State of the art Hybrid tug from Berg Propulsion

US-built hybrid tug from Berg Propulsion featuring a fully integrated electric system is a high-tech win for America’s fleet.

US-built hybrid tug from Berg Propulsion featuring a fully integrated electric system is a high-tech win for America’s fleet.


A new harbor tug, delivered by one of the leading workboat builders in the United States gives form to the Berg Propulsion case that the efficiency, sustainability, and performance gains of hybrid-electric propulsion are optimal for this market.

Spartan is the latest high-power tug to join the Seabulk fleet. It adds to a fast-growing reference list of vessels featuring the fully integrated hybrid propulsion plant from Berg Propulsion. Already operational at Port Arthur following delivery by Master Boat Builders. Hence, the Robert Allan-designed RApport 3000 vessel is the first of two 90-ton bollard pull tugs using this latest Berg package. Note that, the second is due in service in Q3 2022.


The tug incorporates MTA 628 azimuthing thrusters, VS3 variable frequency drives with motors, and its own hybrid control system. Moreover, Berg’s design, supply, and integration include the switchboard with full power management. This involves the control of the tug’s twin Caterpillar 3512E EPA Tier 4 (2,550 hp) main engines and its gensets. Specifically, two CAT C18’s and one C7.1.

Berg’s hybrid-electric propulsion system includes high levels of redundancy for safety. Furthermore, the ability to switch seamlessly between operating modes with the push of a button. A vessel can run on; main engines only, gensets only, or a combination of the two, optimizing energy use across the entire operating profile. A tug in transit can minimize energy consumption and eliminate main engine wear by running on a single generator set. In hybrid mode, power balances between diesel engines and electric motors. Thus, optimizing fuel consumption, maneuvering response, and bollard performance.


“During the first weeks in operation, Spartan has been living up to the promises made for hybrid propulsion vessels… Seabulk’s commitment to improving the sustainability of its operations is represented by its investment in a new generation of vessels whose flexibility is proving that hybrid tug technology is our choice for the future.”

Daniel Thorogood, President and CEO, Seabulk

Moreover, Berg’s distributor and partner in the area, Thompson Marine managed the installation at the yard. Eventually, the solution is the most advanced hybrid electric package, ever delivered by Berg Propulsion.

“Thompson Marine managed the details from the earliest design phase through sea trials together with Master Boat Builders, Seabulk, Berg Propulsion, and Caterpillar. This delivery sets down a marker that – with the right team in place – the sustainability and performance benefits of advanced hybrid electric propulsion are available to all.”

Richard Tremayne, Marine Business Manager, Thompson Marine

“This has been a landmark delivery for Master Boat Builders in next generation tug construction, and a testament to the value of teamwork… The approach was collaborative throughout the design, engineering, and building phases and we look forward to completing work on the second of these innovative Seabulk tugboats later this year.”

Garrett Rice, President, Master Boat Builders
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