• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.2
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• pp.157-164
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• 2024

In 2020, 24,000 TEU ultra-large container ships began arriving at the Busan New Port. In this study, the wind pressure and hydraulic force acting on the hull were calculated to obtain the horsepower required for the tugboats for safe berthing and unberthing of a 24,000 TEU ultra-large container ship at the Busan New Port. When the wind speed is 10 m/s (20 kts), 13,000 TEU container ships meet the tug horsepower standard of the current Busan port tugboat operation rules, but 16,000 TEU and 24,000 TEU container ships do not satisfy the regulations. Therefore, it was proposed to raise the standards for tugboat use by dividing the size of ships of "G/T 150,000 tons or more," which is the largest vessel under the current tugboat use standards, into two stages. Because 140,000 tons requires 12,100 horsepower, 170,000 tons requires 14,500 horsepower, and 230,000 tons requires 18,000 horsepower, the study proposed 16,000 horsepower for 150,000 to less than 200,000 tons and 18,000 horsepower for 200,000 tons or more for the use of tugboats.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.5
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• pp.442-449
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• 2024

The pilotage rate of car carriers at Mokpo New Port is increasing and ships are becoming larger. In this study, wind pressure and hydraulic force are calculated to determine the horsepower required of a tugboat to safely operate a 7,500 unit car carrier entering Mokpo New Port. At the Mokpo New Port automobile pier, the maximum flood and ebb currents are 1.6 and 0.7 kts, respectively, at a point 1.0 km away from the pier. In such conditions, the required tugboat standards are satisfied only in the case of "ebb current and westerly wind" under certain situations. Under a current of 0.5 kts, for the case of "ebb current and easterly wind," the required tugboat standards are satisfied only in certain situations, whereas for the case of " flood current and westerly wind," berthing or unberthing is impossible at wind speeds of 18 kts or higher. Additionally, in cases without any current, if the wind speed exceeds 21 kts, then the current standards for the required tugboat are not satisfied. Therefore, for large car carriers of approximately 70,000 G/T entering Mokpo New Port, they are planed to the vessel's docking point when the current speed is less than 0.5 kts. However, when the current and wind speed exceed 0.5 and 20 kts, respectively, the horsepower of the tugboat must be increased accordingly.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.2
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• pp.209-216
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• 2024

Four accidents occurred between 2020 and 2022 after car ferries built according to a coastal passenger ship modernization plan collided with other ships or came into contact with the dock when entering Jeju Port. Accidents primarily occurred owing to careless ship handling and drift by wind during ship handled by herself using bow and stern thrusters without tugboats. Accordingly, in this study, we analyzed the collision accident focusing on car ferry H and the critical wind speed at which the ship cannot be controlled using its own power, tugboat operation plan in increasing wind speed were proposed based on the power required for the ship to berth parallel to the pier without a tugboat considering the external force and moment generated while the ship is berthing. A analysis of the critical wind speed of car ferry H by relative wind direction when using tugboats or not according to the loading status and the berthing speed, showed that one tugboat should be used at the stern when the lateral wind speed is over 10 m/s and two tugboats should be used when the lateral wind speed is over 14m/s berthing at Jeju port.