Objectives  This paper aims to analyze the dynamic cooling loads of ship on fixed routes and conclude with their changing laws.

  Methods  To this end, the ship cabin is modelled to compare the dynamic cooling load changes in 6 different regions of the route(i.e. Hong Kong, Shantou, Fuzhou, Wenzhou, Shanghai, Dalian). Besides, the relation between the course angle and the sun azimuth angle is established to analyze the variation of dynamic cooling loads due to change of these angles.

  Results  It is shown that the maximum total cooling load in Wenzhou area can reach 9.63 kW, while that in Shantou area only accounts for 53% of Wenzhou area, i.e. 5.11 kW. Course angle has great influence on the dynamic cooling load. At the course angle of 40° east by north, the total dynamic cooling load, the cooling load resulted from the heat penetration on wall surfaces(including windows)and the cooling load resulted from absorption of solar radiation increase by up to 21%, 43% and 62% respectively. The greater the deviation from the normal north direction is, the greater the increase of the total dynamic cooling load will be. The increase of cooling load is related to the concentration time and the course angle.

  Conclusions  The load variation caused by course angle during navigation should be considered, to accuately calculate the maximum load of air conditioning, and to select proper equipment model or optimal controlling strategy. Moreover, the air conditioning load calculation of each voyage should take into account the environmental conditions of covered areas.