Normal vessels will also encounter freezing conditions, particularly when venturing to the northern ports of Europe and Asia, and the cold conditions experienced can cause severe damage
Trang 1It is not my intention to go through all the problems that ice can cause, particularly when deliberately entering ice on ice class ships As a Chief Officer, if you are appointed to such ships then you should have had ice experience in a more junior capacity and there are excellent books available on the subject of ships in ice, such as the 'Ice Navigation Manual' Normal vessels will also encounter freezing conditions, particularly when venturing to the northern ports of Europe and Asia, and the cold conditions experienced can cause severe damage to the ship Even as far down as Hamburg and the North Sea, ships have been badly affected by freezing temperatures
If you are going into such areas in winter, and there is a chance of you encountering freezing conditions, there are certain precautions that you should consider taking
10.1 Preparation and Precautions
The following items are to be checked prior to entering ice or carrying out ice operations:
General
□ Check the inventory of cold weather gear onboard and replenish any deficiencies
10 Freezing Conditions
Account for ice allowances.
Trang 2□ if the ship is not fitted with double glazing, perspex or cling film placed over windows can help insulate the accommodation
□ examine towing fittings on the foc'sle and ensure that a suitable messenger is available to pick up a bridle or towline
□ ensure regular monitoring of the water level in all spaces and compartments This could be as frequently as hourly in areas of heavy ice concentrations This should also be instigated after a strong ice impact
□ searchlights fitted and tested
□ pilot ladders should not be lowered too early as ice can accumulate from spray
□ ship's hydraulic systems filled with a fluid suitable for cold weather operations, ships fitted with tunnel thrusters should not use these as they are liable to damage from ingested ice, which could damage the blades
Deck Service Lines
□ Isolate and drain the following lines, leaving the drains open
□ fire mains Valves must be left cracked open
□ general service line and fresh water line to all deck outside taps
□ deck air line
□ chain locker eductor
□ anchor wash lines
□ winch cooling lines
□ all external taps
□ drain bridge window wash systems unless antifreeze has been added
□ be alert for the formation of ice at any overboard discharges
Whistles
□ Drain main and forward whistles and close drain cocks
Safety Gear
□ Stow forward liferaft and LSA gear
□ stow deck foam and water fire extinguishers in heated areas
□ stow lifebuoys
Lifeboats
□ Drain fresh water tanks
□ ensure potable fresh water tanks are full and located in a warm room nearby
□ fit lifeboat drain plugs
□ Consider the addition of:
o Sets of sub-zero temperature insulated clothing (S, M and L sizes)
including hooded jackets, trousers, gloves and boots
o sets of thermal underwear and socks
o sets of face masks and goggles
o sleeping bags (down filled)
o Arctic type igloo shaped survival tents
o additional high energy food supplies, such as chocolate bars
Trang 3Grease
Grease should be applied liberally to all the moving parts on the decks including:
Note: A little anti-freeze is effective when mixed into the grease
Halyards and Stays
□ If halyards are left up then they should be slacked down Protection
□ Covers off all searchlights
□ covers on hatch control boxes
□ covers on all fire hydrants
□ covers on all fire hose boxes
□ covers on all mooring lines on drums, leaving lashings clear before making fast to enable release
□ covers on bunkering sounding pipes
□ grease and burlap (hessian) hatch drive motors and gypsies
Heaters
□ Foc'sle fan and space heaters switched on
□ winch hydraulic header tank and hatch hydraulic heaters switched on
□ anti-condensation heaters on hydraulic systems switched on
□ winch, hatch pump and exhaust fan motor heaters switched on
□ any deckhouse space heaters switched on
□ fire pump and davit heaters switched on
□ space heaters in emergency headquarters switched on
□ Windlasses
□ mooring winches
□ cargo winches
□ engaging clutches
□ pins
□ operating handles
□ brake clamping bolt threads
□ all nipple points
□ sounding pipe cap threads
□ hatch dogs
□ davits
□ cranes
Trang 4Additional Items for Tankers
□ Decontamination showers and eyewash stations to be accessible to crew in all weather conditions
□ drain foam lines
□ cargo heating coils either to be empty or steam to be circulated
□ aft peak tank to be heated, if ballasted
□ pressure vacuum (P/V) breaker to have the correct amount of anti-freeze (glycol)
□ steam to be opened to deck water seal and cargo oil pump separators
□ crude oil wash (COW) lines and COW machine stand pipes to be drained
□ P/V valves to be operated to ensure free movement
□ insulate lines from cold with a trace-heating system Care should be taken that thermostats are functional and have enough power to run through cables to provide effective trace-heating
Tankers - Cargo Heating Systems
If cargo heating system is not required:
□ Drain/blow through inlet/exhaust lines to remove all presence of water
If cargo heating is required:
□ Introduce steam to the cargo heating system before encountering freezing temperatures
□ consider fitting a small diameter line (jumper line) between the supply and return manifolds on the forward tanks to prevent freezing of the exhaust returns
□ test all steam and exhaust valves for tightness so as to prevent leakage into 'dry lines'
□ maintain heating until ship reaches warmer climates
□ blow through all coils/lines with air immediately after turning off the steam
Additional Items for Gas Carriers
□ Drain both deck water spray/sprinkler lines and safety relief valve drains
□ drain both safety relief valves and vent masts
□ cargo heaters and cargo condenser fresh water cooling systems to be kept on
□ emergency eye wash and decontamination shower lines and tanks to be drained
□ attach and post a pipeline drawing of the number and location of the drains and indicate which drains are to be blanked and drained The same should to be clearly marked at their location
□ isolation valves of lines to be posted and clearly marked at their location if space heaters are not provided Cluster-lights may be safely rigged close to the machinery and electrical panels and kept on
Note for Dry Cargo Ships
Ships regularly trading in ice should carry a long-handled blowtorch fired by
propane and a sufficient stock of cylinders should be maintained onboard
Trang 5If you take freezing spray on your decks the ice will build up very quickly To work the ship, this
will have to be cleared from areas such as the windlasses, doorways, etc This will have to be
done manually Steam lances are used in some circumstances, but the problem with these is
that the steam can freeze as it leaves the lance, adding to the problem rather than helping
Shovels are essential for removing newly fallen snow before it freezes on top of that already
there You will have to ensure that you at least have a path along your decks for personnel to
move around Ice can be knocked off using wooden mallets and pickaxes and crowbars can be
used with care This equipment should be stowed in an enclosed space, such as the foc'sle or
aft store, to be ready for use When working on deck in the ice, care must be taken of ice falling
from the rigging and masts Much of this can be shaken off by hand or with mallets
De-Icing
If you do not have heated bridge windows or blown hot air systems, you must have a good
supply of de-icing sprays If you have bridge wing controls, keep the dials free of ice with the
sprays
Anti-freeze
Anti-freeze must be used in all the boat engine cooling systems
10.2 De-Icing Tools
Have equipment and machinery prepared
Trang 6Scuppers
Clear the scuppers of the grilles so that when freezing water is taken onto your decks, it can run away freely Insert rubber hose piping into the scuppers so you can remove it when the pipes are frozen to give you ice free scuppers that allow water to run away
10.3 Crew Clothing
It is essential that the crew have suitable cold protective clothing to wear and that spare clothing
is carried to replace wet gear Winter weight padded boilersuits, padded work gloves and winter boots must be supplied Liners for hard hats, with ear coverings, must be fitted It is important that frequent breaks are given and that there is always an adequate supply of warm food and drinks Thermos flasks are very useful when securing or letting go as these actions can be prolonged in ice conditions
10.4 Damage Control
Although you will not generally be navigating in Arctic waters, there is a possibility that you will find yourself in waters with ice
The IMO 'Guidelines for Ships Operating in Arctic Ice-Covered Waters' state:
All ships navigating in Arctic ice-covered waters should be adequately equipped and their crews properly trained to provide effective damage control and minor hull repair
Damage control equipment should, in accordance with the above, be sufficient to enable a ship, as far as practicable, to make temporary repairs to a minor hull breach or to take precautionary measures to prevent escalation of damage or flooding, so that the ship may proceed to a location where a more substantial repair can be affected
Not many crews are trained in damage control, particularly on ships that only occasionally transit ice waters On modern merchant ships the equipment for damage control of the hull has generally been discarded on the premis that the majority of hull damage suffered will be so large that the crew could not attempt temporary repair
However, ice provides a totally different scenario, While catastrophic damage can still result, about which the crew can do nothing, there is a very real possibility of damage below the waterline being small but still capable of allowing water to jet into the ship The smaller the hole, the stronger the force of water While the pumps could probably cope with the water flow any such ingress is bad, regardless of where it is and regardless of whether or not the pumps are coping However, if the hull penetration is in way of the engine room this could cause
Trang 7damage to the machinery and/or electrics that would render essential pumps
Inoperative and leading to, in an extreme case, the loss of the ship
There are a number of temporary damage control devices that seem to have come from
a bygone age, but that could still prove very effective
The first are wooden wedges, both flat and pointed If a box of these is kept in the engine room, and any other strategic place required during ice transit, they will be ready for instant use
The next is a rigid bottom weighted large canvas or tarpaulin square, with ropes attached
If this is stowed in a locker on deck, it will be ready to be thrown over in the area of damage The weighted bottom drops the square down in the water alongside the hull and the force
of the water entering the ship drags it towards the damage, forming a cover over the hole This will not stop all water from entering, but the force of the jet will be reduced substantially, enabling those inside to take more effective action and providing temporary respite The difficulties of getting wedges in against the force of the water and working with ice cold water flooding over the bodies of those attempting repair must also be remembered
In the damage control inventory on warships there is a piece of equipment called a splinter box, which comes in different sizes It is a dome shaped device with rubber seals around the rim and a long screw with a folding bar device through it The long screw can be pushed through the wedges or canvas and then, as it is screwed, the bar opens to form a crosspiece
to hold the cup while it is screwed tight and in place
Perhaps consideration should be given to making such equipment a standard
requirement for ships navigating in ice
In 1999, I encountered damage from ice on the bottom of the ship - it was only a small penetration but it had to be dealt with The Chief Officer and I entered the DB for inspection and used wooden wedges to stop the flow of water Then the crew put a cement box over the hole and all was well What was interesting was that we were able to identify the hole not only from the sound of water spurting in but from the light beam coming from the hole, which was rather surprising considering that it was on the bottom of the ship.
Trang 8A few last points if you are to work cargo in cold weather Hydraulic oil has a lower viscosity in cold weather, which means that the colder the weather gets the thicker your oil becomes Therefore, if you do not have heaters for your hydraulic system, switch the motors on well before they are needed It is always embarrassing to get alongside and not be able to open your hatches, and even more so when you are put off-hire
If you have a build-up of ice or snow on your hatches, try to get this off before opening them as weight puts severe strain on chains and hydraulics If the hatches are iced up and beyond your ability to clear before getting alongside, notify ahead to the agent for a de-icing company to be ready for your arrival
A few last points if you are to work cargo in cold weather Hydraulic oil has a lower viscosity in cold weather, which means that the colder the weather gets the thicker your oil becomes
Therefore, if you do not have heaters for your hydraulic system, switch the motors on well before they are needed It is always embarrassing to get alongside and not be able to open your hatches, and even more so when you are put off-hire
If you have a build-up of ice or snow on your hatches, try to get this off before opening them as weight puts severe strain on chains and hydraulics If the hatches are iced up and beyond your ability to clear before getting alongside, notify ahead to the agent for a de-icing company to be ready for your arrival