The noble would need to issue the sail order as captain of a ship to move north into the South Sea. Route distances are rated in the number of days it would normally take a lightly loaded noble, walking, to traverse them. Actual travel times may differ from the rated times. Nobles overloaded with belongings will make slower progress. Horses usually speed progress, but over especially rough or treacherous terrain, they may actually slow travel because they must be led and managed.
Inventory is considered for the stack as a whole.
For instance, if one noble possesses enough horses for every member of the stack, the stack may ride. Similarly, if one noble is badly overloaded, but other nobles have extra carrying capacity, they will assist their stackmate. Distribution of goods between units within a stack is irrelevant to movement. The units stacked beneath a moving noble will move with the stack leader. If the unit issuing move is stacked beneath another noble, he will first automatically unstack before movement begins.