Handling Ships in Ice
The below is a compilation of various sources for risks during navigation in cold weather or ice conditions.
FREEZING SPRAY & SHIPBOARD ICE ACCRETION
The danger posed by the formation or accretion of ice on exposed ship’s structures and equipment is not always fully appreciated. Serious ice accretion adversely affects several areas of a ship’s operation and safety such as stability, strength, equipment, securing and closing arrangements.
A very severe case has been documented. A 120m vessel left a European port with a 0.2m trim by the stern and reached the Quebec City port with trim by the bow of approximately 4.0m.
A heel of five degrees developed and the vessel also became directionally unstable. The master was totally unaware of the serious icing forward until a boarding pilot reported the developing condition.
ANCHORS
Vessels likely to encounter freezing spray conditions at sea must have means of clearing ice from anchor hawse pipes and windlasses before arriving in restricted waters.
For windlass ensure the following:
1) Drain the waterside of the cooler
2) Keep the Electric Motor heaters always on
When approaching a freezing spray area, it is good practice to leave anchors slightly lowered (approx. 0.5 meters) in the hawse pipe to pull them free of ice accretion when needed. Depending on sea conditions, care should be taken to avoid hull damage. It is also advisable, to maintain securing claws in place because of slippery brakes taking into account, that the anchors must always be able to be readily released in case of a blackout.
RISKS AND CONSEQUENCES
The icing of ships and their securing arrangements may require de-icing. This could delay off-loading operations. Ice accretion on hatch covers requires considerable clearing-up operations. These procedures are not only time consuming but, could result in mechanical damage if carried out without care. Clearing-up operations should, therefore, always be followed by careful inspection.
POSSIBLE HULL DAMAGE
At temperatures below freezing point, the impact resistance of steel is reduced. Hard contacts with ice, docks and fenders may result in structural failure at a significantly lower level of impact. A close examination of the contact areas is strongly recommended. Immediately upon clearing heavy ice, or areas where cold weather procedures are in force, an inspection should be made of all accessible cargo compartments, void spaces, forepeaks, forward deep tanks, cofferdams and pump rooms to verify the integrity of the hull. Relevant entries should be made in the Deck Log Book.
LIFESAVING APPLIANCES
Ice accretion should be regularly removed from lifeboats and launching equipment to ensure ease of launching where required. An ice removal mallet should be available in the vicinity of lifeboat and liferafts.
LIFEBOAT AND SURVIVAL CRAFT
An uncovered survival craft, as well as the access ladder, should be protected from snow or rain with an appropriate tarp. Avoid material made from natural fibres for painters, embarkation ladders, ropes and protective tarps since natural fibres absorb moisture resulting in a loss of flexibility and durability under cold weather conditions.
LIFEBOAT PROPULSION
The International Life-Saving Appliance Code (LSA) stipulates:
Section 4.4.6.1 “(…) No engine should be used for any lifeboat if fuel oil has a flashpoint of 43° C or less (closed-cup test).”
Section 4.4.6.2 “(…) The engine starting systems and starting aids should be able to start the engine at an ambient temperature of –15° C within two minutes of commencing the start procedure (…)”
FUEL OIL
Ensure the following:
- Cooling freshwater of Boat Engine: check if antifreeze liquid is added as per maker’s mixing ratio and act accordingly.
- Allowing sufficient ullage space for expansion in Life Boat FW cooling tank.
- If the engine sump tank not equipped with a heater, then a heating lamp/heater to be installed.
Distillate fuels
When the fuel temperature drops to or below the Cloud Point, wax crystals start to form, filter clogging takes place, resulting in fuel starvation and engine stoppage. Satisfactory storage, transfer and filtration need a fuel temperature about 3~5°C above the Cloud Point.
(The Cloud Point (CP) of a distillate fuel is the temperature at which wax or other solid substances begins to separate from petroleum oil and form a cloudy appearance)
The Cloud Point of fuels used for emergency equipment should be below the ambient temperatures the equipment is operating or likely to operate in.
The additives used can also cause operational problems as some of the chemicals get absorbed by filter materials, causing them to appear blocked. This problem is exacerbated for emergency equipment which are typically fitted with very fine filters. Cautions:
- Visual inspection of the filter element will not indicate any reason for the blockage
- Cold flow improving chemicals may be effective in one fuel and may not be effective on another.
Since fuels in the emergency equipment storage tanks remain unused for long periods of time, quality of such fuels may deteriorate due to the following:
Water can originate from contaminated fuel or condensation, and engines may not run because of water in the fuel lines.
The presence of water can promote the growth of microorganisms such as bacteria, yeast and fungi, and can also lead to blockage of fuel lines and filters due to icing when the ambient temperature drops below 0o C.
Visibility/Ignition
Visual Appearance: Fuel grades DMA/DMZ/DMX should be bright and clear. If the fuel is hazy, it could indicate the presence of water or a high could point. Haziness could also indicate poor oxidation stability
Cetane Index – Allow cetane index may lead to starting difficulties at low ambient temperatures.
ELECTRIC HEATER
The lifeboat engine electric heater should be in function. A temporary heater (portable electric heater or protected light) can be installed under or on the side of the engine with a fire-resistant blanket over it to preserve heat. An approved electrical appliance to avoid electric shock or fire hazard is to be utilized. Electrical cables running through openings such as access doors and windows are not acceptable.
WATER COOLED ENGINE
The antifreeze mixture should sustain weather of at least –35° C to avoid damage to the cylinder block. Record temperatures back in 2003 were recorded in Port-Alfred, Québec at -40° C for four consecutive days.
PROPELLER SHAFT
Special precaution must be taken if the stern tube is water-cooled as it may be frozen. Before starting and clutching, the engine propeller shaft should be turned manually to avoid damages.
DAVITS
Every pulley, drum, and cable where water can infiltrate, should be greased to eliminate water and to protect against frozen water, which may damage or harm the movement of such equipment.
Emulsified oil from the davit gearbox may solidify under cold conditions. This contaminated oil is to be renewed. Investigate the cause of contamination and then take corrective action. Excessive moisture in the gearbox may lead to braking system failure.
LIFERAFTS
Liferafts have to be protected from snow, rain and ice accretion with an appropriate protective tarp as well as for embarkation ladders. Avoid material made from natural fibres for painters, embarkation ladders, ropes or protective tarps since natural fibres absorb moisture and lose their flexibility and durability under cold weather conditions.
ACCOMMODATION
a) Steam heating to accommodation is to be 'ON'. Steam is to be the primary heating system, backed up by individual cabin heaters (where fitted). This helps to cocoon the accommodation spaces from the cold and prevents freshwater pipes from freezing. If the ship is not insulated and provided with a vapour shield, introduction of moisture in the air should be avoided for cold climates as vapour will condense between walls and ceilings causing a fire hazard around electrical circuits.
b) It is advisable to cover portholes and window cavities with polyethylene or Perspex, to provide an air buffer insulation (where not double glazed or heated). This is a good contribution towards reducing ice formation on interior surfaces.
c) Ensure all double doors to accommodation, doors to stores, passageways and holds are kept shut at all times. Keep accommodation spaces in a state of light pressurisation. Recirculate air, taking care of all of the above.
d) All steps, decks, walkways and passages into and around accommodation to be kept clear of accumulated snow and ice by regular shovelling and salting. Coarse salt to be liberally dispersed on deck walkways, gangways and ladder steps to prevent slipping accidents. Sufficient stock of de-icing salt should be kept on board and readily available for this purpose.
CREW PROTECTION
a) All shipboard personnel are to be instructed in the hazards of working in exposed locations and instructed in the type and amount of minimum clothing to be worn.
b) Several layers of clothing (instead of one heavy suit) are preferable as air trapped between layers of clothing, provides greater insulation and consequently, a reduction in loss of body heat. Wear mittens (not gloves), wind-proof and water-resistant many-layered clothing and two pairs of socks (cotton next to skin, then wool).
c) Use of clothing with some ventilation decreases perspiration, which can freeze. Wet flesh freezes faster than dry flesh.
d) While working, it is natural to perspire. Do not remove clothing while in an exposed environment. Go into the accommodation to dry off.
e) As far as practicable, work with back towards the wind.
f) Gloves to be sufficiently loose for circulation to be maintained.
g) Hoods and caps to be worn with ears fully covered. Much of body heat is lost through an unprotected head and neck.
h) Never rub a numb area as this could damage frozen flesh. Suspected frozen flesh is to be warmed-up gradually and not immersed in hot water. Immersing immediately in hot water may cause permanent damage to skin and body tissues.
i) In extreme temperatures, feel your cheeks and nose with your fingers for sensation. Hands, face, ears and feet are areas particularly susceptible to localized freezing. No sensation means a likelihood of frostbite. Enter a warm area immediately. When working in groups, keep an eye on each other to look for any numbness or whiteness (frostbite occurs when skin tissue starts to freeze).
j) When going into sub-zero temperatures, be aware that the wind chill factor increases the effect of colder temperatures, therefore frostbite can occur faster.
k) Frostbite and hypothermia are very real dangers associated with cold weather. Guard carefully against them. Never work alone in extremely cold temperatures.
l) Note, clothes by themselves do not warm the body. The body is warmed-up by its heat generation and the body heat, in turn, warms the layers of air trapped between the skin and the clothing.
m) Shivering is the first sign that the body is trying to combat cold by generating more heat. However, if the exposure is severe, the body is unable to conserve or generate enough heat to maintain body core temperature. Shivering will stop, unconsciousness follows and then death due to cold exposure or hypothermia. Carry out "Active Warming or Passive Warming". If nothing is readily available, apply body-to-body heat to preserve life.
BRIDGE NAVIGATION
All ships should be fitted with a suitable means to de-ice sufficient conning position windows to provide unimpaired forward and astern vision. Humidity in the air from the heating system should be avoided to prevent window fogging and icing.
The windows referred to above, should be fitted with an efficient means of clearing melted ice, freezing rain, snow mist and sea spray from the outside and accumulated condensation from the inside. A mechanical means to clear moisture from the outside face of a window should have operating mechanisms protected from freezing or ice accumulation that could impair effective operation.
a) Ensure individual heating to bridge windows remain on at all times (where fitted), when temperatures are below freezing. Drastic changes in temperatures created by a chill factor may cause the glass to crack, due to thermal shock.
Note: if the above arrangement is not available, installation of transparent heat shrink film over each window, will reduce heat loss and prevent frost and condensation.
Another method consists of forced ventilation, aimed at each window, using portable fans or improvised ducting made of polyethylene fed from the ship’s heating system.
b) Handheld ice scrappers and lint-free paper towels are a must in many cases.
c) Individual heaters in the wheelhouse to be kept on during winter (where fitted). If not fitted, at least two portable heaters (5000 watts each, with ventilator) should be safely and adequately installed, temporarily.
d) Every effort shall be taken to prevent exterior windows from ice accretion.
e) Drain the bridge window wash-water line and leave drains open or use -45° C antifreeze window wash.
f) Ensure whistle and horn heater remain on at all times. Ensure compressed air is moisture-free.
g) Slack down all signal halyards.
h) Radar scanners to be kept running at all times.
i) Special attention should be taken to avoid freezing of navigation and deck lights (Turn on Navigation Lights at all times).
j) Switches for the duct heaters to be switched on (where fitted).
k) Clear-view screens to be kept running when needed.
l) A container of coarse salt to be kept readily at hand in the wheelhouse especially in pilotage waters to prevent slipping accidents.
m) Search lights, port and starboard, to be functional.
n) Ensure trace-heating to EPIRB is on. It comes on automatically by thermostatic control as the temperature drops below –2°C.
- o) Engine control air should be free of moisture. Line passage through cable trunk should be protected from freezing.
p) Switch on Heaters of the Air horn, Bridge Clear View Screen, Windows, etc.
BALLAST – CARGO CONDITION
Bring the vessel down in the water to a draught at which the sea suctions and propeller are well below the level of any ice. When taking this action, ensure that the vessel remains at a safe draught with adequate under keel clearance.
Restrict the trim (1 to 3 metres - preferably no more than 1 meter) to avoid the possibility of ice moving under the bottom of the ship and being picked-up by the sea suction.
Take in cargo prior to discharging ballast to maintain the maximum safe draught (seen in relation to the level of ice).
If discharging cargo, reverse the procedure outlined above. Maintain maximum safe draught by taking in ballast simultaneously while discharging.
Note: This procedure may be unsuitable with freshwater ballast in extremely cold conditions. Seek local advice.
COLD WEATHER PRECAUTION PROCEDURES WITH BALLAST
a) Seawater freezes around -3°C (28°F). Ensure only warm seawater ballast is retained onboard, i.e. ballast to be exchanged in mid-Atlantic as per specified procedures. Freshwater temperature record tables are included for Montreal, Sorel, Trois-Rivières, and Québec.
b) Steam heating opened on all wing ballast tanks (where fitted), even in empty tanks. This will prevent condensate freezing and damaging lines.
c) To allow for expansion due to freezing, slack down all ballast tanks and fresh water tanks which are pressed up. When alongside, if practical, empty ballast tanks below the waterline to prevent freezing. Pour environmentally safe antifreeze liquid into sounding pipes to prevent freezing of water in the pipe or use heaving lines for the same reason. In severe winter conditions, where double bottoms are used for main engine internal cooling, stability calculations should be taken into account for the resultant loss of stability, if required to slack the tanks.
d) Ballasting and de-ballasting operations to be carried out only after confirming air-pipes are clear. Continuously monitor ballast pump gauges. When de-ballasting, it is advisable to strip each tank completely to prevent freezing of any small volumes of water.
e) Ensure that steam to heating coils in freshwater tanks is cracked open (if fitted). Monitor temperatures of freshwater tanks at regular intervals.
f) Note that ballast water does not freeze below the waterline, except when cargo hatches are open.
MACHINERY & EQUIPMENT
Deck :
a) Freeze prevention for Pipelines and Valves / Systems related: Drain Fresh and Seawater Pipelines, Valves, Fireline, Deck wash lines, ballast water lines. (Same pipes to be blown by compressed air if necessary).
b) Where remaining water cannot be drained by gravity because of piping layout, flanges shall be removed for draining.
c) Drain valves of the above systems must be opened.
d) Water pipelines outside/around accommodation/engine casing to be also drained
e) If any empty Fuel oil Storage tanks, then keep minimum steam supply to their heating coils.
f) Allowing sufficient ullage space for expansion in all water ballast tanks.
g) Electrical panels and motor space heaters to be on (Accommodation, Pilot Ladder, Slewing Gear of Crane, Rescue Crane, Windlass, Hatch Covers).
h) Steering gear pump to be operated even if the ship stops.
i) Steering gear to be turned to 30 degrees every 30 minutes in case that the ship is stopped or at port
j) Sounding pipes to be de-iced by adding salt if necessary.
k) Accommodation to be under adequate heating.
l) E/R ventilation fans to be properly adjusted in order E/R to maintain a proper temperature.
m) De-icing/Salt to be applied where necessary to prevent slipping of the crew.
Emergency generator:
a) Add sufficient quantity of Antifreeze liquid inside the Radiator if found necessary.
b) Ensure full tanks have sufficient volume to allow expansion.
c) Space Heater of emergency generator room to be always below 100°C.
d) Engine Heater to be always in operation in any weather condition.
Freeze prevention for Deck machinery:
a) No-load operation of the Windlass, Winches and other Deck machinery for 30 minutes before taking the load.
Freeze Prevention in Machinery space:
a) Close any E/R openings
b) Adjust the number of ventilating fans on operation in the machinery space to maintain proper temperatures.
c) Switch On the Heaters in the Steering gear room
Cranes:
a) Make sure that: the Hydraulic oil level is sufficient. The oil temperature in the oil tank is more than +5°C. The Oil level in the slewing and winch gears are sufficient.
b) Before any operation, check the cleaning of the windows. No ice part on the window before rubber wiper is in operation.
c) If the crane has an oil heater and the ambient temperature is below -10°C you have to heat the oil as per instructions
d) Before operation of A/C check if the evaporator sides are blocked by snow from top of the cabinet.
Hatch covers:
Warming Up Oil in Tank
a) Oil cooler switch in position "manual"
b) Main power switch of the starter "on" and the oil heating switch
c) Oil heater starts heating automatically if the oil temp is +10°C or lower.
d) At -10°C or colder, switch on the heating two hours before starting the pumps
e) Do not cold start the pumps until the oil in the tank is warmed up to +0°C
Cold Start of Pumps
The following "inching mode" starting procedure must be used then the oil temperature in the tank is below 10°C and always when the room temperature is -5°C or lower. Follow the next steps:
a) Before starting the pumps check the fluid level in the tank, add fluid if necessary.
b) Check that all the control valves are in a neutral position and the piping warm-up valves are in the closed position.
Warming Up piping in Hull
a) The oil in the hydraulic piping needs to be warmed up at low ambient temperatures.
b) For the location of the warm-up valves see detail A in the hydraulic piping drawing.
Open one of the warm-up valves and start the pump unit to circulate the oil in the piping:
a) 15 min at an ambient temperature of approximately 0°C
b) 30 min at an ambient temperature of -10°C or lower
c) After warming up close the warm-up valve. Repeat with the other warm-up valve.
General:
a) All sponge rubbers IWO booby hatches, weathertight doors, Gooseneck type air vent with cover to be greased in the surface of contact with steel plates.
b) Drain FW washing pipe for Rubber wiper in navigation deck/wheelhouse.