Distances Between Post

Is a publication that lists the distances between major ports. Reciprocal distances between two ports may differ due to different routes chosen because of currents and climatic conditions. To reduce the number of listings needed, junction points along major routes are used to consolidate routes converging from different directions.

This book can be most effectively used for voyage planning in conjunction with the proper volume(s) of the Sailing Directions . It is corrected via the Notice to Mariners.

The positions listed for ports are central positions that most represent each port. The distances are between positions shown for each port and are generally over routes that afford the safest passage. Most of the distances represent the shortest navigable routes, but in some cases, longer routes, that take advantage of favorable currents, have been used. In other cases, increased distances result from routes selected to avoid ice or other dangers to navigation, or to follow required separation schemes

Passage planning or voyage planning

Is a procedure to develop a complete description of a vessel's voyage from start to finish. The plan includes leaving the dock and harbor area, the en route portion of a voyage, approaching the destination, and mooring. According to international law, a vessel's captain is legally responsible for passage planning, however on larger vessels, the task will be delegated to the ship's navigator.

Studies show that human error is a factor in 80 percent of navigational accidents and that in many cases the human making the error had access to information that could have prevented the accident.The practice of voyage planning has evolved from penciling lines on nautical charts to a process of risk management.

Sailing Directions

Is a 47-volume American navigation publication published by the Defense Mapping Agency Hydrographic/Topographic Center. Sailing Directions consists of 37 Enroute volumes and 10 Planning Guides. Planning Guides describe general features of ocean basins; Enroutes describe features of coastlines, ports, and harbors.

Sailing Directions are updated when new data requires extensive revision of an existing text. These data are obtained from several sources, including pilots and Sailing Directions from other countries.

One book comprises the Planning Guide and Enroute for Antartica . This consolidation allows for a more effective presentation of material on this unique area.

The Planning Guides are relatively permanent; by contrast, Sailing Directions (Enroute) are frequently updated. Between updates, both are corrected by the Notice to mariners.

Notice to Mariners

advises mariners of important matters affecting navigational safety, including new hydrographic information, changes in channels and aids to navigation, and other important data.

One example is the American publication made available weekly by the National Geospatial-Intelligence Agency NGA, prepared jointly with the National Ocean Service (NOS) and the U.S Coastguard. The information in the Notice to Mariners is formatted to simplify the correction of paper charts,Sailing Directions, LightsList, and other publications produced by DMAHTC, NOS, and the U.S. Coast Guard.