PBCF (Propeller Boss Cap Fins)

Category: Marine Propeller

Marine propeller PBCF (Propeller Boss Cap Fins) is an extra hub with small fins attached to propeller cap to increase power efficiency. It is being widely accepted for its economic value in fuel saving and low investment, especially for medium and large vessels.

Fountom is experienced in designing such PBCF according to each ship’s arrangement to ensure the most power efficiency and hydrodynamic performance. The number of fins is usually the same as number of propeller blades, for (FPP) controllable pitch propeller, review of the propeller drawing is needed to decide if a PBCF can be added to it.

Results to expect with Fountom PBCF installed

  • Practical fuel consumption saving by ~ 5% (statistic under same vessel knots);
  • Lower propulsion vibration;
  • Smaller (almost none) rudder impact erosion from propulsion flow.

Other standout features PBCF brings

  • No certificates or approvals required from ship class societies;
  • No adjustments to original shafting designs required;
  • Easy to install with bolts just as conventional propeller caps;
  • Suits for both propellers of new building ships and on-service ships.

Hydrodynamic mechanism of PBCF

PBCF can rectify the strong down stream from propeller blade trailing edge, eliminate the hub vortex, and recover the energy loss due to wake rotation. 

propeller without PBCF propeller with PBCF
Propeller without PBCF simulation Propeller with PBCF simulation

 

hub pressure comparison

The fins reduce the axial velocity of the wake, restore the hub pressure and reduce the hub resistance.

Propeller Performance Simulation

Propeller performance with/without PBCF

Pressure Distribution

Pressure distribution on the hub and cap of propeller with/without PBCF

 

How to order a PBCF for your ship

It takes 7 days to design and about 50 days to manufacture the PBCF (actual date to be confirmed in sale), files below are necessary to quote and design process:

1. Propeller drawing (with offset table on);

2. Arrangement drawing of propeller and rudder;

3. Drawing of propeller cap or alternatively hydraulic bolts (to measure inner space of the cap);

4. Extra notes if the PBCF is for an existing propeller:

  a) End user/Buyer need to make sure that actual positioning of bolt thread holes on boss cap matches the drawing (as the bolt hole positons decide fins positions eventually);

  b) In case of small bolt thread hole, it will be expanded or re-drilled as the rotary inertia of a PBCF is bigger than merely propeller cap, stronger bolts are needed to ensure safe working of PBCF.

Propeller Type Fixed Pitch Propeller, Controllable Pitch Propeller
No. of Blades 4 Blades, 5 Blades, 6 Blades