Underwater PBCF Installations Bring Fuel Savings

Last month Hydrex installed  Propeller Boss Cap Fins (PBCF) on two tankers during their respective stops in Ghent and Antwerp. As a result of the underwater operation, the ships will not have to wait for their next drydock visit to start benefitting from the fuel savings the PBCF’s will bring them.

The Propeller Boss Cap Fins (PBCF) is a device for propeller efficiency improvement developed by Mitsui O. S. K. Lines, Ltd. The PBCF can recover energy loss of a propeller hub vortex in the propeller’s backward flow. This decreases fuel consumption by 5% when operating at the same speed, or boosts speed by 2% with the same fuel consumption.

The 5% energy saving effect has been verified by world research institutes including International Towing Tank Conferences (ITTC) and by owners.

With the current emphasis on global environment problems, the demand for the PBCF has been continually growing and this as an energy saving device and an environment-friendly product because it realizes a 5% reduction in CO2, NOx and SOx gases emission from vessels.

The first operation was performed on a 183-meter tanker berthed in Ghent. After the team arrived at the vessel’s location with one of the Hydrex workboats, they started the operation with a full inspection of the propeller. Next the diver/technicians cleaned the area where the spinner cone (PBCF) was to be installed. They then lowered the cone into the water and positioned it on the propeller. When this was done, grease was inserted in the space underneath the propeller cone for lubrication and the bolts were put on torque and secured with wire, finishing the replacement of the PBCF. The Hydrex team worked around the clock to finish the operation as quickly as possible.

The exact same procedure was used during the operation in Antwerp on a 130-meter tanker. The alignment of both Propeller Boss Cap Fins was monitored on an underwater video camera and supervised by the manufacturer’s specialist on the workboat.

Last year Hydrex had already replaced two PBCF’s on a 110-meter tanker in Singapore. This was the first underwater installation of a PBCF, according to the manufacturer.

By performing the operation on-site and underwater, the owner of both tankers could immediately start enjoying the fuel savings the system offers. Otherwise he would have had to wait for the next scheduled drydocking before having the PBCF’s installed. This would have cost him up to two years of savings. Calculations show that he will have earned back the money of the underwater installation in about eight weeks, so the savings for the customer are enormous