Challenging Underway Sound Speed Profiling Project in New Zealand

Two complete Oceanscience Underway SV systems including the Valeport Rapid SV profiler were recently supplied by Swathe Services (Australia) to IXSurvey Australia ahead of a challenging hydrographic survey project in the Fiordland National Park, New Zealand. Rapidly changing sound velocity caused by fresh water inflow from the numerous waterfalls and rivers, combined with a short time frame allowed for completion of the project resulting from frequent extreme weather conditions, meant that the job was an ideal application for the underway profiling system.

Two multibeam-equipped survey vessels were each mobilised with Underway SV systems; the two-month project benefitted from a grand total of 417 sound velocity casts, each collected with no associated survey acquisition downtime. The deepest of these sound velocity profiles reached 400 metres, with even this cast taking only a few minutes at the survey speed of 6kts. Based on the estimated down-time of collecting sound velocity profiles with conventional techniques, over a hundred hours of survey data acquisition was saved and the project objective was achieved remarkably well with survey data of a high standard being collected.

(Image courtesy of iXSurvey Australia).