ARCHIVED - CHAPTER 2: Navigation in Ice

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2.6 Ships Navigating Independently

Experience has shown that non-ice-strengthened ships with an open water speed of about 12 knots can become hopelessly beset in relatively light ice conditions, whereas ice-strengthened ships with adequate power should be able to make progress through first-year ice of 6/10 to 7/10 concentration. Such ships are often able to proceed independently without any assistance other than routing advice.

2.6.1 Entering the Ice

The route recommended by the Ice Operations Officer through the appropriate reporting system i.e. ECAREG, is based on the latest available information and Masters are advised to adjust their course accordingly. The following notes on ship-handling in ice have proven helpful:

  1. Do not enter ice if an alternative, although longer, route is available.

  2. It is very easy and extremely dangerous to underestimate the hardness of the ice.

  3. Enter the ice at low speed to receive the initial impact; once into the pack, increase speed to maintain headway and control of the ship.

  4. Be prepared to go "Full Astern" at any time.

  5. Navigation in pack ice after dark should not be attempted without high-power searchlights which can be controlled easily from the bridge; if poor visibility precludes progress, heave to and keep the propeller turning slowly as it is less susceptible to ice damage than if it were completely stopped.

  6. Propellers and rudders are the most vulnerable parts of the ship; ships should go astern in ice with extreme care - always with the rudder amidships.

  7. All forms of glacial ice (icebergs, bergy bits, growlers) in the pack should be given a wide berth, as they are current-driven whereas the pack is wind-driven.

  8. Wherever possible, pressure ridges should be avoided and a passage through pack ice under pressure should not be attempted.

  9. When a ship navigating independently becomes beset, it usually requires icebreaker assistance to free it. However, ships in ballast can sometimes free themselves by pumping and transferring ballast from side to side, and it may require very little change in trim or list to release the ship.

The Master may wish to engage the services of an Ice Pilot, Ice Advisor or Ice Navigator in the Arctic.

2.6.2 Use of Radar for Navigation in Arctic Waters

Fixing solely by a radar range and bearing, from a point of land or by the use of radar or gyro bearings, is not recommended. Fixing by two or more radar ranges is the best method in Arctic waters, but care is required in the correct selection and identification of prominent features on the radar screen. The following difficulties, peculiar to radar fixing in the Arctic, may be encountered:

  1. Difficulty in determining where the ice ends and the water-line begins. A reduction in receiver gain should reduce the ice return.

  2. Disagreement between ranges, caused by ranging errors or chart inaccuracies. The navigator should attempt to range on the nearest land and should not range on both sides of a channel or long inlet.

  3. Uncertainty as to the height and, therefore, the detection range of land masses because of a lack of topographical information on the chart.

  4. Lack of charted fixing aids in the area and dated survey.