Often the laytime is indicated with the following clauses:
"With customary despatch"
"With all despatch"
"As fast as the vessel can receive (deliver)"
"Liner terms with customary quick despatch"
"In reasonable time"
Et al.
These clauses are not attractive for the Ship Owner as terms such as customary, reasonable, as fast as, etc. are very vague and inaccurate and therefore subject for several interpretations. The Ship Owner will have difficulty in showing that the Charterer has not exercised the necessary diligence at the loading or discharging and that he has loaded (or discharged) the ship to such a slow degree that he has the right to demurrage.
It will be difficult to determine when a ship has been loaded or discharged "as fast as can" (f.a.c.) and since the burden of proof lies with the Ship Owner it will be generally very problematic whether he will receive the demurrage he normally has right to.