The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community
Issue link: http://sea-technology.epubxp.com/i/112603
tween the profling probe and transmitting data server, as well as extremely low energy demand allowing long-time battery operation, represents a breakthrough in solving these obstacles. APB5 buoy with STD204/208 probe and wireless data transfer by the Internet via GPRS (general packet radio service) or EDGE (enhanced data rates for global evolution). biofouling, i.e., the settlement and growth of sessile aquatic organisms on exposed surfaces. In many marine environments, such biological processes are fast, and require frequent cleaning and maintenance. In short, the technical problems of automatic profling from unmanned stations with restricted energy supplies have been too complicated to solve adequately from small, easily manageable and inexpensive offshore installations. However, SAIV AS���s (Laksevag, Norway) APB5 buoy, which has a wireless short-distance radio-transmitted interface be- Buoy Development The buoy has a height of 130 centimeters, a diameter of 150 centimeters and weighs 200 kilograms. Constant exposure to seawater and extreme weather events, such as storms, make high demands on the endurance and stability of the buoy. Its body is made entirely of rotational molded foamflled polyethylene, and all bolts, nuts and tackle are stainless, acid-free steel. The buoy is designed to prevent sinking and capsizing even under extreme events. All external cable connections are sealed or joined by SAIV AS���s deepwater sockets, which are widely used on ROVs. SAIV AS has for the past 20 years gradually developed and improved its portable, compact CTD probe, STD204/208. In contrast to many other similar probes on the market, the STD204/208 will store all relevant calibration coeffcients, and continuously process and deliver the measured data directly in physical units. Recently, the model was further developed to support wireless data transfer via shortwave radio, while still maintaining extremely low energy requirements. This feature enabled the possibility of developing an automatic selfsustained profling buoy without the previous obstacles described above. Most importantly, the wireless communication solved all the conventional cable problems. Secondly, the low energy requirements make the probe operable on batteries for hourly profling for at least a year without replacement. Lastly, the airborne data transfer in between profling that requires the probe to be hoisted out of the water has unexpectedly and inadvertently proven to be effective for antifouling. Thus, Monthly average temperature and oxygen profles (means with 95 percent confdence limits) in 1-meter depth intervals from inside a salmon aquaculture holding pen September to December 2011. www.sea-technology.com FEBRUARY 2013 / st 11