New Curtin Maritime hybrid-electric tugs paves way for US E-harbor craft

Curtin Maritime, which provides tug assist services at the Ports of Los Angeles and Long Beach, will soon deploy hybrid/electric tugs thanks to a collaboration with project manager Arc. This will begin the transition away from diesel tug and harbor craft and toward battery-electric power.

“At Curtin, we don’t wait for someone else to build the future; we build it ourselves,” said Martin Curtin, CEO. “We’re focused on innovation that drives real efficiency and cost savings for our operations. These tugs will do exactly that by delivering the power and reliability we need while giving us a smarter, low-maintenance fleet. Partnering with Arc gives us the tech to do what we do best — challenge the status quo and deliver results.”

In September 2025, Arc, the Los Angeles-based electric boat company, announced a $160 million contract with Curtin Maritime, a leading US marine company, for hybrid-electric ship assist tugboats. Built in collaboration with the Snow & Co shipyard based in Seattle, the project partners said this marks the largest commercial deployment of electric workboats. The first four tugboats are committed for delivery by the end of 2027.

Industry reports suggest the deal was motivated by Curtin, domiciled in California, facing strict air quality standards enforced by the California Air Resources Board (CARB). The surprise was the choice of Arc which while specializing in electric propulsion has been focused on consumer boating.

Each tugboat will be powered by Arc’s vertically integrated electric powertrains, delivering over 4,000 horsepower and backed by a 6 megawatt-hour battery buffer.

However, the tugs will also deploy a diesel engine as an Arc spokeswoman explained: “During normal operations, it runs entirely on batteries and plugs in to recharge. On especially demanding days, a small diesel generator can top off the batteries. The tug is designed to operate all electric first, with the diesel system as support.”

“Tugboats are the workhorses of our ports. They are critical for our national supply chains and defense logistics, yet are largely powered by outdated, unreliable, and harmful diesel engines,” said Mitch Lee, CEO of Arc. “Our goal is to rebuild the commercial industry around modern, efficient, and reliable hybrid-electric powertrains, and this deal is a huge first step… We’re at an inflection point for the entire marine industry.”

Arc’s motto is: “We build electric boats from scratch by blending modern aerospace design and manufacturing techniques with traditional marine craftsmanship. By designing our battery packs, powertrain, thermal control systems and software in-house, we create boats with a cohesive feel, optimal performance, and unique features you won't find on any other watercraft.

In an interview with AJOT, Ryan Cook, Arc’s Co-Founder and Chief Technology Officer, said that following the signing of the contract with Curtin, “We're … bidding on a large number of ferry projects. And in conversations with other tugboat operators, barge operators, and pilot boat operators.”

As Cook explained, “We started about five years ago. It was just my co-founder, Mitch. My background is primarily aerospace. I was at SpaceX for about eight years. And our mission is to electrify the entire marine space. That has been our mission from day one.”

Arc’s foundation in consumer boating set the stage for moving to tugboats. “So, there's a whole big corpus of software there that does directly carry over to the tug.”

Cost Savings

This has resulted in major cost savings compared to more traditional diesel-powered vessels:” And I'll focus just on the power electronics and … grid converter side. And the quotes they have gotten is 33 linear feet of electronic cabinets in the tug. And I mean, that is just insane to us. Ours … for the equivalent system is 12 linear feet of cabinets. And we are able to do that because we design the entire system. So, we design the battery system, but then we also … are designing it around the power conversion and motor system, which eliminates a lot of duplication …”

For example, “There’s DC (Direct Current) to DC converters or AC (Alternating Current) to DC converters on board. And when you do that conversion … the output of your power, it's never perfect. There is always … a little bit of a ripple, … maybe like plus minus a volt or something like that on it. The standard equipment that you would get quoted or buy forces you into a very tight voltage ripple range … Because we design the whole system, we can design the thing on the other end to be able to accommodate a much wider voltage ripple range.”

The result is, “We can just delete that $200,000 component that forces a very steady voltage, because we know that we can design this other one over here to accommodate a wider voltage swing. And again, we do that with software …”

The result is a more compact vessel. “I mean, our power electronics take up … almost a third of the space, as to what people are used to. That gives space back for … more bedrooms on board, crew quarters … More battery is where we are going with some other projects because we're able to save that space. We will just put more battery on board, so you get more range and more capability. So, there's savings on the cost side and … also the space side.”

This makes the new tugs competitive with a conventional diesel tugboat enhanced by lower shipbuilding costs: “We're able to be the same or cheaper than a brand-new diesel tug. The reason for that is: One, battery prices are substantially lower than they used to be, and so we can capitalize on that. Two is … being able to save cost with the power electronics, because we designed the entire system, ... we are also able to save on the shipyard scope. There are no fuel tanks, there is no fuel distribution, no exhaust … Lots of that additional steel work and pain … just goes away when you go to electric. So, the shipyard costs also come down.”

Lower Maintenance

In terms of maintenance, Cook projects the electric power will reduce maintenance costs by $10 million over a ten-year period: “We have estimates that over 10 years you will save somewhere on the order of $10 million in maintenance costs. Going electric versus your diesel.”

Another reason is engine efficiency: “There are many, many components that make up that savings. Some of it … is the transmission. Certainly, a large portion … is that … Diesel is just very inefficient at revving way up and then revving way down, which happens a lot when you're on a tug and …you're trying to go full throttle … to … maneuver a ship. And gas engines notoriously have only … very specific efficient fuel set points … Electric is way more efficient across a broad spectrum of RPM (Revolutions Per Minute) ranges … There is a long tail of reasons, but they all add up to … the cheaper operating cost by going to electric.”

The advanced electronics will also provide better monitoring of performance functions that will improve maintenance and reduce costs: “These tugs … have Starlink on them. They are constantly streaming all the telemetry. We have outfitted the tug with far more sensors than a traditional tug would have. I mean, the cooling system we have complete visibility into, as an example. And so, we are able to remotely monitor and support the vessel in a way that … most people are not used to. In fact, we will set up automated alerting, so if … a pump in the cooling system is drawing higher current than usual, we will get an automated ping, we will reach out to Curtin, and just schedule service preventative maintenance. So, it should be a much easier burden of ownership than what folks are used to.

Another cost savings comes from avoiding the most advanced reduced emission diesel engines, which are “enormously expensive today because you have ammonia systems and scrubbers and all these other ancillary systems and components that need to be added on. And so, with all the savings that we have, plus the increased cost of those engines … we can be neutral and, in most cases, cheaper than a new diesel tug.”

12-Hours and Beyond

The tugboats can operate for 12 hours before they need charging: “Basically, we look at … how much are you paying for electricity to run a 12-hour shift on electric? How much are you paying for diesel to run a 12-hour shift on diesel? And then many, many components make up that savings.”

There are several charging possibilities to keep the battery recharged past its 12-hour range: “The first is with shore power. Another way to do it is with a fast-charging station. Think of … the Tesla supercharger station … We are installing one of those right now in the Port of LA to support these tugboats. Curtin Maritime is also working on its own charging system as well to support these tugs …The system we are installing could charge the tug from 10% to 90% over the course of an hour or two. So relatively fast.”