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

Propulsion Performance Analysis of Ship Moving in Old Ice Channel
Marina M. Karulina1, Evgeny B. Karulin1,21Krylov State Research Centre
St. Petersburg, Russia

2State Marine Technical University
St. Petersburg, Russia

estimation procedures for ship resistance in brash ice layer (FinnishSwedish Ice Class Rules, FSICR 2010; Riska et al., 1997; Karulina etal., 2019). Far fewer studies are available on brash ice effect regarding
propeller operation (Kostilainen, 1981; Wang et al., 2009; Karulina etal., 2021). Meanwhile, the full-scale data on shipping in the Ob Bay,
Russia, specifically near Sabetta harbour, demonstrate a noticeable
drop of propulsion performance in navigation areas clogged with brash
ice, including propeller efficiency factors (from personal contacts withshipowners). Cargo carriers, which often navigate ice channels, inparticular around the Ob Bay ports, are not able to sail independently
and request icebreaker assistance. Icebreaking tugs, providing support
services to ports, also experience increased hull resistance and drop ofbollard pull in brash ice. This has defined the purpose of our study totheoretically assess the changes in propulsion performance of ships
operating in brash ice.

ABSTRACTThis paper gives numerical assessment results for the change of ship
propulsion performance in old ice channel clogged with brash ice ascompared with open-water conditions taking ice-going ship Yury
Topchev as a case study. The authors have shown that two factors must
be taken into account: increasing of the ship hull resistance andreduction of the propeller efficiency due to brash ice presence. The
results of this study may be used in planning of long ship voyages inice conditions, when the changes in propulsion performance due tobrash ice become especially relevant.

KEY WORDS: Ship performance; ice channel; brash ice; shiprouting; propulsion.

INTRODUCTION

The attainable speed of ship moving in old ice channel at her available
power plant output is determined by brash ice resistance and her own
propulsion efficiency. Until now the comprehensive estimations of ship
propulsion performance in old ice channels have not been done: as arule, the estimates have been limited to the ship hull resistance increase
due to build-up of the brash ice layer. The presented paper provides theship performance calculations accounting for effect of brash ice on bothfactors: the hull resistance and the propeller efficiency. As a case study,
a multi-purpose icebreaking vessel Yury Topchev has been taken. The
ship is currently in service severe ice conditions of the Ob Bay (Fig. 1).

Ice class vessels usually reach their ports of destination in polar waters
sailing through old ice channels made previously. If such ice channels
are made in cold temperature regions with high navigation intensity, theship speeds drop after repeated use of these shipping routes. It is causedby accumulation of brash ice, whose layer in time becomes as deep as
ship drafts. Brash ice is a mixture of water and small ice pieces (onaverage, measuring 0.3 – 0.5 m across). Reduction of ship speeds in achannel clogged with brash ice is related to increased hull resistanceand reduced efficiency of propeller partly or fully immersed in thismedium. It is necessary to appraise variations of ship propulsion
performance in old ice channels for the purposes of planning ship
voyages and laying tracks in ice-covered waters. Based on this data theoptimum ship routing is made between points of departures anddestinations.

Comparison of the ship performance in open water and brash ice has
indicated that the maximum speed reduction by about 1.6 knots can beexpected while the ship moving in ice channel clogged only a layer of0.5-m thick brash ice. And up to 50% of this penalty can be due toreduced propeller efficiency. A growth of brash ice layer to 3-mthickness, when brash ice squeezed by the ship sides is commensuratewith the ship draft, may reduce the maximum speed by about 2.5 times.

Evolution of ice channels, in particular, changes of cross-sectional
geometric parameters versus temperatures and shipping schedules havebeen examined before and are given in some works (for example,Sandkvist, 1981; Riska et al., 2014; Karulin et al., 2019). There are also

The estimated speed drop agrees approximately with the observationsof shipowners (from personal contacts with shipowners), but cannot be1276