227
1 INTRODUCTION
The study considered navigation conditions that
occur when passing through the Northern Sea Route
(NSR) in two stages. First stage concerns transit
passage in one direction to the intermediate port.
Second stage concerns passage in same navigation
season but back to the first port of departure. In order
to plan a transit voyage of a vessel through the NSR,
it is necessary to know probable route with the
lightest ice conditions. For vessels without ice
strengthening, the lightest ice conditions are "ice-free"
conditions (Shapaev 1975, Parnell 1986, Arikaynen
and Tsubakov 1987, Jurdziński 2000, Buysse 2007,
House et al. 2010, Pastusiak 2020, 2018, 2016c). This is
particularly important during the period of opening
of the NSR seas for ice-free navigation, when ice-free
transit corridor begins to appear in ice and connects
the Barents Sea with the Bering Sea. Then process of
ice decay in individual seas leads to appearance of
ice-free zones (Pastusiak 2020). These zones, forming
a transit corridor, allow navigating vessels without ice
reinforcements of theirs hull. In both cases, it is
important to set time frame for possible transit
navigation on the NSR. This applies to the moment of
opening transit corridor and its closing (Pastusiak
2016b). In addition, probability of repetition of transit
corridor opening and closing dates in subsequent
summer navigation seasons should be considered
(Pastusiak 2020, 2018, 2016a,b,c).
The most important questions in economy of
vessel voyage planning are moving with normal
transit speed, without risk of possible waiting for sea
releasing from ice, without risk of necessity of moving
back from planned route due to retreat of drifting ice
and without risk of being beset in ice. It is assumed
that vessel plans to pass the NSR as soon as possible
(during period of ice decay and ice disappearance). In
this situation, vessel should commence its voyage
Navigating a Vessel without an Ice Class on the NSR
C
lose to the Front of Ice-free Zone During Ice Melting
P
eriod
T. Pastusiak
Gdynia Maritime University, Gdynia, Poland
ABSTRACT: The research work described in this paper extends the author's research results described in the
previous monographs. During ice melting period on the NSR ice drifts in different directions under the
influence of changing atmospheric pressure systems and thus wind and sea currents. The forehead of transit
corridor re-leased from ice moves in different directions and even goes hundreds Nautical miles back (in the
opposite direction to vessel's planned voyage). A vessel without ice reinforcements, which follows just behind
the forehead of ice-free transit corridor, would also have to move in such direction and speed to avoid entering
ice and potentially beset or even damage its hull or sink.
This paper presents results of research on impact of number of days of vessel's delay against the forehead of
transit ice-free corridor released from ice in ice melting period and by this way possibility of entering vessel
into ice-covered zone. Probability of incurring certain additional voyage expenses was determined. described.
http://www.transnav.eu
the
International Journal
on Marine Navigation
and Safety of Sea Tra
nsportation
Volume 14
Number 1
March 2020
DOI:
10.12716/1001.14.01.29
228
immediately and very close to retreating ice, in which
there are zones of clean water free of ice. Important
are only those clean water zones that open in general
direction of connection with the next sea. Only then
will they allow to cross one sea to the next.
Ultimately, geographical distribution and dates of
occurrence of ice-free zones, which form a transit
corridor for vessels throughout the entire NSR,
should be taken into account. This is especially
important for vessels without ice strengthening.
If route of vessel passing through the NSR is
calculated as late as possible (during the built-up of
ice cover), it should be assumed that vessel will
resume voyage back to the first port of departure just
before the progressing ice, which occupies areas
previously free of ice. In such situation, only those ice-
free zones and those accessible to vessels without ice
strengthening are important, which close on general
direction to the exit from the NSR area. The forehead
of melting and disintegrating ice is the most ice-deep
part of clean water (ice-free) zone. It is usually deep
inside the ice and looks like bight in ice (Fig. 1).
Directions of movement of ice-free corridor and
their most likely course, as well as dates of beginning
of opening, date of complete opening of transit
corridor, date of commencing of closing and date of
final closing of transit corridor were described in
earlier works by the author (Pastusiak 2018, 2020).
The forehead of ice-free transit corridor changes its
position under influence of winds and sea currents
caused mainly by moving baric systems. For this
reason, the forehead of transit corridor and the entire
ice-free corridor change theirs position. It can move in
general direction towards destination port (forward)
or in general opposite direction (backward) (Fig. 1).
Vessel without ice reinforcements that is moving close
at the forehead of moving ice-free corridor must move
in directions and with speed of that forehead.
Sometimes it must go back hundreds of Nautical
miles to avoid being surrounded by ice, be potentially
beset or even nip, with damage of its hull or even
sink. This navigation (close do the forehead of ice-free
corridor) on one hand is more risky. But on other
hand it increases probability of successful completion
of second part of voyage back to the initial port of
voyage and, most probably, increases probability of
obtaining higher economic benefits of vessel voyage.
The problem to be solved is therefore determination
of distance and time vessel follows after the
forehead of transit corridor released from ice for
specific probability of adverse events occurring for
vessel (beset, nip, damage to hull or even sink).
Figure 1. Path of forehead of transit corridor released from
ice in the Kara Sea in 2018: ─── path of forehead of ice-free
corridor moving in a general direction towards destination:
─── path of forehead of ice-free corridor moving in
general opposite direction to the destination, • • • the
forehead of transit corridor that is released from ice.
Compiled by the author based on NATICE (2018). Provided
courtesy of the U.S. National Ice Center. Made with Natural
Earth – Free vector and raster map data
@http://www.naturalearthdata.com
2 PURPOSE AND SCOPE OF THE STUDY
Based on results of the author's previous work
(Pastusiak 2016a, b, 2018, 2020) it is possible to specify
date of opening of the NSR seas for ice-free
navigation towards east and towards west as well as a
number of additional factors characterizing the NSR
opening time for ice-free navigation. However, these
are statistical data that are characterized by means of
average value, median, Gaussian curve or cumulative
distribution curve. However, these factors do not
indicate whether a vessel should move close behind
the forehead of ice-free corridor or vessel should
proceed with a certain delay. This delay can be
expressed in time or distance.
In process of releasing sea from ice, the forehead of
corridor released from melting and disintegrating ice
changes its position in geographical space and with
the passage of time. The forehead moves in general
direction of releasing the sea from ice cover, but ice
changes its position under influence of wind and
currents. Impact of wind direction and speed
(resulting from movement of low baric zones and
high baric zones) on movement of transit corridor was
noticeable in each summer navigation season from
2008 to 2018 (NATICE 2018). Under their influence ice
moved both in general direction of releasing sea from
ice and in general opposite direction.
It was therefore necessary to determine at what
distance or at what time delay a vessel should move
behind the forehead of zone released from ice in
different directions, so that there was no need to turn
back from general direction of sea opening. Such a
forced return of vessel from route would cause
additional losses of time and losses of fuel
consumption. To this end, it was assumed that
distances of daily movement of the forehead of zone
released from ice should be examined. Movement of
the forehead was divided into general direction
towards destination (east or west) and opposite
229
(backward) direction to the destination were taken
into account.
Particular attention was paid to both, time
(number of days) and route (distance) of a vessel's
position delay relative to the forehead of sea release
zone from ice. Therefore, a minimum distance and
time to move behind the forehead of transit corridor
released from ice was sought. Taking them into
account when planning a vessel's voyage is to ensure
that a vessel will not be surrounded by receding ice.
In this way, a vessel would constantly move in
general direction towards destination outside zone
occupied by ice.
3 RESEARCH METHOD
The seas belonging to the NSR and approach seas to
the NSR (Barents Sea and Bering Sea), where ports of
commencing and completion of voyage are located,
were analysed. Beginning of period under analysis
took place on date of commencement of systematic
formation of ice-free corridor on the first external NSR
sea towards the next sea, after which ice-free corridor
would not go beyond the border of the first sea on the
NSR. This concerned the Kara Sea from the west and
the Chukchi Sea from the east of the NSR. The end of
period under analysis took place on date of creation
of ice-free zone, which connected beginning of first
external sea on the NSR with next two seas and
formed a transit corridor throughout the entire NSR.
Designated route was composed of Rhumb Line
sections.
Taking above into consideration, voyages
commencing on western side of the NSR (for the Kara
and Laptev seas) and voyages commencing on eastern
side of the NSR (for the Chukchi and East Siberian
seas) were analysed separately. Spatial distribution of
ice edges presented on MIZ ice concentration maps
issued by the NIC in the United States named
nic_mizYYYYDDDnc_en_a.zip in ESRI Shape format
available at http://www.natice.noaa.gov/-
MainProducts.htm for the year 2008 to 2016 was
analysed (NATICE 2018). Contour maps of the world,
in ESRI Shape format in scale 1: 10,000,000, available
at http://www.naturalearthdata.com (Natural Earth
2017) and borders of the oceans and seas specified in
IHO documents (1953, 2002) were included.
Based on collected research materials, number of
days and path of the vessel moving behind the
forehead of transit corridor released from ice was
determined, as well as probability of not having to
return a vessel from general direction towards
destination (in opposite direction to the planned
route). Daily average and total distance of path of the
forehead of ice-free corridor, number of days of delay
and distance of delay of a vessel that assure no need
to move back were also calculated. These values made
it possible to determine range of distance losses and
thus fuel losses, which would be a consequence of
navigating too short distance or too short time behind
the forehead of the sea being released from ice.
4 THE RELEASE OF THE NSR SEAS FROM ICE
FROM WEST TO EAST
For release of seas from ice from west to east (Kara
Sea and East Siberian Sea), total length of path of
released transit corridor from ice was on average
1,445.7 Nm (median 1,410 Nm) with minimal value of
1,106 Nm and maximal of 1,858.0 Nm (Table 1).
Meanwhile, path of release from ice of the Kara Sea
and the Laptev Sea "straight ahead" was about 500
Nm. Rest of the route towards destination was free of
ice. Therefore, values of path of vessel moving
directly behind the forehead of released transit
corridor would be more than 2 times longer than
straight route in ice-free zone. One of main reasons
for such high maximum values was, for example, the
need to return vessel navigating directly behind the
forehead of ice-free corridor to another route variant.
For example, Figure 1 shows the need to return from
corridor of ice-free zone in the Kara Sea straight
ahead to the strait south of the Novaya Zemlya
archipelago (but north of the Nordenskiöld
Archipelago) and designate new route variant south
of the Nordenskiöld Archipelago. Second reason was
much longer ice-free transit corridor forehead path
along coast instead of straight across the sea to the
straits of archipelagos. Therefore, it should be
assumed that one of tasks of voyage planning to the
east is to determine beginning of voyage with such
delay in relation to the forehead of released seas from
ice that vessel without ice reinforcements moves at
safe speed straight ahead along designated route
without having to stop and wait for further releasing
the sea from ice, moving in different directions behind
the forehead of ice-free corridor and even more so
vessel did not have to move back from general
direction towards destination.
Number of days vessel's position was delayed in
2008-2016 relative to the forehead of ice-free corridor
in western part of the NSR and ensuring that there
was no need vessel to move back was on average 32.4
days (median 21 days) with minimal value of 15 days
and maximal of 86 days (Figure 2). Path length of
maximal movement back of the forehead of transit
corridor released from ice (for the Kara Sea and the
Laptev Sea opening eastwards) was 77.3 Nm (median
67.0 Nm) with minimal value of 49.0 Nm and
maximal of 132.0 Nm. Number of days required for a
vessel to be delayed relative to the ice-free corridor
forehead for each of above results was approximately
half of time of release of these seas towards east.
Average daily distance that the forehead of ice-free
transit corridor moved was 21.1 Nm (median 21.0
Nm) with minimal value of 12.7 Nm and maximal of
39.2 Nm. Distance from first quartile to median was
approximately half distance from third quartile to
median. This indicates asymmetrical distribution of
the phenomenon. Average speed of the forehead was
therefore 0.9 knots. Vessel navigating at 12 knots
would cover this route in 1.75 hours. So it would not
be possible to constantly move vessel behind the
forehead of corridor released from ice. Waste of time
and fuel, even due to waiting in drift for forehead
movement would be significant.
Total distance of maximal movement back of the
forehead of ice-free corridor was 141.0 Nm (median
95.0 Nm) on average with minimal value of 59.0 Nm
230
and maximal of 448.0 Nm. One of main reasons for
such high maximum values was the need to return
vessel navigating directly behind the forehead of ice-
free corridor along straight route to the strait south of
the Severnaya Zemlya archipelago and to designate
new route variant. These delay distances should be
taken, in addition to delay time (both named
“effective delay”), as additional information
characterizing vessel's delay relative to the forehead
of ice-free corridor. This information should ensure
that vessel do not have to move back from general
direction of releasing seas from ice. Average distance
of reversal of the forehead of transit corridor
corresponds to 11.75 hours of voyage at full
maneuvering speed 12 knots in range of possible
deviations from 4.9 hours to 37.3 hours.
From all data described above, it was assumed
that knowledge of number of days of delay is
particularly useful in planning time of vessel
departure. Therefore, in addition to discrete results
(Table 1), continuous relationship graph was
developed for probability of not exceeding number of
days of delay ensuring avoidance of the need vessel
to move back due to retreat of the forehead of ice-free
transit corridor or the need vessel to return from
general direction of releasing seas from ice (Figure 3).
This delay was named “effective delay”. This graph
also shows curve of "raw" delay values obtained on
basis of ice maps (NATICE 2018) analysis. From raw
data chart, it can be seen that most of results are
within 15-34 days of delay. For this reason, median
number of days of delay ensuring no need to move
vessel back was 21 days with average of 32.4 days
(Figure 2). It should be noted that such relationships
have shown all studied factors (Table 1). It was
assumed that for purposes of vessel voyage planning
the function of cumulative distribution of number of
days of delay (not exceeding number of days of delay)
should be used.
Figure 2. Distance and time of effective delay of vessel in
relation to the forehead of transit corridor released from ice:
─── movement in general direction to the destination, ───
movement in general opposite direction to the destination,
▬ ▬ ▬ forehead position in the first day of opening, • •
• in any day of opening of ice free corridor, ▬ ▬ ▬ the
way of vessel "straight ahead" through the sea released from
ice, ◄───► searched delay (distance and time) of vessel
movement behind of forehead of ice-free corridor.
Compiled by the author based on NATICE (2018). Provided
courtesy of the U.S. National Ice Center. Made with Natural
Earth – Free vector and raster map data
@http://www.naturalearthdata.com
Table 1. Statistical results for the forehead of the ice-free corridor on the NSR moving towards east. Compiled by the author
based on NATICE (2018)
__________________________________________________________________________________________________
Factor Aver. St. dev. Rel. st. Median Min. Max.
value σ dev.RSD [%]
__________________________________________________________________________________________________
Number of days of delay that ensure no need to move vessel back [days] 32.4 24.3 75.0 21.0 15.0 86.0
Total distance of delay that ensure no need to move vessel back [Nm] 417.8 195.7 46.8 403 214 825
Maximal distance of retreat of forehead [Nm] 141.0 126.3 89.6 95.0 59.0 448
Number of days of opening seas towards east [days] 77.3 26.6 34.3 67.0 49.0 132
Total distance made by forehead [Nm] 1446 257.4 17.8 1410 1106 1858
Average daily distance of the forehead [Nm] 21.1 8.1 38.4 21.0 12.7 39.2
Standard deviation of average daily distance [Nm] 30.0 9.9 32.8 30.0 17.8 49.7
Daily distance median [Nm] 8.5 2.8 33.0 8.0 5.0 14.0
Distance of first quartile from median [Nm] 5.9 2.5 42.6 6.0 4.0 12.0
Distance of third quartile from median [Nm] 14.7 7.0 47.5 11.5 8.0 30.0
__________________________________________________________________________________________________
Table 2. Statistical results for the forehead of ice-free corridor on the NSR moving towards west. Compiled by the author
based on NATICE (2018)
__________________________________________________________________________________________________
Factor Aver. St. dev. Rel. st. Median Min. Max.
value σ dev.RSD [%]
__________________________________________________________________________________________________
Number of days of delay that ensure no need to move vessel back [days] 44.7 20.4 45.6 48.0 17.0 76.0
Total distance of delay that ensure no need to move vessel back [Nm] 603.4 278 46.1 540 258 1041
Maximal distance of retreat of forehead [Nm] 228.3 231.7 101.5 215 32.0 796
Number of days of opening seas towards east [days] 76.2 22.4 29.4 72.0 59.0 132
Total distance made by forehead [Nm] 1648 498 30.2 1530 927 2486
Average daily distance of the forehead [Nm] 23.2 9.2 39.6 24.5 9.2 38.5
Standard deviation of average daily distance [Nm] 57.7 31.5 54.5 57.7 23.2 105
Daily distance median [Nm] 9.3 5.9 64.1 8.0 2.5 19.0
Distance of first quartile from median [Nm] 6.8 3.9 56.6 5.0 2.5 13.5
Distance of third quartile from median [Nm] 11.8 4.5 37.8 11.0 6.5 20.5
__________________________________________________________________________________________________
231
Figure. 3. Probability of not exceeding number of days of
delay ensuring avoidance of the need vessel to move back
due to retreat of the forehead of ice-free transit corridor
from general direction of voyage from west to east; ▬▬▬
data obtained on the basis of analysis, • • • cumulative
distribution graph based on average value and standard
deviation. Compiled by the author based on NATICE (2018)
5 THE RELEASE OF THE NSR SEAS FROM ICE
FROM EAST TO WEST
For release of seas from ice from east to west (the
Chukchi Sea and the East Siberian Sea), total length of
path of the released transit corridor from ice was on
average 1,647.8 Nm (median 1,530 Nm) with
minimum value of 927 Nm and maximum value of
2,486 Nm (Table 1). Meanwhile, path of release from
ice of the Chukchi Sea and East Siberian Sea "straight
ahead" was about 1,037 Nm. Rest of route towards
destination was free of ice. Therefore, values of path
of vessel moving directly behind the forehead of
released transit corridor would be 1.5 times longer
than straight route in ice-free zone. One of main
reasons for such high values was the need to return
vessel navigating directly behind the forehead of ice-
free corridor, e.g. route north of Wrangel Island and
routing around Wrangel Island and later proceed
through the De Long Strait. Therefore, it should be
assumed that one of tasks of voyage planning to the
east is to determine beginning of voyage with such
delay in relation to the forehead of released seas from
ice that vessel without ice reinforcements moves at
safe speed straight ahead along designated route
without having to stop and wait for further releasing
the sea from ice, moving in different directions behind
the forehead of ice-free corridor and even more so
vessel did not have to move back from general
direction towards destination. Total lengths of paths
along transit corridor of release of sea from ice for
both directions (east and west) are comparable. This is
despite the fact that path length in western part of the
NSR is about twice less than in eastern part of the
NSR.
Number of days vessel was delayed relative to the
forehead of ice-free corridor at which there would be
no need to reverse vessel was on average 44.7 days
(median 48 days) with minimal value of 17 days and
maximal of 76 days (Table 2). Length of path of
maximum regression of the transit ice-free corridor
(for the Chukchi Sea and East Siberian Sea opening
westward) was 76.2 days (median 72 days) with
minimal value of 59 days and maximal of 132 days.
The number of days delayed by vessel relative to the
forehead of ice-free corridor westbound for each of
above data was less than for eastbound sea releases.
This delay was approximately two-thirds of its
corresponding eastward time release data.
Average daily forehead movement was 23.2 Nm
(median 24.5 Nm) at minimal of 9.2 Nm and maximal
of 38.5 Nm. Distance of first quartile of daily forehead
distance from median was approximately half
distance of third quartile from median. This indicates
an asymmetrical distribution of the phenomenon.
Average forehead speed was therefore 1.0 knot. A
vessel navigating at speed of 12 knots would cover
this route in 1 hour and 56 minutes. So it would not
be possible to constantly move vessel behind the
forehead of corridor released from ice. Waste of time
and fuel, even due to waiting in drift for forehead
movement would be significant. These results, for
westward opening of seas are comparable to those for
eastward opening of seas.
Total length of path of maximal recession of ice
release corridor was 228 Nm on average (median 215
Nm) with minimal of 32 Nm and maximal of 796 Nm.
One of main reasons for such high maximum values
was the need to turn back vessel navigating directly
behind the forehead of the ice-free corridor route
north of Wrangel Island and designate new route
through the De Long Strait. These delay distances
should be taken, in addition to delay time, as
additional information characterizing vessel's delay
relative to the forehead of the ice-free corridor. This
information should ensure that vessel do not have to
move back from general direction of releasing seas
from ice. Average distance of reversal of the forehead
of transit corridor corresponds to 19 hours of voyage
at full maneuvering speed 12 knots in range of
possible deviations from 2.7 hours to 66.3 hours.
Dispersion of results of total length of path of
maximal recession of the forehead of corridor released
from ice in general direction from east to west is
about 1.5 times greater than in case of general
direction from west to east.
Figure 4. Probability of not exceeding number of days of
delay ensuring avoidance of the need vessel to move back
due to retreat of the forehead of ice-free transit corridor
from general direction of voyage from east to west; ▬▬▬
data obtained on the basis of analysis, • • • cumulative
distribution graph based on average value and standard
deviation. Compiled by the author based on NATICE (2018)
232
From all data described above, it was assumed that
knowledge of number of days of delay is particularly
useful in planning time of vessel departure.
Therefore, in addition to discrete results (Table 2),
continuous relationship graph was developed for
probability of not exceeding number of days of delay
ensuring avoidance of the need vessel to move back
due to retreat of the forehead of ice-free transit
corridor or the need vessel to return from general
direction of releasing seas from ice (Figure 4). This
graph also shows curve of "raw" delay values
obtained on basis of ice maps (NATICE 2018)
analysis. From "raw" data chart, there is lack of data
below 17 days and fairly even increase in delay. For
this reason, median number of days of delay ensuring
no need to move vessel back was 48 days and was
comparable to an average of 44.7 days (Figure 4). It
should be noted that such relationships have shown
all studied factors (Table 2). It was assumed that for
purposes of vessel voyage planning function of
cumulative distribution of number of days of delay
(not exceeding number of days of delay) should be
used.
6 SUMMARY AND CONCLUSIONS
Economic efficiency of vessel's planned voyage
through the NSR is influenced by correct
determination of date of departure. To do this,
statistical relationships should be used. One such
relationship is probability of an ice-free zone along
whole or along western or eastern parts of the
Northern Sea Route to designated day of the year in
summer navigation season. Second relationship is
probability of surrounding vessel by retreating
forehead of ice-free transit corridor. In order to avoid
vessel beset in ice moving in opposite direction to
general direction of opening of the NSR, vessel must
move in directions opposite to general direction of
expected opening of transit corridor (proceed same
direction and speed as forehead). This results in a loss
of time, increasing length of voyage, increasing fuel
consumption and thus deteriorating economic results
of planned voyage.
Diagrams received as a result of the study can be
used to support decision making. They are not
intended to replace the human factor in making
decisions. The decision maker (shipmaster or planner
in the office) makes long-term decisions on date of
beginning of voyage of vessel based on his own
knowledge, experience and ice navigation conditions
expected to be in current summer navigation season.
Proposed decision making method is multi-
criteria. Decision criteria are date of beginning of
voyage (the earlier date, the higher probability of
completing voyage before beginning of ice cover
growth and closing transit route on the NSR),
probability of existence of ice-free transit corridor for
the entire NSR (and at the same time the risk of
incurring additional costs of icebreaker services, the
cost of waiting time for ice conditions improvement,
the cost of damage to the hull, propulsion system or
steering system), date of opening and date of closing
of the transit corridor for ice-free (open water)
navigation, delay in distance and time of vessel's
position relative to the forehead of transit corridor
through ice at the beginning of summer navigation
season.
Tabular results taking into account discrete
changes in statistical data, such as average value and
standard deviation, do not fully represent changes in
occurring phenomena. Median, first and third quartile
values are better representing boundaries of data
series. Thus, they will be conducive to effective
planning of date of beginning of vessel's voyage
through the Northern Sea Route. More precise and
flexible than discrete relationships will be use of
cumulative distribution function or lines
approximating "raw" statistical data. With their help,
it could be smoothly determined number of days and
distance of movement of vessel behind the forehead
of ice-free transit corridor released from ice at
beginning of summer navigation season, together
with probability of having to stop or turn back from
the general direction of designated route.
Dependencies presented in this way can be used to
plan date of commence and completion of vessel
voyage, taking into account probability of an ice-free
zone leading through the whole NSR or selected part
of the NSR with probability of having to stop or turn
back from the general direction of designated route.
Probabilistic approach to determining time of
beginning of vessel’s voyage should minimize risk of
increasing length of intended route, risk of increasing
voyage time and risk of damage to vessel’s hull,
propeller or steering gear. Therefore, economic
efficiency of maritime transport in high latitudes
should be increased.
REFERENCES
Arikaynen A.I., Tsubakov K.N. 1987. Alphabet of ice
navigation. [in Russian] (Aзбyкa лeдoвoгo плaвaния).
Transport, Moscov: 224
Buysse J. 2007. Handling ships in ice, A practical guide to
handling 1A and 1AS classed ships. The Nautical
Institute, London: 166
House D.J., Lloyd T., Toomey P.R.M., Dickins D. 2010. The
ice navigation manual. Witherby Seamanship
International Ltd: 409
International Hydrographic Office, 1953. Limits of oceans
and seas. Publication S-23: 40
International Hydrographic Office, 2002. Limits of oceans
and seas. Publication S-23, Draft 4th Edition, 2002: 235
Jurdziński M. 2000. Planning the navigation in ice [in
Polish] (Planowanie nawigacji w lodach). Wyższa Szkoła
Morska, Gdynia: 192
NATICE, 2018. MIZ ice concentration maps in ESRI Shape
format. U.S. National Ice Center,
http://www.natice.noaa.gov/Main_Products.htm.
Accessed 19.12.2018
Natural Earth, 2017. Free vector and raster map data at 1:10
m, 1:50 m, and 1:110 m scales, http://www.naturalearth-
data.com. Accessed 01.01.2017
Parnell G.Q. 1986. Ice seamanship, Monograph. The
Nauitical Institute: 87
Pastusiak T. 2016a. The time window for vessels without ice
strengthening on the Northern Sea Route, Annual of
Navigation, No. 23: 103-119
Pastusiak T. 2016b. The Northern Sea Route as a shipping
lane. Expectations and Reality, ISBN 978-3-319-41832-2,
ISBN eBook 978-3-319-41834-6, Springer International
Publishing AG, Switzerland: 247
233
Pastusiak T. 2016c. Principles of Vessel Route Planning in
Ice on the Northern Sea Route, TransNav, the Inter-
national Journal of Marine Navigation and Safety of Sea
Transportation, Vol. 10 No. 4 - December 2016
Pastusiak T. 2018. Planning independent transit voyages of
vessel without ice strengthening through the Northern
Sea Route [in Polish] (Planowanie samodzielnych
podróży tranzytowych statku bez wzmocnień lodowych
przez Północną Drogę Morską). Akademia Morska w
Gdyni, Gdynia, ISBN 978-83-7421-286-1: 278
Pastusiak T. 2020. Voyages on the Northern Sea Route,
Springer International Publishing, 1st ed. 2020, XXXVIII,
Print ISBN 978-3-030-25489-6: 279
Shapaev V.M. 1975. Hydrometeorological conditions and
navigation [in Russian] (Гидрометеорологические
условя и мореплавание). Moscov, Transport: 248
