Criteria for (un)-loading Container ships

Criteria for (un)-loading Container ships

Goedhart, G.J.

Ligteringen, H. (mentor)
Rijsenbrij, J. (mentor)
Groenveld, R. (mentor)
Van der Lem, J.C. (mentor)

Civil Engineering and Geosciences

2002-10

Time matters in the world of container shipping. Every shipping company focuses on maximizing the use of its ships. This means maximizing the sailing hours and thus reducing the hours spent in ports For this reason shipping companies demand a turnover time of less than twenty four hours from the transhipment company. During these twenty four hours containers are lifted off and later on the ship. To meet the imposed time requirements it is of importance that ship motions are reduced to a minimum since the tolerances for placing containers are quite narrow. When designing a new container terminal it is necessary to know how much ship movement is allowable under normal conditions. The allowable ship motion determines the amount of protection that is needed for the berth. This research project has been initiated to determine improved "criteria for (un)-loading containerships". Beside these criteria the focus has been on establishing a relation between the handling rates and the motions of the vessel that is un-loaded. First a literature study has been undertaken. In this literature study five related papers are discussed and compared to each other. By comparing the papers it was possible to find a new approach to the subject. The new approach has been found in research done by Slinn, in 1979. He placed a steel frame on a quay that could be given a sine shaped motion. The frame represents the cell guides and the motions represent ship motions. He then asked a number of crane operators to participate in the test. The crane drivers were asked to place a container in the moving cell guides. During these tests Slinn gave the frame a certain amplitude and period and noted the number of attempts a crane driver needed to place a container into the frame. Further more he observed the steps taken by the crane drivers to place a container in the cell guides. He found out that crane drivers have no interest in following the moving cell guide but that they simply waited for the cell guide to pass under the container. Based on these two results from Slinn a model has been developed that calculates the reduced handling rates in case of increased ship motion. Full details of the model can be found in chapter 4. Furthermore a questionnaire has been sent out to verify the opinions of harbourmasters. Unfortunately the response was so disappointing that the questionnaire could not be used for scientific purposes. From this research project the conclusion is drawn that the criteria as proposed by PIANC are not strict enough. For undisturbed handling rates the maximum surge motion needs to be limited to 0.3 m (peak to peak) and for sway the criteria should be 0.2 m (peak to peak). Furthermore the reduction of the handling rates depends on the period of motion.

http://resolver.tudelft.nl/uuid:286a1d04-043f-4b66-b830-35541b2a116c

TU Delft, Faculty of Civil Engineering and Geosciences, Hydraulic Engineering

Student theses

master thesis

(c) 2002 G.J. Goedhart