Block erection sequencing in shipbuilding with general lifting and joining times

This article studies the scheduling of block erection in shipbuilding. A mathematical model is formulated to minimize the makespan, i.e., the time between the start and finish of the erection schedule, when there are different lifting and block joining times. Structural stability and the no-skipped-blocks property are taken as constraints. The model is used to study the erection in three special cases. First, the case with a short lifting time is analyzed. Second, a solution is constructed for the case in which joining times are short and, third, the case in which the lifting and joining times are the same is analyzed. The article shows how these three cases can be solved efficiently, and, in addition, it gives insight into the erection scheduling such as the effects of the number of blocks in the horizontal and vertical directions on different joining times.