Northern Offshore Services´ Green Technology initiative will transform our company into a sustainable shipping company ready to meet the future. We have two focus areas for the coming years.

The first is to develop and produce vessels with low environmental impact, still with high offshore availability, safety, and range. Our second focus area is to prepare and adapt our existing fleet for alternative energy sources.



E-CLASS series, N-O-S 4th Generation design, is a 40 meters Crew Transfer Vessel that offers offshore accommodation for charterer’s personnel. The focus of the E-Class design is high offshore performance and reduced carbon footprints. Through a diesel-electric propulsion system together with batteries and one effective propulsion system, the vessel can run in direct diesel mode with PTO and peak shaving, diesel-electric mode, and purely on batteries in standby mode or during slow steaming operations. With the possibility to replace the diesel engines with electrical engines already in place, the E-Class is a vessel designed with the future in mind. The E-class design allows significant CO2 reductions with increased performance. The effective propeller design reduces CO2 by up to 50% during push-on compared to traditional CTVs. This 40-meter-long Crew Transfer Vessel built for the toughest challenges is a real power vessel expected to perform with 30 tons bollard push.

I and G-Class development process

Northern Offshore Services have extensive experience in operating Crew Transfer Vessels and there are several generations of CTVs designed in-house. The experience and knowledge gained through the years have now resulted in the Crew Transfer Vessels of the future: The G and I-Class.

The vessel classes are both based on the same hull shape and design but with different superstructures and propulsion systems. In close collaboration with Volvo Penta, both the G-Class and I-Class are fitted with the new Volvo Penta IPS propulsion system. The G-Class is a diesel hybrid CTV and I-Class is a Zero Emission CTV.


The N-O-S designed G-Class is a future generation Crew Transfer Vessel ready to take on tougher challenges than before. Every part of the design has been thoroughly evaluated, measured, and analyzed in order to create a state-of-the-art vessel that will revolutionize the industry. With significantly increased performance this vessel will work even safer and more effectively in harsh weather conditions. The revolutionizing diamond-shaped hull together with the new Volvo Penta IPS system will make the transfers more comfortable than ever and at the same time minimize the emissions and effect on the environment. The G-class is a diesel/hybrid CTV and is fitted with two conventional diesel main engines and two electric motors with connecting batteries. The innovative vessel design gives us the possibility to upgrade the G-Class to become fully electrical in the future.


I-Class design is Northern Offshore Services' first Zero CO2-emission Crew Transfer Vessel. The vessel is a guiding star that will lead the industry into the future. The I-Class is built on the same new and innovative hull as the G-class and possesses the same offshore performance. The four electrical motors run by batteries with onshore and offshore charging equals zero emissions. As optional, I-Class can be fitted with range extenders with energy from renewable energy sources, for example, hydrogen. Imagine the comfortable and safe journey onboard this 30 meters pure electric wind farm service vessel. It is ready to take us into the future.

Offshore charging

What is the next step? To enable the highest offshore availability in Zero emission mode there is a need for offshore charging. The electrification of the shipping industry needs it. Northern Offshore Services research and development for different offshore charging options are ongoing.

Energy simulations

We want to provide our clients with reliable marine battery solutions. Together with our preferred shipyard, our R&D department has developed the N-O-S Energy Simulation software. This enables calculations of the battery capacity required for specific wind farm projects. The system allows us to enter parameters such as distances, push-ons, transits and calculate the battery capacity needed to run a full day in the field. With the N-O-S Energy Simulation clients can feel safe that we provide safe, reliable, and efficient service and solutions at sea.


We believe in Electrification. But until we are fully there, we need to explore and assess the alternatives to provide our clients with environmentally effective and reliable solutions. We focus on how to adapt our existing fleet to alternative fossil-free energy sources today. Whether it is methanol, green hydrogen, or HVO we evaluate all alternatives when it comes to environmental benefits and plan for upgrades of our entire fleet.



The second focus area for N-O-S sustainable future is to take care of what we have and update our current fleet. We have about 45 vessels that will be upgraded. We have a plan in place and we have already started.

M-Class hybrid

Two vessels from our M-Class series, Mover and Maker are the first in line for battery preparations. During early 2022, we will carry out a complete upgrade of the two. The vessels will have a new Volvo Penta IPS propulsion system and be prepared for battery installation. The preparation entails making rooms for batteries and preparing the main engines for diesel-electric propulsion. In short, enabling the engines to run on a combination of fuel and electricity.


In 2020 one of our A-Class vessels – Assister – was rebuilt and upgraded. The vessel was extended from 19 meters to 25 meters, utilizing recycled aluminum. The vessel upgrade included a new driveline with 4 x Volvo Penta IPS system and the interior was refurnished with 12 additional seats, making former Assister, now Traveller to a 24 Pax CTV. The transformation from Assister to Traveller gave the vessel a whole new lifespan.


Northern Skagerrak

Northern Skagerrak is a 45 meters tanker vessel currently operating in Gothenburg-Skaw area between Denmark and Sweden. The vessel is scheduled for engines conversion from conventional diesel propulsion to diesel-electric propulsion. With diesel-electric propulsion, the vessel is able to use the electricity generated by the auxiliary engines to propel the vessel, and the other way around, it enables the main engines to generate electricity. The main goal is for the vessel to operate with zero emissions in the harbour of Gothenburg, which will improve the air quality in the area.