Euphoria has broken out in the ice-class market, underpinned by the booming Russian oil industry, environmental concerns and red-hot tanker rates.
On the back of these positive influences, market analysts have predicted that the ice-class fleet could grow to 18M dwt by 2008. Nobody doubts that the demand will continue on an upward path but the question is just how steep will the path be?
As we see it, Russian exports are expected to remain concentrated on ports in three areas – the north Baltic, the Russian Arctic and the far eastern areas of Russia. The high infrastructure costs involved in developing exports from the northern parts of Russia seem to indicate a large scale operation, and exploitation of Russia’s large oil reserves will undoubtedly mean the use of many high-spec ice-class tankers.
Over the years, stricter international rules and regulations, and advances made in design and safe operation of tankers, have resulted in a significant improvement in the tanker industry’s safety record. The challenge is to continue this positive trend in the future when oil transport expands into Arctic areas.
DNV focuses on additional risks when ship operation moves from worldwide trade to cold climate areas. The different risk elements known from ship operation worldwide are examined in order to find ways to mitigate them. If the probability of incidents is assumed to be the same in cold areas as in more temperate climates, the risk will be larger because the consequences of a possible incident in cold areas may be much more severe.
Increased operation in the moderate cold of the Baltic and the extreme cold of the Arctic brings the obvious challenges of thicker and harder (multi-year) ice and temperatures which can go as low as –55°C. Vessels operating alone in such remote areas are very vulnerable, necessitating higher requirements for redundancy and reliability. As traffic increases, there will inevitably be less icebreaker support available unless local or national governments are mobilising more icebreaker support by re-arranging existing support fleet or by placing new contracts for construction.
Trends to date
These challenges must be set against the trends already identified of larger vessels and higher ice-class. The width of these large vessels poses a problem for existing icebreakers – either two acting together will be required to create a wide enough channel, or vessels will have to be designed for independent icebreaking. Double-acting vessels, optimised for astern operation in ice and forward operation in open waters, are a possible answer.
There is also a trend towards the use of diesel-electric and podded propulsion, which in itself poses challenges in determining minimum-maximum power requirements. Decisions on necessary power are increasingly being made on the basis of model testing.
It is likely that some transport will be carried out by shuttle tankers from the Arctic fields to oil storage vessels in ice-free ports for subsequent transfer to large tankers for the European and US market. This would reduce the number of very large vessels exposed to this most challenging environment.
On the other hand, there is concern that the number of ships on order with high ice-class may exceed the need for the Baltic and Arctic areas. If so, many of these ships will only operate sporadically in ice and will not be able to build up and maintain the necessary experience to operate safely in cold climates.
DNV’s cold climate competence is based on a long history. Requirements for additional strengthening for ships which may operate in ice were mentioned in the DNV Rules for the first time in 1881: The frames have to be put closer together in the bow section in addition to proper internal strengthening.
In 1932, DNV introduced the first special requirements for ships intended for operation in ice-covered waters. These rules included increased scantlings of frames, plates and stringers specified as percentage increase (15–25%) above standard class rules.
The Finnish-Swedish Maritime Authorities have long experience with operation in ice in Baltic waters. In 1960, DNV introduced new rules with ice classes in conformity with the established Finnish-Swedish ice regulations. In addition, the first requirements for icebreakers were introduced in 1962, with the class notations Icebreaker and Polar Icebreaker.
Around 1980, DNV was heavily engaged in projects intended to improve understanding and knowledge of ice mechanics, Arctic ice conditions, identification of hazardous ice features, methods and tools for prediction of ice loads on ships and offshore structures, ice-induced structural vibrations, model testing and icing of structures.
At the same time, Canadian authorities focused on Arctic operations as a consequence of high oil prices. DNV opened an office in Calgary with its main focus on maritime operations in cold climates. This resulted in a set of new rules for cargo ships intended for unassisted operations in ice-infested waters, approved by the DNV Board in 1988; with minor adjustment these still are the official DNV rules. The notations dat(– x°C) (design ambient temperature) to ensure adequate material properties at low temperatures to avoid brittle fractures and ram(– m/s) (maximum design ramming speed for icebreaking) were introduced at the same time.
DNV has a large menu of class notations corresponding to different functional needs when operating in cold climate or ice-infested waters. As the major class society of tankers with ice strengthening and with almost 1,900 DNV-classed vessels of different types prepared for operation in cold climate, it has over many years gained valuable experience for developing rules covering different operational needs. These cover:
- Rules for soft ice
- Baltic rules, assuming support from icebreakers
- Arctic rules for more independent operation
- Icebreaker rules for functioning in heavy ice conditions
- Rules for materials, taking into account extreme low temperature
- Deicing rules for proactive preparedness to ensure operational safety
Icing problems
Icing caused by sea spray or snow freezing and forming a layer of ice on deck and superstructure when operating in low temperatures may have a major impact on the stability, safety and general operation of a vessel. Ice covering navigational equipment and equipment operated by the crew will reduce the safety level. DNV has developed the class notation DEICE to ensure operational safety through proactive preparation.
This notation covers anti-icing requirements for certain equipment/ areas where continuous operation is required, such as navigational equipment and fire lines, and de-icing requirements for equipment/areas where accumulation of ice is acceptable. However, the ship has to be equipped with de-icing equipment to remove the ice within a period of 4–6 hours.
Typical icing problems encountered are the impairment of stability due to the lifted centre of gravity, limitation on safe navigation caused by antennae and radar equipment being out of operation, and icing on wheelhouse windows. Ice accumulation can completely disrupt the functioning of certain deck equipment. For example, it may be impossible to get rescue equipment such as lifeboats and liferafts out of storage due to icing on release mechanisms or davits, or to release anchors. Air pipes may become clogged with ice and P/V valves and other valves may cease functioning.
Gangways and railings covered by ice make it dangerous and almost impossible to move around safely, and scuppers in bulwarks may be reduced in size and even completely clogged by build-up of ice.
Beyond the basics
The basic rules cover the necessary strength for the hull and propulsion system for a given ice condition. However, depending on the area of operation and anticipated ice conditions, additional requirements have to be fulfilled in order to be able to operate.
The skill and experience of the crew will also have a significant and direct impact on the safety level. Special safety considerations at low temperatures relate to people, the vessel itself, cargo handling operations and safety functions. It is particularly important that crew members have been prepared to react and function in the conditions in which they find themselves. When a ship is operating in ice, the major increase in noise and vibration will affect their ability to get proper rest when off duty, and hence reduce their ability to work safely while on duty. The vessel must be truly ‘fit for purpose’, and have structures and equipment of a material quality that is appropriate for low temperatures. Provision of fire-fighting equipment and arrangements for lifeboats and emergency towing arrangement require particular consideration.
In addition, there are some environmental concerns. Arctic areas are very sensitive to discharge of oil and other pollutants. The low temperature will preserve the pollutants, and due to the sensitive ecological balance there should be ‘zero tolerance’ with regard to discharge. Due to the remote location of many of the new oil fields, shore-based contingency plans and resources are limited and represent a challenge for the industry and national authorities.
Furthermore, most ship operations are different in ice and low temperatures and require experienced crews in order to maintain the same safety level as for worldwide operations. Unavailability of competent crews may limit safe operation.
Operation in Russian Arctic waters also require that local rules and requirements are fulfilled. DNV has, through co-operation with Russian institutions, knowledge of applicable rules and regulations, and can consequently support owners in this respect. An Ice Certificate is required when operating in the Northern Sea Route or ports in Russia when the ice conditions become more severe than defined by the ship’s ice-class. When building to the Russian flag, national flag and statutory requirements have to be fulfilled. The so-called ‘sanitary rules’, including requirements for noise, vibration and ventilation, are example of rules which have to be fulfilled.
The additional risks of operating in cold climates require a systematic approach, focusing on planning and preparation. Ensuring sufficient fire-fighting capability in extreme temperatures, and coping with new propulsion alternatives in a robust, safe and reliable manner have to be taken into account. Regulations alone are not enough.
DNV is prepared to support and be a discussion partner for owners, yards and authorities in the further development of shipping activities in cold climates. We endeavour to make shipowners, operators and their crews aware of the challenges of operating in cold climates and icy conditions.
Such communication becomes increasingly important when one realises that one-third of all DNV-classed tankers currently on order are specified with ice strengthening and this proportion seems to be increasing.
Baltic rules
Applicable for ships operating in broken channels made by icebreakers in first-year ice or in open waters with small ice floes. They include the rules issued by the Finnish and Swedish authorities (FMA).
- 1A* Extreme ice conditions, ice floes of 1.0 m thickness are anticipated
- 1A Severe ice conditions, ice floes of 0.8 m thickness are anticipated
- 1B Medium ice conditions, ice floes of 0.6 m thickness are anticipated
- 1C Light ice conditions, ice floes of 0.4 m thickness are anticipated
The following notations are also available:
- ICE-1A*F Vessels complying with ICE-1A* including additional strength for regular service in ice-infested water, to a certain degree independent of icebreaker
- ICE-C Vessels which may operate in very light ice conditions. Only bow region reinforced. Considered to be similar to Ice Class II by the Finnish authorities and not accepted as fully ice strengthened.
Arctic rules
The Arctic rules ICE-05, ICE-10 and ICE-15 are used for vessels breaking their own way in first year winter ice with pressure ridges but built for another main purpose. No ramming anticipated.
POLAR-10, POLAR-20 and POLAR-30 are used for vessels breaking their own way in multi-year winter ice with floes and glacial inclusions. Accidental ramming anticipated. They include the DAT notation (Design Ambient Temperature) with requirements for material quality in selected areas.
Icebreaker notation used together with ICE-05 (or 10 or 15) or POLAR-10 (or 20 or 30). Repeated ramming anticipated.
Items covered by ice-class notations
Baltic ice-class
- Hull – ice belt
- Machinery output
- Shaft – system
- Propeller
- Mooring
- Heating of ballast tanks
- Sea chest
- Air capacity for starting compressor (1A*)
- Rudder and steering gear
- Corrosion protection
Arctic (additional)
- Hull girder transverse strength, line loads due to vessel being trapped between moving ice flows
- Significantly increased requirements to rudder, pods and hull appendages with respect to local dimensions and effect of direct ice loads
Polar (additional)
- Hull materials exposed to low temperature (DAT)
- Subdivision, intact and damage stability (additional)
- Requirements to main structure in bow area and hull girder longitudinal strength due to beaching and ramming
Area Thickness (cm) Ice type
- The Baltic (Gulf of Finland/Gulf of Bothnia) 40/80 One year ice
- The Caspian Sea 70 One year ice
- Azov Sea (Black Sea) 70 One year ice
- The White Sea 80 One year ice
- Barents Sea (Arctic) 120 First year and multi year ice
- The Sea of Okhotsk (East Siberia/Sakhalin) 140 First year and multi year ice
- The Kara Sea (Arctic) 180 First year and multi year ice
Temperature in the Baltic, typically –15ºC. Temperature in the Arctic, down to –45ºC
Date: 2005-06-09