Study of the effect of changing the ratio of main dimensions on the seaworthiness of container ships

There is currently an increase in container traffic, which has led to an increase in the design and construction of new types of container ships, which are being developed not only to increase their main dimensions and container capacity, but also to provide better seaworthiness at the same time. Increasing the size of container ships takes into an account the requirements for accommodating a whole number of containers by length, widths and depth of the holds. For the five months of 2021, container ships with a total capacity of 2,2 million TEUs (twenty-foot equivalent, a unit of measurement for container capacity) have been ordered. This is 12 times more than for the same period in 2020 and 60 % higher than the previous record set at the beginning of 2005. The vast majority of the tonnage ordered in 2021 will be done in 2023. It is estimated to be around 1,5 million TEUs, and 2023 will be the record year for delivery of container ships. The paper analyzes 112 container ships built between 1979 and 2021, which were divided into three groups. The calculations show that the length to width ratio is greater for ships built between 2000 and 2011 than for "old" container ships, however, for container ships built between 2011 and 2021 the ratio is practically equal for "old" ships. The width to draft ratio of ships built in 2011–2021 is higher than that of container ships built in 2000–2010 and ships built in the 1980s. Container ships built between 2011 and 2021 have a shorter length to height ratio than "older" ships and container ships built between 2000 and 2010. The ratio of side height to draft for container ships built in 2011–2021 is greater than that for container ships built in the 1980s and for container ships built in 2000-2010. The length to draft ratio of container ships built in 2011–2021 is higher than that of container ships built in the 1980s and of container ships built in 2000-2010. An increase in the main dimensions of container ships has a favourable effect on all seaworthiness, but sea straits, canals with certain lock sizes and ports with limited depths in the fairways and at berths, do not allow a further increase in the main dimensions of the ships.

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