In voyage estimation, if loading or discharging operation is to take place over some important public holiday such as New Year, Christmas or Ramadan, then more port time margin should be allocated. On the other hand, if allowed laytime is specified as SHINC instead of SSHEX, less allowance for laytime will be needed. Nevertheless, even with SHINC laytime terms, there might be unavoidable delays during shifting berth, waiting for tides, etc. Unfortunately, there is no magic formula that can be used to calculate overall port time in normal SHEX or FHEX situation. In rough calculation, estimator should multiply the original number by a factor of 1.4. For example, 50,000 mtons of cargo is divided by 5,000 mtons loading rate = 10 days x 1.4 = 14 days. In the voyage estimation table, 14 days should be entered in the estimate box under loading port time. With this estimated loading port time, port bunker consumption should be based. This estimation is totally sufficient for most cases. Generally, full time allowance should be placed in estimate form and allowance for demurrage and/or despatch money should be ignored.
A different criteria have to be used for voyage estimation in despatch trades. For example, it is well-known by dry bulk chartering market players that ships generally load or discharge well within permitted laytime in bulk sugar trade. However, shippers or receivers expect to earn substantial despatch money. During voyage estimation in demurrage in despatch trades, in order to reach a more realistic result, the actual expected port time should be entered in the itinerary section. Furthermore, the amount calculated to be payable for despatch should be entered as an expense. All other miscellaneous costs that are expected should be properly organized and analysed.