HYDROGRAPHIC SURVEY


Sound velocity profiling from a moving vessel


 Kevin Edwards reports on a system to produce sound velocity profiles from a moving vessel.


A


partnership between a well- established UK instrument manufacturer and a USA developer


of oceanographic deployment systems has resulted in an innovative system which can produce sound velocity profiles from a moving vessel. Valeport Ltd (UK) and Te Oceanscience


Group (USA) have produced a package that could save surveyors both time and money when surveying.


Hydrodynamic nose Traditionally performed profiles using SVPs or XBTs are the accepted method, but stopping or slowing vessels for sound velocity profiles is both expensive and time consuming.


Fig. 1. Underway SV system in operation.


Group. Te Rapid SV probe has been designed to freefall through the water column at up to 5m/s whilst sampling at 32Hz. Te transducer is mounted in a


hydrodynamic nose section to ensure good water flow and the electronics are housed in a 2000m rated titanium casing. A Bluetooth module allows fast and easy data recovery once the probe is out of the water. Te Underway SV winch features a large


capacity reel with a high-torque dc drive unit and motorised level wind, for fast and safe probe deployment and retrieval. Te reel holds up to 2000m of high


strength line for maximum profiling flexibility. Te main winch not only pays out line


during deployment as the probe drops through the water column, but is rotated to provide line for re-spooling onto the probe using a tail re-winder for deep profiling. Te microprocessor controlled Underway


SV tail spool re-winder precisely loads the profiler tail spool with high strength line; typically 350 to 550m of line is added from the main winch for each deployment. Te unit may be programmed for different profile depths and is automated for quick turnaround.


Freshwater intrusion Te Underway SV is suitable for surveys where fluctuations in temperature or freshwater intrusion may create highly complex sound speed patterns. Te rapid profiling afforded by the


Underway SV results in minimisation of downtime and reduced costs to quantify these sound velocity features. Operating costs for the Underway


Te Underway SV allows vertical sound velocity profiles in minutes without ever having to stop the vessel with the ability to cast down to 1000m @ 4 knots vessel speed, or up to 10 Knots and 600m depth. Te Underway SV system approach


utilises the best in sound velocity probe technology from Valeport and a winch deployment system from Te Oceanscience


SV are also minimal. Te system uses no expendable components which makes it environmentally friendly and it also requires little maintenance as the profiler returns to the vessel after every cast, leaving no trace in the environment. 


Enter 6 or ✔ at www.engineerlive.com/ihss


Kevin Edwards is with Valeport Limited, Totnes, Devon, UK. www.valeport.co.uk


IHSS 6


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21