Move a position reference frame to the work deck. Presentation by Nicolàs de Hilster (Starmountain Survey and Consultancy) en Erich Gaickhorst (GeoVisie).

1. N. de Hilster
E. Gaikhorst
HSB Workshop Vessel Geometry and Calibrations
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The Inverted Heading Calibration:
a field case
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2. Project Outline
Create a copy of the reference
marble on the aft weather deck.
Required heading accuracy: 3'
(0.05°)
While being afloat!
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3. Traverse?
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4. Or direct?
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5. Project Solution
No direct line of sight
Traversing not possible
Solution: the inverted
heading calibration
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6. Implementation
dFOG (Geovisie)
autocollimation set (Starmountain)
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7. Autocollimation Set
Tilting base for T2
Groove for FOG pins
Alignment accuracy: 0.002°
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8. Autocollimation Set
2D prism target
Alignment accuracy: 0.002°
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9. Autocollimation
Rotating bases for FOG and T2
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10. Procedure
dFOG for initial pitch and roll
B
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A
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11. Procedure
Physical heading alignment
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12. Procedure
dFOG for final pitch and roll
B
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A
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13. Procedure
dFOG on the weather deck
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14. Procedure
Create Master Training Datum
Markers
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15. Procedure
Repeated on the other side
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16. Result
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17. Quality Control
Post Alignment Check with dFOG
Independent survey of all six markers
Calculation of parallelism (target: 3')
Vessel
dHeading
dRoll
1
2.5' (0.72mm/m)
1.0' (0.29mm/m)
2
0.1' (0.02mm/m)
1.5' (0.44mm/m)
3
0.9' (0.25mm/m)
2.1' (0.61mm/m)
Average
1.1' (0.33mm/m)
1.5' (0.45mm/m)
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18. Conclusion
Accurate gyro's (FOGs) can be used
to transfer heading on dynamic
objects
Sensors of the highest accuracy are
required
Achievable accuracy approximately a
third of the FOG specification
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