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Understanding Propeller Roughness: A Guide

It’s been observed that about six months out of dry-dock, the fuel efficiency of vessels begin to decrease. While there are several factors that may contribute to this, propeller roughness is one of the most significant factors.

As a vessel’s propeller spins and produces the thrust required to drive the ship forward, it is continually exposed to various attacks underwater. Such attacks include cavitation erosion, electrolytic action, biofouling (aquatic organisms attaching to the propeller), and more. This continuous exposure to attacks contributes to the propeller’s roughness, which only increases if not addressed. If maintenance is not carried out properly, that can also contribute to the propeller’s roughness.

A propeller that’s unmaintained and burdened with calcareous deposits and incrustations leads to several undesirable outcomes, including a possible shaft damage, diminished fuel efficiency, and lost thrust. The result of which includes more fuel costs, which impacts business competitiveness and profitability.

In this piece, we’re going to everything you need to know about propeller roughness. Take a look.

Propeller Roughness: Using the Rupert Scale

The globally accepted standard for propeller blade roughness is the Rupert scale. The Rupert ‘A’ grade roughly equates to a surface with a roughness of .65 microns, which is the highest quality finish achieved by reconditioning and polishing the vessel’s propeller blades.

Why Polished Propellers Provide More Power and Better Performance

As mentioned earlier, propeller roughness has a direct impact on the performance of the vessel and its fuel economy. Poorly maintained propellers can negatively impact the speed and power of a vessel by up to 5 percent. This is why a smooth, clean, and shiny propeller that’s properly maintained is critical to establishing optimal fuel efficiency.

Propellers should be polished frequently by a professional diving service provider who will perform the cleaning while the vessel remains afloat at anchorage or when berthed and loading cargo.

We are a leading underwater hull cleaning and biofouling removal services provider in Thailand. We also offer ship maintenance services, such as ship and boat hull cleanings, subsea welding, and propeller polishing.

Get in touch with our team for more information.