Ice breakers

SA Agulhas II: the unbreakable

Ice trials.jpeg
An informative seminar took place about the S.A. Agulhas II Full-scale Ice Measurement Project recently - at the picturesque Stias Wallenberg Conference Centre at the Stellenbosch University campus.

The consortium present included, representatives from; STX Finland, the Department of Environmental Affairs South Africa (DEA), DNV Classification Society, Professors and students from the Universities of Aalto and Oula in Finland and Stellenbosch University South Africa. This consortium had agreed to share results from the ice trials that took place on the new S.A. Agulhas II in March earlier this year in the Bay of Bothnia, Finland.

The extensive results have been shared amongst the consortium and will be used by the owner. The three-day seminar included discussions of the results from the Bay of Bothnia, measurement and analysis of the results, further research activities during the upcoming Antarctic voyage, what kind of research the results can be used for and practical activities of further research work.

The seminar opened with Håkan Enlund, Sales and Marketing Director of STX Finland, who welcomed the guests with a smile and an enthusiastic approach. He said, “we are proud and glad to be sharing this with you. I feel honoured as I did not expect such a great response.”

The overall aim of the ice trials was to create a scientific basis for design of ice-going ships e.g. ship hull, propulsion, power requirement, and comfort for passengers and crew onboard. This was conducted by researchers involved in the project who each performed specific scientific tests in the Bay of Bothnia during the ice trials. 

Aalto and Oula Universities, Finland

Professor Pentti Kujala is a professor in Marine Traffic Safety at the Aalto University in Finland. He has been doing research in his field for 35 years on different vessels, however this is the first vessel that he can do measurements both in the Baltic Sea and in Antarctica.

The aim of his study was to measure the ice loading on the hull and on the propulsion. “The ship is going in ice so we want to know what kind of load the ice is causing on the hull and the propulsion so we can develop our design methods in long tem. We also measure vibration and noise so that we know the vibration levels onboard,” said Professor Kujala.

The results were determined in the Baltic Sea in half a meter ice, which is quite thin. The tests proved that the systems are working onboard as it is very complicated instrumentation.  The load on the hull and load on the propulsion and the noise measurements seem to have given new results as it is the first time they measured noise onboard and noise under seawater. 

Professor Kujala also mentions that these results and the future studies will impact future ship building designs as they now know how much loading is affecting the ship and can design the hull so that it is safe in all conditions.

The measurement of ice loads of the ship’s hull and propulsion will be an ongoing study as the S.A. Agulhas II departs for the Antarctic in December where further measurements will be made by Professor Kujala and his research team.

Stellenbosch University, South Africa

The university’s research aim was to create a scientific basis for the design of ice-going ships, in particular the relationship between operational conditions and ice load on the hull and human comfort in terms of vibration and sound. 

The contribution of the Sound and Vibration Research Group of the University of Stellenbosch was to aid in the assessment of occupant dynamic and acoustic comfort associated with these various ice load conditions in order to contribute to the development of occupant comfort metrics for ice- going vessels. The focus was rather to measure dynamic seat comfort in one location under a variety of ice-loading conditions, rather than the measurement of a variety of seats under different ice loading conditions.

The results proved that most significant vibration was experienced when the ship was breaking out of channel in reverse, reversing straight in a freshly broken channel, cruising through level ice with ridges, cruising through rafted ice with ridges and when the ice level experience vibrations with magnitudes roughly ten times higher than those on the bridge. “The Captain was not uncomfortable at all in his seat,” said Doctor Annie Bekker, a Stellenbosch University Senior Lecturer and Researcher.

DNV Classifacation Society (Det Norske Veritas)

DNV is a classification society organised as a foundation, with the objective of safeguarding life, property, and the environment. DNV assists their customers within the maritime industry to manage their risks in all phases of a ship's life, through ship classification, fuel testing and a range of technical business risk, environmental and competency-related services.

The objective of their study on the ice trials was to test the dynamic response in shaft line reated to ice-loads on propeller blades. They also tested the interior noise meausurement onboard.

The short-term data acquired from the trials were good, however, the ice was thin and should have preferably been thicker.
The interior noise measurements proved that the noise levels on high deck levels are less influenced by noise from ice as expected but should preferably have had thicker ice. The measured noise levels are clearly dominated by noise from ice in forward areas, but also observed in aft areas.

The extensive results proved that the S.A. Agulhas II is more than capable of performing its requirements both in ice conditions and open water. The DEA is particularly happy and supportive of the ice studies carried out and the ongoing studies yet to be implemented as it can only benefit the ship owner in many ways. “I am very pleased to say we are absolutely delighted with the ice trials and what we are going to get out of it ultimately. 

There are lots of benefits to the designers, the engineers, the classification society, SAMSA but as the owner, we will ultimately get information that will allow us to navigate the ship safely and economically under very difficult conditions,” said DEA’s Alan Robertson, Project Manager of S.A. Agulhas II.

The S.A. Agulhas II embarks for Antarctica in December this year were all research participants will be joining the crew to partake in further studies.
comments powered by Disqus


This edition

Issue 2020