2,000 orders for energy-saving boss fins

12 Aug 2011
PBCF being installed.

PBCF being installed.

Mitsui OSK Lines and MOL Techno-Trade say that the propeller boss cap fins (PBCF), developed by MOL, West Japan Fluid Engineering Laboratory and Mikado Japan, and sold by MOL Tech, has received 2,000 worldwide orders.

MOL describes the PBCF as an energy-saving device attached to a vessel’s propellers. It breaks up the hub vortex generated behind the rotating propeller, resulting in a decrease of more than 9,000 tons of CO2 emissions per year due to a 3-5% reduction in fuel consumption by a large containership.

Research and development on the PBCF started in 1986, and sales began the following year. Since then an increasing number of shipowners, mainly in Japan, began to adopt the system. By 2006, the PBCF had been ordered for 1,000 vessels. Since then, it has gained wider recognition from vessel owners and operators, and the number of ships adopting it has doubled in five years, now reaching the 2,000 vessel milestone.

A paper presented in June 2011 by BMT Defence Services of UK reported a before and after speed test using an Aframax tanker, showing nearly 4% energy saving. MOL says that this independent study has again brought the PBCF to the attention of the shipping industry and the wider public.

The MOL Group is promoting its next-generation vessel concept known as Sempaku ISHIN, and the PBCF is one of its key technologies. With the mandating of energy efficiency measures at the recent IMO environment meeting, regulations on greenhouse gas emissions will , claims MOL,make the PBCF even more valuable in the future.

The main features of PBCF are summarised as follows:

  1. 3-5% reduction in fuel consumption and a corresponding reduction in CO2 emissions;
  2. reduction in propeller torque;
  3. reduced vibration in the stern less underwater noise;
  4. reduced rudder erosion;
  5. simple installation, requiring only the removal of the propeller boss caps and replacement with the PBCF; no hull modification is needed;
  6. the PBCF is an integral part of the propeller, with no other moving parts;
  7. the PBCF system is custom made, with design optimised for the shape of the vessel’s propellers; lead time is three to four months from order to delivery; and
  8. maintenance-free after installation, requiring only inspection and polishing when the vessel is in drydock, and performance does not decline over time.

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