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September 16, 2019   |   Diesel Technology Forum

Policy Insider

Beating Traffic Gridlock on the Water

Last year, 119 million Americans took a ride on a ferry boat. There’s a 95.4 percent chance that it was powered by diesel.

From New York City to San Francisco and Nantucket to Catalina, millions of Americans are increasingly turning to water transport via water taxi and ferry boat for commuting and reducing miles traveled. From passenger-only transport, to vessels carrying vehicles and passengers, ferry boats are providing an important new strategy for reducing urban congestion.  According to the most recent data compiled by the U.S. Department of Transportation, over 600 ferry boats operating in 36 states transported 119 million passengers in 2016.

What enables these vessels to move masses of people and vehicles in a safe, reliable, efficient manner? Diesel is the technology of choice powering over 95 percent of all vessels. Boats manufactured or repowered since 2015 are equipped with the newest generation of diesel power that ensures that each trip is accomplished with near-zero emission impacts.

 Ferry Boats

How is Diesel Clean?

Thanks to decades of innovation, the latest near-zero emissions diesel technology is now available in the very largest marine engines (5,000-10,000 hp). Using the latest in emissions-reducing engine technologies coupled with advanced, active emissions treatment systems like Selective Catalytic Reduction (SCR), new engines reduce emissions by almost 90 percent relative to older engines. The tremendous advancements in diesel engine and emissions control technology aren’t limited to new boats, but can also be incorporated into existing vessels.

Diesel is the technology of choice for water transport thanks in part to its durability and reliability, which means engines can deliver decades of efficient and reliable service with proper maintenance and rebuilding. The opportunity for upgrading and replacing ferry boat engines is gaining new attention. Recent research commissioned by the Diesel Technology Forum (DTF) and the Environmental Defense Fund (EDF) finds that there are  1960’s-1970’s engines still in active revenue service today. In fact, the oldest ferry boat in operation, the Adirondack in service in Vermont, is first hit Vermont waters in 1913 – more than 100 years ago! Meticulous attention to vessel maintenance and a series of engine rebuilds during that time are a testament to the durability of the technology.

Replacing older engines that power a single ferry with a new clean diesel model works out to the same emission reductions as replacing almost 100 older trucks, according to research commissioned by DTF and EDF. When clean diesel engines are used to power ferries, they can have an enormous beneficial impact, reducing emissions for both passengers and for the communities near where they serve.

Ferry fleets are also turning to renewable, bio-based fuels, instead of traditional fossil fuels. Just look at the Red and White Fleet, a sightseeing cruise company operating in the San Francisco Bay Area, that switched its entire fleet of vessels from operating on conventional diesel to using 100 percent Neste MY Renewable Diesel.

What’s the Impact?

As urban populations expand across the U.S., city managers often look for innovative ways to get people around; ferries are often an attractive option for transit districts. This is certainly true of the Bay Area in northern California, which has seen ferry ridership expand 25 percent in just two years, sparking demand for newly manufactured vessels. Newly manufactured ferries are also entering service in New York City linking outer boroughs and other suburban locations with lower Manhattan.

The best part? These new ferries are powered by the latest clean diesel engines that meet the U.S. EPA’s near-zero emission “Tier 4” standards.

EPA regulations governing new off-road engines (like cargo handling equipment and locomotives) also apply to harbor craft, including ferries. Those rules require that all new engines manufactured beginning in 2015 meet “Tier 4” near-zero emissions standards. According to the EPA, these Tier 4 rules reduce emissions of particulate matter by 90 percent and nitrogen oxides (NOx) by 80 percent.

On average, replacing the older engines that power marine workboats with new clean diesel models can reduce NOx emissions by 30 tons per year. This is the equivalent of taking more than 26,000 cars off the road for a year. 

While diesel technology is the dominant choice for ferry operators, there are other powertrains in use in U.S. waters. The Badger, in operation between Michigan and Wisconsin, is actually powered by coal, while Hatton Ferry Service in Virginia operates the only manually powered car ferry in the U.S.

Replacing older marine engines is also one of the most cost-effective investments from an air-quality improvement perspective. A single workboat engine replacement project, while expensive, delivers many more emission reductions than other projects, and can maximize clean air investments for near-port communities. This cost-effectivity is critical, especially as clean air agencies and ports consider the use of incentive funds provided by a variety of federal programs, as well as the Environmental Mitigation Trust fund established in the settlement with Volkswagen.

Check out some of these diesel-powered ferries from top marine engine manufacturers.


In Europe you can take a ferry from Ireland to England on the Irish Ferries flagship Jonathan Swift, powered by four high-performance Caterpillar diesel marine engines.

Another Irish Ferries’ boat, the W.B. Yeats, won “Best Ferry of the Year” in addition to the “Ferry Concept Award” and is powered by four Caterpillar diesel engines for a total power output of 45,100 hp that can propel her up to 22.5 knots.


In San Francisco Bay and Fisherman's Wharf, the Enhydra is Red and White Fleet's first hybrid diesel-electric ferry boat; it also runs on 100 percent biodiesel. The ferry has two diesel generators, both modified Cummins diesel engines. These can start up to charge the boat’s batteries and power the two electric motors that propel the boat. There is no main engine, as the generators power dual electric prop motors while also charging the batteries.

Far away between the islands of Zanzibar, Pemba and mainland Tanzania, the ferry Kilimanjaro VII features the newest, most powerful Cummins diesel engine for the marine market with power output with ratings ranging from 3,200 to 4,200 hp for propulsion, auxiliary, generator and diesel electric applications.

John Deere

Fire Island’s famous beaches are now accessible by a new ferry. The Isle of Fire is powered by three John Deere diesel engines and has a cruising speed of 20 knots with space for 400 passengers.

Washington State Ferries updated the 14-year-old 149 passenger Spirit of Kingston with service in Seattle that included a Tier 3 repower with four Deere marine engines. The project replaced older Tier 2 with Tier 3 diesel engines, reducing exhaust emissions by 22 percent, particulates by 45 percent and improved fuel consumption by 7 percent.


The first U.S. passenger ferry with Tier 4 emissions controls went into service with the San Francisco Bay Ferry system in March 2019. The 445-passenger high speed Pyxis is powered by two MTU Tier 4 diesel engines and serves the San Francisco Bay Ferry system.

Vacationers can take a high-speed passenger ferry in Rhode Island between Quonset Point and Martha’s Vineyard. The catamaran Julia Leigh is powered by twin MTU 12V4000M64 diesel engines can came into service in June 2019.

Mexico’s largest ferry operator has two new ferries, the Lady D and Lady A, both powered by twin MTU engines.

Volvo Penta

The Faroe Islands is an archipelago in the North Atlantic that consists of 18 rocky islands, and so ferries are vital for transportation for inhabitants and tourists. Volvo Penta’s marine gensets provide prime power for the Teistin along with excellent operational efficiency in challenging weather conditions and more than a 20 percent reduction in fuel.

Volvo Penta’s IMO Tier III engine package is at work on ferries in Sweden, reducing emissions of nitrogen oxides (NOX) by up to 75 percent. The ferry company, Trafikverket Färjerederiet, is maximising the reduction of emissions, well ahead of 2021 IMO deadline.


Vacationers in Cozumel and the mainland port near Cancun can travel on catamaran ferries powered by Yanmar common rail diesel engines that provide lower emissions while maximizing torque at low or high revs.

The Seychelles sit about 1600 km off the coast of Africa in the Indian Ocean; they have a catamaran ferry powered by twin Yanmar engines that create low particulates and NOx, SOx and carbon monoxide emissions. This means they meet strict International Maritime Organization air pollution requirements.


Isuzu provides advanced marine diesel engines for a range of vessel applications.  Visit http://ies-isuzu.co.jp/en/marine/


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Allen Schaeffer
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