Deformation effects
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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
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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.
Transcript of Deformation effects
Deformation effects on vessels The effects of flexibility on calibrations
HSB Workshop Vessel Geometry and Calibrations15 January 2014
Erich Gaikhorst
The effects of flexibility on calibrations
Index
• Two examples • Fallpipe vessels– Flexibility– Temperature
The effects of flexibility on calibrations
Remaining error after calibration
The effects of flexibility on calibrations
Remaining error
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)
+
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
The effects of flexibility on calibrations
The effects of flexibility on calibrations
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The effects of flexibility on calibrations
-15.000 -10.000 -5.000 0.000 5.000 10.000 15.000
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Top view
PS DockSB DockPS floatingSB floating
Fwd
Aft
Surveyed
• Points SB and PS
The effects of flexibility on calibrations
-40.000 -20.000 0.000 20.000 40.000 60.000 80.0000.000
0.020
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0.060
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0.100
0.120
0.000
0.020
0.040
0.060
0.080
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SBSeries3Best fit circle SBBest fit circle PS
Average angle (pitch err) between Sb and Ps: 0.13°
Difference between docked and floating
The effects of flexibility on calibrations
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
65m
The effects of flexibility on calibrations
• Geometry December +5°C– Steel +5°C
The effects of flexibility on calibrations
• First calibration May +23°CSteel +30°C;Water +25°C
• Last calibration August +35°CSteel +60°C ;Water +27°C
The effects of flexibility on calibrations
35m
Steel Lenght [m]
temp [°]
0 5 10 15 20 25 30 35 40 45 50 55 60 65 705 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
10 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 8.415 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 12.620 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 16.825 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 21.030 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 25.235 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 29.440 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 33.645 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 37.850 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 42.055 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 46.260 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 50.465 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
coefficient of linear expansionSteel 1.20E-02 mm/°CAluminium 2.30E-02 mm/°C
The effects of flexibility on calibrations
65 m5 3.9
10 7.815 11.720 15.625 19.530 23.435 27.340 31.245 35.150 39.055 42.960 46.865 50.7
The effects of flexibility on calibrations
Thank you for your attention
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