Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Experiments on tabular icebergs towing in the calm water
Konstantin A. Kornishin1, Yaroslav O. Efimov1, Petr A. Tarasov1, Yuri P. Gudoshnikov2, Igor V. Buzin2,Alexander V. Nesterov2, Dmitriy V. Nikushchenko3, Dmitriy S. Khmara3, Nikita V. Tryaskin3
1Department of Marine Operations, Arctic Research Centre, Moscow, Russia
2Arctic and Antarctic Research Institute (AARI), St. Petersburg, Russia
3State Marine Technical University (SMTU), St. Petersburg, Russia•
significant weight of the iceberg compared to the vessel
towing it;•
effect of various environmental factors (wind, currents, seawaves).

ABSTRACTThe article discusses results of three experiments on towing of tabularicebergs carried out in 2017 in the Barents Sea. Towed tabular icebergs
differed in size and mass (16, 90, 1150 thousand tons), which made it
possible to study their characteristic features during towing. For eachof the three icebergs, aerial photography of the above water and sonar
survey of the underwater parts were carried out, which made it possible
to build their 3D models and perform numerical simulation of theirhydrodynamic parameters. Drag coefficients (for steady movement)
and added mass (for accelerated movement) were determined fordifferent angles of attack. In experiments, the trajectories and all
kinematic parameters of tabular icebergs and the towing vessel wererecorded, as well as the towing force, wind speed and direction, speed
and direction of sea currents (for different horizons) in the immediate
vicinity of the iceberg. Using these experimental data full verificationof the simulation results was performed. The article discusses
similarities and differences between measurements and simulation
results. Exceedance of the towing force was recorded during two
towing experiments, the calculated value was less than one obtained in
the experiment.
The issues of the iceberg spatial orientation during towing areconsidered, as well as comparison of this orientation with the positionsof zero torque obtained from the simulation. The results presented in
the paper can be used in planning and carrying out marine operationsof tabular iceberg towing.

In order to understand the mechanics of iceberg towing, it is necessary
to conduct both full-scale iceberg towing experiments, andnumerical/basin modeling. Each of these methods has its own
advantages and disadvantages. Full-scale experiments make it possible
to obtain real data on behavior of the “vessel-rope-iceberg” system, but
are very costly and do not allow a quantitative assessment of theinfluence of each factor that determines the movement of an iceberg.
Modeling and simulation allow to evaluate all the aerodynamic andhydrodynamic characteristics of the iceberg, but are limited by thescope of the simplified iceberg towing model, that usually omits some
important phenomena that are typical for real iceberg towing. Iceberg
towing operations are described in many scientific publications (forexample, Allen, 1972), some research has also been carried out onmodeling the movement of an iceberg during towing (for example,Marchenko et al., 2011). C-CORE has also studied icebergs for ice
defense of offshore exploration and production units (for example,McClintock et al., 2007, O’Rourke et al., 2020, Kubat et al., 2005).
There were no comprehensive studies of iceberg towing, that covered
all the stages: iceberg’s morphometry (measurements of above- andunderwater parts with UAV and an echo sounder for the 3D model),towing of this iceberg (with recording of all kinematic/dynamic
parameters of movement and environmental characteristics), and thena basin and mathematical modeling of hydrodynamic and aerodynamic
characteristics of the iceberg. In this research, the authors attempt to fillthis gap. This study was based on the results of experiments on towingicebergs in 2017, as well as on the results of processing of theseexperiments. A detailed description of the iceberg towing trials is givenin (Kornishin at al., 2019); hydrodynamic and aerodynamic
characteristics of the studied icebergs are discussed in (Tryaskin et al.,2021) and (Kornishin et al., 2021). The main objective of this study was
to compare the obtained data and to explain the differences.

KEY WORDS: iceberg; towing; ice defense; modelling.
INTRODUCTION
Iceberg towing is a common marine operation carried out in a numberof offshore exploration and production projects on the shelf of the North
Atlantic and the Arctic Ocean in order to avoid iceberg’s collision with
offshore structures. Movement of an iceberg in the process of towing,as the movement of any material body under the action of applied loads,
obeys the basic laws of mechanics. But mathematical modeling of thismovement has some features associated with:•irregular shape of the sail and keel of icebergs, identificationof which is complicated in marine conditions;This approach made it possible to verify the simulation results on
experimental data of iceberg towing, which allowed to:•determine the conditions under which the simulation model
adequately describes the real processes of iceberg towing;

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