Master Yachts | Seamanship(ICE) -

Question 1

Describe first year ice - thickness and how it is divided.

Answer 1

• Greater then 30cm thick.
• Divided into thin first year, medium first year and thick first year.

Question 2

What is old ice & colour?

Answer 2

• Survived one summer melt
• Also called second year ice
• Colour changes from white to greenish-blue

Question 3

What is multi-year ice, thickness, density and colour?

Answer 3

• Sea ice that has survived two summer melts.
• Averages 3 - 6 metres thick and is almost salt free - therefore the density is almost like concrete.
• Stronger colour of blue.

Question 4

What approximate fraction of ice sits above the water?

Answer 4

1/7 - ice increases thickness from below.

Question 5

What is the general potability of ice?

Answer 5

• First year ice may be too brackish but drinkable as tea after 6 months.
• After 10 months old the ice is mostly fresh.
• Water from sea ice does not become ‘as fresh’ until two or more years.

Question 6

What are the two main types of ice?

Answer 6

1. Drift ice (forms at sea, from pieces of fast ice)
2. Fast ice (forms on the coast, made fast to the coastline)

Question 7

What are the direct concerns when navigating in ice?

Answer 7

1. Affects piloting landmark features.
2. Affects aids to navigation
3. Affects use of electronic equipment and propagation of radio waves
4. Changes surface features and radar returns
5. Affects charts by introducing plotting problems

Question 8

How is a gyro and magnetic compass affected at high latitudes?

Answer 8

• Gyro compass becomes unusable N or S of 85 degrees - generally reliable up to 75 degrees.
• Magnetic compass is of little value for navigation near the poles. In parts of the polar region the magnetic compass can be used if recently swung.
• Frequent check of comparisons should be made and logged.

Question 9

Is it practically possible to conduct celestial navigation in the polar regions?

Answer 9

As much of the navigational season is in daylight, only the sun can be used for observations, and the moon at times.

Question 10

What can be used to assist in navigation when using dead reckoning?

Answer 10

• Ice bergs can be used as they may be regarded effectively as stationary for the period of a plot.
• At time of a celestial position, a conspicous ice berg ahead on an intended line of advance is plotted, it can be used then as a nvigational mark.

Question 11

What are some key elements to consider when planning a polar voyage?

Answer 11

• Empty or slack wing tanks, and slack water tanks
• Ensure bridge window heating systems functional
• Ensure all heating systems are operational
• Drain external fire mains
• Lifeboats fitted with working heaters and engines with anti freeze
• Sufficient supply of salt for melting ice
• In port never stop hydraulic pumps for controllable pitch propellers
• Spare NUC lights carried
• Searchlights working, prefereably forward

Question 12

How should the radars be set up when navigating in ice regions?

Answer 12

• S band set to 12 to 24nm, and, X band set to 3 to 6nm.
• The S band is likely to be better detecting ice in open waters

Question 13

What causes an abrupt smoothing of the sea in polar regions?

Answer 13

It is an indication of drift ice to windward.

Question 14

What does a sea surface temperature of -0.5 degrees C indicate in polar regions?

Answer 14

It can be assumed that the neareast ice is not more than 50 miles away.

Question 15

On meeting dangerous ice, what must a Master report?

Answer 15

• type of ice
• position
• time/date

Question 16

On encountering air temperatures below freezing, causing severe ice accumulation on vessels, what must the Master report?

Answer 16

• air and sea temperatures
• force and direction of wind
• position
• date/time

Question 17

What is best practise when operating in ice?

Answer 17

• keep moving even if slowly
• try to work with ice rather than against
• excessive speed leads to ice damage
• always try to achieve a right angle approach to any floe
• ensure rudder is amidship before making any stern way.
• avoid anchoring in moving close-pack ice

Question 18

What principles govern entry into ice?

Answer 18

• Do not attempt where existence of pressure is evident from hummocking and rafting
• Ice entered from leeward as windward may be more compact.
• Ice entered at slow speed and at right angles

Question 19

If a vessel is stopped by pack ice, what actions should be taken?

Answer 19

• Put rudder amidships and keep engines slowly turning ahead.
• This will wash ice clear of the stern, once checks of propellers made vessel can come astern.

Question 20

When a vessel is beset in ice, what are the dangers?

Answer 20

• Ice under pressure can nip the vessel, and may crush the hull - changes of heel and trim should be noted.
• Risk is greater when there is an ice concentration of 7/10 or more, currents or strengthening winds.

Question 21

What is a method for freeing a vessel beset in ice?

Answer 21

By going full ahead and full astern alternately with full helm one way then the other.

Question 22

What is the survival time in water for the following temperature?
1. 0
2. 5
3. 10
4. 15
5. 20

Answer 22

1. 20 mins to 90 mins
2. 30 mins to 2.5 hours
3. 1 hour to 4 hours
4. Unconsciousness may occur after 2 hours, death unlikely
5. Unconsciousness and death unlikely

Question 23

Before starting work in freezing temperature, what should you do to your clothes?

Answer 23

They should be opened up or cold weather gear removed so the work is started ‘cold’. Clothing is then added until a comfortable body temperature is reached.