Mechanism & Effect
Technology

Principle

Simple Structure,
Proven Energy Saving Effect

Conventional propeller boss caps generate a strong vortex called the "hub vortex" from the rear end of the cap, which leads to energy loss in propeller efficiency. By installing PBCF, the fins of PBCF change the flow of the propeller slipstream and eliminate the hub vortex. As a result, thrust is increased, propeller torque is reduced, and propeller efficiency is improved.

What is a Hub Vortex?

The water flowing around a propeller has both the velocity of the ship and the rotational velocity of the propeller. This water flows onto the propeller blades at a suitable angle of attack. However, after passing through the blades, it turns sharply downwards. This creates the "hub vortex".

Without PBCF

The water flow through the propeller blades is strongly deflected in the direction of rotation due to the velocity difference between the upper and lower surfaces of the blades, creating a hub vortex.
Due to the hub vortex and other factors, about 10% of the energy transferred to the propeller is wasted.

With PBCF

The water flow deflected by the propeller blades pushes the PBCF fins in the direction of shaft rotation, reducing shaft torque resistance by about 3%.
In addition, the ground effect of the PBCF fins improves the lift-to-drag ratio of the propeller blades, and the thrust also increases by about 1%.

By installing PBCF, the following effects can be obtained.
Fuel saving effect: Up to 5%
Speed increase effect: about 2%

When sailing at the same speed, fuel consumption can be reduced by up to 5%.
When sailing with the same horsepower, it can sail about 2% faster.

PBCF effect

Reduction of propeller torque

Since the propeller torque decreases, the load on the hull and propeller is reduced.

Reduction of stern vibration and underwater noise

Since the hub vortex is suppressed, stern vibration and underwater noise are reduced.

Elimination of rudder erosion

Since the influence of the hub vortex on the rudder decreases, the occurrence of rudder erosion can be suppressed.