The International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA) defines a Marine Aid to Navigation (AtoN) as, “a device, system, or service, external to a vessel, designed and operated to enhance safe and efficient navigation of all vessels and/or vessel traffic.”
The placement, management and monitoring of Aids to Navigation (AtoN) for offshore wind farms may not get much media coverage, but it is a critical activity both in the planning and installation phases as well as the continued, safe operation and maintenance of completed sites. As the General Manager for AtoN and Moorings at Briggs Marine, it is also a subject close to my heart!
With the continued growth of the offshore renewable energy sector, safe navigation around marine wind farm sites remains of paramount importance. Before any construction work can start, alongside other key preparational activities, demarcation buoys need to be located around the perimeter of the site to indicate a safe direction of navigation to mariners.
Buoy types and selection
There are two types of demarcation buoys; cardinal buoys (or marks) that mark the north, south, east and westerly points of a site and ‘special marks’. These two types of buoys are similar in size and colouring but with different markings, as can be seen in the images. The number of special mark buoys used depends on the size (area) of the site.
Briggs Marine offers a bespoke service where we recommend, advise and supply the buoy with its chain and sinker system in line with the position it will occupy. Many factors need to be taken into consideration, including water depth, location, the nature of the seabed, as well as the rise and fall of the tide in order to select the right design.
We can manufacture buoys at our Burntisland facility and usually recommend steel buoys, as opposed to plastic, as they are durable (lasting for 50-60 years) and 100% recyclable. Briggs-manufactured buoys also use aluminium elements above the water, which give a strong echo on vessel radar and are also replaceable in situ.
Intelligent Floating AtoN
At most wind farms, the buoys’ specifications require a conspicuous daymark and a lantern providing a 5nm range during darkness. Many also now have telemetry, communicating data via satellites for remote checks and monitoring. Specialised floating Aids to Navigation also incorporate AIS (Automatic Identification System) to provide additional navigational information for mariners.
Wave data analysis buoys are deployed to record and transmit data on weather, wave height, direction and current. Their applications are numerous, but in feeding their data back to a web-based portal, they become an invaluable tool for offshore wind stakeholders in validating operational decisions made based on weather conditions.
Deployment, monitoring and lift services
The AtoN team at Briggs Marine offers a comprehensive package of consultation and advice, manufacture (if required), deployment, monitoring and eventual lift and removal of AtoN for offshore wind developers. Briggs’ 61m offshore supply ship Kingdom of Fife and 33m moorings vessel MV Cameron take care of deployment and routine interventions.
We offer long-term buoy rental as well as sale and a full maintenance service including an annual lift and calibration of the chain and sinker. The whole process is documented into a detailed report, with imagery, once the floating AtoN are installed, with similar communication processes being followed for routine maintenance checks.
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Briggs Marine currently holds long term-contracts for demarcation buoys at Ørsted’s Duddon Sands and West of Duddon Sands offshore wind farms and EDF’s Neart na Gaoithe (NNG) site. We have also worked with numerous other developers on short-term construction buoy projects.
I am proud to be part of one of the largest independent suppliers of Aids to Navigation services in the UK. Being passionate about aids to navigation certainly helps, as Briggs Marine currently holds contracts to supply, inspect and refurbish some 1000 buoys, 12 lighthouses and around 150 beacons for a wide range of customers, including the Ministry of Defence, major ports and utility providers, as well as the UK renewable energy sector.
It is a buoyant part of our marine business!