As we celebrate World Oceans Day on 8th June, it is a perfect opportunity to learn more about waves.
Recently, the Bureau of Meteorology (BOM) has replaced its two existing wave buoys, one approximately 10km off the west coast of Tasmania and the other nearly 8km from Kangaroo Island in South Australia, with TRIAXYS wave buoys. These buoys record the waves experienced over a 20 minute period, typically at the start of each hour – this is called the record. The summary of this data is then sent via satellite and displayed in near real-time every 20 minutes on the BOM website. But what do the observations mean?
Easiest to appreciate is Hmax, or the maximum height of the waves, which is the biggest wave measured in the record. The wave is measured from the trough to the peak of the wave and is reported in metres.
Significant Wave Height, or Hs. is more representative of the conditions and is the average height of the highest one third of the waves in the record. Care should be taken as the likely maximum wave height can be up to twice the significant wave height.
Also reported is the average time (Tz) which is the average time (in seconds) between all waves in the record while Tp is the period (again in seconds) of the waves with highest energy in the record.
Each buoy is moored with a combination of chain, rope and a rubber bungy cord which is used to attach the buoy to a 500kg weight. Although the site off Tasmania is moored in water depth of 100m, the mooring has to be much longer than this to make sure that it is not dragged under water. It also has to be able to withstand the tremendous force of the Southern Ocean. In 2012, a wave of 20m was measured at this location and waves of over 10m are frequently recorded.
As well as the sensors inside the buoy to measure the waves, the buoy has a water temperature sensor, 4 large batteries, solar panels to charge them, GPS, satellite modems and a processor to make it all run. Alarms trigger if water enters the buoy or if it moves off location and the sensors can be remotely monitored via satellite. They have the option to be upgraded in the future with the addition of current profilers should they be required by BOM.
Although the buoys can use and recharge their batteries for over 3 years, the buoys are serviced annually to remove marine growth and to replace the mooring. The buoys were sold by Hobart and Cape Town based company Metocean Services International, who themselves have deployed buoys in over 50 countries.
The wave buoy off Cape Sorrell was named Captain Fathom by ABC listeners in 2015 to celebrate the centenary of BOM.
As well as being referred to on ABC Radio, data is quality controlled and made freely available by BOM at http://www.bom.gov.au/products/IDT65014.shtml (Tas)
Prototypes of the next generation of AXYS surface buoys integrated with advanced current profilers were presented at Oceans last September. Discussed was the process on how AXYS chose the newer technology available with the Nortek Signature Series (500 kHz and 1000 kHz) and the design considerations that they had to do to accommodate these sensors to the AXYS Metocean Solutions lineup that consists of the TRIAXYS Wave and Current Buoy, WatchKeeper Buoy and 3 Metre Buoy.
You can read more about this as well as more information on what type of new data options can be derived from the Signature ADCP-integrated surface buoys here: 2019 Next Gen Currents Paper
More features ready for the TRIAXYS Wave Buoys:
Do you know that the TRIAXYS can now be integrated with an AIS (Aid to Navigation) radio? Aside from Message 21 that sends the system’s location, Message 8 (Waves Stat Data) can also be transmitted to oncoming ships equipped with an AIS radio.
The TRIAXYS Float Collar option is now available that practically transforms the 1 metre buoy to a 1.8 metre platform. The improved buoyancy means these buoys can now be deployed in high currents (up to 3 m/s) and up to 3,000-meter depths.
DeepTrekker have just announced the launch of the new generation of their ROVs – the DTG3 and the DTX3.
Powered by BRIDGE Technology, these new ROVs take industry leading affordable ROV technology to new levels. BRIDGE technology is comprised of custom hardware, software and integration, developed in response to a growing market demand. Utilising the latest in technology, this platform will become the base for future products, new and advanced features and third-party integrations by Deep Trekker.
“BRIDGE allows the user to experience wireless control and viewing, multi-vehicle operation over the internet, and software upgrades from anywhere in the world,” says Chad Plesa-Naden, Embedded Systems Engineer Lead, Deep Trekker.
Deep Trekker’s world-class are already being used around Australia and by thousands of customers globally. Their portability, reliability and cost make them an ideal tool for a range of industries including aquaculture, construction, inspections, sampling, security checks, etc.
The DTG3 ROV now has advanced power, heightened capabilities and high-end performance at a breakthrough price with the standard offering being:
The new auto heading sensors makes the ROV drive effortlessly straight through the water making flying easy, combined with exceptional vertical depth hold with camera stabilization.
The DTG3 “Expert” also comes with:-
Reaching depths of 305 meters (1000 ft), the DTG3 is designed to last longer with hybrid power boasting 12-hour battery life. An enhanced viewing and recording experience provide smarter inspections with its live, 4K video and waterproof hand held controller – no smart phone displays here.
The bigger brother of the DTG is the DTX and this has also seen a substantial upgrade. The DTX3 now has 6 powerful, vectored and vertical thrusters for maneuverability unmatched in this vehicle class. The new 7″ display controller and 4K video with recording elevates the DTX3 to new heights. Rated for depths of up to 300m and with speeds approaching 3.5 knots and 13 kgs of thrust with 8 hours of battery life, the DTX3 is as powerful and strong as it is nimble and easy to use.
Introducing the RBRduet³ T.ODO – a compact and rugged self-contained logger for measuring high accuracy temperature and DO measurements.
The optical oxygen sensor provides high stability for very long deployments where accurate dissolved oxygen concentration and oxygen saturation measurements are critical. The |fast version has a 1s time constant for dissolved oxygen. The |slow version has a protective layer over the optical foil to allow wiping to remove fouling for long-term moored applications.
The marine thermistor provides the highest accuracy temperature measurement with 1s time constant.
The compact size and self-logging ability is versatile and enables DO measurements in a variety of applications including oceanographic moorings, fishery studies, benthic pods, and non-integrated attachments on AUVs, glides, and profiling floats.
Metocean Services International (MSI) in partnership with AXYS Technologies Inc (AXYS) is pleased to announce that they have recently won a tender to supply Australia’s Bureau of Meteorology (BoM) with four TRIAXYS Wave buoys.
The Bureau of Meteorology is Australia’s national weather, climate and water agency. Through regular forecasts, warnings, monitoring and advice spanning the Australian region and Antarctic territory, the Bureau provides one of the most fundamental and widely used services of government. In support of the Bureau’s marine weather and ocean services, a wave observing system that enables continued automated observation and reporting of hydrological surface waves at Kangaroo Island, South Australia and Strahan, Tasmania was required.
The TRIAXYS accurately measures and transmits directional wave data using the TRIAXYS solid state wave sensor, which provides near real-time access to continuous wave measurements and does not require annual calibration.
The first two TRIAXYS Wave buoys have been delivered to BoM and are scheduled for deployment in August. The remaining two wave buoys will be built and sent in the second half of 2018. The MSI technical team will be on hand to assist BoM with deployment of the buoys and setting up operations.
Over the last decade, more than 300 TRIAXYS wave buoys have been deployed on various projects throughout the world. The TRIAXYS has been reliably proven to assist with safe Aid to Navigation activities, port operations, offshore construction, offshore wind farms, wave resource assessment, and National Meteorological coastal monitoring. The buoy has extensive success surviving harsh marine conditions at depths ranging from 10-300m and is easy to deploy with low maintenance costs.