Polar Code navigation
The IMO’s Polar Code which had been in development for several years is now a fact and its text has been distributed in RESOLUTION MSC.385(94) (adopted on 21 November 2014). As a consequence there is a new chapter XIV of SOLAS that entered into force on 1 January 2017.
One of the requirements of the Polar Code is for ships affected by it to have a Polar Waters Operational Manual (PWOM). The structure and aims of the PWOM have their own section in the Polar Code but with particular regard to navigation matters such as passage planning and details of the limitations of any equipment must be included. It may be that much of this information is already included in the safety management system of vessels that frequent Polar Waters and in such cases the procedures and instructions can be easily incorporated into the PWOM. For all affected new ships, it will be necessary for the ship operator to devise a PWOM perhaps using a template but bearing in mind that some information will be ship specific.
Although there is little in the Polar Code as regards additional navigational equipment there are requirements for certain additional items with a period allowed for retrofitting through to January 2018.
Navigation with magnetic compasses at extreme latitudes has always been difficult due to the proximity of the magnetic poles in both hemispheres. This is recognised within the Polar Code which requires all affected vessels to be equipped with two nonmagnetic compasses able to operate independently of each other.
This would seem to suggest the need for two gyro-compasses, but as German navigation specialist Raytheon points out ‘very close to the North Pole, even the gyro compass loses some of its accuracy. The gyro error at Spitzbergen (80 degrees N) is 2.3 degrees; at a latitude of 85 degrees north (300 nm from the pole) the error is 5.6 degrees. In the new Polar Code, therefore, IMO requires that for travel in latitudes above 80 degrees N a satellite compass must be on hand as well’.
There is also new requirement for ice training. Previously many of the ice specialist working on ships that operated in ice-infested waters were well qualified by experience but with little if any formal recognition of their skills. This will need to change but since there is little likelihood of any immediate surge in the number of ships operating in ice, the pressure on the few specialist training courses that do exist will probably not be too great for them to cope.
Initially it was planned that the necessary changes to STCW would have an effective date of 1 January 2018 but at MSC 96 in May 2016, it was decided to defer adoption of the new changes to MSC 97 and for the date to be altered to 1 July 2018.
An issue that has come in for particular attention in recent years is navigation in high latitudes and especially use of the northern sea routes for commercial traffic and oil and gas exploration. However, since 2015 the falling price of crude oil and a slowdown in world trade looks likely to delay any major growth in Arctic operations in the short to medium term and possibly longer.
Ships have always navigated through ice-infested waters but the conditions found in the Baltic, Black Sea and other areas that freeze although harsh and damaging to ships are quite benign compared to conditions nearer the poles. The interest shown in Polar navigation has led the IMO to undertake the development of a Polar Code that places new requirements on ships operating in such regions.
As part of the work, the IMO first adopted voluntary guidelines for ships that have since evolved into the IMO’s mandatory Polar Code which has now been adopted and which came into effect for new vessels on 1 January 2017 and for existing ships a year after that. The Polar Code is less extensive in many ways than the earlier guidelines with three chapters (9-11) covering navigation related aspects including equipment, communications and procedures.
With regard to functionality and the type of equipment, almost nothing is said in the code leaving the guidelines as the most comprehensive source of information. The guidelines are laid out in IMO document A 26/Res.1024 GUIDELINES FOR SHIPS OPERATING IN POLAR WATERS. The document was published in March 2010 and flag states have been ‘invited’ to apply it to ships built after January 2011 and ‘encouraged’ to apply it to older vessels as far as practical. The guidelines cover a number of areas with Chapters 1 and 12 (reproduced below) being of particular interest to those involved in navigation.
Chapter 1 deals with the requirement for special ice navigators and refers to a later chapter as regards qualification. In some parts of the world – Canada is a good example – ships were obliged to have an accredited ice navigator on board when operating in ice even before the guidelines were adopted and published. In recent years, the number of courses developed to teach ice recognition (there are more than thirty different types of recognised ice formations) and ice navigation has multiplied and there are even simulator courses available in some locations.
Changes to STCW covering duties and skills for ships operating in the Arctic have also been made and although these were planned to enter into force on 1 January 2018 at MSC 96 in May 2016, it was decided to defer adoption of the new changes to MSC 97 and for the date to be altered to 1 July 2018. The changes relate to STCW Chapter V and are detailed in tables A-V/4-1 and A-V/4-2 covering basic training and advanced training requirements respectively.
Chapter 12 of the guidelines is as follows:
• `12.1 Application.` • `It should be noted that the provisions prescribed in this chapter are not to be considered in addition to the requirements of SOLAS chapter V. Rather, any equipment fitted or carried in compliance with the requirements of SOLAS chapter V may be considered as part of the recommended equipment complement detailed in this chapter. Unless specifically provided in this chapter, the performance standards and other applicable guidance for equipment and systems contained in this chapter should be applied in accordance with SOLAS chapter V, as amended.` • `12.2 Compasses.` • `12.2.1 Magnetic variations in high latitudes may lead to unreliable readings from magnetic compasses.` • `12.2.2 Gyro-compasses may become unstable in high latitudes and may need to be shut down.` • `12.2.3 Companies should ensure that their systems for providing reference headings are suitable for their intended areas and modes of operation, and that due consideration has been given to the potential effects noted in paragraphs 12.2.1 and 12.2.2. For operations in polar waters, ships should be fitted with at least one gyro-compass and should consider the need for installation of a satellite compass or alternative means.` • `12.3 Speed and distance measurement.` • `12.3.1 All ships should be fitted with at least two speed and distance measuring devices. Each device should operate on a different principle in order to provide both speed through the water and speed over ground.` • `12.3.2 Speed and distance measuring devices should provide each conning position with a speed indication at least once per second.` • `12.3.3 Speed and distance measurement device sensors should not project beyond the hull and should be installed to protect them from damage by ice.` • `12.4 Depth sounding device.` • `All ships should be fitted with at least two independent echo-sounding devices which provide indication of the depth of water under the keel. Due account should be taken of the potential for ice interference or damage to any device designed to operate below the waterline.` • `12.5 Radar installations.` • `12.5.1 All ships should be fitted with a total of at least two functionally independent radar systems. One of these should operate in the 3 GHz (10 cm, S-band) frequency range.` • `12.5.2 Radar plotting systems that may be installed should have the capability of operating in both the sea and the ground stabilized mode. ` • `12.6 Electronic positioning and electronic chart systems.` • `12.6.1 All ships should be provided with an electronic position fixing system.` • `12.6.2 A satellite system (GPS or GLONASS or equivalent) should be fitted on any ship intending to navigate in areas outside of reliable coverage by a terrestrial hyperbolic system.` • `12.6.3 Systems described in paragraphs 12.6.1 and 12.6.2 should provide input to allow for continuous representation of the ship’s speed provided by a speed and distance measuring device according to paragraph 12.3, and the ship’s course provided by a compass according to paragraph 12.2.` • `12.6.4 Where fitted, electronic charting systems should be able to use position input from systems compliant with paragraphs 12.6.1 and 12.6.2. ` • 12.7 Automatic identification system (AIS).` • `All ships should be provided with automatic identification system (AIS).` • `12.8 Rudder angle indicator.` • 12.8.1 Separate rudder angle indicators should be provided for each rudder on ships with more than one independently operable rudder. • `12.8.2 In ships without a rudder, indication should be given of the direction of steering thrust.` • `12.9 Searchlights and visual signals.` • 12.9.1 All ships operating in polar waters should be equipped with at least two suitable searchlights which should be controllable from conning positions.` •` 12.9.2 The searchlights described in paragraph 12.9.1 should be installed to provide, as far as is practicable, all-round illumination suitable for docking, astern manoeuvres or emergency towing.` • `12.9.3 The searchlights described in paragraph 12.9.1 should be fitted with an adequate means of de-icing to ensure proper directional movement.` •` 12.9.4 All ships that may be involved in an escort of more than one ship following in an ice track should be equipped with a manually initiated flashing red light visible from astern to indicate when the ship is stopped. This should be capable of use from any conning position. The flashing light should have a range of visibility of at least two (2) nautical miles. The colour and frequency of the flashing light should be according to standards given in COLREG. The horizontal and vertical arcs of visibility of the flashing light should be as specified for stern lights in COLREG.` • `12.10 Vision enhancement equipment.` • `12.10.1 All ships should be fitted with a suitable means to de-ice sufficient conning position windows to provide unimpaired forward and astern vision from conning positions.` • `12.10.2 The windows described in paragraph 12.10.1 should be fitted with an efficient means of clearing melted ice, freezing rain, snow, mist and spray from outside and accumulated condensation from inside. A mechanical means to clear moisture from the outside face of a window should have operating mechanisms protected from freezing or the accumulation of ice that would impair effective operation.` • `12.10.3 All persons engaged in navigating the ship should be provided with adequate protection from direct and reflected glare from the sun. ` •` 12.10.4 All indicators providing information to the conning positions should be fitted with means of illumination control to ensure readability under all operating conditions.` • `12.11 Ice routing equipment.` • `12.11.1 All ships should be provided with equipment capable of receiving ice and weather information charts.` • `12.11.2 All ships operating in polar waters should be fitted with equipment capable of receiving and displaying ice imagery.`
The additional requirements of Chapter 12 of the guidelines are not particularly onerous but the final requirement is one that equipment makers have responded to in a number of ways. Conventional marine radars are inadequate for ice navigation (except when following an icebreaker) because they make use of echo stretching, or expansion. This technique stretches’ a radar echo to enable the target to be determined easily against background clutter. It is useful in high seas where the only high-intensity radar echoes are those from vessels, land or weather clutter but when used in ice the resultant radar image is at such a consistent high intensity that the radar operator must make adjustments to reduce the number of echoes – invariably removing many of the ice echoes.
With the prospect of extended navigation in arctic waters, several leading radar makers have developed systems specifically designed for use in ice-infested waters. These include Rutter, Simrad, Consilium and Kelvin Hughes.
The technologies used by the companies to enhance their radar systems vary. Some prefer to make use of standard 9GHz X-band navigation radar with special software being used to enhance the image. Mention has already been made of Kelvin Hughes ETD radar systems and an ice version called MDICE is available as an upgrade. MDICE uses a scan-to-scan correlation technique which integrates the returns from a large number of scans to improve target detection. Advanced image processing techniques enhance the visual quality of these returns, allowing clearer target differentiation via a quasi-3D representation. Adjustments are possible to fine-tune the system to suit prevailing conditions.
The Simrad ARGUS system also uses enhanced software that can display different types of ice in different colours. This allows navigators to distinguish softer younger ice from more dangerous and older hard ice and solid objects. In order to gain the best image of the ice, Simrad advocates having a dedicated X-band ice radar with its antenna sited a little lower than the main S-band radar and says it is better still to have two ice radars located at a distance from each other. Coupled with the software this can produce an almost stereoscopic image and having two ice radars also adds a degree of redundancy. The software needed can be pre-loaded into the radars but will only be activated if an upgrade key is purchased.
An alternative method adopted by other system makers is to split the signal feed from the X-band antennae into two, with one branch going to the conventional display and the other to the ice radar display by way of a processor module containing the necessary software. Rutter’s S6 radar is one such system but its display is 12 bit as opposed to the normal 4 bit maximum systems used by most vessels. This allows for a display with 256 intensity levels and a much higher definition. Rutter also plans to incorporate wave and current information into its products to generate more information for end users.
Furuno’s FICE-100 ice radar is another hybrid device and when installed is connected to Furuno FAR 2xx7ARPA navigation radar without affecting any of that device’s properties or performance. Furuno says in its product description that the ice radar’s principle of operation is the opposite of the navigation radar, so it is not suitable to the actual navigation. It requires its own processor and device in order to be efficient due its different calculation algorithms.
Complementing radar with other methods of ice detection is a comparatively new idea. One means that has been tested by Kelvin Hughes is the use of thermal imaging cameras. The company the Kelvin Hughes worked with – FLIR – has also conducted its own tests in Greenland. FLIR claims its equipment is of particular use for detecting smaller pieces of ice known as bergy bits and growlers. A good lookout can spot these during daytime but at night the combination of darkness and fog or snow can limit the capability of regular eyesight to detect ice hazards even further.
Thermal imaging cameras record the intensity of electromagnetic radiation in the infrared spectrum. All matter emits infrared radiation and even cold objects such as ice emit infrared radiation. In a thermal imaging camera the infrared radiation is focused by a lens onto the detector. The intensity of the recorded infrared radiation is translated into a visual image.
Because thermal imaging cameras rely on thermal contrast instead of colour contrast they do not need lighting to produce crisp images during the night. They provide a good overview of the situation giving a much better idea of the surroundings than the narrow beam of a searchlight.
During tests in Greenland thermal imaging cameras were successfully used to detect pieces of ice of different sizes and shapes. These are generally divided into three categories: icebergs, bergy bits and growlers. Icebergs are floating chunks of ice with more than 5 meters of its height exposed above sea level. Bergy bits are pieces of icebergs showing 1 to 5 meters above sea level. Growlers are pieces of icebergs showing less than 1 meter above sea level. With the thermal imaging camera all of those three categories were detected.
Due to their size icebergs are usually relatively easy to detect by radar. In most occasions using radar should suffice in detecting them. The bergy bits are smaller than full-grown icebergs, making them harder to detect, both by radar and visually.
Even the large bergy bits can be difficult to detect using marine radar, due to their shape. The sides of bergy bits are often oriented in such a way that radar energy is deflected away from the antennae. Combined with sea clutter this bergy bit characteristic can make it very difficult to spot them on the radar. During the test, many bergy bits were observed with the thermal imaging camera, they showed up very clearly in the thermal image.
Growlers, being the smallest category, are the most difficult form of ice to detect both visually and on radar. Though small, growlers can still pose a serious threat even for ice strengthened vessels. Growlers made out of ice less than one year old should not be able to cause much damage to such vessels, if they maintain a safe speed. Due to its pressurised environment ice from glaciers and multi-year sea ice can have a much higher density, so growlers made of multi-year ice can be a lot heavier than those made out of the less dense younger ice.