Propeller Shafts & Propellers
The condition of a vessel’s propeller and hull will have the biggest impact on fuel consumption and exhaust emissions. Despite having a much smaller surface area than the hull, the hydrodynamics of the propeller are critical to propulsive efficiency, engine load and ultimately the operator’s bottom-line.
Mechanical prop-cleaning regime
The relatively simple underwater shape of a ship’s hull is easy to clean with ROVs. However, the complicated geometry and location of propellers usually necessitates the use of specialist divers or access during drydock.
There are a number of companies that have developed in-water hull cleaning systems, including Ecosubsea, CleanSubSea and HullWiper. But in-water propeller cleaning is still exclusively carried out by divers
- Mechanical cleaning of the prop is a very effective means of removing bio-fouling and maintaining vessel performance.
- It is relatively easy to arrange during drydocking.
- Relies on the drydocking schedule or expensive specialist divers and equipment between drydocks.
- Propeller performance will deteriorate over time as fouling re-establishes and must be accounted for in the vessel running costs and transit times
As well as being fitted to box coolers and pipework, ultrasonic transducers can also be fitted to stern tube bearings or the stern frame in order to transmit protective ultrasonic waves through to the prop shaft, hub and blades.
- Fits easily on the dry side of the stern arrangement without the need to drydock
- Protects clean propellers continuously without any drop in performance
- Ultrasound frequencies used are safe on all types of lube oil and grease.
- Works 24/7, even works when a vessel is idle in port.
- Very low MRO costs and quick ROI.
- Requires careful consideration of the General Arrangement drawings to ensure predictable propagation of the ultrasound waves.
- High initial capital outlay, which is recouped very quickly by reduced fuel consumption and prop-cleaning schedules.