Posted on 28.11.2011 - 12:00 EST in SURVEY NEWS by Rons_ROV_Links
Peter Gas surveyors smash Oceanscience Underway SV profiling depth record in the Black Sea
Surveyors from the Russian survey company Peter Gas used some lateral thinking to avoid time-consuming sound velocity (SV) profiling activities during an AUV multibeam pipeline survey in the deep waters of the Black Sea. A Hugin AUV deployed from the offshore support vessel GSP Prince surveyed the 500 nautical mile route, with about 50% of the pipeline to be laid in water as deep as 2000m.
The survey team wanted a fast and economical way to gather sound speed profiles in support of the deep ROV operations, and decided to use the Oceanscience UnderwaySV profiler. Developed in partnership with Valeport (U.K.), the UnderwaySV uses the latest RapidSV "free fall" sound velocity probe. By deploying the RapidSV profiler from a stationary vessel, deep sound speed profiles can be collected much faster than using conventional methods based around a hydrographic winch CTD or sound velocity instrument.
The Valeport RapidSV probe free falls at over 5m/s reaching 1000m depth in only 3-4minutes! The key to this down-cast profiling speed is the innovative XBT-style tail spool attached to the probe. The tail spool is loaded with up to 1000m of high strength tether line before each deployment, allowing the probe to drop with little or no drag from the tether line. The high speed winch allows fast recovery of the profiler, greatly reducing the overall profiling time for a high quality sound speed cast. This time saved equates to a more efficient survey job.
The surveyors on the GSP Prince were amazed at how fast the system could gather a complete high quality SV profile. The maximum profile depth achieved was 1,730m, and the cast was completed in about 35 minutes from start to finish! This result smashed the Oceanscience profiling depth record, previously standing at 1,563m, held by NOAA's National Data Buoy Center. Where deep water CTD or SV profiles are needed, and the vessel does not have the hydrographic winch capabilities, the Oceanscience UnderwaySV or UnderwayCTD are now proven options for fast, deep profiling from a stationary vessel.
To find out where the Oceanscience profilers have been in action around the world, take a look at the interactive cruise map, or copy and paste: http://www.oceanscience.com/Products/Underway-Systems/UnderwayInteractiveMap.aspx