Waiting costs money and for a very long time the question who is to pay has been a prolific source of litigation. The risk is foreseeable and no doubt in an ideal world the parties to every contract would settle the matter when they contracted. But experience shows that business is not done in that way. Parties are inclined to adopt well tried forms leaving it to the court to determine their meanings.
In Monroe Brothers Ltd v Ryan (1935) 51 L1 L Rep 179;  2 KB 28 per Greer LJ at pp 182 and 38:
Now I am satisfied that there is no authority which carries the area of exceptions beyond the time when the ship starts on any agreed voyage. It is not confined to the time when she loads under the charter-party, but includes the period of time when she is steaming with all convenient speed to arrive at the loading port. I agree with the view expressed in Carver’s Carriage by Sea, 7th Ed, Sect 148, as follows:
"But it seems that the exceptions do not apply to matters which may happen before the ship has entered upon the voyage dealt with by the charter-party."
And per Maugham LJ at pp 183 and 39:
I agree entirely … that the exception of losses arising from a number of things, including unavoidable accident or hindrances, … , does not apply to accidents and preventions and so forth incurred in the performance by the shipowners of the subsidiary or intermediate charterparty, that being a contract which has nothing whatever to do with the charterers … and one with regard to which they have no interest. … The vital part of the judgment of Willes J. for the present purpose is where he says (Barker v M'Andrew (1865) 18 C. B. (N. S.) 759):
"The commencement of the voyage is the commencing to do that for which the shipowner is to be paid freight,…"