Schottel Controllable Propeller design helps EEXI compliance

Schottel SCP retrofit propeller blade (Photo: Schottel)

Following on from the introduction of the Energy Efficient Existing Ship Index (EEXI) in January 2023, an increasing number of ships have been operating at lower speeds to reduce fuel consumption and achieve compliance.

The Schottel Controllable Propeller (SCP) can be fitted to maximise efficiency and gain the most from those lower engine speeds.

Using custom designs based on computational fluid dynamics, the SCP is said to deliver a 5% increase in propulsion efficiency. This can lower fuel consumption, reduce emissions and cut operating costs.

The propeller design can also reduce cavitation and pressure fluctuations, while also lowering noise emissions.

The SCP is designed to be both robust and user-friendly, ensuring minimum maintenance and a long working life. The props are suitable for vessels with a broad operating profile, providing optimal propulsion at variable speeds and/or loads.

The EEXI is part of the 2023 IMO GHG Strategy which sets out a timeline over which ships need to reduce emissions by 40% by 2030, based on 2008 figures. The goal is to reach net-zero emissions by about 2050.

A given ship’s EEXI indicates its energy efficiency compared to a baseline. The attained EEXI is then compared to the EEXI based on an applicable reduction factor expressed as a percentage relative to the Energy Efficiency Design Index baseline.

The figure needs to be calculated for ships of 400 gt and above, in accordance with different values set for the ship size and size categories. The calculated attained EEXI value for each vessel must be below the required EEXI to ensure the ship meets a minimum energy efficiency standard.