Operating in Icy Waters
Prior to sailing into the cold area the following should be checked:
1. Pipelines containing water:
- On outside decks and in compartments/holds without heating, all pipelines must be drained carefully to avoid damage by freezing.
- Check also fire lines and cooling water lines (hydraulic systems) for instance in forecastle.
- Check the cooling systems for emergency generators and lifeboat engines. If freshwater-cooled, check the freezing point. Drain the seawater system.
- Check the emergency fire pump if situated in a room without heating. Add antifreeze to the pump housing and suction line if needed to be kept with water.
- After draining lines, keep outside deck valves open and close any valve inside (to avoid flooding when starting up).
2. Ballast tanks must not be filled completely to avoid freezing
- In general, pump out minimum 10% after filling (consider the possible free water surface effect of the vessel’s stability).
- Be aware that the tank ventilation deck valve and ventilation pipe could freeze and hamper the free airflow to and from the tank resulting in over/under pressure of the tank.
- Side tanks containing ballast are much more exposed to freezing in extreme weather, especially when installed above the water line. Great care should be taken if any water is required to be kept in side tanks. If possible side tanks should be kept empty, or only partly filled if necessary.
- Change the ballast for clean seawater if tanks contain freshwater or brackish water.
- Check the chain lockers for water and pump out prior to reaching the cold area.
3. Seawater inlet suctions:
- Check if there is a possibility to partly circulate the sea cooling water outlet from the machinery back into the sea chest to keep this heated.
- Check and test if there is air supply connected to sea chest in order to blow out ice if necessary.
- Check if steam can be supplied to your sea chest for heating in case freezing starts.
- To minimize ice sludge accumulation in the seawater inlet strainer, adjust the overboard valve and reduce the water to minimum flow required to obtain cooling.
- Use one inlet only, preferably the lower one, and keep the other on stand-by.
- Oil systems will work very slowly under extreme cold. If equipped with oil heating element this must be switched on. If not temporary heating could be arranged by using portable heaters at the oil tank.
Start oil systems prior to operation and run without cooling until proper temperature is reached.
- Hatch covers, emergency exits and watertight doors fitted with rubber gaskets should be greased with Vaseline or silicon grease to avoid damage to the gaskets when opening.
- Freshwater tanks in lifeboats to have necessary ullage to avoid damage during freezing.
- Gas oil for lifeboat engines must be of a type suitable for cold weather to avoid wax formation.
- Gas oil for emergency generator must be of correct type for cold weather operation unless installed in heated area.
When entering the ice, please consider:
- Always keep minimum one lookout at the bridge.
- Consider additional officer on watch depending on visibility and weather conditions. In bad visibility one person will need to operate the radar at all times.
- Follow instructions given by local authorities / ice-breaker.
- Sailing alone in fixed ice might damage the vessel’s hull and shell plating depending on vessel strength and ice class. The ice thickness and vessel speed/power must be considered by the captain.
- Consider waiting for a convoy.
Sailing in a Convoy
- Sailings in an open lane, for instance by following other vessels or the ice-breaker in the convoy gives the minimum impact on the vessel’s hull.
- Make sure to find and use correct VHF channels for communication/information from the icebreaker and between convoy vessels.
- A danger of sailing in convoys is if one vessel gets stuck in the ice or stops in case of engine / cooling problems, it could be hit by the following vessel. In these circumstances the following vessel must keep a safe distance to be able to stop because she will not manage to leave the lane and swing into the fixed ice. Going astern with the propeller should be avoided.
- The stopping vessel must immediately inform the convoy on VHF that she has problems to avoid being hit from the aft (many accidents have occurred).
Manoeuvring in Ice
Manoeuvring in the port area is often the operation that causes damage to the vessel.
Always keep in mind:
- Use tugs for harbour manoeuvring to avoid using own propeller, especially astern operation.
- The trim of the vessel must be arranged to keep aft draft as deep as possible to minimise the ice hitting the propeller and rudder.
- Going astern will suck ice into the propeller that might damage the propeller blades.
- Rudder must always be kept in centre position if the vessel is to move astern at any speed. The pressure of the ice – even loose ice – can easily twist the rudder stock of any vessel, ice classed or not.
Alongside in Port
- Be careful when opening hatches and side doors if frozen. If possible, use steam or hot water to de-ice to avoid breaking hydraulic systems or damaging the rubber gaskets.
- A correct preparation as mentioned above (item 4) will reduce the possibilities of damage.
- Before closing, a thoroughly control of all sealing surfaces must take place to ensure that no ice is left in between which could hamper correct water tightness.