This document provides guidance on vessel navigation in ice-covered waters. It discusses how ice buildup can affect a vessel's trim, stability, and maneuverability. It describes reduced turning ability in ice and techniques for clearing ice from propellers. The document also outlines ice convoy systems, icebreaker design, passage planning considerations, and precautions to take regarding vessel trim, propeller protection, and engine use when transiting ice-covered areas.

1. NAVIGATION IN ICE
ASCENT MARINE INSTITUTE

2. Vessel’s maneuvering ability
A build up of slush or ice on the vessel’s
flat bottom is directly proportional to the
vessel’s trim. The more trim that a vessel
has the more ice and slush accumulation
can be expected. The hazards associated
with this include an actual increase in the
vessel’s draught, significant changes in the
maneuvering and handling characteristics
of the vessel and possible changes in the
vessel’s buoyancy and stability.

3. Handling and maneuvering are adversely
affected fairly quickly – in anything other
than loose ice.
• As a rule of thumb, if the ship is stopped in
30 or 40 cm. ice, when getting under way
unassisted the turning circle may be so big
(due to constraints on power and rudder
angle), that hazards 1 mile away may not
be avoided.
• Thus, if the ship is to turn to stbd., the
breaker should work on clearing the port
side, to enable the stern to swing to port.

4. Ice Convoy
This system of ice convoy operates
primarily in the former soviet Baltic States
and Russia. Vessels will be directed to a
rendezvous position where convoys will
be marshalled and then escorted through
the ice fields in stages by icebreakers.
Notice of readiness is traditionally
tendered upon encountering the ice edge,
but instructions will ordinarily be provided
by the ship operator.

5. Icebreaker theory
The design of the bow breaks ice into
pieces, which are forced around the stern
by the hull-form, thus the channel very
quickly fills and closes. Ships designed for
the Baltic trade have bows which force ice
ahead to break, and raft over the ice to
each side – thus the channel remains
clear, and the ship may go astern if needs
be.

6. Passage Planning
In addition to the normal company
requirements on passage planning, the
vessel’s Passage Plan should include all
relevant information with respect to ice
and cold weather possibilities along with
all the sources of information available.
Traffic Separation Schemes
TSS (Traffic Separation Schemes) may
be suspended in ice conditions. This
information is transmitted via “Navtex”.

7. Vessel’s Trim
The vessel’s Master should manipulate
ballast and cargo to keep sea suctions and
the propeller well below the ice, keeping
trim to a minimum to prevent ice from
sliding under the vessel, as well as
maintaining more positive vessel control. As
a guide 2meter coverage over the propeller
is considered a minimum.

8. Ballast Condition
Use of heavy weather ballast conditions
after departure the berth is recommended to
minimise the risk of ice sticking in the
cooling water sea chest and better propeller
immersion and protection of the tips from
ice damage. A balance needs to be
maintained between delaying departure and
delaying the berth of other vessel’s on the
same berth.

9. Use of Astern Propulsion
Engines must be prepared to go full astern
at any time. Astern movements should be
used with caution and always with the
rudder amidships as these astern
movements can draw chunks of heavy ice
back into the propeller blades causing
damage to the tips. Propellers are the most
vulnerable part of a ship and second to shell
damage form the most commonly damaged
part of the vessel.

10. Engine movements astern pose dangers to
the propeller – so a movement astern
should be preceded by a movement
ahead to clear the area around the prop.
This greatly diminishes the effectiveness
of the astern movement. In practice,
approaches to berths, for instance,
should be planned and executed without
the need for astern movements. Similarly
in ice the bowthrust should not be used.

11. If a ship is stopped by a heavy
concentration of ice, the rudder should be
put amidships and the engine kept turning
slowly ahead. This will wash the ice astern
clear and will enable the ship to come
astern, after making certain that the
propeller is clear of ice.

12. Drifting in Ice.
Although the ship may appear to be fast in
the ice, the ice itself in the Gulf of Finland
is generally slowly drifting, as influenced
by the wind and current. Thus the ship will
move over the ground, and also relative to
other ships, which also appear to be fast.
Therefore it is important to continue
regular and frequent position fixing, with
each fix being recorded.

13. Vessels should so far as practicable give
all navigational hazards a more than
normal wider berth.
Anchoring
Anchoring is generally not feasible in ice or
if ice is expected – the weight and
movement of the ice will part the cable or
cause you to drag and drift with the ice
movement.

14. Whilst the vessel is moored
So far as possible, vessels shall be
moored so as to stem the worst ice
conditions that could be experienced.
Since, historically, and when in tidal
areas, ice is heavier on the flood tide, the
vessel should so far as practicable be
docked with the bow to the flood tide.

15. Vessels should maintain a manned engine
room space with engines on immediate
stand by and, if necessary, man the bridge
during heavy ice or as conditions dictate.
A watch shall be continually maintained to
monitor the mooring lines particularly at
the change of tide when, due to the
movements of concentration of ice,
excessive and unusual loading can be
placed upon the vessel’s moorings.

16. Near or sub zero conditions
Calling the Master
The Master must be called
immediately when ice is sighted. If
necessary the OOW shall take the
required action to ensure the safety of
the crew and vessel. If required when
in the vicinity of ice speed shall be
reduced or the vessel stopped for any
period that is deemed necessary.

17. Navigational
􀂃 Radars are a valuable aid in ice
detection but shall be used with caution. It
is essential to maintain a two-radar watch
at all times along with a visual lookout.
􀂃 In the dark searchlights shall be used
together with a visual lookout ahead for
smaller pieces of ice that may have
escaped radar detection. Searchlights
should be used in a manner so as not to
embarrass any other vessels.

18. Under normal circumstances icebergs
shall not be passed close by. Bergy bits
and growler debris from bergs generally
trail to leeward.
􀂃 If it is necessary to pass close to
icebergs a very close watch for bergy
bits, growlers and also ice-feet / rams
shall be kept. Ice-feet / rams protrude
from bergs under the sea surface,
generally marked by a lightening of the
sea colour.

19. General Preventative Precautions
􀂃 In order to predict when icing of the
vessel will occur, both wet and dry air
temperatures, and sea temperature must
be regularly monitored and recorded.
When approaching zero degrees C, cold
weather precautions must be introduced
to elevated and the Master informed.
Engineering
􀂃 The Duty Engineer shall always be
informed, and the engine room fully
manned prior to the vessel entering ice.

20. Personal Welfare
In order to best prepare the crew it is
important that information regarding the
approach of cold weather is passed on
to all concerned. All personnel should be
kept fully updated with possible change
in conditions on the vessel’s daily work
plans.
It is essential that all personnel be fully
appraised of the requirement to be
careful when moving around the deck in
icy conditions.

21. Warm clothing should be available as free
issue to persons whose primary role is
working outside on deck, at sea or in port.
This should collected in, cleaned and re-
stowed for future use after vessel returns
to warmer climates.
• “Long Johns” / Long sleeved vests.
• Balaclavas / Gloves (proper woollen
inner gloves and larger heavy working
over gloves).
• Thick socks. Quilted jacket liners.

22. Exposure
Exposure to cold and the effects on the
body.
In severe low temperatures actions must
be taken to protect the body and its
extremities. It is important that minor
injuries are reported and treated
immediately, particularly minor cuts and
abrasions, which provide a ready entry
point for frostbite.

23. Exposed tissues in low temperatures,
particularly the ears, nose, cheekbones
or chins, and uncovered fingers are
susceptible to frostbite. This is initially
painless and may only be detected by
noticing typically white patches on the
skin. Minor frostbite can, when the
person has retired to warmer
surroundings, be thawed using the palms
of the hands over the affected areas.

24. Conclusion:
You are treading on thin Ice during Ice
Navigation. Care needed.
Thank You