results of the rv simon stevin em2040 sea acceptance test ... · survey 23/07/2012 @ 300 khz cross...

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

http://www.vliz.be/NL/HOME

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



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

http://www.vliz.be/NL/HOME


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


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!



~ 200 m

SURVEY 23/07/2012 @ 300 kHz

1

4 3

5



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



~ 200 m

SURVEY 23/07/2012 @ 300 kHz

1

4 3

5



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?


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


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


18/09/2012: measurements in a lock (Vandammesluis)

HV Ter Streep EM3002D RV Belgica EM3002D RV Simon Stevin EM2040

Zeebrugge harbor

EM2040

paving 4x2m



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


Along track profile


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



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



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



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…



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)


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


-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


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


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:


February 2013: final test by Kongsberg

Comparison between OCTANS IV and MRU 5




OCTANS

SURVEY 13/02/2013 @ 300 kHz


Asymmetry across track of the lines – depth difference between lines



MRU

Asymmetry across track of the lines – depth difference between lines

SURVEY 13/02/2013 @ 300 kHz




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?


Website: http://economie.fgov.be/continentalshelf

Continental Shelf Service

results of the rv simon stevin em2040 sea acceptance test ... · survey 23/07/2012 @ 300 khz cross...

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