탱커선대의 실형분석에 따른 돌핀부두의 설계조건에 관한 연구

Abstract

The issue of energy acquisition due to the increase of oil price is one of the most important issue and policy of every nation. Various tankers have been built in the world and sent to the trade market. It is necessary to build the port infrastructure and facilities to give them proper services such as mooring, packing, storing, and tranship, etc. However, The domestic guidelines or standards for design and construction for the dolphin berth among these facilities are out of date and do not meet the recent trend of tanker types. Therefore, it requires amendment on the guidelines or standards.

In this study, a detailed analysis of the tanker fleet, covering 8,000 ships under operation and order to build, is made to estimate the proper PBL of each tanker class. After discussion and comparison on the dolphin berth design and construction code of various countries, those are the leading countries of tanker operation and management, suggestion to amend on the design code. The referred codes are of Korea, Japan, UK, USA, and Canada. In order to verify the deduced amendment on the domestic design code for dolphin berth, it was selected one of the domestic dolphin berth, located at the Yeosu oil terminal, which is almost completed to construct. The design criteria and expected tankers to moor in that terminal were analyzed and the appropriateness and countermeasure for deficiency were summarized as follows:

1) From the 8,000 tankers in operation in the worldwide trade, the trend of LOA, PBL, PBL/LOA under full loading condition, normal ballast condition and lightship condition with respect to DWT were deduced by the least square method to fit the curve. The estimated PBLs were 0.47L for full loading condition, 0.45 for normal ballast condition, and 0.32L for lightship condition, respectively.

2) In order to figure out the fore & aft mooring and breast line linking points of ship side on the design plan, the analyzed tankers' general arrangement drawings show that the fore & aft mooring winch are located at 3.7m~24.7m from the ship's edges and breast winch is located at 3m~5m from those winches.

3) Precaution is necessary to the PBL because it is varying depending on the cargo loading condition on the tankers. Under the normal ballast condition, PBL is 79∼98% of the full loading condition and the lightship condition gives PBL 50∼85% of the full loading condition. Therefore, the loading condition will change the mooring status at the breasting dolphins(B/D)and the limit of B/D interval will be changed, too. It is necessary to prepare for the shorten PBL with respect to the B/D intervals of each pier.

4) The interval of B/D in the design code taking account of the actual variation of geometry of the vessels to be berthed, from the trend of tanker type should be in the range of 0.3L ~ 0.5L as US code. The analysis of tanker fleet shows the PBL as 0.45L under the normal ballast condition.

5) The number of B/D is usually two and M/D is four to six, depending of the size of tanker. B/D interval should be such as to allow the smallest design tanker to be able to lie alongside with at least two dolphins in contact with the straight run of the hul (PBL). Where the range of tanker sizes is large, then provision of two sub B/D may be necessary.

6) The present design code for horizontal mooring line angles is proper for the tanker fleet mooring such that the angles between fore & aft lines and the vessel's should not be smaller than 30°~ 45°. The breast mooring line angles do not exceed 10° at M/D and the spring mooring line angles do not exceed 10° at B/D, too.

7) As per the analysis of the tanker fleets in the world trade service, the straight line defining the outline of the central part which accounts for about 3/4L and two curves defining the outline of the bow and stern parts which accounts for about 1/8L in the Korean and Japanese dolphin design codes need to be erased or amended as 1/2L of central part for the straight line and 1/4L of bow and stern parts for the curve.