Standard deviation in percent of water depth relative to beam angle in degrees.
Sea Acceptance Test survey
From the 23rd to the 25th April the Norwegian Defence Research
Establishment (FFI) using the research vessel HU SVERDRUP II conducted a Sea Acceptance
Test survey for the newly installed EM 710, 0.5x1 degree multibeam echosounder system.
The system is installed in a gondola arrangement at 5.50 metre below waterline.
The test was performed outside Harstad, Norway, with fairly calm sea conditions
at depths varying from 200 to 250 metre.
In the first part of the survey, calibration of the system was performed with
a performance analysis of the system. Several lines were run with 200 % overlap
to check the repeatability of the soundings from the EM 710.
Manual and automatic calibration
The calibration of the system was done using both the manual and automatic routines
available in the topside SIS software - Seafloor Information System. Afterward
the results from both were compared. The automatic procedure is developed by FFI
and implemented in the SIS as an option. The user gets an overview after the software
has done an analysis of the recorded data. The results from both the manual and
automatic method were the same, proving that auto-calibration is a cost effective
Average error of 0.1 % of sea depth
From the data collected, the accuracy of the soundings was defined. The plot
shows the standard deviation in percent of water depth relative to beam angle in
degrees. On average the error is approximately 0.1 % of the sea depth with a maximum
of 0.16 % of the sea depth.
The customer concludes that results from the performed test confirms that the
EM 710 is the most accurate multibeam echo sounder ever produced. The customer
further comments that they also had good data at 750 metre depth at sea state 5. The data density
and the quality of the data was very good.