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GIS-Based Technology of Ship Routing in Ice

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The fourth meeting of the International Ice Charting Working Group (IICWG) St.Petersburg, Russian Federation, April 7-11, 2003 Igor Stepanov, Sergey Frolov, – PowerPoint PPT presentation

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Title: GIS-Based Technology of Ship Routing in Ice


1
Igor Stepanov, Sergey Frolov, Sergey
Klyachkin, Yury Scherbakov (Arctic Antarctic
Research Institute, St. Petersburg, Russia)
The fourth meeting of the International Ice
Charting Working Group (IICWG) St.Petersburg,
Russian Federation, April 7-11, 2003
  • GIS-Based Technology of Ship Routing in Ice

2
The general principles for selection of the
optimal ship route in ice
  • total ice concentration is minimum
  • quantity of young ice forms (in autumn-winter)
    and melting stages of ice (in spring-summer) are
    maximum
  • minimum hummock and ridge concentration and
    increased ice fracturing are observed
  • prevailing orientation of discontinuities in the
    ice cover (fractures, cracks and leads) coincides
    with the general course of convoy motion
  • depths correspond to the navigation safety
    requirements for the given ship

3
At winter-spring navigation (January-May) the
selection of the easiest transit variant is
determined in general by
  • drifting ice edge position
  • extent of development of flaw polynyas
  • distribution of dynamically active zones (ice
    pressures or discontinuities in the ice cover) in
    the ice massif

4
The computer system concept is based on the
following main principles
  • as a design environment capable to ensure a
    full-value functioning of the prototype, the
    geographical information system (GIS) was
    selected
  • remote sensing data from satellites present the
    main source of ice information
  • a criterion of the optimal route is minimum
    transit time for navigation of a convoy of ships
  • calculation of speed (transit time) is made
    taking into account a possible ice cover
    redistribution during the period of marine
    operation

5
  • Generalized functional scheme of the system
    prototype for selecting an optimal ship transit
    route in ice

6
Preparation of the satellite ice chart
  • expert assessment of the uniform ice cover areas,
    their classification and identification
    (interpretation of satellite images)
  • delineation of boundaries of the ice cover
    uniform areas (contouring) with the formation of
    a digital set of contour coordinates
  • creation of an object containing a set of contour
    coordinates and attributive characteristics of
    the uniform ice area

The electronic ice chart (shape-file) based on
the satellite image processing is formed
7
Usage of the numerical model of ice cover
evolution Principal blocks of the model
  • forecast of the sea thermal state and dynamics
    (both in the absence and presence of the ice
    cover)
  • forecast of the thermal growth and dynamics of
    the ice cover

8
Models of ship motion in ice
  • Model for prediction of leading icebreaker(s)
    speeds
  • Model for prediction of escorted ship(s) speeds

9
Model of leading icebreaker motion
empirical-statistical model of the quantitative
assessment of ice navigation difficulty
  • Two blocks of the model
  • a transfer from the general distribution of ice
    cover characteristics in the transit area, which
    is fixed on the composite ice charts to the
    distribution of ice cover characteristics
    directly along the transit route determined by a
    selective character of ship motion in ice
  • an assessment of the influence of ice cover
    characteristics with which the ship interacts on
    the efficiency of its navigation expressed
    through its motion speed in a uniform ice zone

10
Model of the escorted ship motion the
analytical model based on the mathematical
description of the physical processes
accompanying the ice-ship interaction
  • The characteristics of the conditions of safe ice
    navigation
  • Safe speed the maximum ship transit speed in
    ice at which no damage of hull structures occurs
    under the action of ice loads.
  • Attainable speed the maximum speed a ship can
    develop when moving under the given ice
    conditions at a given shaft power regardless of
    whether maintaining such speed by ship leads to
    ice damages of the hull structures or not.
  • Speed limit the maximum ship speed prescribed
    by the ice passport that it could develop moving
    in ice without hull damage it is determined as
    the least of the safe and attainable speeds.

11
Calculation of the convoy speed
  • The expected convoy speed is defined as the least
    value among the known speeds of the leading
    icebreaker and the escorted cargo ship moving
    along the channel

12
The criterion of the optimality of the navigation
variant the minimum time expenditure
13
The example of the model system usage for
selecting the optimal ice navigation route
  • The icebreaker of Yermak type (capacity is 30
    Mwt) and one tanker of Aframax type
  • March 1988
  • The Sea of Japan, Tatar Strait

14
The electronic chart of ice conditions. March
20, 1988
15
Prognostic chart of ice conditions. March 21,
1988
16
Prognostic chart of ice conditions. March 22,
1988
17
The scheme of ice routing using the prognostic
ice chart and the calculation of time
expenditures for the selected variant
18
The calculation results
  • The average speed western route 6.9 kn.,
    eastern route 6.0 kn.
  • Total time expenditure western route 32.15
    hrs, eastern route 40.35 hrs.
  • Thus, the western route is recognized as the
    optimal one because it allows the convoy to
    economize about 8 hours.
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