Harbor Sentinel tug boat is going electric with Arc

Arc is transforming the power and performance of a working harbor tug alongside Pacific Maritime Group and Glosten.

The Harbor Sentinel, an iconic 50-foot harbor tug (owned and operated by Pacific Maritime Group), will swap out its twin diesel engines for an advanced electric powertrain designed by Arc. Supported by the Port of Long Beach's Technology Advancement Program (TAP) and SWIFT program, along with a Volkswagen Environmental Mitigation Trust grant administered by the Bay Area Air Quality Management District, the project will demonstrate how electric propulsion can deliver better performance, reliability, and efficiency to the busiest commercial environments — like the PMG’s Long Beach terminal.

“Harbor Sentinel will outperform even newly constructed tugs when we’re done,” said Mitch Lee, co-founder and CEO of Arc. “Going electric delivers better performance, reliability, and ultimately economics, regardless of the age of the surrounding structure.”

A new chapter for a working tug

Powered by twin Cummins diesel engines producing a combined 950 horsepower, the Harbor Sentinel joined PMG's fleet in 2023, where it moves barges and supports construction and shipyard operations. It’s a proven workhorse, and with the Arc powertrain it goes full throttle into a new future of hard-working commercial performance.

The retrofit includes a revamped powertrain system targeting 2 MWh of usable energy, electric motors and drivetrain, rapid recharging, and a modern helm with Arc's intuitive vessel controls and displays. The system also includes advanced telematics for continuous remote monitoring, allowing the Arc team to support the vessel and its crew long after it returns to service.

“In pursuing this conversion, we want to see exactly how Arc's powertrain handles the rigors of our Long Beach operations,” said Grant Westmorland, CEO of Pacific Maritime Group. “We are eager to measure the real-world impact on fuel savings, maintenance downtime, and operational torque.”

Raising the bar for future work boats

Working alongside Arc, naval architecture firm Glosten is adapting the vessel's hull and onboard systems to meet U.S. Coast Guard Subchapter M requirements.

Once commissioned, Harbor Sentinel will return to PMG's Long Beach terminal for a 12-month demonstration period, performing regular harbor operations while Arc collects data on performance, efficiency, and charging.

The results of the demonstration period will help evaluate the operational and economic benefits of converting existing diesel-powered workboats to electric propulsion, providing a potential roadmap for wider adoption across the commercial maritime industry.

“This electric conversion is exactly the kind of forward-looking project the Technology Advancement Program was designed to champion,” said Port of Long Beach CEO Dr. Noel Hacegaba. “We’re excited about the potential of Arc’s electric powertrain to deliver next-generation efficiency and reliability for the tugs we rely on to keep our cargo moving.”

One platform. More possibilities.

The technology powering Harbor Sentinel is part of Arc's growing portfolio of electric commercial vessels. Built on the same high-voltage architecture first proven in the Arc Sport, the platform also powers eight ship-assist tugs being built for Curtin Maritime, including the latest Tulli C tug.

From recreational boating to demanding commercial applications, Arc is demonstrating how a single electric platform can deliver powerful, reliable performance across a wider range of vessels.

To learn more about Arc's tug powertrain, explore the technology and innovation behind our commercial projects.