The deformation of a vessel by its load, and that of positioning piles by temperature have consequences for the accuracy of the survey. This presentation by Erich Gaickhorst (GeoVisie) shows how.

1. Deformation effects on vessels
The effects of flexibility on calibrations
HSB Workshop Vessel Geometry and Calibrations
15 January 2014
Erich Gaikhorst
The effects of flexibility on calibrations

2. Index
• Two examples
• Fallpipe vessels
– Flexibility
– Temperature
The effects of flexibility on calibrations

3. Remaining error after calibration
Offset Survey Noise (Quality offset survey)
Sensor Noise
(Quality sensor)
Sensor Drift
(Quality sensor)
Calibration Noise (Quality calibration survey)
Vessel Deformations(Load/Sea state/temperature/design)
+
Remaining error
The effects of flexibility on calibrations

4. Example 1: Flexibility
•
•
•
•
High accurate sensors
Offsets with mm accuracy
Angles with 0.01° accuracy
Correct calibrations
• Position jumps (xy) of the ROV
• Why
The effects of flexibility on calibrations

5. The effects of flexibility on calibrations

6. The effects of flexibility on calibrations

7. Loaded
Empty
The effects of flexibility on calibrations

8. 60.000
Top view
Surveyed
Fwd
50.000
• Points SB and PS
40.000
30.000
20.000
PS Dock
SB Dock
10.000
PS floating
SB floating
0.000
-15.000 -10.000 -5.000
0.000
5.000
10.000 15.000
-10.000
-20.000
-30.000
Aft
-40.000
The effects of flexibility on calibrations

9. Difference between docked and floating
0.120
0.120
0.100
0.100
0.080
0.080
0.060
0.060
SB
Series2
Best fit circle SB
0.040
0.020
0.040
Average angle
(pitch err)
between Sb and
Ps: 0.13°
0.020
0.000
-40.000
-30.000
-20.000
-10.000
0.000
0.000
10.000
20.000
30.000
40.000
50.000
The effects of flexibility on calibrations
60.000
Best fit circle PS

10. Example 2: Temperature
• High accurate sensors
• Offsets with mm accuracy
• Angles with 0.01° accuracy
• Placing tolerance gravel +/-35mm
• Temperature a significant part of the error
budget.
• Height influenced by temperature
The effects of flexibility on calibrations

11. 65m
The effects of flexibility on calibrations

12. • Geometry December +5°C
– Steel +5°C
• First calibration May +23°C
Steel +30°C;Water +25°C
• Last calibration August +35°C
Steel +60°C ;Water +27°C
The effects of flexibility on calibrations

13. 35m
The effects of flexibility on calibrations

14. coefficient of linear expansion
Steel
1.20E-02
mm/°C
Aluminium 2.30E-02
mm/°C
temp [°]
Steel
Lenght [m]
0
5
10
15
20
25
30
35
40
45
50
55
60
65
5
10
15
20
25
30
35
40
45
50
55
60
65
70
0.3
0.6
0.9
1.2
1.5
1.8
2.1
2.4
2.7
3.0
3.3
3.6
3.9
4.2
0.6
1.2
1.8
2.4
3.0
3.6
4.2
4.8
5.4
6.0
6.6
7.2
7.8
8.4
0.9
1.8
2.7
3.6
4.5
5.4
6.3
7.2
8.1
9.0
9.9 10.8 11.7 12.6
1.2
2.4
3.6
4.8
6.0
7.2
8.4
9.6 10.8 12.0 13.2 14.4 15.6 16.8
1.5
3.0
4.5
6.0
7.5
9.0 10.5 12.0 13.5 15.0 16.5 18.0 19.5 21.0
1.8
3.6
5.4
7.2
9.0 10.8 12.6 14.4 16.2 18.0 19.8 21.6 23.4 25.2
2.1
4.2
6.3
8.4 10.5 12.6 14.7 16.8 18.9 21.0 23.1 25.2 27.3 29.4
2.4
4.8
7.2
9.6 12.0 14.4 16.8 19.2 21.6 24.0 26.4 28.8 31.2 33.6
2.7
5.4
8.1 10.8 13.5 16.2 18.9 21.6 24.3 27.0 29.7 32.4 35.1 37.8
3.0
6.0
9.0 12.0 15.0 18.0 21.0 24.0 27.0 30.0 33.0 36.0 39.0 42.0
3.3
6.6
9.9 13.2 16.5 19.8 23.1 26.4 29.7 33.0 36.3 39.6 42.9 46.2
3.6
7.2 10.8 14.4 18.0 21.6 25.2 28.8 32.4 36.0 39.6 43.2 46.8 50.4
3.9
7.8 11.7 15.6 19.5 23.4 27.3 31.2 35.1 39.0 42.9 46.8 50.7 54.6
The effects of flexibility on calibrations
5
10
15
20
25
30
35
40
45
50
55
60
65
65 m
3.9
7.8
11.7
15.6
19.5
23.4
27.3
31.2
35.1
39.0
42.9
46.8
50.7

15. Thank you for
your attention
Questions?
The effects of flexibility on calibrations