The submergence depth of the floating dock is adjusted according to the ballast water and determined by the quantity of the ballast water in the ballast tank. And the length of the air pipe in the ballast tank is the key factor affecting the quantity of the ballast water. The length of the air pipe in the floating dock is very important to the ship performance, because too long air pipe will affect the lifting capacity of the floating dock, while too short air pipe will cause the floating dock to capsize. It focuses on the theoretical calculation method of the length of the air pipe in order to solve the problem of accurately positioning the length of the air pipe in the floating dock, which has been proved by the sinkage test in a full scale. The results can provide reference for the subsequent design and manufacture of the floating dock.

According to the relevant requirements of the resolutions and circulars adopted at the 75th session of maritime safety committee and MSC.1/Circ.1238 and the international code for the fire safety systems (FSS Code), it analyzes and studies the evacuation path and time for a 5 000 t pipe-layingcrane vessel ready to abandon in case of danger. The evacuation process is evaluated from the base case by maximizing the simulation and analysis of the practical events. The crowded points and critical regions are clearly calibrated, and reasonable suggestions are provided for the location of the calibrated points.

Three different schemes of pipeline arrangement are analyzed according to the International Maritime Organization (IMO) guidelines for the damage stability calculation. The influence of the pipeline arrangement on the damage stability of a special purpose ship is studied in order to select the optimal pipeline arrangement. It can provide reference for the design and development of the similar ships in the future.