Aegir – from Deep Water Construction to Offshore Heavy Lift Vessel

Ulstein not only has a vast track record in designing new-build heavy lift vessels but is also actively involved in vessel conversions and upgrade engineering. And with the turn in market sentiment, many vessels from the oil and gas industry are being redeployed towards the offshore renewables and the decommissioning industry. The departure of the Aegir vessel from Singapore to Taiwan makes a good example and marked the safe and successful completion of an extensive 3 months campaign to perform all crane and vessel upgrades on Aegir at Sembcorp.

After Heerema Marine Contractors’ (HMC) strategic reposition on its core business of Heavy Lift, Decommissioning and Renewables, Ulstein Design & Solutions BV was contracted in 2018 to provide design and engineering services to convert their deepwater construction vessel Aegir into a fast sailing heavy lift vessel for foundation installation work on offshore wind farms.

The Aegir joined the Heerema fleet back in 2013 as a deepwater construction vessel featuring J-lay and Reel-Lay capabilities via a large moonpool. Equipped with a large heavy lift crane, she was the first vessel to use such a portable reel system, saving time that is typically taken by sailing back and forth to a shore base.

The vessel has now been converted into a dedicated offshore heavy lift vessel. Aegir’s already massive 4,000-ton main crane and the fact that her hull design is based on Ulstein’s SOC 5000 heavy-lift vessel design, has been a key benefit in this development. Nevertheless, innovative solutions and smart engineering work were needed to make the vessel an efficient asset for the new markets that Heerema is targeting.

As Ko Stroo, project manager/lead naval architect at Ulstein mentioned:

"It has not been just simply removing the tower and pipelay lay equipment that turned Aegir into a heavy lift vessel. The obvious (but not necessarily the easiest) areas of attention were the closing of the large, 25sqm moonpool, creating a flush main deck and modifications to marine, ballast and venting systems. For the latter, the impact of applying Ulstein’s patent-pending venting solution was checked, as it is originally developed for newbuilding projects. In addition, extensive probabilistic stability calculations and a full FEM analysis were made in relation to the new modes of operation."

"Furthermore, Ulstein also performed CFD analysis to assess if hull optimisation could reduce fuel consumption and emissions for the new operational profile of the vessel. A comprehensive and sometimes rather complex engineering scope, where experience, creativity and open communication provides for pleasant and effective cooperation between Heerema and Ulstein."