A brief guide to marine navigational charts

I. Vocabulary. Study the following words and word combinations:

1. to depend on [dI'pend Pn] – залежати від

2. scale [skeIl] – масштаб, шкала

3. chart datum [CQ:t 'deItqm] – нуль глибин (на морській карті)

4. feature ['fi:tSq] – характерна риса, особливість (рельєфу)

5. aid [eId] – допоміжний засіб

6. tide [taId] – приплив

7. current ['kArqnt] – течія

8. prominent ['prPmInqnt] – видний

9. traffic separation scheme [ski:m] – система розділеного руху

10. essential [I'senSql] – важливий, необхідний, основний, істотний

11. to proceed [prq'si:d] – йти, просуватися вперед

12. conventional [kqn'venS(q)nql] – традиційний, звичайний, загальноприйнятий

13. to issue ['ISu:] – видавати, випускати

14. sailing chart – шляхова карта

15. coastal chart – карта узбережжя

16. sounding ['saVndIN] – вимір глибини (ехолотом)

17. rough [rAf] – нерівний

18. shoal [SqVl] = shallow ['SxlqV] – мілина, мілководдя

19. to measure ['meZq] – вимірювати

20. depth contour [depT 'kPntVq] – ізобата (рельєф дна)

21. compass rose ['kAmpqs ˏrqVz] – зображення картушкі компаса на карті, компасна троянда

22. to plot [plPt] – прокладати курс

23. to take bearing ['be(q)rIN] – брати пеленг

24. passage (routeing) planning chart – маршрутна карта

25. latitude ['lxtItju:d] – широта

26. longitude ['lPnGItu:d] – довгота

27. to confirm [kqn'fE:m] – підтверджувати

28. conformal [kqn'fO:m(q)l] – рівнокутний

29. magnetic variation [mxg'netIk ˏve(q)rI'eIS(q)n] – магнітне схилення

30. magnetic deviation [mxg'netIk ˏdi:vI'eIS(q)n] – магнітна девіація

31. accuracy ['xkjqrqsI] – точність

32. allowance [q'laVqns] – допуск

33. foolproof – вірний (захист від випадкових помилок)

34. to approve [q'pru:v] – стверджувати, схвалювати

35. to release [rI'li:s] – звільняти, випускати

II. Do you remember the following words? Translate them into Ukrainian:

height – ___________________________ to ensure – _________________________ to provide – ________________________ sufficient – _________________________ density – __________________________ traffic – ___________________________ entrance – _________________________ tool – _____________________________ obstruction – _______________________ shape – ____________________________ rhumb line – _______________________ hydrographic survey – ________________

chart – ____________________________ nautical – __________________________ approach – _________________________ to cover – __________________________ destination – _______________________ software – _________________________ to avoid – __________________________ to destroy – ________________________ to steer – __________________________ to collide – _________________________ virtually – _________________________ to be intended for – __________________

III. Read and translate the following text:

A marine navigational chart also known as a nautical chart – is a graphic representation of maritime and coastal areas, ports and harbours and approaches to these. There thousands of these charts which cover the earth’s oceans, rivers and ports. Depending on the scale of the chart, it may show depths of water (chart datum) and heights of land (topographic map), natural features of the seabed (for anchoring), details of the coastline, navigational hazards, locations of natural and human-made aids to navigation (details of lighthouses and buoys), information on tides and currents, prominent land features (e.g. church towers), traffic separation schemes, local details of the Earth’s magnetic field, and human-made structures such as harbours, buildings, and bridges, and in short anything which could assist navigation.

Navigational charts are required to be carried by law for the passage planned. It is an essential tool for a navigator to plan and ensure that his ship proceeds safely to the destination.

Nautical charting may take the form of charts printed on paper or computerized electronic navigational charts. Conventional nautical charts are printed on large sheets of paper at a variety of scales. Mariners will generally carry many charts to provide sufficient detail for the areas they might need to visit. Electronic navigational charts use computer software and electronic databases to provide navigation information. However, electronic charts are not yet mandated as a legal replacement for paper charts. Electronic charts are slowly becoming more popular, it will be a long time before they replace paper charts completely.

How is a chart made?

Charts are made by hydrographic departments across the world. Admiralty charts are nautical charts issued by the United Kingdom Hydrographic Office. The British Admiralty (BA) charts are the most commonly used ones worldwide. Over 3,000 charts are available and cover virtually the entire world in various levels of detail depending on the density of traffic and hazards. Large-scale charts often cover approaches and entrances to harbours, medium-scale charts cover heavily used coastal areas, and small-scale charts are for navigation in more open areas.

Types of charts and some terminology

Charts are made with all kinds of scale, depending on how much detail is required for navigational safety.

Sailing charts are open sea charts. Land may be depicted as a rough contour and these charts are used far from land in ocean regions.

General charts cover coastal areas outside the immediate areas of reefs or shoals (where the water depth is very low and navigation more dangerous).

Coastal charts cover areas closer to the coast and give greater detail of outlying dangers.

Harbour charts are intended for use in approaching harbours and in mooring ships to berths, usually under pilotage. They have the greatest detail.

Soundings refer to the depth of the water at a location and is marked on the chart after hydrographic surveys. Depths which have been measured are indicated by the numbers shown on the chart. Depths on charts published in most parts of the world use metres. Depth contour lines show the shape of underwater relief. Coloured areas of the sea emphasise shallow water and dangerous underwater obstructions. Depths are measured from chart datum, which is related to the local sea level.

A compass rose is an easy means (for a navigator) of finding direction on the chart and also plotting a ship’s course, besides taking bearings (angles) of objects with a compass. Called because it looks like a rose petal opened up, it is graded from 0 degrees to 360 degrees, with 0 being North, 90 being E, 180 being S and 270 being W.

Routeing and Passage Planning charts are small scale (cover large areas) and give information on winds, currents, icebergs and general information which assists us in planning a voyage at sea. These charts are not directly used for navigation.

The largest scale chart available is used since it gives us the best detail of topography and landmarks. On this, a ship’s planned course is plotted (drawn with a pencil) by the navigator. As the ship proceeds on the passage, its position (latitude and longitude) is plotted on the course line to confirm that the plan is being followed, and to steer away from any dangers.

Map projection and bearings

The Mercator projection is almost universally used in nautical charts. There are however some exceptions for very large or small scales where projections such as the gnomonic projection may be used. Since the Mercator projection is conformal, that is, bearings in the chart are identical to the corresponding angles in nature, bearings may be measured from the chart to be used at sea or plotted on the chart from measurements taken at sea. Although allowances must be made for magnetic variation and magnetic deviation if accuracy is important. Use of this projection also has the advantage that straight lines drawn on the chart represent lines of constant bearing although in reality such lines are not straight but segments of a three dimensional “loxodromic” spiral known as a rhumb line.

A bearing is the angle between the line joining the two points of interest and the line from one of the points to the north, such as a ship’s course or a compass reading to a landmark. On nautical charts, the top of the chart is always true north, rather than magnetic north, towards which a magnetic compass points. Most charts include a compass rose depicting the variation between magnetic and true north.

Chart correction

Marine navigation charts are in constant use by navigators. But conditions at sea and under the sea (the seabed and the features charted) keep changing and so we must have the latest information on them for safety. Is there a new wreck, and, if so, where exactly is it so we can avoid it? Has a buoy been destroyed in a storm, and, if so, do we know this so we can avoid colliding into it at night? Are their shallower depths reported in a particular location, and how do we know this? Since information is changing constantly, there has to be a foolproof, controlled and approved system of chart correction.

Hydrographic organizations that produce charts are responsible for their correction. Old or uncorrected charts should never be used for navigation. The chart in use must always be corrected to the latest notices to mariners on board.

All charts should be updated regularly to maintain accuracy and safety. Updates are released in Admiralty Notices to Mariners weekly. Second Officers on ships are responsible for chart correction. They receive the notices and cross reference them with which charts they have on board (or in the ‘ship’). They then correct them. This is a continuous process, and a critical one. The safety of the crew, cargo and the ship depends on a systematic and accurate means of chart correction.

IV. Make-up word combinations and translate them:

1) new field 1)____________________________

2) chart water 2)____________________________

3) old level 3)____________________________

4) magnetic scale 4)____________________________

5) nautical datum 5)____________________________

6) true wreck 6)____________________________

7) water charts 7)____________________________

8) shallow correction 8)____________________________

9) chart depth 9)____________________________

10) large deviation 10)___________________________

11) magnetic charts 11)___________________________

12) sea north 12)___________________________

V. Translate the following word combinations into English:

1. істинний північ – _____________________________________________________

2. кут між лінією, яка поєднує дві точки – __________________________________

3. забезпечувати точність та безпеку – _____________________________________

4. підходи до портів – ___________________________________________________

5. навігаційні небезпеки – ________________________________________________

6. щільність руху – ______________________________________________________

7. небезпечні підводні перешкоди – _______________________________________

8. прокладати курс судна на карті – ________________________________________

VI. Translate the following sentences into English:

1. Другий помічник капітана є відповідальним за коректуру карт.

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2. Морські навігаційні карти виготовляються у різних масштабах.

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3. Маломасштабні карти використовуються для судноводіння у відкритому морі.

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4. Вгорі морської навігаційної карти завжди є істинний північ.

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5. Електронні карти стають все більше популярними серед судноводіїв.

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6. Морська навігаційна карта повинна містити у собі наступну інформацію: глибину води, інформацію щодо течій, маяків та буїв, систему розділеного руху, навігаційні небезпеки та характеристики морського дна. – _____________

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7. Карти великого масштабу використовуються штурманами для прокладання курсу судна. – _______________________________________________________

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VII. Self-assessment questions:

1. What is a marine navigational chart?

2. What scales may the charts be?

3. What information can we find in the chart?

4. What do you know about electronic charts?

5. How is a chart made?

6. What types of charts do you know?

7. On what chart is a ship’s planned course plotted?

8. What projection is universally used in nautical charts?

9. Where can you find the true north on the chart?

10. Should we use old or uncorrected charts?

11. Who is responsible for chart correction on ship?

12. How are the depths of the water measured and indicated on the charts?