Helping to Make Maintenance Safer, More Efficient and More Comfortable

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. Heath 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) has 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.

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 three hours to the place of work in seas up to two and a half metres 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 away 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 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 six 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 these components results in the prediction of the causes of motion sickness.

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 per cent representing the subject actually vomiting, there is a 20 per cent work failure rate at 50 per cent, and a 60 per cent work failure rate at 100 per cent. Carrying out work when you have an expected 60 per cent 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 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 has 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.

Training

A two-week one-on-one 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 per cent 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, 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.

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