Finally, it may be that a vessel cannot be laden to her full available draft at the port of loading, because of the necessity of crossing restricted loading zones en route to the port(s) of discharge. A vessel cannot enter a winter line, for example, when loaded to summer marks and thereby submerging winter freeboard. The ‘cargo calculations’ section of the ‘estimate form’ makes allowance for loadline considerations and for deductions from the appropriate deadweight tonnage of bunker quantity remaining on board, and for constant weights. However, knowledge of loadline zones is essential. Maps can be obtained showing these, and the subject is covered in Lesson Nine of this course. Which brings us back to Stage 1 since, knowing the cargo quantity as well as the loading/discharging rates per day of the proposed cargo, it is now possible to deduce port time with some accuracy, to enter the information in the appropriate boxes of the estimate form, and to calculate port bunker consumption. However, as always it seems, there may be further pitfalls to avoid. As we have seen from the previous Lesson on Laytime, weekends and holidays will frequently not count as laytime in dry-cargo shipping and, in fact, dry-cargo ships are often left idle and unworked during such periods. Moreover there may be weather delays, the effect of which it may be reasonable to anticipate and to allow for by an adjustment in expected port time. Let us take an example: ‘m.v. “KINGFISHER” is to load 35,000 tonnes of cargo, the c/p loading rate being 2,500 tonnes per weather working day of 24 consecutive hours, Saturdays, Sundays and Holidays excepted. By dividing 35,000 by 2,500 we calculate that the loading time allowed to charterers is 14 days. This calculation, however, is to be conducted on the basis of ‘Sshex’ terms.