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Файл:Learn to read charts and pilot-books. Практикум для СПО
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61
ebb tide ~
отливное течение
flood tide ~
приливное течение
in-going ~
входящее течение
out-going ~
выходящее течение
perceptible ~
ощутимое течение
rotary ~
водоворот; вращательный
semidiurnal tidal stream
приливо-отливное течение с полусуточным
периодом
side ~
боковой поток
tidal-stream
приливо-отливное течение
strength
сила
considerable ~
значительная сила
predicted ~
предсказуемая сила
significant ~
значительная сила
great ~
большая сила
of little ~
небольшой силы
ebb ~
(максимальная) скорость отливного течения
flood ~
(максимальная) скорость приливного течения
flow ~
энергия потока
2. Remember some useful information.
• Neap tide – a tide of minimum range occurring at the first and the third
quarters of the moon.
• Spring tide – a greater than usual tide occurring at each new moon and
fool moon.
3. Learn the following abbreviations.
• High(low) water springs — полная (малая) вода в сизигию.
• MHWS — Mean High Water neaps — средний уровень полной воды в
сизигию.
• MLWS — Mean Low Water Springs — средний уровень малой воды в
сизигию.
• High (low) water neaps — полная (малая) вода в квадратуру.
• MHWN — Mean High Water neaps — средний уровень полной воды в
квадратуру.
• MLWN — Mean Low Water neaps — средний уровень малой воды в
квадратуру.
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4. Read and translate the text, paying attention to the meaning of the
words in italics.
Tides
Tide is a periodic rise of sea waters due to changes in gravitation forces of the
moon and the sun. Tides can either help or hinder the mariners. A high tide can provide
enough depth to clear the bar while a low tide can prevent entering the harbor.
At times of the new moon and fool moon the earth, the sun and the moon are
aligned, causing the greatest difference in tidal elevations, called spring tides. Neap
tides, producing the least extreme tidal differences, occur midway between spring
tides. The maximum height of water is called high water and the minimum level is
low water. The difference in height between HW and LW is the range. The period
during which we do not observe any apparent change in the water level is slack water.
The speed with which water moves in and out the harbor is called the rate of tide.
It is necessary to distinguish between tides and currents. Tide is a vertical
movement of the water, it rises and falls. Tides are astronomical in their origin and
can be predicted for any period in the future. We can find information about tidal
streams for any region in tables printed on the charts. Current is a horizontal
movement. Currents mostly depend on meteorological conditions like winds,
barometric pressure, positive and negative surges, storm surges. Tidal currents
preceding low water are called ebbs. Those preceding high water are floods.
Tides are classified as diurnal, semidiurnal and mixed according to the
characteristic of the tidal pattern. In the semidiurnal tide there are two high waters
and two low waters each day. In the diurnal tide there is only one high water and one
low water.
There are some special tidal effects which can influence the safety of navigation.
Overfalls are short breaking waves occurring when a strong current or stream
passes over a shoal or other underwater obstruction.
Rip is agitation of water caused by meeting of tidal streams and wind or by
tidal stream setting over an irregular bottom.
Race is a very rapid tidal stream through a relatively narrow channel.
5. Give the definitions of the following terms.
Tide, spring tide, neap tide, high water, low water, slack water, range of tide,
rate of tide, rise of tide, fall of tide, current, ebb, flood, diurnal tide, semidiurnal tide,
overfall, rip, race.
63
6. Study the following symbols used on admiralty charts.
64
7. Match the words with the opposite meanings.
1
ebb a off-shore
2
neaps
b
slow
3
commence
c
low
4
inshore
d
accelerate
5
rapid
e
decrease
6
high
f
flood
7
retard
g
variable
8
slacken
h
finish
9
violent
i
speed up
10
constant
j
springs
11
increase
k
calm
8. Match the words with the similar meanings.
1
rate
a
counter
2
inshore
b
fall
3
accelerate
c
coastal
4
commence
d
flood
5
contrary
e
speed
6
daily
f
constant
7
ebb
g
fast
8
rise
h
influence
9
gradual
i
retard
10
decline
j
prevalent
11
rapid
k
deflect
12
affect
l
speed up
13
predominant
m
diurnal
14
Slacken
n
start
9. Complete the sentences.
1. The streams are (слабые) in both directions.
2. The (течение) in the strait is usually E-going.
3. A SW wind produces a similar current (в противоположном направлении).
4. The streams (устанавливаются) strongly along the coast.
5. The (приливные течения) set more or less parallel to the coast.
6. The in-going streams (достигает скорости) of 3½ kn at springs.
65
7. It is prudent not to leave the harbour at strength of the (входящего) stream.
8. The current in the strait is usually (южное) at maximum rate 2 knots.
9. Currents (в бухте) are not appreciable and dependent on the direction of
the wind.
10. The strength of the current (зависит от) the level of the river.
10. Make up sentences, using the words below.
1. Information, estuary, not, the, streams, in, regarding, is, tidal, available, the.
2. Weather, in, ½ kn, good, the, not, at, stream, even, does, exceed, springs, tidal.
3. The, the, streams, inwards, within, run, harbor, outwards, directly, tidal, and.
4. There, a, eddy, E-going, which runs, is, W, during, the, stream, slight.
5. A, tide, high, consists, one, and, one, low, diurnal, of, water, a, day.
6. Clockwise, the, stream, in, bay, sets, tidal, the.
7. About, the, streams, the, area, information, is, tidal, on, in, the, given, chart.
8. Not, are, summer, in, gulf, variable, during, and, do, the, exceed, currents,
the, the, rate, of, ½ kn.
11. Read and translate the following passages from the Pilot-book.
1. Water levels in the estuary are highest between the middle of April and the
middle of June and lowest in the autumn. Fresh winds raise or lower the water level
by as much as 0,5 m above or below mean level.
2. Current. During the spring the current sets outward at a rate not exceeding
2 kn, except in the narrow channels and the mouth of the estuary where it may attain
a rate of 3 kn. After the middle of May the current slackens and in the summer its rate
is between ¼ and ¾ kn.
3. Currents in Kerch Strait depend manly on the winds and to a lesser extent on
the flow of water from the Sea of Azov. A S. current is most common particularly
when wind are from N. A N. current from the Black Sea is less common and usually
occurs with winds from S.
4. Mean speed of currents is between 0,1 and 0,5 kn, but in the narrows when
there is a strong wind, the strength of the current may reach 3 kn. The strongest and
best established current has been observed between Mys Fonar’ (45°23'•00N,
36°38'•50E) (8.51) and Kosa Chushka and between Mys Pavlovs’kyi (45°18'•40N,
36°28'•70N) and Kosa Tuzla, 2 miles SE.
66
5. Currents are almost entirely dependent on the direction of the wind and have
an average rate of ¼ kn. Strong winds may increase the rate to 1kn. In calm weather
the effect of the outflow from the mouth of Reka Kuban’ (45°21’.00N 37°24’.00N) is
appreciable.
6. .Range of water level. Prevailing wind cause large fluctuations in the water
level of the gulf. W an d SW winds raise the level, N and NE winds lover it. West of
Begliskaya Kosa (47°07'•00N, 38°34'•00E) it is exceptional for the water level to fail
by more than 0.6m, however, E of this spit winds of moderate strength cause a range
in level of 0,6 to 1,2 m.
7. An area within 5 miles of the head of the gulf may completely dry and at
such a time the level of the approach channel to Taganrog may fall by as much as
2 m. A further variation in the water level of the gulf is caused by the changing
volume of the discharge of the rivers flowing into the gulf. The level from this cause
is highest in June and lowest in December.
8. The general current of the main Black Sea circulation, supplemented by
water from the Sea of Azov, sets W along the coast. It is especially strong off the
headlands and off the stretch of coast between Mys Chauda and Mys Kyz-Aul,
23 miles E, where an inshore set is sometimes experienced. The normal current is
from ½ to ¾ kn., but in certain conditions it is as much as 2 kn in the offing, the
current is weak and imperceptible.
9. The current in the approaches to Novorossiyskaya Bukhta flows NW in a
band about 30 miles wide at a rate of about ½ kn, but there may be a drift current SE
at the same rate.
10. The main current setting directly S from Mezar Burnu creates a complex
eddy in the bay.
11. The associated counter-current flows N, normally in excess of ⅟2 kn in the
S part, across the middle of bay back towards Mezar Burnu. It does not normally
reach this point unless it is stronger than usual.
12. Current depends on water level. A red flag Izmayil Chatal signal station
indicates the existence of currents running towards the banks in Tulcea. A black flag
signals strong currents in Braţul Sulina.
13. When winds are from NW, strong currents out of Dnistrovs’kyi Lyman
have been observed which make entry to the inlet and anchorage near the channel
dangerous. Navigation is prohibited when the rate of the current is in excess of 4 kn.
67
14. In normal weather the current sets S off the harbour entrance at a rate of ⅟2
kn. The current extends for about 3 miles offshore where its outer limit can be
distinguished, as the water forming the current in darker in colour.
12. Answer the questions.
1. What causes tides?
2. What is the difference between tides and currents?
3. Where can we find information about tides in a certain area?
4. What are the types of tides?
5. What special effects are connected with tides?
6. What is called spring tide?
7. What do we call neap tide?
8. What forces produce exceptionally strong tides?
9. What factors influence the duration and the rate of tidal streams?
10. What is the difference between diurnal and semidiurnal tide?
68
BIBLIOGRAPHY
1. Данилова, С.В. Pilot-book reader / С.В. Данилова, О.В. Сапунова,
Т.А. Цирулёва. — Санкт-Петербургб : Изд-во ГМА им. С.О. Макарова, 2007.
2. Сологуб, Т.Н. Символы и сокращения, применяемые на английских
адмиралтейских картах / Т.Н. Сологуб, Е.Ю. Новикова. — Ростов на Дону :
Ростиздат, 2001.
3. Сологуб, Т.Н. English for Navigators / Т.Н. Сологуб, Е.Ю. Новикова. —
Ростов на Дону : Ростиздат,2001.
4. Navigation English / Н.А. Ивасюк, Е.М. Мелентьева, В.В. Молодцова,
Е.А. Зимина. — Одесса : Феникс, 2016.
5. Admiralty sailing directions. — London : UKHO, 2002–2008.
6. Guide to port entry 2011–2012. — Shipping guides, 2011.
7. Symbols and abbreviations used on admiralty charts. — London : UKHO,
2016.
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