ICE

Question 1

Ice Navigation - Hazards

Entering pack ice?

Answer 1

Hull damage due to excessive speed
o Hull damage due to entering ice at an acute angle
o Damage to bulbous bow, propeller and rudder by ice due to inadequate draught
o Blockage of suctions by iceFog due to presence of ice.

Question 2

Problems with equipment in ice and high latitudes

• Echo
• Gyro
• Radar?

Answer 2

Thermal stratification giving incorrect results

• Damage to transducer causing inaccuracy
• Water density different from standard
• Low directional force reducing stability of direction
• Speed errors if vessel speed does not match that fed to gyro
• Transient errors due to large course changes
• Incorrect measurement of range if fast ice is present around land
• Incorrect measurement of bearings if fast ice is present around headlands

Question 3

In Pack Ice Outline five factors to be considered when maintaining a plot of vessels position?

Answer 3

Fast ice on land will give a false coastline on radar, and the edge of the fast ice must be distinguished from the land when taking radar bearings and distances.
The presence of ice may make the identification of shore marks uncertain when taking visual bearings. Ice on shore lights will reduce the detection range, may alter the bearings of light sectors, and may alter the colour of lights.
Floating marks are unlikely to be present and are likely to be out of position if present. Loran may be subject to errors due to the different propagation of radio signals over ice compared to land and water, for which the system will be calibrated.
The gyrocompass may be subject to transient errors due to alterations of speed from that set. The log may be inaccurate due to temperature variations within the water body. The ice field may be drifting due to the effect of wind and current. Celestial observations may be inaccurate due to abnormal refraction.

Question 4

Generally Accepted Months for Icebergs in North Atlantic as well as Extreme Geographic Limits

Answer 4

• February 01 – July 31.

- Icebergs unlikely south of 40 N or east of 040 W.

Question 5

Sources and type of info available to Master regarding North Atlantic Icebergs?

Answer 5

• North Atlantic Ice Service. (International Ice Patrol - Environment Canada) Daily fax charts and text messages, limits and concentrations..
• Mariner’s Handbook: General description of icebergs, areas and seasons.
• Routeing charts. Iceberg limits.
• Sailing Directions. Areas, seasons and limits.
• Mariners’ Handbook. General information.
• Ocean Passages of the World. General limits.
• GMDSS. Fax charts. Vessel reports.
• Weather Routeing service. Relayed information

Question 6

Which similar instances other than Ice should Master carry out Mandatory Reporting?

Answer 6

A dangerous derelict:
- Any other direct danger to navigation,
- A tropical storm,
- Sub-freezing air temperatures associated with gale force winds causing severe ice accretion on
superstructures,
- Winds of Beaufort force 10 and for which no storm warning has been received,
- Any other hazard to navigation

Question 7

Ice Navigation - Hazards

ii) Manoeuvring in pack ice

Answer 7

o Damage due to excessive speed
o Damage to bulbous bow, propeller and rudder by ice due to inadequate draught
o Damage to hull when turning due to impacts aft. Variable ice thickness
o Ice concentration increasing due to wind driven movement of ice. Besetment due to inadequate power. Blockage of suctions by ice. Fog due to presence of ice

Question 8

Ice Navigation - Hazards

iii) Approaching port in ice conditions?

Answer 8

o Lights obscured and sectors inaccurate due to icing.
o Floating marks absent, or displaced by ice
o Navigation aids damaged or obscured
o Channels obstructed by ice
o Berth obstructed by ice.