The Arctic Ocean is almost completely surrounded by Eurasia and North America. It is partly covered by sea ice throughout the year and almost completely in winter. This makes navigation in the Arctic Ocean treacherous and almost impossible. Because of the increasing concentrations of greenhouse gases resulting from human activity such as fossil fuel burning and deforestation, global warming will be strongest in the Arctic and will be associated with continuing retreat of glaciers, permafrost and sea ice. This, on the other hand, creates a new opportunity for steamship companies to rethink about deploying their ships across the Arctic Ocean in an effort to reduce fuel costs, improve transit time, and increase the ship's turnarounds in summers. For instance, a ship would steam 10,937 nautical miles from Kobe, Japan to Rotterdam, Netherlands via the Suez Canal or 14,195 nautical miles via the Cape of Good Hope, South Africa. The distance between the same ports via the North Pole could be shortened to 6,830 nautical miles or 37.6% less as compared to her Suez Canal transit. The benefit is even greater (51.9% reduction) as compared to her Cape of Good Hope transit.

From the shipmaster's prospective, it creates many new challenges not only by the treacherous weather conditions but also by the navigation techniques. Navigation in polar regions, or navigation above Latitude 70° requires unique considerations and knowledge. This page is to examine the differences between an ordinary navigation and a polar navigation and the challenges that the shipmaster faces in crossing the Arctic Ocean. Any modern technology could help him navigate through this dangerous and icy water.

Polar Climate — Winters are characterized by continuous darkness (polar night), cold and stable weather conditions, and clear skies; summers are characterized by continuous daylight (midnight sun), damp and foggy weather, and weak cyclones with rain or snow. The temperature of the surface of the Arctic Ocean is fairly constant, near the freezing point of seawater, slightly below 0 °C (32 °F). Very cold air over open water sometimes produces steaming of the surface, occasionally to a height of several hundred feet. This is called frost smoke or sea smoke. Sharp discontinuities or inversions in the temperature lapse rate sometimes produce a varsity of mirages and extreme values of refraction. False horizons are not uncommon. In the polar regions, the principal hazard to ships is ice, both that formed at sea and land ice which has flowed into the sea in the form of glaciers. “Arctic whiteout” may also occur when snow obliterates surface features and the sky is covered with a uniform layer of cirrostratus or altostratus clouds.

Nautical Charts — The shipmaster is accustomed to the rectangular coordinates on the Mercator projection charts. In the Arctic Ocean, he has to switch to the modified Lambert conformal Polar projection charts. The meridians radiate outward from the pole, and parallels are concentric circles with their common center at the pole. This projection has a constant scale over the entire chart with straight meridians and correct angle representations. Great circle lines show as straight lines. Another issue is the scarcity of the large-scale nautical charts available for the polar regions. The shipmaster may not be able to find his navigation charts in the various scales of the polar regions that he would otherwise find in the Mercator projection charts for the other regions.

Available Aids to Navigation — The natural landmarks may not be shown on the chart, or may be difficult to identify. The appearance of some landmarks changes markedly under different ice conditions. When snow covers both the land and a wide ice foot attached to the shore and extending for miles seaward, even the shoreline is difficult to locate.

Accuracy of the nautical charts — Charts of the polar regions are less reliable than those of other regions, because relatively little surveying has been done in the polar areas and Because relatively few soundings are shown on charts. In many cases, the shipmaster may have to rely on his shipboard echo sounder. Furthermore, icebergs that break away from the Arctic ice pack in summers make the landmark unpredictable.

Measurement of direction — Direction is measured largely by a compass. The magnetic compass becomes unreliable in the vicinity of the magnetic poles of the Earth, and the north-seeking gyrocompass becomes unreliable in the vicinity of the geographical poles of the Earth. One solution to the directional problem in high latitudes is to use a directional gyro, a gyroscopic device that maintains its axis in a set direction but must be reset at frequent intervals, as every 15 min, because of gyroscopic drift. Unfortunately, Directional gyros are not generally used on board the ship. The shipmaster may use the celestial compass. It is a tedious and time-consuming alternative because the magnetic or gyro compass error is determined by the compass azimuth of a celestial body against the computed azimuth of the same. The other options include the sun compass or sky compass. The former indicates direction by means of a shadow cast by a shadow pin exposed to sunlight. The latter indicates direction by means of the polarizing effect of the earth's atmosphere on sunlight.

Distance and direction in ice — In the icy Arctic Ocean, most logs are inoperative or inaccurate due to clogging by the ice on the water. Engine revolution counters are not the accurate speed indicating device when a ship is forcing its way through ice. On the other hand, Course and speed or distance through the water can be determined by tracking a floating ice-berg or other prominent floating ice feature. However, an error may be introduced by this method if the effect of wind and current upon the floating feature is different than upon the ship.

Plotting on polar charts — In polar regions, as elsewhere, dead reckoning involved measurement of direction and distance traveled. A protractor or AN Plotter is used to measure the bearing or direction. The shipmaster places the center hole of the plotter over the meridian used or close to his Dead Reckoning position. The straight edge part of the plotter is placed along the line to be drawn or measured. The angle is read on the protector of the plotter at the same meridian which passes under the center hole. On the polar chart, a distance of 400 nautical miles from Point A to Point B may change its direction of 140°. It is because its course is measured against the closest meridian. All meridians on the polar chart are not parallel to each other as they are on the Mercator chart. For this reason, a grid direction is adopted in the polar navigation. North along the Greenwich meridian is taken as Grid North in both the northern and southern hemispheres. All the grid meridians are parallel to the Greenwich meridian. The direction that measures against the Grid North is therefore constant throughout the entire course. On the polar charts, Grid North direction is equal to True North direction plus its meridian of which the course intersects in the western hemisphere, or minus from its meridian of which the course intersects in the eastern hemisphere. Distance on the polar chart is measured by means of the latitude scale as on a Mercator chart. A mile scale is sometimes shown in or near the margin of this chart. It can be used anywhere on that chart.

Celestial navigation — At the pole, the zenith and celestial pole coincide. stars circle the sky without noticeable change in altitude. Only celestial bodies of north declination are visible at the North Pole. Planets rise and set once each sidereal period (12 years for Jupiter or 30 years for Saturn). At the North Pole , the sun rises about March 21, slowly spirals to a maximum altitude of about 23° 27´ near June 21, slowly spirals downward to the horizon about September 23, and then disappears for another 6 months. The moon rises and sets about once each month. The full moon at this time rises relatively high in the sky. Light from the aurora borealis in the Arctic is often quite bright. All time zones, like all meridians, meet at the poles. Local time does not have its usual significant, since the hour of day bears no relation to periods of light and darkness or to the altitude of celestial bodies.

Coverage of electronic navigation systems — Loran C sky waves are available throughout the Arctic, but ground waves extend only to some parts of this area. Radar is useful, but experience in interpretation of the scope in polar regions is essential for reliable results. A radio direction finder is useful only when radio signals are available. The use of electronics in polar regions is further restricted by magnetic storms, which are particularly severe in the aurora zones.

Modern Technology — Advances in technology have contributed significantly to the safety and reliability of navigation in polar regions. The availability of modern echo sounders has made possible a continuous plot of the bottom profile beneath a vessel while under way. Sonar indicates the presence of an underwater obstruction. Reliable inertial navigators are available to make aircraft navigation in polar regions almost routine, providing both positional and directional data. The NAVSTAR Global Positioning System (GPS) network is operated by the U.S. Department of Defense to provide highly accurate navigation information to its military forces around the world. Now it is available to the public. It makes navigation much simpler and easilier anywhere around the world. The GPS has 24 Earth-orbiting satellites circling the globe in 6 different orbits at about 12,000 miles above the sea level and making two complete rotations every day. The orbits are designed in such a way that at least 4 satellites are visible in the sky by anyone on Earth. Each satellite broadcasts a ranging signal as well as a data message containing its ephemeris. The shipboard GPS Reciever receives both signal and data message from its nearest satellites. It then calculates the distances by means of trilateration from at least 3 satellites in order to determine its geographic location on Earth.