Two advanced subsea mining crawlers, each weighing 370 tonnes, have been developed for Debmarine Namibia’s flagship vessel, the MV Benguela Gem.
Built by De Beers Group’s Upstream Technology division in Cape Town, the Next Generation Crawlers (NGCs) are engineered to operate at depths of 100 to 135 metres beneath the Atlantic Ocean.
Each crawler measures 28 metres long, 8 metres wide, and 8 metres high, and operates on tracked undercarriages designed for stability on the seabed.
A hydraulically powered mining arm sweeps a 21-metre arc in 25 seconds, loosening sand and gravel to create a slurry of seawater and diamond-bearing sediment.
The slurry is drawn through an 800-millimetre-diameter pipeline by a powerful dredge pump and transported through a vertical riser to the Benguela Gem’s onboard processing plant for diamond recovery.
The crawlers are semi-autonomous and controlled through automation systems that regulate track movement, suction, and hydraulic pressure.
A network of sensors monitors vibration, torque, and temperature, transmitting real-time data to the vessel’s control room and to De Beers’ remote operations centre in Cape Town.
Automation enables precise, consistent mining, optimised energy use, and reduced mechanical wear.
Navigation is supported by forward-looking sonar and high-resolution imaging systems that map the seabed in real time.
These instruments enable operators to identify diamond-rich gravel and guide the crawlers to mine down to the geological footwall.
The positioning system integrates inertial navigation and acoustic transponders linked to the vessel’s GPS, ensuring accurate coverage of designated mining panels.
Each crawler features a hydraulic track-tensioning system that automatically adjusts to seabed resistance, reducing wear and improving traction.
More than 2.2 kilometres of cabling and 10,000 sealed connections power and control the systems, all linked to the vessel by a high-voltage umbilical that transmits both electricity and data.
The new technology provides a 20 per cent increase in mining rate and a 30 per cent improvement in pump life compared to previous crawler models.
The design also increases engineering availability from 82 to 87 per cent, enabling higher throughput without a significant increase in operating costs.
Before deployment, each crawler undergoes full-scale land-based simulations to test every system under realistic operational load. Predictive maintenance features monitor wear patterns and alert engineers to potential component failures before they occur.
The crawlers were assembled at De Beers’ Upstream Technology Innovation Hub in Cape Town, where engineers used synchronised crane lifts to install the 47-tonne dredge motor and carried out precision alignment of all structural components.
A second identical crawler has been built to ensure continuous production while the first undergoes maintenance. Together, the two machines are expected to increase the Benguela Gem’s annual recovery by about 80,000 carats, replacing production from retired vessels such as the MV Grand Banks and MV Coral Sea.
The Next Generation Crawlers differ significantly from the retired systems used on Debmarine’s older vessels. The previous crawlers, typically weighing 250-280 tonnes, were smaller and operated with less automation and imaging capability.
They relied heavily on manual hydraulic control and were designed for finer gravels, limiting their throughput and efficiency.
The new crawlers, by contrast, are heavier, more powerful, and equipped with larger pumps and pipelines — an 800NB (Nominal Bore) system compared with the older 600mm designs — allowing them to process coarser, denser gravel at greater depths.
They also use adaptive hydraulics and automation to regulate suction and traction in real time, replacing the manual systems of earlier models.
Navigation and seabed imaging have also advanced. The retired crawlers used downward sonar and low-resolution imaging. In contrast, the new systems use forward-looking sonar and three-dimensional mapping, allowing operators to mine down to the footwall with precision without disturbing barren ground.
Their hydraulic track-tensioning systems automatically adjust to seabed resistance, extending track life by up to 30 per cent and improving gearbox torque efficiency.
Each crawler is also built around predictive maintenance and telemetry.
Earlier machines offered minimal data feedback, but the NGCs transmit live operational data — including pressure, temperature, and vibration — to the vessel and to De Beers’ control hub in Cape Town.
This enables remote diagnostics, reduces downtime, and increases engineering availability from 82 to 87 per cent.
The new generation also improves environmental and energy performance. Controlled suction and adaptive power use reduce seabed disturbance and turbidity, while improved pump design lowers fuel consumption per tonne mined.
These gains are coupled with a 20 per cent higher mining rate and a 30 per cent longer pump life, ensuring the Benguela Gem can maintain optimal throughput.
According to Debmarine Namibia, the Next Generation Crawlers integrate advanced engineering, automation, and predictive control to deliver greater efficiency and reliability in offshore diamond mining, reinforcing Namibia’s position as a global leader in marine diamond recovery.
