Innovative Diesel-Electric Propulsion: The Role of MAN L21/31 GenSets in Offshore Vessels

[By: MAN Energy Solutions]

Wenchong shipyard, part of the CSSC Group in China, has placed an order for four sets of 3 × MAN 8L21/31 MK2 GenSets. This is in line with their project to build four 96-meter Construction and Commissioning Service Operation Vessels (C-CSOVs) for Deutsche offshore Schifffahrt (DO).

C-CSOVs are specialized vessels that play a crucial role during the setup and operational phases of offshore wind farms. DO is taking this concept up a notch by enhancing adaptability,making these vessels more versatile not just for construction but also in cable-grid operations. The design comes from Norway’s Salt Ship Design AS, while CMP—an authorized builder for MAN Energy Solutions—will manufacture the engines in China, with deliveries expected to start in early 2027. There’s even an option included for additional vessels.

The engines will be optimized to operate efficiently at partial loads, contributing to better fuel economy. They’ll also be integrated into a cutting-edge diesel-electric system that meets Dynamic Positioning stage 2 (DP2) standards as per DNV classification guidelines.

Johannes Wolters, Managing Director at Deutsche Offshore, shared his thoughts: “The L21/31 from MAN Energy Solutions is pivotal as we aim to create a vessel with minimal environmental impact. These engines not only deliver top-notch performance now but also align perfectly with our future decarbonization goals.”

Colin Peesel from MAN Energy Solutions highlighted the importance of this deal: “These twelve engines represent over 20MW of power—a major contract! The L21/31 stands out due to its extraordinary fuel efficiency and low noise levels. Importantly, it’s designed to adapt easily to various fuels; beyond MGO, it can utilize biofuels like HVO and FAME and is ready for methanol use.”

The vessel’s design allows easy retrofitting of the L21/31 gensets for methanol operation—far exceeding current class requirements—which means transitioning towards carbon neutrality will be straightforward thanks to existing infrastructure.

MAN Energy Solutions notes an increasing trend toward constructing offshore vessels in China. With a robust network supporting local engine builders and an expanding range of new engine models available there, they’re well-positioned in this market segment. Their after-sales service division—MAN PrimeServ—is equally strong globally irrespective of where DO’s vessels operate.

“We’re seeing rising demand for efficient engine designs tailored specifically for offshore wind,” said Hakon Juel Hansen from MAN Energy Solutions’ engine Promotion & Business Development team.”Our small-bore propulsion engines meet these needs effectively while being backed by our thorough after-sales support through PrimeServ.” With these advanced offshore vessels on deck, DO exemplifies how adaptable our engine offerings can be.”