The Benguela Gem (AMV3) ship owned and operated by Debmarine Namibia is one of the most technologically advanced vessels in the marine diamond industry, valued at more than US$420 million. Equipped with advanced subsea crawling equipment, the vessel can recover high quality diamonds from the seabed at water depths of 90m to 150m.
The ship is a combination of a complex and DP2 capable offshore vessel, adapted for the specific purpose and integrated to mission equipment. The mission equipment comprises the subsea crawler which recovers diamonds and gravels from the seabed, the launch and recovery system which deploys the crawler to the seabed and an advanced treatment plant which recovers the diamonds from the gravels and returns almost 99% of the gravels to the seabed.
The vessel was designed and built in Europe and the mission equipment was designed and built in Cape Town, South Africa, in large modules in parallel to the vessel build in Europe. The mission equipment was then integrated into the vessel in Cape Town by De Beers Marine.
Mammoet was tasked by De Beers Marine to lift and install the modules of the vessel’s mission equipment. To optimize the installation schedule and to speed up integration works, Mammoet engineers offered its Focus30 crane as the best option to install the components, due to its capacity and outreach to lift and install all components onto the vessel from a single position.
Erected vertically in sections, the crane requires no laydown area during assembly of its boom, which meant less infrastructure needed to be disrupted or closed. Moreover, its low ground bearing pressure – below 10t/m² – meant that no special ground civil works would be needed on the berth.
Ten modules weighing up to 428t needed to be integrated with the vessel: including the lower and upper launch and recovery towers, a winch and a crawler. These main modules were built positioned in a semi-circle, so that they would be within the lifting radius of the crane.
Later, the Focus30 was erected among them and was fully lift ready just over two weeks following the start of its assembly. Once the vessel arrived for outfitting, the 177-meter ship was ready for integration. In a three-week operation, Mammoet’s project team lifted and installed the modules on the deck ten days ahead of schedule.
Ewan Labuscagne, project manager, Mammoet Southern Africa branch, commented: “We’re proud to have worked on the construction of the world’s largest diamond recovery vessel using one of the most innovative cranes in the world. I am particularly proud of the entire team: the resilience, flexibility and the teamwork shown, and having played a part in the delivery of the project ahead of schedule, despite the challenges of the pandemic.”