Calculation formulas for ice loads and ultimate strength, alternatives to ice ridge drilling – winter navigation research serves many purposes

10/31/16, 12:00 PM

Four new research reports have just been published in a series on winter navigation. These publications examined the ultimate fracture toughness testing of nodular cast iron used in vessels' propulsion machinery parts, involved the development of a calculation method for ice loads affecting azimuthing thrusters, measured ship resistance in an ice channel and sought alternative methods to drilling for the measurement of the underwater parts of ice ridges and ice channels.

Joint research activities and the related series of reports by Trafi, the Finnish Transport Agency, and the Swedish maritime authorities began in the 1970s.
“The aim of continuous research related to winter navigation is to guarantee that ships operating in the Gulf of Finland and in the Gulf of Bothnia have sufficient capabilities to operate in ice, thus making traffic as smooth and safe as possible”, said Chief Adviser Jorma Kämäräinen who is responsible for the research series at Trafi.

“Research results often bring direct benefits that help to improve winter navigation. For example, the research results published now will be directly applied in the development of the Finnish-Swedish Ice Class Rules”, he continued.

“As regards icebreaking, the Gulf of Bothnia in particular is a common playground for Finland and Sweden, and our joint research activities form a natural part of our fruitful cooperation. Furthermore, research provides input for regulations related to assistance and icebreaking services provided for merchant ships”, says Helena Niemelä, Senior Maritime Officer and Winter Navigation Specialist at the Finnish Transport Agency.

Below is a brief presentation of the latest research reports. The winter navigation research reports are in English.

Report No 90: Relevance of Charpy-V impact criteria to nodular cast iron

The Charpy-V test is applied when determining the ultimate fracture toughness of steel based on the Finnish-Swedish Ice Class Rules. This method is quicker and cheaper than direct methods for determining ultimate fracture toughness.
In this research, an alternative criterion for the application of the Charpy-V test was created, in order to determine the ultimate fracture toughness of nodular cast iron, which is more ductile than steel. Nodular cast iron is used in the propulsion machinery parts of vessels.

The results of this research will be used when making the currently planned amendments to the Finnish-Swedish Ice Class Rules.

Report No 91: Azimuthing thruster ice load calculation and simplified ice contact load formulation

As part of this research, a simplified calculation method was created for measuring ice loads affecting azimuthing thrusters. In addition, the key load formulation cases, in terms of ice class rules, were determined. Regulations on the dimensioning of azimuthing thrusters are not yet included in the Finnish-Swedish Ice Class Rules, although such systems are already used in ice navigation vessels.

The results of this research will be used in the currently planned amendment of the Finnish-Swedish Ice Class Rules.

Report No 92: New methods for measuring ice ridges and ice channels in full scale

Ridged ice creates one of the most difficult sets of conditions for vessels operating in the Baltic Sea. Measuring ice ridges in field conditions is necessary when analysing the presence of ice ridges and their impact on vessel performance in ice conditions.

Today, the underwater parts of ice ridges and channels are measured by drilling, which is slow and involves large margins of error. This research proposes the use of sonar for measuring the underwater sections of ice ridges. The proposed method is considerably faster than drilling, but additional research is needed before its implementation.

Report No 93: Ship-ice interaction in a channel

The purpose of this research was to examine the use of the discrete element method (DEM) for determining ship resistance in an ice channel. DEM is a numerical calculation method that can be used to simulate mechanical systems involving a large number of interacting pieces, such as fragments of ice in an ice channel.

The results are promising, but additional research is needed before the method can be implemented for predicting ship resistance in an ice channel.

Ship resistance in an ice channel is applied under the Finnish-Swedish Ice Class Rules for determining the required engine output of a vessel.

Additional information is available from:

Winter navigation research reports

Jorma Kämäräinen, Chief Adviser, tel. +358 29 5346 440, jorma.kamarainen(at)
Special Adviser Lauri Kuuliala, tel. +358 29 5347 078, lauri.kuuliala(at)

Finnish Transport Agency:
Winter Navigation Specialist Helena Niemelä, tel. +358 29 534 3321 helena.niemela(at)