The importance of Hull Cleaning for ships
The Importance of Hull Cleaning for Ships | Hull cleaning of ships is when the corrosive materials, fouling by algae, marine organisms and old paintwork are removed from the hull of the ship. The method of hull cleaning depends on the required level and degree of cleaning and the condition of the ship, further taking into account the thickness of the paint layers and the condition of the shell plating.
The Importance of Hull Cleaning for Ships and The impact on Hydrodynamic Performance
The biological fouling or roughness on the hull of a ship has an impact on overall hydrodynamic performance as it increases the drag of the vessel. It can be detrimental to the speed of the vessel as well as result in increased fuel consumption. Certain shell fouling like barnacles can, in fact, interfere with speed logs, performance sonars and sensors mounted on the hull of the ship.
When is it necessary to clean the hull of a ship?
The importance of Hull cleaning for ships | Regular hull cleans are vital for manoeuvrability, speed and to increase the longevity of the ship lifetime use. It is recommended to clean the hull and propellers of a ship when there is a noticeable increase in fuel consumption, a decline in speed and if there is a noticeable decrease in the efficiency of the cooling system on-board. Another example of when a hull should be cleaned is after a vessel has returned from a long voyage.
When cleaned properly, most traces of fouling are removed with little to no damage left to the hull of the ship. Underwater cleaning is performed by highly trained divers with specific hull cleaning equipment. Propeller Polishing should be done at regular planned intervals. A smooth propeller surface reduces drag and enhances efficiency of the propeller resulting in better speed. A regular prop polish should be done at six to twelve-month intervals depending on the size of the ship to optimise the vessel’s performance. An underwater inspection is usually performed after the above activity and is necessary to maintain industry quality standards.
Evidence to support the need for Hull Cleans and Quality Control
During a test, Marine Asset Intelligence (see reference 1. ) used specialised analytics to determine the need for frequent hull cleaning. In one particular study, fuel consumption data was collected before and after the hull clean and it was revealed that it was costing the owner nearly $1.3M in excess fuel consumption by only cleaning the hull once every 2 years.
Before each hull clean, primary and secondary data is collected. Firstly, a direct interview to determine the specific needs and to assess what the primary goal is then, secondly, through observation, taking photographs or checking areas visible to the naked eye. During the interview process, questions as the below are usually posed:
- What type of fouling paint is applied?
- What interval of time after fouling paint is applied?
- What fouling organisms mostly attach to the vessel’s hull?
Overall, Hull Cleans are important for conserving energy, saving the vessel owner money as well as playing an important role in protecting the environment. Dry-docking is becoming inefficient and unnecessary with the aid of commercial divers. These underwater specialists contribute immeasurably to the industry and with the emerging industry of quality control being performed on the work conducted by the dive team, the hull cleans are performed under even stricter conditions.
1. Reference: https://www.cat.com/en_ZA/support/operations/cat-connect-solutions/energy-transportation/customer-stories/marine/marineassetintelligenceoptimizeshullcleaningfrequency.html
We believe in driving quality standards within the industry, and believe that the importance of hull cleaning for ships cannot be underestimated. With over 30 years experience in quality control assurance within the shipping industry relating to husbandry activities performed by the commercial diving sector, we are here to assist you.