Global container shipping companies have continuously enlarged the ship's size to reduce fuel cost, port charge and CO2 emissions to transport more cargoes at a time by a ship. Loadable space on deck has significantly increased by ship's size enlargement, but the container ship can not load containers up to designed capacity of container as shipbuilding's design plan due to the existing installed lashing system's limitation. Each Classification restricts to load containers on deck when lashing force exceeds permission load for safety lashing. It leads to business loss for Shipping company due to unable cargo spaces of the ship.
Cargo stowage planner and ship's crew must observe the regulation of lashing force's permission load required by the Classification for safety cargo transit. In case of lashing force’s over, it is necessary to study the ship's characters affecting cargo securing system to maximize loadable ship's space as well as cargo weight distribution when planning cargo loading stowage.
This paper is intended to provide improvement method after analyzing the correlation of ship's characters with lashing force. Analysis procedure of the this study is as follows.
Firstly, this study specifies parameters which are GM(metacentric height), Loading position of container, Draft except of ship’s static characters and external factor. Additionally, this paper tries to makes inferences any features from data which was gotten to comparison analysis of container lashing force by ship’s sizes.
Secondly, This study was carried out targeting 4.5K, 8.5K, 13.1K container ship of H shipping company having been to enter Pusan new port H terminal during the recent 6 month period(2015.09~2016.02). Pusan new port is last port of ‘Trans Pacific Service’ and main port of ‘Asia-Europe Service’. So these conditions are suitable for this study because ship’s cargo spaces were stuffed full of containers.
Thirdly, Lashing calculation tool(Certificated by KR classification) which was made by H-UNI was used for lashing force calculation by parameters. There was a correlation between parameters and lashing force through data which was obtained by lashing calculation tool.
As a result, parameters such as GM, Loading position, Ship size’s characteristic change the lashing force significantly. The utilization of this parameters can make additional loadable spaces and safe lashing status reduce lashing force.
Lastly, this paper suggested improvement method for reducing lashing force when making cargo stowage plan. And these improvement method was verified by actual used loading stowage plan.