adaptive search procedure (GRASP) is developed to handle instances where the branch-and-bound algorithm takes too much time. [@NAV:NAV20121] have strengthened the MIP formulation of [@kim2004crane] by deriving sets of valid inequalities. They propose a branch-and-cut algorithm to solve the problem to optimality.

[@doi:10.1080/03052150600691038] also study the scheduling of multiple QCs for a single vessel with the objective of minimizing the loading/unloading time. In their setting, a task refers to the loading/unloading of a single hold, but [*no-passing*]{} constraints for the QCs are explicitly taken into account. A heuristic that partitions the holds of the vessel into non-overlapping zones and assigns a QC to each zone is proposed. The optimal zonal partition is found by dynamic programming. [@ZhuYandLiA2006] consider the same setting, but formulate a mixed integer programming model and propose a branch-and-bound algorithm for its solution (which outperforms CPLEX on small instances). A simulated annealing algorithm is developed to handle larger instances.

[@NAV:NAV20108] study a dynamic variant of the problem considered by [@RePEc:eee:transb:v:23:y:1989:i:3:p:159-175], which accounts for movement time of QCs and that QCs cannot pass each other, and enforces a minimum separation between vessels. By limiting the movement of QCs to be unidirectional, i.e., either from “stern to bow” or 