When all necessary conditions are fulfilled for the laytime to start, then the laytime will effectively start. As a general principle, one can say that once the laytime has started to run it keeps on running continuously, seven days per week and 24 hours per day, in spite of possible interruptions in the loading or discharging of the ship. (See also further, Interruption of the Laytime.)
In some ports work goes on 24 hours per day, therefore day and night, but more and more, work is only done during working days with one or two gangs and with interruptions at night and during holidays. The loading and discharging can also be interrupted if goods are not available, if the receiver cannot receive the goods "as fast as the ship can deliver", if the weather is too bad, if the cargo handling gear breaks down, or in case of strike, work-to-rules, etc. (Gorton, Ihre, R. and Sandevärn, A., Shipbroking and Chartering Practice, London, Lloyd's of London Press, 1980, 143.)
According to most legislation, those disruptions will only interrupt the laytime if this is clearly indicated in the charter party. In the "Laytime clause" the holidays and bad weather are generally excluded or excepted from the laytime. There is about this matter a large diversity of clauses and both the Ship Owner and the Charterer must understand the content and meaning of each used expression very well.
Frequently used clauses are:
"Sundays and holidays excepted" (SHEX).
Sundays and holidays are excepted and consequently do not count as laytime. If work is nevertheless done on Sundays and holidays, then the owner may not consider these days as laydays.
"Sundays and holidays included" (SHINC).
Sundays and holidays are not excluded and therefore count as laytime. They are thus considered as ordinary working days.
"Fridays and holidays excepted" (FHEX).
Fridays and holidays are excluded and therefore don’t count as laytime.
"Fridays and holidays included" (FHINC).
Fridays and holidays are considered as normal working days and consequently regarded as laytime.
FHEX and FHINC are used in the Arabic countries where Fridays are normal days of rest.
"X working days of 24 consecutive hours, Sundays and holidays excepted unless used".
With the addition "unless used" the Ship Owner has the right to consider the Sundays and holidays, on which work has been done, as laydays. If on Sunday e.g. only 8 hours have been worked then those 8 hours count for an entire layday (because they are consecutive hours).
"X working days of 24 consecutive hours, Sundays and holidays excepted unless used, but only time actually used to count".
This clause is less strict for the Charterer because only the real working time on Sundays and holidays will be charged. If on Sunday e.g. work is done from 08 00 hours till 12 00 hours and from 13 00 hours till 17 00 hours then those 8 working hours will count for 1/3 of a layday. The time used for opening the hatches, for lunch, etc. is not taken into account as laytime.
"X working days of 24 consecutive hours, Sundays and holidays excepted, even if used”
The expression "even if used" is a confirmation of the SHEX clause. If work is done during the excluded days, the Ship Owner may not consider these working days/hours as laytime.
"X working days of 24 consecutive hours, weather permitting, Sundays and holidays excepted".
With the words "weather permitting, w.p" the time lost due to adverse weather may not be considered as laytime. Through this the Ship Owner cannot determine exactly how long the ship will remain in port as this will depend on the weather condition.
As already mentioned before, the expression weather working (w.w.) is often used (See also Weather Working Days). With this expression it does not really matter whether the work is effectively interrupted so that the time during which work is stopped (e.g. due to rain) outside the normal or planned working hours, may not be charged as laytime. To avoid arguments this clause can be better defined as follows: .... any time lost on a working day due to weather conditions shall not count provided work is actually stopped or prevented thereby".