A Heuristic Procedure for a Ship Routing and Scheduling Problem with Variable Speed and Discretized Time Windows

Table 1

Overview of graphical nomenclature.

Graphical nomenclature:	Represents
	Ship 𝑖.
	Node or instant of time.
	Contract with the corresponding discrete feasible starting times for cargo of the trip. Consider the illustration that the node is the earliest time instant and is the latest time instant.
	Arc representing a ship 𝑏 that departs at time instant 𝑖 from the origin port and arrives at time instant 𝑗 at the destination port.