Whole-body vibration on icebreakers is way below current safety limits. This information comes from a new report by the Swedish Maritime Administration. Despite this fact, crews experience that vibration is troublesome at times.
Olof Johannesson carried out several hundred measurements of vibration on the two icebreakers, Oden and Frej, in autumn 2015. He spent two weeks on board the ships that operate in the Arctic ice north of Svalbard. The ice they broke was up to two metres thick in places, but despite this fact the measurements showed that there were low levels of whole-body vibration for the crew on board.
“At first I thought that it was down to faulty instruments, but I had two sets of equipment and they both gave the same results,” says Olof Johannesson, who carried out the study. “The vibration that I measured was far below the maximum limit.
Even though the measured vibration levels were low, there were variations from place to place on the ships. While there was very little vibration on the bridge, the highest values were measured lower in the ships, but even there it was within the limits.”
“The values I measured were those applicable to shore-based jobs, since shipping is exempted from vibration requirements. Vibration on board is considered to be acceptable and that it is too difficult or expensive to tackle the issue. But my measurements were even lower than the guideline values for comfort on ships,” says Olof Johannesson.
The reason for the study was that a large number of crew members on icebreakers said that whole-body vibration was a problem on board. The questionnaire which Olof Johannesson handed out at the same time as making measurements also showed that the crew felt that vibrations were irritating at times.
Connection between noise and vibration
“Vibration may be experienced as a problem on ice breakers because the sound levels are quite high. I made some measurements of noise and there was a statistical correlation between perceived comfort related to vibration and the amount of noise. This is an area that needs to be examined in more detail before making any certain pronouncements, but my report has been taken into consideration when planning new icebreakers in Sweden.”
The study is entitled Investigation of exposure to whole body vibration for icebreaker crew and was published in July 2016. It includes 274 vibration measurements and 102 noise measurements, as well as a questionnaire. Olof Johannesson’s current job is work environment engineer at Feelgood in Malmö.
Linda Sundgren, text