Far offshore windfarms present communications challenges

This is an interesting article debating the different types of communication that can be used over a long distance, and as they distance moves further and further, the different types of communication drop off or become part of an infrastructure. As engineers battle with this problem, knowledge of how radio frequencies and applications becomes paramount.

As offshore windfarms are built further and further from land, alternatives to conventional VHF communications are going to be required

A cornerstone of any major project is clear communication between all parties. As we move windfarm construction further offshore, maintaining efficient voice and data communications becomes essential. With many projects now being constructed beyond the range of VHF radio and cellular telephone, such as a Gemini or Dudgeon offshore windfarms, crew transfer vessel (CTV) operators and their clients are experiencing challenges achieving practical and affordable offshore communications. My experience on two far offshore projects in the last 15 months has shown that creative thinking can work together with existing equipment such as TETRA radio to reduce the risks and stress that poor communications can generate.

Communication solutions on offshore windfarms depend on the phase that the operation is in, the size of the project and the distance from shore. Many smaller, older windfarms rely on VHF radios to communicate between shore and vessel and shore/vessel and work team on the turbines. However, VHF is limited in range being a line-of-sight system, and the signal has trouble penetrating structures such as wind turbines due to the Faraday cage effect. Conventional cellular telephone coverage is also possible on nearshore sites, with some windfarms installing a cellular mast within the windfarm. Vessels at anchor off the Dutch port of IJmuiden can thank the windfarm industry for good connection when waiting for a pilot if they have contracts with the provider KPN.

When moving further offshore, luxuries such as a cellular mast will not be installed during the construction phase, and it is most likely that VHF radios will not be sufficient. It is common for the developer to install a TETRA radio network – similar to those used by national emergency response services such as police and fire departments.

TETRA, or terrestrial trunked radio as it is properly termed, is a secure network allowing one-to-one, one-to-many and many-to-many communications. This means that the marine controller can speak directly and privately to one party or to the entire offshore spread depending on what is needed. It transmits on a lower frequency than VHF so covers a greater range. This still is not enough to cover the distances experienced on far offshore windfarms. If multiple base stations are used, each base station can then automatically rebroadcast a message thus expanding the network coverage. On a recent construction project, it was found that there were communications blackspots in the area of the sea passage from the base port to the site. This was later eliminated by fitting full base station units rather than just handheld transceivers on the CTVs. The CTVs then became vital links in the communications network and ensured the blackspots were reduced or eliminated altogether.

TETRA has many other advantages, including the ability to penetrate the tower of a wind turbine, and calls are not dropped when moving between base station carriers due to the network configuration. This is especially important if vessel-carried base stations are relaying far offshore. The network is also secure, which ensures that commercially sensitive information cannot be intercepted. With the one-to-one mode, it also means that managers can have detailed conversations on sensitive subjects.

However, anecdotal information received from vessel crews in the field appear to indicate that TETRA, although a good system, is not foolproof. One vessel master reported that, after 15 months on site, they still had blackspots with TETRA and sometimes have to use the cell phone application WhatsApp to request that turbines be started or stopped so that he can land a team.

TETRA does not solve the operational problems experienced by vessel-operating companies who require frequent voice and data communication with the CTVs to ensure a smooth delivery of service. As most sites far offshore are outside of cell phone coverage and clients demand that daily reports are issued on time, creativity is needed. There is a simple solution that could solve all of the communication problems far offshore – installing VSAT satellite communications on each CTV, which allows instant telephone and data transfer.

However, the practicalities of chartering in today’s windfarm industry eliminates this option, as the client will not want to pay for installation and operation, and a vessel owner cannot afford such a luxury. Charterers therefore need to make a decision: either they assume responsibility and the costs for practical workable satellite communications on their vessels or look for practical alternative solutions to deliver what is needed far offshore.

One practical solution to maintain communications between the marine co-ordination centre and vessels is to step back a generation and use medium frequency/high frequency single side band radios, which are common equipment on larger CTVs and is standard on service operation vessels (SOVs) or installation vessels.

When used in conjunction with the digital selective calling (DSC) function of the GMDSS standard, voice communications can be maintained at long distance without operating cost. Unfortunately, current guidance for the marine co-ordination in windfarms as found in the G9 Good practice guideline: The safe management of small service vessels used in the offshore wind industry does not yet consider marine co-ordination and communications in far offshore windfarms.

Another practical solution to improve data communication is to install powerful WiFi antennas on the decks of SOVs and other major offshore assets to allow CTVs to have internet access when they are in close proximity. CTVs can then download passenger manifests and weather reports and upload the daily progress report and synchronise planned maintenance and email systems.

CTVs spend considerable time in close proximity to the SOV during passenger transfer, bunkering or waiting for the next assignment, and it is relatively easy to set up the computers to connect and synchronise without operator input, thus reducing the risk of distraction. SOVs should be designed with space for CTV crews to use as a secure office so that laptops can be left connected to the network. In this way, crews can have two computers and prepare work when on shift, transfer via a data stick and upload when they go off shift.

One of the most effective tools that we have identified is WhatsApp, which seems to require very low signal strength to connect and transfer brief messages. On recent projects, we have found that most vessel/office communication occurs in this medium, including fault finding and incident reporting and investigation. Crews have found it quicker to video a CCTV system playback and send via WhatsApp than download the CCTV video and send it via a file transfer service. As synchronising an electronic planned maintenance system offshore is very time consuming, our superintendents have taken to sending the worklists via WhatsApp to the vessels who then confirm back with text or images when a job is complete. The superintendent then does the PMS administration from their office with the advantage of high speed network connections. Experience with WhatsApp has led me to believe that agile, low data applications will form part of the future of offshore communication.

Far offshore projects have moved from planning and dreaming to reality. However, effective and cost-efficient communication solutions have not moved with them. Like most challenges with far offshore windfarms, there is no single solution, but experience has shown that, with creativity and flexibility, projects can communicate with their teams and operators can manage their vessels.

Better equipment earlier on in the construction phase, such as MF/HF radios in the MCC and on the vessels, TERA base stations on the vessels and open deck WiFi on construction assets will all assist in improving safety and reducing stress while ensuring that unnecessary costs are not incurred.

Offering workers hearing protection options

Much Like Protecting your sight or looking after your health, your hearing should also be protected, this article tackles hearing protection within the workplace and what type of earplugs are best, Enjoy.

OSHA regulations dictate we offer a “variety” of hearing protectors to noise-exposed workers. What is best practice for providing a variety while keeping inventory to a minimum?

Per CFR 1910.95(i)(3), “Employees shall be given the opportunity to select their hearing protectors from a variety of suitable hearing protectors provided by the employer.” But does “variety of suitable hearing protectors” mean two or 10, earplugs or earmuffs, different colors or different sizes?

The wrong approach is to choose a variety based on factors that have no effect on protecting hearing, including the published noise reduction rating. Some safety managers offer several different large foam earplugs that are yellow, green and orange – mistakenly assuming they meet the “variety” requirement and not realizing that a significant portion of their workforce will never achieve an adequate fit with a large foam earplug. In those cases, their supposed “variety” actually limits the number of workers adequately protected.

This bad assumption is often codified into company safety policies that require a minimum NRR: “Approved hearing protectors must have an NRR of at least 32 decibels,” or similar criteria. By definition, that typically means a large foam earplug. Despite the higher NRR based on 10 laboratory test subjects, workers with smaller ear canals will never achieve an adequate fit with those large foam earplugs to stop noise-induced hearing loss.

What are the factors that affect good fit of an earplug?

  • Size: Like a cork in a bottle, an earplug that is too large or too small will never achieve an acoustic seal to protect hearing. Offering a variety of sizes significantly improves the percentage of employees obtaining a good fit.
  • Shape: Ear canal openings may appear round, oval or slit. A foam earplug often fills an oval or slit opening better than pre-molded earplugs.
  • Ease of insertion: Some workers have difficulty rolling or inserting foam earplugs due to lack of mobility. For these workers, an earplug with a stem may be easier to insert.

Based on thousands of fit tests administered to workers in the field, the following four earplug styles provide a selection that would adequately protect nearly every worker:

  • Large foam earplug
  • Smaller foam earplug
  • Large reusable earplug
  • Smaller reusable earplug

The good news is that offering a variety does not necessarily increase cost. Buying 1,000 earplugs of one style or 250 earplugs of four different styles is fairly equivalent in cost. But the bigger variety significantly increases the probability that more workers will be adequately protected.

Many worksites adjust their inventory based on results of their fit-testing of hearing protectors. By reviewing which earplugs repeatedly provide the best fit, these companies identify the gaps or duplications in their offering and can adjust accordingly. Sometimes, this means adding a smaller-size earplug, but many times companies find they can remove some less-effective earplugs from their inventory. It’s not necessary to carry a dozen different earplug styles.

Finally, any offering of hearing protection needs a hands-on training component. How can a workers determine whether their ear canal is large or small, round or oval? It’s impossible to view your own ear canal opening in a mirror. A quick glance by a safety trainer can be of tremendous benefit in helping workers select the right earplug the first time.

Exactly what is the Best two way Radio For Long Range

When choosing the best 2 way radio, it is important to note that doesn’t matter which brand you pick. Whether you pick kenwood, Motorola, Icom, Hytera or any other brand, you should know that they all feature the same technology. Well, you might have noticed that most consumer radios tend to advertise a range that’s up to 30 miles. Truth is, the consumer FRS/GMRS radios don’t even provide anything close to the advertised maximum range; the range that a two way radio advertises is normally the range that a radio can get in the ideal condition. The ideal condition is clear line of sight like from the mountain top to the valley below; without any interference or obstructions.

Two way radios generally operate within VHF (that is Very High Frequency; 130 to 174MHzz) and UHF (that is, Ultra High Frequency; 420 – 470 MHz)) wave bands. Unlike the frequencies that are below 2MHz, the waves in these particularly higher frequencies travel in a straight line (also known as line of sight signal), and generally can’t travel beyond your horizon. This basically means that distance to your horizon, is the actual maximum range for your two way radio; that is without the use of any additional equipment to boost the signals.

VHF waves (about 5 feet wide), are generally longer than the UHF waves, and they’re most commonly used for long range/distance communication. If VHF waves and UHF waves were both transmitted in ideal conditions without any barriers, the VHF waves would travel nearly twice as far; as a general rule, the lower the wave frequency, the greater the distances it can travel.

Key to transmitting the radio waves for a long distance along the VHF waves is keeping the receiver and the transmitting radio above all possible obstructions or interfering objects. The VHF frequencies (because of the length of their waves), cannot transmit through some objects like walls, dense forests and hills. Typically, the transmissions which are sent along VHF waves are received and also sent high above earth’s surface. VHF 2 way radios normally work better when there is a clear line of sight between the receiver and the sender. VHF 2 way radios are commonly used in marine and aviation communications where signals get sent across the open water bodies or between the ground and the sky. Television and FM radios also use the VHF frequencies where the signals are sent and also received high at the top of towers which are spaced all over the towns, cities and counties. VHF band walkie talkies are also perfect for landscaping, open fields, golf courses and also for outdoors security situations where there is less obstruction.

Though VHF can travel much farther, it doesn’t mean it is the better option. Reason is because of the differences between how the VHF and the UHF signals tend to react around buildings or structures. As you will find out below, UHF signals are shorter than VHF, and this is very important when you’re in or around buildings.

UHF doesn’t travel as far as the VHF, but has higher bandwidth occupation. One major advantage of UHF over the VHF, is that the antenna can actually be much smaller when its’ used on the higher frequencies. Sometimes, a base antenna might be needed for radios using VHF frequency, but a small antenna on a radio can be comfortably used for the UHF frequency. Moreover, there are a lot more frequencies which are available when using UHF; this can be very useful in the areas which have a high population density.

The UHF radio waves are much shorter than the VHF radio waves (measuring at about one and half feet); the short length of UHF radio waves typically decreases distances at which the signals can get transmitted. This means that the line of sight between the receiver and the sender is much shorter in length with UHF waves. That being so, you should know that transmission of the UHF waves is usually high enough such that it can penetrate through the building walls and the urban outdoor settings. This is the reason why UHF two way radios usually work best for those who intend to use them in and around buildings and urban areas. A UHF walkie talkie with adequate power and a good sized antenna can reach further into the building, and push through steel, wood, concrete and earth. If you intend to use your 2 way radios exclusively indoors, or maybe indoors and at times outdoors, the the UHF is definitely the best choice. To explain this, let us use an example; assume you’re trying to communicate with someone on the other side of the building and in between there’s a metal wall which has a 3 foot opening. Basically, radio waves can’t pass through metal. However, the UHF wavelength which is about 1 1/2 ft wide, will easily pass through the opening. In contrast, the VHF signal will bounce back since it’s wider than the opening. This shows you that UHF is much better when it comes to navigating through smaller spaces within buildings to reach its’ destination.

When it comes to power, many people tend to think that the power output increases the range, but actually the difference in the range between, say a 25W fixed VHF, and a 5W handheld, is because the fixed mounts the antenna being taller, thus can see farther. When you are trying to increase the range, increasing the height of your antenna is far more effective than increasing the power. Increased power will generally let you push through the static and such other radio traffic much better, but only within a range that’s dictated by the height of the antenna.

In regards to obstacles, there are a lot of things which affect the signal strength of the radio waves. Therefore, it’s important to consider the environment you intend to use your 2 way radios, and the actual range you need. Naturally, a football stadium will have much less obstructions as compared to a dense forest.

In conclusion, I would like to say that it is never about the radio you purchase, but the frequency, antenna and environment it will be used in. If your 2 way radio is going to be used mainly outdoors, where you will have a clear line of sight, then the VHF is the ideal choice, however, if the 2 way radio is going to be used in and around buildings, in urban areas, or in heavily wooded places, then the UHF is the best option.