Umm Al Anber, a 72m (236ft) heavy duty cutter suction dredger operated by Abu Dhabi-based National Marine Dredging Company (NMDC) has completed the refurbishment of its cutterhead shaft bearings as part of an extensive refit at Dubai Maritime City.

Thordon Bearings’ Dubai-based distributor for the Middle East, Ocean Power International LLC (OPI), replaced the cutterhead and intermediate line shaft bearings like-for-like with Thordon’s water-lubricated Composite system. The turnkey project included shaft dismantlement, laser alignment, in-situ line boring, calibration, installation and commissioning.

Mohammed Fawzy Khalifa, Fleet Manager, NMDC, said: “We have been using Thordon’s grease-free elastomeric polymer bearings since the 1990s. Compared to traditional rubber cutterhead bearings, we find that Thordon Composite reduces vessel operating costs substantially. The bearing requires no lubricating grease and extends bearing wear life fourfold, which is very impressive given the type of environments in which these dredgers operate.”

The 1995-built Umm Al Anber has an 800mm (31.5in) diameter suction pipe and can dredge to depths of 16m (52.5ft).

Rafid Qureshi and Ayman Saad, Managing Partners, Ocean Power International LLC, said: “Together, OPI and Thordon Bearings have been optimising the performance of NMDC’s cutterhead dredgers for more than two decades. Thordon Composite bearings are the preferred choice for NMDC dredgers.”

NMDC has converted all of its dredgers except two to the Thordon system.  However, Qureshi revealed OPI is in discussions to convert the rubber bearings aboard these final two vessels. “We are also in talks to convert the intermediate line shaft bearing to Composite. Replacing worn out rubber bearings with Thordon’s ever-lasting material offers NDMC excellent wear rates, high performance in harsh, abrasive environments, and reduced OPEX,” he said.

George Morrison, Thordon Bearings’ Regional Manager, added: NMDC – one of the world’s leading dredging companies with a fleet of more than 90 vessels – has established a strong reputation for delivering high quality projects and services. It is nice to think that Thordon’s water lubricated Composite cutterhead shaft and intermediate bearings have played an important role in that success.”

Late last year, OPI and Thordon replaced the rubber cutterhead shaft bearings on the cutter suction dredger Al Khatem and beaver dredgers Embarka 2, Embarka 5 and Embarka 6. The projects followed the success of similar conversions to the Al Sadr, Al Mirfa, Al Hamra, Umm Al Zemoul and the beaver Dredge 2.

After 100,000 operating hours dredging up silt, sand, rocks and stones in some of the toughest marine environments the Thordon Composite bearing installed on the Al Mirfa’s dredge cutterhead shaft “did not need replacing and was still in perfect working condition,” said Morrison.

“This is due to the bearing’s black homogeneous material, GM2401, which is fused to a stiff, high strength (yellow) polymer sleeve to provide unprecedented performance and environmental safety. Thordon Composite bearings are available for a wide range of shaft diameters in both tube and stave configuration.”