UNIT - 4 Weather Routeing & Weather Reports

Weather Routeing: Weather routing services available to shipping; Shore based weather routeing; Information of current, wind and ice to select an optimum route, use of wave charts to select the best route; Basic considerations in Voyage Planning, selection and use of data; Least time track and ship’s performance curves.

Weather Reports : Types of weather services for shipping; Meteorological Offices; Weather Facsimile Receiver; Digital weather receivers; Ship’s weather code for sending reports; Coding and Decoding of weather messages; Weather reporting and recording procedures; Weather observation reports.

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Define Routeing?

Definition: Routeing is the art of achieving a safe, economic passage across an ocean, taking into consideration all available meteorological and oceanographical factors.

IMO Reference: The International Convention for the safety of Life at Sea 1974(SOLAS 74), as amended in 2000, includes “Ships routeing” in its Regulation 10.

What are the advantages of routeing?

Advantages: The following advantages of routeing add up to greater safety and more economy in ship operation.

(a) Less chances of heavy weather damage.

(b) Less chances of shift of cargo & least damage to cargo.

(c) More comfort for people on board

(d) Faster passage resulting in time and fuel savings.

(e) Schedules demanded by Character and limitations arising from insurance causes are met.

What are the factors to be considered in routeing of ship ?

(a) Distance : The shortest distance(Great Circle track) is not necessarily the best route to follow because of other factors. Unnecessary deviation from the shortest route is, however, to be avoided.(b) Ocean Currents: Adverse currents mean more passage time. A route covering greater distance but having a following currents may result in a quicker passage.

(c) Wind & Waves: Strong adverse winds result in high head seas that cause the vessel’s speed to drop considerably. This drop in speed may be due to:

(i) Wave Resistance to ship’s progress.

(ii) Less propelling power: The axis of the propeller

keeps shifting out of the horizontal, due to pitching, and

sometimes the propeller even comes out of water.

(iii) Wind resistance caused by hull, superstructure, etc.

(iv) Slamming(Pounding)which not only resists the

vessel’s progress but also causes severe structural

stresses.

(v) Voluntary reduction of engine RPM, by the Master,

to reduce slamming.

(d) Ice at sea: The vessel would, as far as possible, have to keep out of pack-ice and iceberg-infested waters. If she has to pass through such areas, the risk is great and speed would have to be considerably reduced. A detour (temporary route), where possible, would increase the distance but would also increase safety and allow full speed.(e) Fog: is the Master’s greatest threat at sea because, in fog, he has not only to combat natural dangers but also rely on the judge ment and discretion of the Masters of other vessels as well. The worst situation is fog, in confined waters with high traffic density, where the deviation is not too much, it would be preferable to avoid the fog area. However, as fog prediction is not available on facsimile charts, the Master cannot decide too much in advance.

(f) Very Low Temperature: Where a great circle track passes through very high latitudes, the vessel is likely to experience very low atmospheric temperatures which should, when practicable, be avoided. Some of the problems associated with extremely cold weather are:-

(a) Freshwater, sanitary water & deck service water tend to freeze in pipes.

(b) Ice accretion on deck – dangerous for crew to go about.

(c) Very cold, gale force winds. Spray & Persistent snow fall.

(d) Morale of the crew reaches a very low level during extreme cold weather

(g)The routeing recommendations are broadly based on the safest and fastest transit times between initial and final waypoints. In addition due regard has been taken in way of navigational considerations as follows:-

1. Weather :

(a) Proximity of tropical revolving storms and depressions.

(b) Predominating wind direction and Beaufort wind scale.

(c) Swell direction and wave height.

2. Ocean currents and tidal streams.

3. Proximity of icebergs and pack ice.

4. Metacentric height (with due regard to ice accretion and water absorbsion ).

5. Nature of cargo 6. Stowage of Cargo 7. Carriage of deck cargo

8.. Ballast condition. 9. Vessel Transit speed

10. Geographical considerations. 11. Deviation points. 12. Load Line Zones.

Write short notes on the following: (a) Weather Routeing (b) Systems of Routeing (c) Climatological routeing ?

Weather Routeing: : It has recently been definitely established that in the temperate latitudes of the North Atlantic & North Pacific, day to day changes of weather are so drastic, due to fronts and frontal depressions, that seasonal routeing is inadequate. The ideal route for a particular passage changes from day to day, week to week. For example, the track to be followed by a vessel on the date of departure may be quite different from that of a similar vessel, on a similar passage, a few days earlier – hence the name ‘weather routeing’ as different from ‘climatological routeing’ However in tropical regions, especially the Northern Indian Ocean and China Sea, climatological routeing is quite successful, as seasonal variation is fairly regular and systematic. Climatological routeing was

developed, based on many years of observations. In some areas of the world there is little variation from day to day, but in other regions e.g. temperate latitudes there are large fluctuations. In these regions synoptic weather forecasts are much more valuable than climatic data as a basis for routeing.

Systems of Routeing: There are alternative systems available for routeing. The master of a vessel may decide to route his own ship, using facsimile charts and radio weather forecasts. Commercial companies and the national weather services of some countries run Routeing services. The Met Office & Team of meteorologists and master mariners runs a Ship Routeing service. The routeing team is supplied with up to date analysis charts, forecast charts, ice information, warnings, bulletins and satellite pictures.

Climatological Routeing: Until recent times, routeing was done solely by the use of Pilot books and monthly or seasonal charts of the winds and currents of the oceans. Under certain circumstances, it is still the best method possible. ‘Ocean Passages of the World’ book is still the standard book for reference, while contemplating climatological routeing.

How the weather forecast helps to predicte ffective routeing ?

Weather Forecast: Weather forecast for effective routeing the winds and waves must be accurately predicted as far ahead as possible. At present this is about 72 hours ahead. Data from ships, satellites, Radio-sondesetc is fed into the computer analyses the data. For each of ten different levels in the atmosphere it produces Northern Hemisphere charts of temperature, humidity, winds and pressure. The computer then produces a forecast using a “model” of the atmosphere.

The forecast of wave height is then produced using an empirical formula and taking fetch etc. into account.

(The wave height marked on the chart is the “significant wave height”. This is the mean height of the highest one third of seas).

At present forecasts at 12 hour intervals for the next 72 hours are used.

What is meant by Performance Curve ?

Performance Curve : Before it is possible to route a ship effectively it is necessary to establish how the vessel will behave in differing sea conditions. Head, beam and following seas are defined as shown.

For some vessels the performance curve may be drawn as the result of testing a scale model in a tank, but usually the performance curve must be drawn by taking information from the log book.

A comparison with proven curves from similar types of ship may also be used.

The curves show the effect of the weather on the ship. It can be seen that as wave height increases then the speed of the ship decreases.

There are two factors contributing to this. Firstly there is the direct effect, where for a given

engine setting the ship’s speed will decrease as sea conditions deteriorate.

Secondly, as ship motions become more violent the master will intervene and deliberately reduce the engine revolutions.

The curves are usually drawn for head, beam and following seas and it is advisable to draw separate curves for ballast conditions, “light ship” and loaded conditions, the curves usually becomes steeper with increasing sea state.Performance curve

24 hours surface prognosis chart

How the velocity of the ship is affected by waves ?.

It is a well known fact that the velocity of the ship is greatly affected by waves. In Voyage Planning, for the purpose of weather routeing performance curves are consulted. Performance curves for a particular ship of a given weight is made from her Long records of the previous voyages relating to the relationship between “Wave Height and Speed of the Ship”.

“Head”, means right in front of the ship, 60o either side at the bow.

“Following” means 60o on either side of the astern (Behind).

“Beam” means 30o on either side of athward ship (sides)

The co-relation between different waves heights slamming the ship from head, following or beam and the velocity of the ship is recorded during voyages of a given ship of particular weight and type for a sufficient period based on which the performance curves are constructed. The performance curves are drawings with maximum speed of the engines. From the performance curve, one can easily assess the actual realised velocity of a ship, given the direction of the wave and its height with respect to ship. This is the basic input information in ship routeing.

The effectiveness of the routeing service depends upon the availability to the organization of ship, Cargo and relevant operational data. Generally, a representative of the organization visits the ship to collect this information and discusses the routeing service with those on board. Ship data include the ship shape, draught, trim, stability and speed made good relative to sea conditions (wind, waves, swell and current). This information is normally extracted from the deck log, or if not available, obtained from a similar type of ship. The organization then constructs for each state of loading, a set of performance curves related to the important characteristics of wave height and relative direction (following, beam or head seas. It should be noted that the

style of presentation of performance data varies from one organisation to another.

For each voyage, the cargo data may relate to factors such as routeing to avoid certain atmospheric conditions, or a deck cargo may need to be protected from continuous heavy seas. Operational factors include fuel economy, schedules demanded by the character, and limitations arising from insurance causes. Thus each passage has a prime objective which may be least time on voyage (usually the objective in the early days of weather routeing), least damage to cargo or vessel, or maximum fuel economy (significant from the early 1970s).

How the route selection of a least time track of a ship is decided based on performance curve ?

Route Selection: The initial route selected takes into account the objective of the passage and the environmental conditions likely to be encountered in the area through which the ship has to pass. The environmental conditions are established from synoptic, prognostic surface and upper air charts. Major pressure stems, weather depressions, anticyclones or tropical cyclones, their direction and speed of movement, development and decay are determined. Thus the critical features of wind direction and speed, icing or reduction of visibility due to fog or heavy precipitation are assessed together with a general appreciation of the future sea state. At this stage, synoptic and prognostic data relating to sea ice and icebergs, ocean currents from current atlases and other environmental factors are considered.

The Forecast Position of Frontal Depression with associated Wave Height Isolines

Fig 3. Wave height lines in Metres

24 hour forecast chart showing the centre of the depression with well-demarcated cold and warm front is prepared, with associated surface wind field (Fig.3) and consequent wave heights (forecast). The wave height Isolines at an interval of 1 metre starting from 2 metres are drawn (Fig.4).

In the next step, a standard line is drawn from the port of departure (P) to the port of arrival (Q) that is a part of Great Circle. Four separate radial lines at 10o intervals are drawn on either side of the Great Circle. Thus, totally there are 9 radial lines, including the Great Circle.

The ship is routed through each radial line and its position is determined at the end of 24 hours with the help of Performance Curve. The ships speed is determined according to the wave height.

All the nine positions in each Radial line at the end of 24 hours are connected by a smooth curve line called “Locus one” Locus Two is found out in the similar way which represents the position of the ship at the end of 48 hours along each Radial line and so on. A curve is drawn connecting P and Q through the concave [viewed from port of departure] point of each locus which represents the recommended route for covering maximum distance in the least time.

What are the various information to be kept in mind while voyage planning ?

The routeing recommendations are broadly based on the safest and fastest transit times between initial and final waypoints. In addition due regard has been taken in way of navigational considerations as follows:-

1. Weather :

(a) Proximity of tropical revolving storms and depressions.

(b) Predominating wind direction and Beaufort wind scale.

(c) Swell direction and wave height.

2. Ocean currents and tidal streams.

3. Proximity of icebergs and pack ice.

4. Metacentric height (with due regard to ice accretion and water absorbsion ).

5. Nature of cargo

6. Stowage of cargo

7. Carriage of deck cargo.

8. Ballast condition.

9. Vessel transit speed.

10. Geographical considerations.

11. Deviation points.

12. Load Line Zones.

In order to accurately evaluate optimum routeing, Masters should ensure that they have all relevant information to hand, which shall include: -

• Fully corrected, latest edition British Admiralty charts. Additional charts should be obtained at the Master’s discretion.

• Routeing and pilot charts

• Ocean Passages for the World

• The Mariner’s Handbook

• Sailing directions

• Navigation warnings, inclusive of ice charts

• Load line zones and seasonal areas

• Notices to Mariners

• Weather reports and weather facsimile charts (initial information shall be obtained at least 24 hours prior to vessel’s departure). The availability of additional weather information should be sourced via vessel’s agents and coastal radio stations.

• Chartco Met Manager weather information & optimal routeing as applicable:-

(a) Experience of other vessels on the same or similar routeing

(b) Port reports from vessel operators

© Piracy reports from vessel operators.

Explain possibility of climatological hazards ?

If there were no other considerations, vessels would use the great circle route from one point to another. Apart from

considerations such as the availability of bunkers etc. the possibility of climatological hazards must be reviewed:-

(i) Sea Ice : Sea ice presents a hazard. Sea ice can cause damage to vessels which are not ice strengthened. It is also possible for the vessel to become beset. Areas of sea ice should be avoided.

(ii) Icebergs: Icebergs, bergy bits and growlers are relatively poor radar targets, but are massive enough to cause severe damage on collision. The extreme iceberg limits reach relatively low latitudes and can be difficult to avoid. Areas where the concentration of icebergs etc. is likely to be high should be avoided.

What is ship based routeing ?

The inputs for ship based routeing include

weather bulletins facsimile picture synopses and prognoses ice reports navtex information on weather storm warnings

Due to the time involved in drawing up, say a synopsis, and then transmitting it, the information received on board could be about 6 hours old. The ship master then has to allow for existing weather observations to update and possibly correct the synopsis received. Official forecasts tend

to cover very large areas and seldom contain enough detail for a small part of the area.

Working out options such as a least time track with least damage to hull and cargo, or constant speed options are time consuming without the right equipment. The existing work load on board would probably not allow for an effective calculation of either of these options.Hence operational savings under whichever option is considered on board, could probably not be quantified over a number of voyages, given the number of variables such as different masters, different routes travelled resulting in a different workload every time, different cargoes etc.

Explain shore-based routeing ?

There are shore based organisations that do weather routeing of ships across the North Atlantic and North Pacific. They employ meteorological experts and experienced Master Mariners and give routeing instructions radio on a request from a ship. Though the routeing procedure is the same as that described earlier, the meteorologist, aided by a computer, has a better idea of the reliability of the prognosis. After studying various facsimile charts(Analysis and Prognosis) such as charts showing isobars of 100, 200, 300, 500, 700 & 850 mb values thickness charts, change of pressure charts, temperature lapse rate charts, infra-red photographs of clouds from satellites and sea temperature charts, the meteorologist has a good idea of

what possible deviation of the weather may occur from the prognosis. The experienced Master Mariners are consulted and routeing instructions are given to the ship by terrestrial or space radio communications, amended as necessary, daily. Routeing of ‘selected ships’ of the Voluntary Observing Fleet is easier and more economic as the regular weather reports sent by the ship, containing its position, course and speed, transmitted free of cost by the ship, are available to the shore-based routeing organisations.

Describe choice of weather routeing by ship or Shore ?

This is entirely up to the ship operator(Ship owner, charterer) and/or ship master. Fast trans-Atlantic liner in fruit trade, container trade or passenger trade, involving high competition and requiring absolute punctually, would perefer to be weather routed by shore based experts. This would partly shift the responsibility from the Master to the ship operator for keeping to the schedules.

Other ships, making regular crossings, would like economical passages but usually have no penalties to pay for a delay of few hours. Owners of such vessels may prefer to leave routeing to shipmasters.

It would be good idea for shipmasters to convince their owners to use shore-based weather routeing, as it is fairly inexpensive. While such a vessel is being routed from ashore, during the trial period, the Master may keep

watching the facsimile prognosis charts and check for himself the reasons why each alteration of course is recommended by the routeing organisation.

What are the weather routing services available to shipping ?

Ship weather routing services are being offered by many nations. Also, several private firms provide routing services to shipping industry clients. Several PC-based software applications have become available, making weather routing available to virtually everyone at sea.

There are two general types of routing services available. The first uses techniques similar to the Navy’s system to forecast conditions and compute routing recommendations, which are then broadcast to the vessel. The second assembles and processes weather and sea condition data and transmits this to ships at sea for on-board processing and generation of route recommendations. The former system allows for greater computer power to be applied to the routing task because powerful computers are available ashore. The latter system allows greater flexibility to the ship’s master in changing parameters, evaluating various scenarios, selecting routes, and displaying data.

What are the types of Weather services for shipping from Met Office ?

Weather Forecasts

Weather Bulletins

Fisherman Warning(Coastal weather warning, Four stage warning, Port warning, Sea weather warning & Cyclone warning)

Weather Observations

Monsoon Reports

Daily rainfall graph/Statics

Local Weather report

Numerical Weather forecast

Seismology

Cyclone Atlas (On line)

The India Meteorological Department (IMD), also referred to as the Met Department, is an agency of the Ministry of Earth Sciences of the Government of India. It is the principal agency responsible for meteorological observations, weather forecasting and seismology. IMD is headquartered in New Delhi and operates hundreds of observation stations across India and Antarctica.

IMD is also one of the six Regional Specialized Meteorological Centres of the World Meteorological

Organization. It has the responsibility for forecasting, naming and distribution of warnings for tropical cyclones in the Northern Indian Ocean region, including the Malacca Straits, the Bay of Bengal, the Arabian Sea and the Persian Gulf. IMD is headed by the Director General of Meteorology. renowned agro-meteorologist is Director General of Meteorology. IMD has 6 Regional Meteorological Centers, each under a Deputy Director General. These are located in Chennai, Guwahati, Kolkata, Mumbai, Nagpur and New Delhi. There are also Meteorological Centres in every state capital. Other IMD units such as Forecasting Offices, Agro meteorological Advisory Service Centers, Flood Meteorological Offices, Area Cyclone Warning Centers and Cyclone Warning Centers are usually co-located with various observatories or meteorological center.

Weather Reporting System: Efficient weather service to shipping depends on the timely location and accurate tracking of weather systems over the open sea which covers over 70% of Earth’s surface. Overland it is easily possible to establish weather observation stations (Observatories) but over sea it is a major capital intensive operation with recurring expenses. It is, therefore, necessary for Merchant ships to send out regular reports of the weather experienced, even if weather is normal.

Weather Reporting and Recording Procedures, Weather observation Reports:

Reporting System: As recommended by the World Meteorological Organization (WMO) each Government recruits a number of Merchant ships called the Voluntary Observing Fleet (VOF). In case of India the Indian VOF consists of Indian ships and also Foreign flag ships which regularly call at Indian ports. Each vessel of the VOF makes weather observations at the fixed UTC (GMT) hours, called synoptic hours, codes these observations and transmits them using the ship’s terrestrial or space radio communication facilities as soon as possible. These messages are sent to any of the designated coast radio stations listed in the Admiralty List of Radio Signals Volume 3 (ALRS 3), which forwards them to the Regional Meteorological Data Collection Center, on a priority basis. The ship does not incur any expense at all. The respective National Weather Authority pays all relevant charges and also provides for all necessary equipment, publications and stationary used by the VOF.

The Codes have been devised in such a manner that the messages can easily be electronically processed and stored to enable better forecast to be made. The Regional Meteorological Centre (RMC) collates all the reports of that area and makes weather forecasts, which are transmitted to ships of that area, as Weather Bulletins, through selected stations at fixed times using terrestrial or space radio communications facilities.

Under normal conditions of weather, the synoptic hours are 00, 06, 12 and 18 UTC. In cases where there is inclement/disturbed weather, additional synoptic hours are 03, 09, 15 and 21 UTC. The coded weather messages should

be transmitted as soon as possible, the time of observation, always being the time when the barometer reading is taken.

In case any unusual but urgent weather phenomena are seen, a special message, in code or plain language may be sent out at anytime. In rare cases, as during a Tropical Revolving Storm (TRS) the RMC may request a ship in particular area for specific urgent observations which should be complied with by the Master.

Indian Meteorological Department: SERVICES FOR SHIPPING AND FISHRIES For the benefit of the ships sailing on high seas and for coastal and fishing craft, weather bulletins are issued four times daily by the Area Cyclone Warning Centers at Mumbai, Calcutta and Chennai and the Cyclone Warning Centers at Ahmadabad, Bhubaneswar and Vishakhapatnam. When there is a depression or cyclonic storm over the Bay of Bengal or Arabian Sea, the bulletins are issued more often during the course of the day and special warnings are issued for fishermen advising them not to venture out into the sea. The bulletins are broadcast through AIR and coastal radio stations. Fishermen’s associations also play an active role in disseminating fishermen’s warnings. System of Port Warning Signals has been established at all major Indian ports, which are hoisted to warn the ships about impending danger from approaching storms.IMD has Port Meteorological Offices at major ports in the country. Officers from these units visit Ships while in harbour to

check and calibrate the meteorological instruments on board and to provide meteorological information to ships about to sail.

Weather Observation Reports:

A REPORT ON REALIZED WEATHER, WIND, VISIBILITY AND WAVE HEIGHT OVER INDIAN SEAS, DATED 03rdJAN 2016(FOR 24HRS W.E.F 0900 UTC OF 02-01-2016)

AI: ARABIANSEA:- EQUATOR TO 10° N AND W OF 80° E

I) WIND DIRECTION AND SPEED:- 1) N OF 05°N: NE-LY 10-15 KTS

2) S OF 05°N: NE/E-LY 05-10KTS

II) WEATHER:- SCATTERED RA/TS.

III) VISIBILITY:- 6- 4 NM.

IV) WAVE HEIGHT:- 1) 1- 2 MTR 2) 0.5-1 MTR

A2: ARABIAN SEA:- N OF 10°N & CAPE GARDAFUI TO 12°N/ 63°E & THENCE TO THE EAST UPTO 23°45’N/68°E.

I) WIND DIRECTION AND SPEED:- MAINLY NE/E-LY 10-15 KTS.

II) WEATHER:- FAIR.

III) VISIBILITY:- 10- 8 NM.

IV) WAVE HEIGHT:- 1- 2 MTR.

A3:- BAY OF BENGAL: EQUATOR TO 10°N BETWEEN E OF 80°E AND W OF 10°N 98° 30’E TO 6°N 95°E AND THENCE S WARDS TO EQUATOR.S OF 05°N

I) WIND DIRECTION AND SPEED:- 1) W OF 90°E:- ENE-LY 15- 20 KTS.

2) E OF 90°E:- NE-LY 10- 15 KTS.

II) WEATHER:- ISOLATED RA/TS.

III) VISIBILITY:- 8- 6 NM.

IV) WAVE HEIGHT:- 1) 2- 3 MTR.

2) 1- 2 MTR

A4: BAY OF BENGAL: N OF 10° N AND E OF 80° E.

I) WIND DIRECTION AND SPEED:- NE-LY 10- 15 KTS.

II) WEATHER:- FAIR.

III) VISIBILITY:- 10- 8 NM.

IV) WAVE HEIGHT:- 1- 2 MTR.

*KTS: Knots, NM: Nautical Mile, MTR: Meter, RA/TS: Rain /Thundershower

Weather Facsimile Receiver: The facsimile recorder is an instrument that reproduces on board a ship. an exact copy of a weather map drawn by a Meteorologist ashore in the local Meteorological office. The meteorological office/centre receives weather reports from all stations- land stations, weather ships and ships of Voluntary Observing Fleet etc, and a Meteorologist draws a Weather Maps. The map is then scanned electronically and transmitted by high frequency waves using the FM (Frequency Modulation) technique, to ensure much clearer and relatively static-free reception on board ship. Facsimile charts fall into two basic categories- Analysis/Synopsis and Prognosis. Analysis or Synopsis is the actual situation existent at a given time, based on actual reports received. Prognosis is the predicted situation at a specified future time, based on present indications, as deducted by an expert Meteorologist/expert on the subject, based on his knowledge, skill and experience. The Ships fitted with facsimile plotters can receive signals by radio which will produce on a moving roll of paper, any chart in the same form as drawn by meteorological office in any organisation.

Impressions of Black or White signals are made on the roll of chemically treated paper, as an electronic marker pen passes on the moving roll. Different types of transmissions require different drum speed so that the reproduction is perfect. It is tuned to a particular frequency of transmission in consultation with ALARS VOL 3 and the sub heading “Facsimile Schedule”.

Digital Weather Receiver ( WX-200 Weather Receiver) : The WX-200 is a highly sensitive, quality receiver, with good front-end protection designed to function in the high RF environment typical of many repeater sites. A digital decoder responds to Specific Area Message Encoded (SAME) alerts transmitted by the NOAA weather station located in your geographic area. Select your county code and the type of alert. Select warnings and or watches. During a weather alert, a relay in the WX-200 will disconnect the transmitter from the controller and connect it to the weather receiver. The relay provides a ground for the transmitter PTT line. Weather audio will be transmitted for the period of the alert announcement. A programmable alert timer provides back-up protection.

Weather Alert Log : As alerts are received the WX-200 stores the date, time and type of alert in non- volatile memory. Storage space is provided for forty alerts. Use the

RS-232 port and the WX-200 configuration program to down load the data. A print driver is also provided.

Discuss in detail ship weather report and codes ?

Ships should make weather reports in Code FM 13-X referred to as the Ships Weather Code. This code is described in detail in ALRS Vol.3. The Ships weather code, each group consists of five characters and the total number of groups may be as many as 20. The ship weather code consists of three sections namely 0,1 and 2. The weather observations are to be encoded and decoded with the help of IMD’s Ship Weather Code of 1982. Routine weather reports observed at synoptic times are encoded and sent to the shore based MET Centre for plotting, analysis and prognostication. However, this strategy has now become obsolete since Wireless Telegraphy has itself become redundant. The messages should be sent with groups of only five alpha-numeric characters each.

The section 0 deals with the position of the ship in the following format

• BBXX XXXX YYGGiw 99LaLaLaQcLoLoLoLo

• BBXX means Ship Report• XXXX means The call sign of the ship• YYGGiw Date and time in UTC• 99 LaLaLa latitudinal position of the ship• Qc LoLoLo Longitudinal position of ship

Section 1 deals with the atmospheric weather conditions in the following coded form• iRix x hvv Nddff 1Sn TTT 2Sn Td Td Td• 4 PPPP 5 a ppp 7 ww W1 W2 8Nh CL Cm CH• iRix hvv --- deals with cloud base and atmospheric

visibility• Nddff --- Total Cloud Amount,wind direction & speed

• 1SnTTT --- Air temperature in oC

• 2SnTd Td Td --- Dew Point temperature

• 4pppp --- Atmospheric pressure in HpA• 5appp --- It is pressure tendency• 7ww W1 W2 --- It is present weather and as well as

past weather• 8 NhCLCMCH --- It is Individual low, medium and

high cloud types

• Section 2 deals with the course and speed of the ship and sea conditions. The following is in a coded format.

• 222DsVs OSnTNTNTN, 2 Pw Pw Hw H w3d

w1 dw1 dw2 dw2 4 Pw1 Pw1 Hw1 Hw1• 222Ds Vs --- Speed and direction of the ship• O Sn Tw Tw Tw --- Sea Surface Temperature

• 2Pw Pw Hw Hw --- Period and height of the wave

• 3 dw1 dw1 dw2 dw2 --- Direction of swell

• 4 Pw1 Pw1 Hw1 Hw2---The Swell’s period and

height

In section 2, there is a provision for reporting ice accretion on the ship in the group (6 IsEsEsRs) so that the thickness

and the rate of ice accretion can be reported. The section 3 commencing with 333 is meant only for regional exchange. The section 4 commencing 444 is for more detailed Information regarding cloud heights. However this section is not reported by the ships. Section 5 contains data for national exchange. So far VOF is concerned three sections namely section 0,1 and 2, are relevant. The weather

observations are to be encoded and decoded with the help of IMD’s ship weather code of 1982.

The MAFOR code means the coded version of maritime forecast which has to be decoded in order to obtain the plain language weather bulletins on board the ship. This is helpful in case of failure of facsimile. The IAC means “International analysis code” which gives the plot position Isobars and the movement and nature of pressure system and fronts. The intensity of the Frontal system whether it is weak intensifying etc are also given.

Example of ship weather report

BBXX ATVH 10123 99408 30492 41398 • (Ship) (C/S) (Time) (Lat) (Long) (Cloud)

62828 10143 20082 40084 56028 76364• (Wind) (Air T) (Dew T) (Pres) (Baro) (Sea)

• 84364 22234 00175 20808 302// 41006 (Cloud) (CMG) (Sea T) (Sea) (Swell) (Swell)

Decode and code the following ship weather report ?

Decode the following ship weather report

BBXX 3FVH 28063 99001 70009 41296 30112 10098 20091 49999 55019 76364 85262 22234 00198 20606 324// 41008

Code the following ship weather report:

SHIP: 7MRJ, Position: 17 47 N, 10153W, CMG last 3 hrs 310 deg at 19 Kts, Visibility: 15 Km, Wind 008 estimated at 28 kts, Pressure: 1019.9 Mb, Baro Tendency : 3.4 mb, Barograph trace decreasing GMT 28d06h 12m, Temp:Dry 29.8 C, Wet 24.8, Sea 21.6 C Clouds: Total 6/8 of sky, Low clouds 4/8 of sky, Base 800 metres above sea, Sc not resulting from Cu, Dense Ns, Ci in hooks progressively invading sky

Weather: Present cloud covering more than ½ sky throughout and intermittent drizzle.

Sea: Period 08 sec, Height 02 metre. Swell: From 030, period 08 sec, height 01 metres