This paper takes a hatchless container ship as research object, applies the numerical calculation software SMAR and HydroStar to forecast the ship motion under extreme sea conditions. Also, Seakeeping model test to estimate ship motion and green water ingress in open cargo holds is carried out to compare with the numeric results. It proves the numerical calculation software meets the computational accuracy requirement. And the maximum green water ingress in open cargo holds happens in bow-quartering seas, and satisfies the requirements.
Hatchless container ship has been developed rapidly in recent years, and it is regared as a realistic alternative for application to conventional containerships becasuse of its advantages. For example,it has a simple structure, the loading and unloading of containers is convenient, so it can shorten the time of ship in port and has good economic efficiency, and so on. But under extreme sea conditions, the research of waveinduced ship motion and green water ingress in open cargo holds is important for the safety navigation in waves.
International Maritime Organization (1994) provided detailed guidance on hatchless container ship. Wang Renkang et al.(1998) calculated for the statistical properties of green water on deck. Zhu Renchuan et al.(2003) estimated the amount of shipping water into a open-top container ship. He Xinyu et al. (2013) studied the seakeeping model test for a 13000 dwt hatchcoverless multi-purpose vessel and provided references for the design of same ship types.
In this paper, a hatchless container ship is taken as the research object. A series of numerical calculations are executed by numerical calculation software SMAR (Ship Motion and Add Resistance due to waves), which is independently developed by SSSRI, and HydroStar, which is developed by BV, is applied to forecast the ship motion under extreme sea conditions. The extreme sea conditions means the irregular long-crest waves which is simulated by JONSWAP spectrum, its worst wave spectrum peak period is 8.5s, which is determined by therotical calcultion, and the wave height is chosen as 8.5m. Seakeeping model test to estimate ship motion and green water ingress in open cargo holds,which is executed according to the criteria proposed by IMO, is carried out under the same extreme sea conditions. The numeric results is compared with model tests, and it proves the numerical calculation software meets the computational accuracy requirement. The green water ingress in open cargo holds is one of the most important factors for designing a type of hatchless container ship, which has the fear of the flood of shipping water in hold. The model test result of green water ingress in open cargo holds shows that the maximum green water ingress in open cargo holds happens in bow-quartering seas, and it is smaller than the required value in specification, which satisfies the requirements.
