HEALTH & SAFETY: Helping to make maintenance safer and more efficient

The Desdemona simulator

The long term employment prospects within the offshore wind industry lie with the Operation and Maintenance work that will keep the turbines producing electricity for the next 20+ years. 

Hundreds of men and women will be climbing up the towers from boats, or down from helicopter dropping areas, into the nacelles for a long time to come. Health and safety issues will not just include how to safely handle heavy pieces of equipment or work with large rotating turbine components; they include the localised physical state of the worker on arrival at the work site.

The Global Wind Organisation, GWO, have started with laying down training standards for these engineers and technicians. The standards not only include some of the basic offshore training used in the oil and gas sectors, but also new training for working at heights, and safely ascending and descending on ladders or using hoists that will be fitted in to increasingly higher towers.

The training for these aspects is possible with teachers, towers, water tanks and ladders. These can be found onshore at training schools all over the world. Onshore, on solid ground, and you can get to them by driving your car or catching a bus. Working offshore is different!

Sea sickness

The ability to climb from a support vessel up to the nacelle is strenuous at the best of times, but when the person concerned has sailed for over 3 hours to the place of work in seas up to 2.5m Hs, he or she, may well be feeling at least a little queasy, and this becomes a health and safety issue when it impairs the judgement and ability of the person involved in the work.

Sea sickness affects people in many different ways, a few sufferers fall victim straight as soon as the vessel leaves the side of the jetty, but most sufferers can manage 60 minutes before succumbing, while others, mainly with vast sea time experience, show little or no effects at all.

Hardened sailors with years of sea time in their log books have described their total helplessness in on board situations when their ‘passengers’ have become sea sick. They have their route planned and orders from the charter party, in short there is nothing they can do to alleviate the misery. The owners of these vessels can select their vessels from a wide range of designs, some better than others in rough seas. They may have better ventilation and temperature control in the passenger areas which can extend the 60 minutes to 90 minutes for example, but design features such as 360° horizon visibility and a hull designed to reduce motions, such as slamming, provide more positive results.

The human factor

The Human Factors division of the world renowned TNO research organisation has been working on solutions for motion sickness for many years. Long before the offshore wind industry existed, the Dutch Navy and Air Force recognised the problem and asked for help from the Soesterberg based TNO facility. Today they have simulators capable of reproducing the 6 degrees of motion experienced by sea going support vessels. Finding volunteers to provide them with data, however, is understandably a problem.

Professor Dr. Jelte E. Bos and Dr. Wilfried Post, both senior Research Scientists at TNO, told us more about their research. Profoundly deaf people do not suffer from this problem, because the inner ear with the balance organs is a vital part of the calculation. A visual input from the eyes and the effect of gravity on the body complete the equation. A proper understanding of these components results in the prediction of the causes of motion sickness.

Their prize piece of equipment for this research and training is Desdemona, an acronym for DESoriëntatie DEMONstrator Amst, a result of collaboration between the Austrian AMST Systemtechnik GmbH, creators of Desdemona, and TNO.

Developed primarily for disorientation training, it is also suitable for maritime, aviation and road vehicle movement simulation for research. The person being subjected to the simulated conditions sits in a cabin which is gimballed to rotate on any axis, rise and fall of up to 2m (simulating heave acceleration) and all of these motions can be superimposed on a rotating arm which gives a G-force of 3G, maximum.

For maximum realism the interior layout of the cabin can be fitted out as a ship’s bridge enabling the subject to attempt to carry out the tasks that would be required at work.

Statistics really do count

The statistics from the TNO research, and other organisations, have provided data showing that on a scale of 0 to 100%, with 100% representing the subject actually vomiting, there is a 20% work failure rate at 50%, and a 60% work failure rate at 100%. Carrying out work when you have an expected 60% failure rate is asking for trouble.

Even after leaving the vessel and standing on the turbine’s stable foundation there is another problem, a condition known as Mal de Debarquement (or MdD) in which the body continues to feel as though it is still at sea, and the subject is unable to get their ‘land legs’ back. This ‘dizziness’ becomes dangerous especially when working at heights, a very common work environment in offshore wind farms.

However all is not lost and the research continues. Professor Bos and Dr Post have provided designs to boat builders that have reduced the effects of heavy seas, and they can train people to be ‘a better sailor,’ but, of course, within certain parameters.


A two-week 1 on 1 training course using a specific design of vessel will result in the subject becoming acclimatised and gaining a greater tolerance for heavy weather, when experienced on that particular vessel. A word of caution though, if the ‘trained person’ does not make use of the recently acquired tolerance, he, or she, will loose the newly gained advantage within a few days.

True engineers believe that any and every problem can be engineered away… This belief does not include the human factor though. There is no solution for 100% of the people and their results so far have only mitigated the problem, not solved it. However their results are much better than using drugs which diminish reaction time and dull the senses, creating another set of dangerous circumstances for a work environment.

Using their research results to change the design of the vessels, change routing of voyages between the turbines, taking sea and wind direction into consideration, and keeping voyage lengths to a minimum of 60 minutes, for example, will all help to reduce the effect of this debilitating sickness and ultimately result in a safer working environment and a healthier worker.

A coincidental result of the simulator data is that the simulator itself can produce its own form of motion sickness. Subjects who are not prone to sea sickness can develop similar symptoms to sea sickness exhibited only in the simulator.

A famous cure, attributed to a life long sufferer of seasickness, Admiral Lord Nelson, is to sit under a tree. The approach taken today is less flippant and certainly more scientific. Vessel owners have become receptive to any advice and the builders of these vessels have recognised the advantages in having their own Human Factor department to advise on possible design changes, but with a lifetime of experience and knowledge the TNO data base is vast and open for consultation.

Dick Hill

This article first appeared in the April 2014 edition of the Offshore WIND Magazine.

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