Frequently Asked Questions

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Frequently Asked Questions and Answers

Q What is "PBCF"?
A It is an energy-saving device installed on propeller, improving propeller efficiency.
Q What does "PBCF" mean?
A It is named after the initials of "Propeller Boss Cap Fins".
Q Who (& When) invented PBCF?
A Mitsui O.S.K. Lines, West Japan Fluid Engineering Laboratory Co.,Ltd and Nakashimamitsuwa Propeller Co., Ltd. (ex. Mikado Propeller) has jointly developed PBCF in 1987.
Q Can PBCF be installed only to a new-building ship?
A No, It can easily be installed on both newbuildings and existing vessels.
Q Does PBCF need Class approval?
A No need. PBCF is not a class approval item same as normal boss cap.
Certain class request to submit PBCF drawing but it will be arranged by MOL Techno-Trade Ltd.
Q What are the PBCF advantages?
A Average 5% FO Saving Effect (at same ship speed) or boost ship's speed by 2% (at same horsepower).
Q Does PBCF an other advantages than energy saving?
  • Reduction of torque-rich conditions
  • Reduction of stern vibration and underwater noise
  • Elimination of rudder erosion
Q How is the PBCF effect obtained?
A PBCF will eliminate the Hub Vortex.
Q Does PBCF effect change by the size or type of vessel?
A PBCF will improve the propeller efficiency and the PBCF effect essentially will not depend on the size or type of the vessel.
Q Does Slow-Steaming influence the PBCF effect?
A You can expect about 5% effect on average at any ship speed.
Q Is there any negative effect for Hull or shafting by installing PBCF?
A There is no negative effect in any way.
We have installed PBCF over 3,200 vessels until now and there has been no problem for Hull or Shafting.
Q In case of newbuildings, is it necessary to change propeller or shaft design for installation of PBCF?
A Not at all
Q Is there any effect for ship-maneuvering performance by PBCF?
A There is no effect for ship-maneuvering performance (forwarding, reversing, circling, stopping)
Q Why are the values of PBCF effect analysis scattered?
A Sea Trial/Voyage Data on actual vessels are included the interference in actual sea way, like wind, wave, sea current and there is a lot of variation in the data.
Q What is the Delivery time of PBCF?
A It takes usually 3 months from receiving firm order. (Based on Delivery in East Asia)
In case of delivery to Middle East, Europe or other area, additional over 1 month will be needed.
Q Which types of vessel can install PBCF?
A All type of merchant vessels, and also high speed vessels, fishing crafts. PBCF is a propeller improver.
Q What is included in the PBCF price?
1) PBCF body
2) Accessories set (Original bolts, Calibrated Torque Wrench, Gasket, locking wire and installation manual)
3) For delivery to East Asia by sea freight: transportation included (CIF at port East Asia)
Q Can PBCF be installed on a Controllable Pitch Propeller (CPP) ?
A Yes, basically possible. However for some propeller maker or type of CPP installation of PBCF is impossible.
Q What drawings are necessary to design PBCF?
1) Propeller (incl. propeller particular and boss cap)
2) Propeller blade offset table
3) Propeller Shaft (shaft end and propeller nut)
4) Stern arrangement (showing the clearance dimension between propeller and rudder)
5) Rudder
Q Of which material is PBCF made?
A It is Nickel-Almi-Bronze, same as material as propeller.
Q Can we switch PBCF between our vessels?
A PBCF is custom made product based on propeller design per vessel.
Therefore, PBCF cannot be switched unless completely sister vessel.
Q Are PBCF fins removable?
A No. PBCF is made by using advanced casting technology, as one unit.
Q Are there any moving parts on the PBCF?
A PBCF has no moving parts.
Q How is PBCF installed?
A PBCF is fastened to propeller boss by bolts, comparable to the installation of conventional propeller boss cap.
Q Does PBCF price include installation fee?
A No, installation fee has not included in PBCF price.
Installation is the scope of the customer and usually this is included in the customer's Dry-dock planning.
Q What is the installation time of PBCF?
A It takes about 5~6 hours by 4 workers.
Q Does your engineer attend during the installation?
A In case of installation on exising vessels at Chinese dockyard, we offer a service to dispatch our supervisor for installation at our expense.
In case of other area, the additional supervising fee is neccessary.
Q What is the most important regarding the PBCF installation?
1) Position relation for Propeller Blade and PBCF
2) To use original installation materials, like fastening bolts, torque wrench.
3) Apply correct fastening torque to the bolts.

Installation is comparable to the installation of coventional propeller boss cap, without welding works.

Q Does PBCF need specific maintenance?
A No specific maintenance instructions.
PBCF may follow the propeller maintenance. For example cleaning and polishing. Further we have no objection for special paint or coatings.
Q May we ask MOL Techno-Trade to assist in the analysis of the PBCF effect, after installation?
A Upon request, we will analyze PBCF effect and submit a report.