ICE NAVIGATION

HISTORY

Sea ice has posed a problem to the navigator since

antiquity. During a voyage from the Mediterranean to

England and Norway sometime between 350 B.C. and 300

B.C., Pytheas of Massalia sighted a strange substance

which he described as “neither land nor air nor water”

floating upon and covering the northern sea over which the

summer Sun barely set. Pytheas named this lonely region

Thule, hence Ultima Thule (farthest north or land’s end).

Thus began over 20 centuries of polar exploration.

FORMATION &TYPES OF SEA ICE

OPEN WATER ICE

PANCAKE ICE

GREASE ICE

NILAS

Frazil iceFrazil ice

young young iceice

In rough water, fresh sea ice is formed by the cooling of the ocean as heat is lost into the atmosphere.

The uppermost layer of the ocean is super cooled to slightly below the freezing point, at which time tiny

ice platelets, known as frazil ice, form. As more frazil ice forms, the ice forms a mushy

surface layer, known as grease ice Frazil ice formation may also be started by snowfall,

rather than supercooling.slush is a floating mass formed initially from snow

and water. Shuga is formed in agitated conditions by

accumulation of slush or grease ice into spongy pieces several inches in size.

Waves and wind then act to compress these ice particles into larger plates, of several meters in

diameter, called pancake ice.

ICEBERGS An iceberg is a large piece of ice from freshwater that has broken off from a snow-formed glacier or

ice shelf and is floating in open water. It may subsequently become frozen into pack ice. Alternatively, it may come to rest on the seabed in shallower water, causing ice scour (also known as ice gouging) or becoming an ice island

Although icebergs float on ocean waters, they are composed of freshwater. An iceberg is simply an extraordinarily large mass of ice that has broken off from an ice cap

or glacier where it met the sea. The first stage of iceberg formation occurs when part of a glacier or ice cap that has been pushed into the sea,

begins to float on the water. Tides and wave action subsequently cause stress fractures, causing a piece of the glacier to break off and a new iceberg is born! This process is calving.

An iceberg’s extraordinary blue and white coloration is a reminder of its glacial origins. Glacial ice appears blue because pure ice absorbs other colors more rapidly than blue.

This colour appears in the deepest layers of the ice that are under such high pressure that all of the air bubbles have been forced out of the ice.

By contrast the surface layers of the iceberg are white because the air bubbles trapped in the snow layers reflect much of the incident light.

These air bubbles also result in iceberg fizz. As an iceberg melts, fizzing results from the release of gases that have been held

under pressure, trapped in bubbles for thousands of years!

FORMATIONFORMATIONAlthough icebergs float on ocean waters, they are composed of freshwater.An iceberg is simply an extraordinarily large mass of ice that has broken off from an ice cap or glacier where it met the sea. The first stage of iceberg formation occurs when part of a glacier or ice cap that has been pushed into the sea, begins to float on the water. Tides and wave action subsequently cause stress fractures, causing a piece of the glacier to break off and a new iceberg is born! This process is calving.

An iceberg’s extraordinary blue and white coloration is a reminder of its glacial origins. Glacial ice appears blue because pure ice absorbs other colors more rapidly than blue.This colour appears in the deepest layers of the ice that are under such high pressure that all of the air bubbles have been forced out of the ice. By contrast the surface layers of the iceberg are white because the air bubbles trapped in the snow layers reflect much of the incident light. These air bubbles also result in iceberg fizz.As an iceberg melts, fizzing results from the release of gases that have been held under pressure, trapped in bubbles for thousands of years!

DRIFTING OF ICEBERGS Iceberg movement is influenced by direct wind push on its exposed area to an extent far

greater than commonly assumed. Although the bulk of the iceberg is below water, in many situations wind has a dominant influence on the movement.

In addition to windage on the iceberg and the ocean gradient current, the wind-induced surface current has the effect of increasing drift speed by about 10 percent for small icebergs and increasing the angle of drift direction.

The wind force on an iceberg does not result in movement directly downwind, but, because of the rotation of the Earth (Coriolis effect), windage on an iceberg is 30 to 50 to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

They move at speeds of 1 knot, or 24 nautical miles per day.

This iceberg moved 140 kilometres at as much as 3 knots across the Labrador Current and

resulted in an emergency move of the North Atlantic shipping lanes to the south

ICE BREAKERSAn ice breaker is a special-purpose ship or boat designed to move and navigate through ice-covered waters..

For a ship to be considered an icebreaker, it requires three traits most normal ships lack: a strengthened hull, an ice-clearing shape,the power to push through ice-covered waters.

PRINCIPLE:PRINCIPLE: it uses its momentum to break the iceit uses its momentum to break the iceHigh strength hullHigh strength hullPowerful enginePowerful engineAzimuth thrustersAzimuth thrusters

Icebreakers are constructed with a double hull and watertight compartments in case of a breach.The ship's hull is thicker than normal, especially at the bow, stern, and waterline, using special steel that has optimum performance at low temperatures. The thicker steel at the waterline typically extends about 1 m above and below the waterline and is reinforced with extra internal ribbing, sometimes twice the ribbing of a normal ship. The bow is rounded rather than pointed, allowing the vessel to ride up over the ice, breaking it with the weight of the vessel. The hull has no appendages likely to be damaged by the ice,and the rudder and propeller are protected by the shape of the hull. The propeller blades are strengthened, and the vessel has the ability to inspect and replace blades while at sea.

DESIGN AND CONSTRUCTION

The optimal shape for moving through ice makes icebreakers uncomfortable in open waterand gives them poor fuel efficiency.

In open-water travel, icebreakers tend to roll side to side to the discomfort of the crew. Some new icebreakers, such as the USCGC Healy, make use of anti-roll tanks, incompletely filled ballast tanks which span the beam of the vessel. Ballast water in these tanks is allowed to move side to side, or slosh, as a free surfaceas a free surface

A greater concern is how well a ship cuts through waves.The ability of a ship to cut through waves can greatly affect its fuel efficiency and even its safety in a storm. Most ships use a sharp or bulbous bow to cut through waves and help prevent waves from slamming the bow of the ship.

DOUBLE ACTING SHIPSDouble acting ship (DAS) is a type of icebreaking merchant ship designed to run ahead in open water and astern in ice. Such ships can operate independently in severe ice conditions without icebreaker assistance but retain better open water performance than traditional icebreaking vessels.

How Double Acting Tankers Work?

A double acting tanker sails in normal sea in the ahead direction, just like any other vessel. However, when it comes to ice breaking,the astern movement of the ship is utilised.

The aft or stern part of the ship hull structure is therefore made up of special reinforced double skin with a fatigue life of around 40 years.Moreover, the conventional rudder and propeller is replaced by Azipod system

with fixed pitch propeller and an electric motor of Mega Wattrating. The azipod system is capable of rotating 360° and the normal ahead speed is above 15 knots.

Additional bow thrusters are also fitted to provide excellent manoeuvrability in narrow channels and ports.

ICE PATROL The International Ice Patrol is an organization with the purpose of monitoring the

presence of icebergs in the Atlantic and Arctic Oceans and reporting their movements for safety purposes. It is operated by United States Coast Guard but is funded by the 13 nations interested in trans-Atlantic navigation.

It was established in 1914 in response to the sinking of the RMS Titanic. "The primary mission of the Ice Patrol is to alert any seacraft traveling the great circle shipping lanes between Europe and the major ports of the United States and Canada of the presence of any icebergs there."

Size Category Height Length

Growler Less than 1 metre (3.3 ft) Less than 5 metres (16 ft)

Bergy Bit 1–5 metres (3.3–16 ft) 5–15 metres (16–49 ft)

Small 5–15 metres (16–49 ft) 15–60 metres (49–200 ft)

Medium 15–45 metres (49–148 ft) 60–120 metres (200–390 ft)

Large 45–75 metres (148–246 ft) 120–200 metres (390–660 ft)

Very Large Over 75 metres (246 ft) Over 200 metres (660 ft)

ICE ACCREATION

Rudder

Inner Bot.

Bulkhead

Fore&Aft

Deck

Bottom

Hull

Unspec/

Ship Side

ICE CLASSES SIGNIFICANCEICE CLASSES SIGNIFICANCE

Not all ships are built to an ice class. Building a ship to an ice class means that the hull must be thicker, and more scantlings (aggregate of girders, beams, and bulkheads resulting in stronger structure) must be in place. Sea chests (openings in the hull for seawater intake) may need to be arranged differently depending on the class. Sea bays may also be required to ensure that the sea chest does not become blocked with ice. Most of the stronger classes require several forms of rudder and propeller protection. Two rudder pintles are usually required, and strengthened propeller tips are often required in the stronger ice classes. More watertight bulkheads, in addition to those required by a ship's normal class, are usually required. In addition, heating arrangements for fuel tanks, ballast tanks, and other tanks vital to the ship's operation may also be required depending on the class.

ARCTIC CLASSESARCTIC CLASSESFINNISH SWEDISH CLASSESFINNISH SWEDISH CLASSESPOLAR CLASSESPOLAR CLASSES

The following areas are subject to requirements depending on the ice class selected. BALTIC ICE CLASSES- Hull – ice belt- Machinery output- Shaft – system- Propeller- Mooring- Heating ballast tanks- Sea chest- Air capacity for starting compressor (1A*)- Rudder and steering gear- Corrosion protection ARCTIC ICE NOTATION (ADDITIONAL SCOPE)- Hull girder transverse strength, line loads due to vessel being trapped betweenmoving ice flows. ARCTIC POLAR AND ICEBREAKER NOTATION (ADDITIONAL SCOPE)- Hull materials exposed to low temperatures (DAT-notation)- Subdivision, intact and damage stability (additional requirements)- Hull girder longitudinal strength due to beaching and ramming- General

Items covered by Ice-Class Notation (Baltic, Arctic andPolar)

ICE CLASS RULES AND OTHER REQUIREMENTS

CLASS NOTIFICATIONS

EQUIVALENT BALTICS ICE CLASSES

VESSEL TYPE ICE CONDITIONS ICE LIMITS

ICE C

ICE 1C

ICE 1B

ICE 1A

ICE 1A*

ICE 1A F*

1C

1B

1A

1A SUPER

ALL SHIP TYPES

VERY LIGHT ICE CONDITIONS

- First year ice and

broken channel

0.4 m ice thickness

0.6 m ice thickness

0.8 m ice thickness

1.0 m ice thickness

1.0 m ice thickness

NO RAMMING

ICE O5

ICE 10

ICE 15

POLAR 10

POLAR 20

POLAR 30

ICE BREAKER

Vessels intended for ice

breaking-Built for another main purpose

-ICE BREAKING IS MAIN PURPOSE

First year ice with pressure ridges

Multi year ice with glacial inclusions

ACCIDENTAL RAMMING

REPEATED RAMMING

North Atlantic • No ice

• -20 deg c

Baltic sea•1 m ice

• -15 deg cBarents sea•1.2 m ice• -30 deg c

Kara sea• 2 m ice

• -40 deg c•Multi year ice

THICKNESS OF ICE IN VARIOUS AREASTHICKNESS OF ICE IN VARIOUS AREAS

CASPIAN 70CASPIAN 70WHITE 80WHITE 80

Typical hazards when operating in cold climate

Overstress of hull• Lack of good ice reports/routing• Ice restriction vs. commercial pressure on

master

Propulsion failure• Stuck in ice, crushing of hull or driftingAground• Remote from rescue and spare parts

Icing (stability, safety functions, cargooperations)•Black-out ( freezing of ship, crew, difficult restart).Evacuation problems in ice

Malfunction of fire fighting

Experience/competence

Crew fatigue (additional work load, lowtemperature, noise/vibrations, 24 hrs

ICING A SERIOUS CHALLNGE

High Wind SpeedUsually above 18 kts or 9 m/s but sometimes lower

Low Air TemperatureBelow freezing (-1.7 deg c)

Low Water TemperatureUsually below + 7 deg c

Ice accretion on the various equipment/areas has unequal importance on the vessel safety.- Category I : to be kept completely ice free- Category II : shall have de-icing arrangements removing ice within a reasonable period of time (4-6 hours)

ICE ACCREATION =WIND+WAVES+LOW AIR TEMPERATURE+OPEN WATER =ICING

REPORTED ICE DAMAGES

Rudder

Inner Bot.

Bulkhead

Fore&Aft

Deck

Bottom

Hull

Unspec/

Ship Side

Ships sideShips side 65%65%

Rudder Rudder 7%7%

BottomBottom10%10%

Fore&aftFore&aft8%8%

Inner bottom 1%Inner bottom 1%

Bulk head 4%Bulk head 4%

Deck 2%Deck 2%

TOTAL NO. OF DAMAGES REPORTEDTOTAL NO. OF DAMAGES REPORTED

486486

FORCES FROM DRIFT ICE

FORCES FROM DRIFT ICE

FORCES FROM DRIFT ICE

FORCES FROM DRIFT ICE

MANAGING OF COLD CLIMATE RISKSCROSS SECTIONS OF FRAM’ BUILT 1892

Ice forces would lift the vessels out of the ice, and save her.A brilliant example of practical risk management

Protected location. Also with heating (i.e. adjacent to heated spaces or hot air ventilation). Protective covers Electric tracing (Note ex-requirements) Heating coils (steam/hot water) Ice-repellant coating Self-draining piping/operating procedures Circulation of liquids (e.g. hydr.oil)

AVOIDING ICING PROBLEMS - METHODSAVOIDING ICING PROBLEMS - METHODS

MEMBRANE LNGCMEMBRANE LNGC

PROTECTION AGAINST ICE PRESSURE DAMAGE

Collision with Growlers andBergy Bits in open waters Uncouple the containment system and theship side leaving space for indentation ofthe side without damage/deformation of thecontainment system Increase double hull width Design for increased energy absorptioncapability of the double hull

Traversing through ice channel or the ship completely frozen in Design hull to lift the ship rather thanpushing it down due to the ice pressure Increase double hull width Design a stronger protective outer hull,stiffer – less deformation

• DA (double acting) - where the ship operates with the stern first when operating in ice. This saves on installed power, and fuel, and makes it possible to optimize the bow of the ship for open water performance. The DAS was made possible through the development of azimuthing electric propulsion--another system which was developed by AARC, together with ABB (Azipod).

• A very new develpoment is the Oblique Icebreaker. By using azimuthing electric propulsion, it breaks ice by moving sideways, utilizing its entire length for breaking a wide channel. This makes it possible to use a relatively small and narrow icebreaker to assist large and wide cargo ships.

Challenges – human factors

Competence and performance of crew is essential for safe operations

• Availability of experienced personnel?• Training/experience!• Increased manning?

• Extreme low temperatures• 24 hours darkness• Noise and vibrations in ice

HUMAN FATIGUEHUMAN FATIGUE

UNDERSTANDING THE CHALLENGES

CAPTAINCAPTAIN

CHIEF ENGCHIEF ENG

CADETCADET

Summary…..

Ship operations in cold climate is much morethan ice strengthening of the ship alone.

Compliance with basic ice class rules andregulations may be insufficient for safe andeffective ship operations in cold climate

Risk evaluation for specific trades and adequate“winterization” for safe and reliable operationsmust be carried out.

ANY QUESTIONS

THANK YOUTHANK YOU