Thus, from a commercial point of view it is not so important to know that the risk should be borne by one party rather than by the other, what really matter is that it should be accurately defined, at the time the charter party is made, by which of them it will be borne.
In Mawson SS. Co. v Beyer  1 KB 304 Bailhache Judge stated at p.312 that:
1. Prima facie, the presumption is that the object and intention of these dispatch clauses is that shipowners shall pay to the charterers for all time saved to the ship, calculated in the way in which, in the converse case, demurrage would be calculated: this is, taking no account of the lay day exception…
2. This prima facie presumption may be displaced, and is displaced, where either
(i) lay days and time saved by dispatch are dealt with in the same clause and demurrage in another clause;
(ii) lay days, time saved by dispatch, and demurrage are dealt with in the same clause, but upon the construction of that clause the Court is of opinion, from the collection of the words or other reason, that the days saved are referable to and used in the same sense as the lay days are described on the clause, and are not used in the same sense as days lost by demurrage.
Per Donaldson J in Navico A.G. v Vrontados Nafiki Etairia P.E.  1 Lloyd’s Rep. 379 at p. 383:
Since the shipowners may have difficulty in obtaining another engagement at short notice or in advancing the date of the ship’s next voyage, he stands to gain less by unexpected expedition in loading and discharging than he stands to lose by delay. Accordingly dispatch is usually payable at half the demurrage rate.