Introduction
This case study shows how the NORBIT STX–4D sonar solution works in different survey examples.
Survey
First objects of interest:
Two large jack up ships located north of Amsterdam.
Surveying with NORBIT STX allows seeing behind the shadowing structure.
Standard bathymetry survey shows gaps due to shadows from the pillars. Using 20 deg scanning allows rays to be steered behind the structure which eliminates some gaps. Performed with 512 ED, Pitch stab, roll stab.
A standard bathymetry survey shows gaps due to shadows from the pillars.
Using 20-degree scanning allows rays to be steered behind the structure, which eliminates some gaps. Survey performed with 512 ED, Pitch stabilisation and roll
stabilisation.
STX characterises objects from different angles
Below Left: Standard bathymetry survey shows gaps due to shadows from pillars and low definition of the structure.
Below Right: STX eliminates many shadows and shows much higher definition due to hits from many angles.
STX fills in the gaps
Below Left: ZARATAN’s pillars are solid steel and give big shadows behind them. Running a normal survey leaves gaps in the data.
Below Right: Running the same survey with the NORBIT STX system fills in the gaps with the scanned beam.
Even as large targets as ZARATAN’s legs can be looked behind
Wider soundings angle gives better observability.
Pilings in Amsterdam port
STX improves the survey efficiency
Running a standard survey next to pillars leaves shadows and gaps in the grid, which need to be re-surveyed (below left) on the other side using STX’s “explore more” feature, the surveyor can look behind the pillars, filling in the gaps in a single line (below Right).
This example shows three lines with a standard system against one line with STX!
Both images are single line, but the one to the right is standard, and the right one is with STX.
Pillars in the port
Complicated steel structure giving big shadow and gaps in the grid.
In both cases surveying with STX gives better bottom coverage and more statistics on objects.
Conclusions
New NORBIT STX 3D sonar improves the characterisation of underwater structures by using scanning features of the transmitted signal to insonifying objects from different angles.
The STX improves survey efficiency by utilising scanning that allows seeing behind structures, which otherwise give shadows and gaps during the standard survey.
