Taiwan is a seafaring country, and in order to enforce the Executive Yuan’s policy, “Ocean Taiwan”, the Ministry of Science and Technology (MOST) is deepening its marine research by successfully combining all low, middle and upstream capabilities in advanced technological research, policy tasks and industrial development, thereby transforming Taiwan into a sustainable sea power. Research ships are an important tool for the study of marine science and technology, and so on the eve of the 2021 Spring Festival, the research ship Legend, developed by NARLabs’ Taiwan Ocean Research Institute (TORI) and under the jurisdiction of MOST, successfully completed a week of maintenance work and returned to Tainan city’s Anping Commercial Port. Furbished with a new look and fully prepared for the new year, Legend is ready to provide even better services to the academic community.
Ship docking and maintenance is similar to that of regular car maintenance, the most obvious difference being that the former’s cost is relatively high. After years of sailing the seas, many aquatic organisms such as algae, vines and sea oysters will adhere to the ship’s hull below the waterline, which will then increase navigation resistance, reduce speeds, and increase fuel consumption. Consequently, the nature of work and age of the ship determines the frequency and type of docking maintenance needed. Generally, merchant ships are docked for two inspections and maintenance work every 5 years. As marine life attaches to Legend’s hull, it also begins to affect the measurement accuracy of its underwater detection instruments, so it must be docked more frequently than ordinary merchant ships. Since its maiden voyage in January 2018, it has been docked twice in three years to ensure that the hull and equipment are optimal.
A Gondola is mounted underneath Legend, making it the first research ship in Taiwan to adopt this hanging mechanism. It is equipped with sonar detection equipment, including a Single Beam Echo Sounder, (SBES), a shallow/deep-sea Multibeam Echo Sounder (MBES), a Sub-bottom profiler (SBP), Acoustic Doppler Current Profiler (ADCP), and more. To avoid this interference to the sonar detection system caused by these marine organisms, annual maintenance can effectively reduce such adverse effects.
In addition to its cleaning, the hull also needs maintenance. According to the water environment, the material of the hull shell, the requirements for protection, the type of coating and performance standards are all different. In general, the part of the hull that is immersed below the water line for a long length of time requires two different paint combinations of anti-rust and anti-fouling. The anti-rust paint protects the hull’s steel plate, and is usually painted directly onto the bottom shell, but is also applicable to all areas of the ship. Likewise, anti-fouling paint is to avoid organisms from attaching and reducing the fuel consumption of the ship when sailing. It is usually used in the hull area below the waterline. The final result is a coating consisting of a double-layer anti-rust primer and a double-layer anti-fouling paint. Simultaneously, in order to improve the adhesion between the paint and the primer and enhance the anti-corrosion effect, an additional layer of intermediate coating is also applied. During maintenance, the hull is repainted, not only restoring the ship’s appearance, but also saves fuel by reducing resistance.
Additionally, to avoid damage to the hull structure due to electrochemical reactions, the zinc metal installed around the propellers on both sides of the cabin and of the stern is replaced, using the sacrificial anode (zinc) to protect the cathode (iron). This is yet another way to protect the hull and slow the corrosion of the steel hull.
After the completion of all this maintenance work, the research ship Legend was immediately released to return to Tainan’s Anping Port. After the Spring Festival, it will soon head out into the wide expanse, thereby kicking off the first ocean exploration voyage this spring, 2021!