CHULA VISTA, California — It took some work and cost a pretty penny, but a Chula Vista boatbuilding and repair company recently converted a tugboat from diesel power to all-electric at its shipyard that covers 1 million square feet of land and water on San Diego Bay.

“Electrification in maritime is important,” said Todd Roberts, president of Marine Group Boat Works. “We wanted to not just do it for ourselves, but to show others that there’s a path forward and here’s how you do it.”

The company bought a new tugboat and then replaced its two 400-horsepower diesel engines with a fully integrated electric operating system, complete with batteries and charging equipment.

Named MARCO V, the refitted tug emits no greenhouse gases while delivering comparable horsepower and torque. Charged from a shore power connector at the shipyard, the electric vessel is used about 80 hours a month.

The small harbor tugboat tows vessels to and from the Marine Group’s boat lift piers and docks. It also transports crew members prior to their vessels being hauled or after they launch.

The original diesel version cost about $300,000 and the company officials said it cost more than twice that amount to convert the tug to electric power. A grant of $470,400 from the state covered about 75% of the conversion costs.

The grant is part of a massive $423 million trust overseen by the California Air Resources Board funded by Volkswagen after the carmaker admitted cheating on vehicle emissions tests a decade ago. The trust helps pay for a variety of projects to reduce the climate impacts from the transportation sector, including commercial marine vessels.

Even with the grant, that’s a lot of money to spend on a tugboat. It took more than 2,000 hours of company labor to remove the diesel engines and install the new system.

“We invested heavily in this, which is consistent with our sustainability mantra here at the boat yard,” Roberts said. “We’ve bought several pieces of expensive equipment that would have been cheaper had we left them diesel … We don’t just talk sustainability, we do it.”

More than 85% of Marine Group’s vehicles and forklifts are electric and the company plans to install a 750-kilowatt solar system later this year to support the construction of vessels. When completed, it will be the only solar-powered boatbuilder in California.

Rules enacted by the Air Resources Board requires commercial harbor craft like tugboats and ferries to reduce their emissions by 2035. The regulations mandate that by 2035, diesel engines on existing vessels must be upgraded and new builds must have zero-emission propulsion systems.

Marine Group officials wanted to demonstrate that converting similarly sized tugs from diesel to electric can be replicated by other companies, such as excursion boats and dinner cruises.

“Our goal was to take a sample project that had a very common horsepower profile and and come up with an ‘in box, off the shelf’ solution for electrification,” Roberts said.

MARCO V was named after Marine Group paint supervisor Marco Vega, who has been with the company for 34 years.

“We wanted to give a nod to the people who make this company possible and that’s our employees,” Roberts said.

In business since 1986, Marine Group Boat Works is a full-service maritime vessel construction and repair company that covers more than 2,000 of dockage on San Diego Bay and employs 230 workers. The company also has a staff of about 25 at a second facility in Los Cabos, Mexico.

MARCO V is the second electric tugboat in the area.

The Port of San Diego last year unveiled the 82-foot eWolf, operated by Crowley Maritime Corporation, that escorts ships entering and leaving the Tenth Avenue Marine Terminal.

Much larger than MARCO V, the eWolf is capable of speeds up to 12 knots and expects in its first 10 years of use to eliminate 3,100 metric tons of carbon dioxide from the port and surrounding South Bay communities such as Barrio Logan and National City.

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