REAL-TIME FEEDBACK ENABLES LEARNING ON THE JOB: How vessel display makes maintenance safer, faster and cost effective

Maintenance of offshore wind turbines is important and necessary. The faster a defect turbine is running again, the faster it produces electricity. Time is money. How do you make sure that the valuable time turbine technicians have, is actually spent on offshore wind turbine maintenance? In practice a lot of valuable time is lost; often by unforeseen weather conditions, or personnel who have been suffering from sea-sickness, or a lack of operational information. How can the industry change this and improve productivity?

Offshore WIND asked BMO Measurement Solutions B.V. (BMO), a Dutch company specialised in providing insight and improving logistical processes in the offshore wind sector, to explain how their vessel display contributes to improving logistics and safety. It concerns the collection of data from, and information of, the vessels working in offshore wind farm maintenance. The BMO on-board measurement equipment measures motions, positions and speed, combined with video images.

Making the best use of valuable time, is a large proportion of making offshore operations more effective. How do you prevent vessels from making a transit in vain, because the sea on site turns out to be too rough to transfer? Under which circumstances do vessels damage foundations or become damaged themselves during transfers? Did the skipper make a judgment error or was there another cause? What information does a skipper need to offer his passengers a safe and comfortable transit?

To answer those questions, it is important to see the various aspects concerned with offshore logistics clearly. These aspects include: duration of the transit; comfort of the technicians and the safe transfer from vessel to wind turbine. Every wind project is different: there are many variables, for example the harbour, the distance of the wind farm to the harbour and the foundation design. The weather conditions also vary from moment to moment: waves, currents and winds. And then the essential human element, choosing the right skipper for the right vessel, further increases the number of combined possible factors.

The right stuff

The maintenance of a wind farm far offshore is either carried out on planned regular programmes, or when it occurs, for unplanned events. Both of which increases proportionally with the number of turbines in the wind farm. The safe arrival of the technicians is of prime importance and for this a new class of vessel, the crew transfer vessel (CTV), has been developed over the past few years for bringing personnel and equipment to the wind farm. The CTVs in use today have a length between 17m to 26m, twin hulls and are capable of a reasonably high speed. Due to the current international vessel regulations in force the majority of them can carry 12 technicians.

With the monitored measurements the best vessel for the specific weather conditions, sailing distances or foundation designs can be selected. Not every vessel is suitable for each situation and sometimes the differences are large, depending on, for example, the payload and passengers that must be taken to the wind farm. Each type of vessel requires different handling techniques to be used by the skipper. When these parameters and techniques are known and documented from measurements already taken the ideal selection of vessel and crew is easy to make.

A successful mission

It is also of great importance to make sure that each voyage is efficiently planned and use of the vessel is maximised for each different type of vessel. A voyage that has to be aborted, due to weather for example, can easily cost ten thousand euros. The good planning of the route between turbines to reduce sailing time, and ensuring the time that each technician or engineer has at the WTG is sufficient for the required work without having to return the following day to complete, all adds up to efficient use of man power and machinery. The BMO measurement equipment makes it easier to predict reliably whether transfers are possible because the sailing conditions have been determined objectively. This enables planners to prevent unnecessary and uncomfortable transits without missing opportunities when it is in fact possible.

Vessel display

Apart from the sailing time also the quality of the transit is important. When the vessel is pitching and rolling back and forth continuously during rough weather conditions, passengers are not happy. Sea sickness is a problem that occurs frequently. Technicians have to recover first before they can get to work which in turn results in a loss of valuable time.

A vessel display presents the skipper with a better view of passenger comfort during the trip. This is based on the real time data on the vessel measurement system. The skipper’s perception of the vessel motion is different to that of the technicians. First of all, as a professional mariner, he, or she, is much more familiar with the movement of the vessel. Other factors are the positions of the wheel house and the passenger area, which are very often separated from each other. The wheel house is close to the vessel’s centre of rotation. While many of the technician passengers on board may become nauseous, the skipper in the wheel house may not be suffering at all. With direct feedback from the display the skipper can adjust his course and speed, to reduce the degree of rolling and pitching enabling the ‘human cargo’ to reach their destination fit for purpose.

Situations such as these all point to the necessity of a VesselBlackBox (VMMS) to provide new insights for improving logistics and safety. The execution of offshore wind turbine maintenance must become not only cheaper and safer but also more comfortable, simply because the industry needs more people for this work.

The human factor

Three years of extensive measurements by BMO prove that the human factor is of great influence on crew comfort and a safe transfer. As a skipper will tell you, ‘a happy technician is a good technician.’ The best way to improve vessel operations is by empowering the skipper to do his job well. Vessel display gives the skipper a complete overview of the vessel, at all times but none more importantly then when the technicians transfer from the vessel to the transition piece, and especially during the higher sea state limits. It is at this point when risky situations can regularly occur, with potential financial consequences for the boat owner or wind turbine owner.

The display shows if the movements of the vessel are within the ‘safe’, ‘caution’ or ‘extreme caution’ categories. The vessel display reports events objectively and assists the skipper to recognise risky situations.

The information is available in real-time so the skipper can act immediately and adjust his reactions and behaviour accordingly. The data of every transit is recorded automatically, which provides another advantage making the feedback immediately available for the skipper. This is also very beneficial for less experienced skippers and new vessel crew who can review earlier critical transfers. This provides a much faster method of gaining valuable experience of complete operations with the vessel.

Learning and developing further together

During the complete trip, measurement data is logged continuously. The vessel display automatically logs all sailing routes and every wind turbine docking, including the individual turbine identity. At the end of every trip, all the data is processed by BMO into a daily progress report (DPR) in a format specifically designed in conjunction with the party requesting the measuring facility. The complete system reduces the administrative workload of the crew and eliminates the human factor in possible logging errors.

During the development of the measurement equipment BMO has closely cooperated with different vessel crews and skippers to optimise it to their needs. It turns out that skippers only want essential information. As required the skipper can increase or lower the intensity of alerts when needed, reducing possible distractions in the wheel house during critical operations.

Conclusion

Vessel display makes it possible to accelerate learning from practice. Wind farms, weather conditions and vessels can be compared objectively. After all, no wind farm is the same. This enables professionals to continuously improve their knowledge and increase their experience. The recorded information is an important factor that can be used by both the skipper and the management on shore. With it personnel, vessel owners and wind farm owners can make the best choices, objectively.

With thanks to Kirstin Timpte, Business Development, and Gijs Hulscher, Technical Director, at BMO