Not Blowing Smoke: Low-emission Cat® Marine engines repower large excursion ship

A popular excursion boat on Lake Champlain has received a significant upgrade to reduce its environmental impact.

In October 2019, Vermont’s Department of Environmental Conservation’s Diesel Emissions Reduction Act Program (DERA) awarded $268,073 to Mesa Leasing, Ltd. to help replace four unregulated, heavy-polluting, other than Caterpillar diesel engines that powered the Spirit of Ethan Allen III. This grant is the largest Vermont Diesel Emissions Reduction Grant ever awarded.

The project will improve air quality along the Burlington, Vermont waterfront, protect public health, decrease greenhouse gas emissions—all while delivering a remarkable 45–50 percent reduction in fuel consumption.


“We want to do our part to protect the waterfront and the lake, to reduce our carbon footprint, and be more environmentally friendly,” said Wilson Tucker, Head Engineer for the Spirit of Ethan Allen III.




We wanted to cut down on our fossil fuel usage and pollution contribution to make the environment much cleaner."

The vessel's owner, Mike Shea, says the new, low-emission Cat® engines emit 95 percent less pollution than the old non-compliant engines.

"I'm down there when she backs out," Shea said. "I smelled it. I breathed it. I'd see that plume of black smoke—unburnt fuel—and I knew it was torturing people. We used to blow out black smoke, and now we don't blow any smoke.”

That's tons of exhaust no longer pouring into the Burlington Harbor Marina—457.2 tons of diesel emissions to be exact—that’re now eliminated by using the new, cleaner burning Cat marine engines.

The 140-ft long, 33-ft beam triple-deck, luxury cruise ship accommodates 363 passengers. After a five-and-one-half month repower process, last spring one of Vermont’s largest banquet facilities returned to Lake Champlain with a significant boost to its mileage rating.

Yet the greater payoff, according to Shea, is much more than simply saving at the fuel pump: It's about being a better neighbor on the Burlington waterfront.

"I knew that we weren't helping the environment, and everybody loves Vermont and cares about the environment, so I wanted to do my piece because all that pollution that was being released into the air, it just wasn't right," he says.

Facing local Covid-19 regulations, the excursion boat will not serve food or drink for the time being, and they're allowing only 10 people per separated deck area for a total of 40 people on board at a time.

Clean, high technology power

The ship’s two powerful new, low-emission Cat C18 TA Tier 3 Marine Propulsion Engines each deliver a whopping 470 hp @ 1800 RPM continuous duty rated with new Twin Disc model MG516 marine transmissions, provided and installed by Milton Cat.

Two companion, six-cylinder Cat C9.3 TA Tier 3 Marine generator sets each deliver 300 kW @ 1800 RPM and easily provide electrical power for the entire ship—kitchen, lighting, navigational and safety equipment. Plus, each generator engine is fitted with a hydraulic pump to provide power to the vessel’s bow thruster.

In addition, all engines were supplied with the most-up to-date Cat electronic displays and instrumentation. Both engine models were built in a state-of-the-art, 1.7-million-square-foot engine plant in Seguin, Texas, and are among the latest and most technologically advanced new engines from Caterpillar.

Back in Vermont, Milton Cat Marine Project Engineers worked throughout the project with the owner, chief engineer, and maintenance team to ensure all Caterpillar best practices and guidelines were strictly followed during the installation.

As experienced mariners know, Cat engine support does not end with the sale, it begins there. Accordingly, ship owner Shea has enrolled in a Caterpillar Extended Service Contract (ESC) with Milton Cat that will ensure long-term reliability through sophisticated engine monitoring and technical support.    

A winning team

Since 2009, Milton Cat and Caterpillar have been chosen as the engine supplier of choice in nearly 30 Diesel Engine Reduction Act (DERA) projects such as the repower of the Spirit of Ethan Allen III

This project was a competitive bid, with Caterpillar selected on the basis of:

  • Best product support (Milton Cat in Richmond, Vermont is just 13 miles / 24 minutes from customer) 
  • Milton Cat’s experienced Marine Division, with more than 85 years’ experience in the marine propulsion and auxiliary business  
  • Best factory and dealer engineering support
  • Compliant with current EPA and IMO Tier requirements
  • Best fuel consumption 
  • Caterpillar factory support in terms of Commercial Repower Incentives: Customer was saved over $17,000 on the project 
  • Best overall value in terms of transaction price and long-term operational cost 



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