From the Ship Owner's point of view this is the most advantageous description of the loading and/or discharging time since the time during which the ship is not loading and/or discharging (e.g. at night in ports where night work is not customary) cannot be deducted from the laytime. If a day is only used partially, then this day counts for a full day unless the charter party stipulates differently (Mocatta, A., Mustill, M. and Boyd, C., Scrutton on Charterparties an Bills or cargo, London, Sweet and Maxwell, 1984, 311).
These are days on which it is customary to work in the port concerned, Sundays and public holidays excluded. The number of hours on which is worked, is stipulated by the local uses or in the charter party. Generally a working day counts for 8 hours. Saturday counts for a full working day unless the charter party has a restrictive provision as it happens in the US where on Saturday only 4 hours are worked.
Under a working day of 24 hours it must be understood that each 24 hours worked must be considered as a layday, even if the working hours are spread over several days. If for instance, in a port one usually works 8 hours per day, then according to that formula only 8/24 or one thirds of a layday will have been used. This is very disadvantageous for the Ship Owner so that he will try to avoid this by using the provision under d. below.
Here now working days of 24 consecutive hours are being considered, by day as well as by night. If no work is done at night, then that time cannot be deducted from the laytime. A port where it is customary to work 12 hours per day e.g. from 6 o'clock in the morning till 6 o'clock at night counts therefore for an entire layday.
Weather working days are working days weather permitting. They have the same meaning as working days provided that on days that the weather conditions makes it impossible to load or to discharge, don't count as laydays. This provision is not attractive and is dissuaded by BIMCO, because there are often disagreements about the question when the weather makes loading or discharging really impossible. The expression "working days weather permitting" has the same meaning as "weather working days". (See also further, paragraph D The Excluded Time, Weather Permitting (w.p.))
Here, consecutive hours are meant instead of consecutive days (cf. days or running days or consecutive days).
Note that in the 1994 revision of the GENCON reference is now made to running days/hours, where previously reference was made to hours only.