선박의 운항성능 평가에 관한 연구

Abstract

As a ship gets bigger and faster lately, ship's structure or cargoes might be often damaged and the ship might be cut in two in extreme conditions by a wave impact on its bow. In this paper, the ship's performance such as seakeeping, maneuvering, stability and boarding comfort was evaluated by the training ship HANBADA.

The vertical acceleration, which is one of the factors for evaluating seakeeping performance, was measured under the various sea states by the hull stress monitoring system(HMS) on the bridge, and the results were compared with those of model test and theoretical studies. Then, we confirmed the seakeeping performance of T.S. HANBADA by comparing it with ITTC seakeeping criteria. This result will be a great help for the safe navigation by making it possible to estimate the possibility of work and the amount of risk under the various sea conditions with which it might confront, and the shipbuilding yard can be possible to construct the vessel with superior performance through these data measured on the actual ship.

Various turning tests were carried out according to the rudder angle, turning direction, loading condition and the ship's speed, after that they were compared with the IMO maneuvering standards. And maneuvering indexes such as K and T were also obtained through the turning tests. T.S. HANBADA has the large superstructures above the water line, so she is supposed to have relatively large leeway or to be difficult to course keeping under the strong winds. These effects will be more significant on berthing, unberthing or proceeding on low-speed at harbour. Therefore, it was calculated the wind forces and moments acting on her, and then found out how much leeway and count rudder angle would be happened with the relative wind direction and velocity.

Three or four typhoons are influencing on the Korean Peninsula in a year. Among them, typhoon 'Sara' in 1959, 'Rusa' in 2002 and 'Maemi' in 2003 accompanied with such a strong wind and heavy rain that they caused a catastrophic damage to the properties and/or lives. Especially typhoon 'Maemi' caused a lot of marine accidents such as sinking, stranding and collision etc. on the vessels at anchor in bay of Jinhae. If T.S. HANBADA will be begun with the influence of the typhoon, she usually escapes from the expected route or anchors at the bay of Jinhae. However, decisions of how to use the anchor and judgement of her safety at anchor depend on the experience of operators by this time. In this paper, the maximum permissible wind velocity was evaluated for keeping her on the safe conditions at anchor by comparing the holding power with the wind force on the hull.

Vessels are often capsized because of the loss of stability. If the rolling is intense because of excessive stability, the ship's machinery and/or cargoes as well as the ship's hull may be damaged and crew and passengers feel uncomfortable. On the contrary, when the stability is not enough, the ship may be easily inclined due to winds and/or waves and also be easily capsized because she will not be recovered soon after the inclination. Therefore, it was calculated the stability for the several loading conditions and compared with the IMO stability criteria. Also, the maximum roll angle was analyzed with the various sea states measured for 2 years on T.S. HANBADA. And then, it was presented how to escape the excessive roll from the parametric rolling.

When a vessel is underway in a heavy weather, passengers and crew have experience of seasickness which causes drowsiness, dizziness, headache, stomachache etc. In extreme conditions, they suffer from a serious trouble which is physiologically unrecoverable. Therefore it results in delay of spiritual activities or making errors from decrease of motivation, dropping off skills, poor recognition and poor judgement. In this paper, the international standards concerning about the occurrence of sickness and the possibility of works were analyzed, and the boarding comfort was evaluated by conducting several times of survey on cadets boarding on T.S. HANBADA. The result showed that one of the main factors of occurring the sickness was the vertical acceleration and the level was more than 0.2g. Also, it was presented the way how to reduce the sickness by changing the ship's speed and/or course in relation to the encounter period with the wave.