changes and infrequent valve adjustments, Sea Level and Swan Quarter will experience exceptional uptime and reliability, both of which contribute to lower lifecycle costs. Outside of this schedule and normal daily maintenance, NCDOT crews are finding the engines require minimal repairs or changes.
One of the most dramatic differences is in the low level of engine noise detected in the new ferry. According to Waldrep, the engine is undetectable in the passenger lounge. This significant reduction in noise can be attributed to the mounting of the engine—mtu’s engines in these ferries are isolated on rubber mounts designed specifically for mtu, while other engine manufacturers sometimes still use the “mount on a hard surface” practice.
“It’s really smooth. That’s one thing everyone’s noticing. You don’t hear the boat. In other boats, you shake, rattle and roll,” said Waldrep. “mtu only mounts on soft mounts, they do not put engines on hard mounts. It’s a standard mtu policy—I love it.”