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http://economie.fgov.be
Results of the RV Simon Stevin EM2040 Sea Acceptance Test and comparison with EM3002D data from
the HS Ter Streep and RV Belgica.
Cattrijsse Andre, Degrendele Koen, De Mol Lies, Naudts Lieven, Roche Marc, T’Jampens Michiel, Vanparys Kris, Versteeg Wim and Verstraeten
Johan
A new research vessel, the
Simon Stevin
A new project to map the
entire Belgian Continental
Shelf
And troubles with the
EM2040 on board the Simon
Stevin
Why do we always
have problems with
multibeams?
A mix of the following topics:
• Flag: Belgium
• Port of registry: Ostend
• Length: 36 m • Beam: 9.4 m • Draught: 3.5 m • Maximum speed: 12 kn
• Area of operations: Southern Bight of the North Sea & eastern part of the English Channel
• Physical oceanography
• Fisheries research
• Marine geology
• Microbiology
• Chemical oceanography
• Geochemistry
• Maritime archaeology
• Marine pollution
• Year of construction: 2012
• Shipbuilder: Damen Shipyards Group
May 2012: the new RV Simon Stevin
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Research Facilities Vlaams Instituut voor de Zee vzw Flanders Marine Institute VLIZ – InnovOcean site
Acoustic equipment
• EM2040 Single Head
• Draught sensor : ATM
• SV profiler : Valeport
• Mini SV sensor : Valeport
• Octans IV from IXSEA
• RTK GPS MGB Tech (LRK-RTK)
• ADCP : RDI instruments, 600kHz
• Odom CV300 : 200 & 33kHz
• Singlebeam (navigation) : 50kHz (JRC, jfe-380/200)
• Speedlog : 2 MHz (JRC, jln-205)
May 2012: the new RV Simon Stevin
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SAT area 1: flat gravel area
Belgica EM3002D SAT area 1 reference model Min depth = -27.6 m Max depth = -29.3 m
~ 200 m
SURVEY 23/07/2012 @ 300 kHz CROSS SECTION (x and y in m) Along nadir of line 1, across lines 3, 4 and 5
1
4 3
5
Without tide reduction
0 50 100 150 200 250 300 350 400 450
-32.6
-32.4
-32.2
-32
-31.8
-31.6
-31.4
July 2012: SAT of the Simon Stevin EM2040
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With tide reduction
0 50 100 150 200 250 300 350 400 450 500
-28.6
-28.5
-28.4
-28.3
-28.2
-28.1
-28
-27.9
-27.8
CROSS SECTION (x and y in m) Along nadir of line 1, across lines 3, 4 and 5
= 0.3 m
Complete inability to model a coherent surface from this data!
SAT area 1: flat gravel area
Belgica EM3002D SAT area 1 reference model Min depth = -27.6 m Max depth = -29.3 m
~ 200 m
SURVEY 23/07/2012 @ 300 kHz
1
4 3
5
July 2012: SAT of the Simon Stevin EM2040
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Real-time HEAVE (in m) statistics:
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
1
3 4
5
+ ? heading and vessel speed dependent
0 m
SAT area 1: flat gravel area
Belgica EM3002D SAT area 1 reference model Min depth = -27.6 m Max depth = -29.3 m
~ 200 m
SURVEY 23/07/2012 @ 300 kHz
1
4 3
5
July 2012: SAT of the Simon Stevin EM2040
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August 2012: dynamic draught and heave tests
Influence of heading and vessel speed?
Impact of speed and heading on pitch and heave
-0.5
-0.4
-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
5 kt 7 kt 8 kt 9 kt 10 kt 11 kt
Pitch (mean, °)
Vessel speed
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
5 kt 7 kt 8 kt 9 kt 10 kt 11 kt
Heave (range, m)
Vessel speed
E N S W -0.2
-0.1
0.0
0.1
0.2
Heave (mean, m)
Vessel heading
Can dynamic draught explain the large differences in bathymetry?
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50 sec
Heave signal:
slowly undulating during a single track (with constant speed and heading)
Problem with the motion sensor?
August 2012: dynamic draught and heave tests
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September 2012: Comparison of 3 multibeam systems
Part of the project to chart the entire surface of the BCS with high resolution. Two federal agencies: • MUMM • FPS Economy
RV Belgica EM3002D
Two regional agencies • MDK - Afdeling Kust
Ter Streep EM3002D • Flanders Marine Institute – VLIZ
Simon Stevin EM2040
Quality assessment and regular comparison between systems
From Vera Van Lancker, MUMM
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18/09/2012: measurements in a lock (Vandammesluis)
HV Ter Streep EM3002D RV Belgica EM3002D RV Simon Stevin EM2040
Zeebrugge harbor
EM2040
paving 4x2m
September 2012: Comparison of 3 multibeam systems
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16.57 m 16.57 m
15.11 m
-16,8-16,6-16,4-16,2-16,0-15,8-15,6-15,4-15,2-15,0-14,8-14,6-14,4
27 32 37 42 47 52 57 62 67
De
pth
(m
)
Distance (m)
reference
Ter Streep 18/09/2012
Belgica 18/09/2012 shift 0.40m
Simon Stevin 18/09/2012
September 2012: Comparison of 3 multibeam systems
Along track profile
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16,2
16,3
16,4
16,5
16,6
16,7
16,8
16,9
De
pth
(m
)
“real” depth 16.57
IHO SO
Ter Streep Belgica
mean ± 2 std
Simon Stevin
mean ± 2 std
“real” depth 15.11
IHO SO
Ter Streep
Belgica
Simon Stevin
14,8
14,9
15,0
15,1
15,2
15,3
15,4
De
pth
(m
)
Only the central part of the swath is compared
Bathymetry results
September 2012: Comparison of 3 multibeam systems
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full swath
Stable gravel area:
L0 (speed ~ 5 kt)
EM2040 measurements: SURVEY 18/09/2012 @ 300 kHz
L3 (speed ~ 10 kt)
Same Heading Tide corrected
-22.5
0 500 1000 1500 2000 2500 3000 -25.5
-25
-24.5
-24
-23.5
-23
CROSS SECTION (x and y in m)
L0 L3
Medium dunes area Gravel area
Locally, Z = 25 cm
September 2012: EM2040
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September 2012: EM2040
Real-time heave low frequency fluctuations:
SURVEY 18/09/2012 @ 300 kHz ANALYSIS OF THE L3 REAL-TIME HEAVE:
0 500 1000 1500 2000 2500 3000 -1
-0.5
0
0.5
1
1.5
L3 (speed ~ 10 kt)
1: Raw heave
2: Filtered heave (moving average on 150 pings)
3: BATHY
L3-L0
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September 2012: EM2040
Correlation with low frequency fluctuations of real-time heave:
0 500 1000 1500 2000 2500
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
Filtered heave (moving average on 150 pings, m) and BATHY L3-L0 (m)
Line by line correction of the bathymetry with the low
frequency real-time heave signal…
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September 2012: EM2040
0 500 1000 1500 2000 2500 3000
-24.5
-23.5
-22.5
-25.5
-25
-24
-23
Line by line correction of the bathymetry with the low frequency real-time
heave signal after tide correction:
SURVEY 18/09/2012 @ 300 kHz line 0 (5 kt) and line 3 (10 kt)
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November 2012: SAT part 2
Visit and installation of different software for the OCTANS IV:
SURVEY 22/11/2012 @ 300 kHz
• No apparent bias (all median ~ 0 m) • All distributions symmetrical
Heave low frequency artifact problem looks solved
But still inconsistent bathymetry
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-0,15
-0,10
-0,05
0,00
0,05
0,10
0,15
-70 -65 -60 -55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70
∆ m
ean
(m
)
Beam pointing angle (°)
line 0 line 1 line 2 line 3 line 4 line 5
line 6 line 7 line 8 line 9 all lines
Asymmetry across track:
Confirmation of the difference in depth between the lines (range ≈ 0.08m)
Asymmetry of the bias curves – sharp drop of the values outside 55° and -65°
Construction of bias curves of the
measurements (points) for each line
with reference model:
November 2012: SAT part 2
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December 2012: SAT part 2
Bathymetry differences between lines:
SURVEY 19/12/2012 @ 300 kHz
Perfect cross correlation observed for all lines Suggests a major X lever arm problem?
Cross section of all lines along diagonal:
-0,3
-0,2
-0,1
0
0,1
0,2
0,3
0 100 200 300 400 500 600 700 800 900 1000
PITCH DERIVATIVE HEAVE DERIVATIVE RESIDU
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December 2012: SAT part 2
Asymmetry across track:
SURVEY 19/12/2012 @ 300 kHz
Asymmetry across track of the lines + dropping of outer beams From beams 0-40 and 360-400 the performance is very bad
Evaluation of the standard deviation:
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February 2013: final test by Kongsberg
Comparison between OCTANS IV and MRU 5
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February 2013: final test by Kongsberg
Comparison between OCTANS IV and MRU 5
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February 2013: final test by Kongsberg
Comparison between OCTANS IV and MRU 5
OCTANS
SURVEY 13/02/2013 @ 300 kHz
Cross section of all lines along diagonal:
Asymmetry across track of the lines – depth difference between lines
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February 2013: final test by Kongsberg
MRU
Asymmetry across track of the lines – depth difference between lines
SURVEY 13/02/2013 @ 300 kHz
Cross section of all lines along diagonal:
Comparison between OCTANS IV and MRU 5
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o EM2040:
o IHO SO S44 compliant for -65° to 65°
o Inconsistency of the bathymetry from one line to another
o Asymmetry across track of the lines + Quality of outer beams
o Need for explanation!
o Comparison HV Ter Streep, RV Belgica and RV Simon Stevin:
o Simon Stevin’s EM2040 is provisionally out-of-competition
o average solution of EM3002D systems within 2cm of reference
o EM3002D’s are both fully IHO SO compliant
Conclusions: A happy ending?
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Website: http://economie.fgov.be/continentalshelf
Continental Shelf Service