Obviously, climatic influences affect trade and a clear example is that ice will interrupt voyages at certain times and seasons of the year. Thus seaborne trading to and from the Great Lakes of North America is not possible between January and March. Trading to the Northern Baltic is at the very least difficult during that period and voyages to and from the Hudson Bay are possible only between July and October each year. There are many other hazards to be borne in mind, however, e.g. Monsoons in certain areas at certain times, Hurricanes or Typhoons at others. Close attention must also be paid to the route between loading and discharging port(s). Does it entail the crossing of load-line zones? Will these affect cargo intake? Does it entail expensive pilotage? Or passing round an obstacle such as the Magellan Straits or Cape Horn, or navigating via a Canal? Has the cost and risk of this element in the voyage been calculated? Reference to the Port Information books will provide details of canal and waterway size restrictions also the equipment that needs to be fitted on a vessel before transit. Certainly vessels timechartered for either trip or period charters involving any of these canals or waterways should include clauses in which the ship owners/operators confirm that the vessels reasonably conform to local requirements and have appropriate fittings. In the case of the Panama and Suez Canal, include the Canal Gross and Nett Registered Tonnages which differ from the usual NRT and GRT and upon which transit tolls are based. Most shipping people tend to have an “international” and a “commercial” view of the world and its events rather than a political one. Nevertheless, the ports of certain nations are not popular calling places, because of future repercussions affecting vessels and their owners/operators as a result of trading there. It is, therefore, common practice to list certain political exclusions in timecharter parties and those engaged in voyage trading should also be especially careful in fixing cargoes to or from those nations.