|Fig. 1. An ocean sunrise over calm seas at 33º South.|
|Fig. 2. The base of the SVP unit housing the velocity measurement tool (indicated by red arrow).|
Tim Kane, the multi beam technician from NIWA made several phone calls throughout the day in an effort to fix the SVP and retrieve the data while the boat carried on making measurements using a data set from 2015. With a little luck and a lot of perseverance Tim was able to diagnose the problem as a faulty cable connection inside the machine housing and he was able to retrieve the new water column data.
As we are surveying a major submarine ridge care must be taken to check that the water properties are the same on both sides. A major ridge could deflect currents and cause changes in water salinity or other properties that would affect the topography measurements made with the multi-beam.
|Fig. 3. Tim Kane (at right of first image) preparing the SVP unit (black cylinder in the cage) for deployment. Deck crew then attach the unit to a winch cable and lower it over the side with the hydraulic arm in the far right image.|
|Fig. 4 The polystyrene skulls (top left before and top right after) and cups (large cup didn’t go down with the others). The skulls didn’t shrink as much as we had hoped but the cups, having more open space at their centre, shrunk significantly.|