The document discusses the inverted heading calibration conducted by N. de Hilster for achieving precise heading accuracy (3' or 0.05°) on a vessel while afloat. The procedure involved using a DFog for initial and final pitch and roll adjustments, alongside an autocollimation set for high alignment accuracy. The results indicate that accurate FOGs can effectively transfer heading on dynamic objects, achieving a precision that is about one-third of the FOG specification.

1. N. de Hilster
E. Gaikhorst
HSB Workshop Vessel Geometry and Calibrations
15 January 2014
The Inverted Heading Calibration:
a field case
15 January 2014
N. de Hilster, The Inverted Heading Calibration: a field case
1/18

2. Project Outline
Create a copy of the reference
marble on the aft weather deck.
Required heading accuracy: 3'
(0.05°)
While being afloat!
15 January 2014
N. de Hilster, The Inverted Heading Calibration: a field case
2/18

3. Traverse?
15 January 2014
N. de Hilster, The Inverted Heading Calibration: a field case
3/18

4. Or direct?
15 January 2014
N. de Hilster, The Inverted Heading Calibration: a field case
4/18

5. Project Solution
No direct line of sight
Traversing not possible
Solution: the inverted
heading calibration
15 January 2014
N. de Hilster, The Inverted Heading Calibration: a field case
5/18

6. Implementation
dFOG (Geovisie)
autocollimation set (Starmountain)
15 January 2014
N. de Hilster, The Inverted Heading Calibration: a field case
6/18

7. Autocollimation Set
Tilting base for T2
Groove for FOG pins
Alignment accuracy: 0.002°
15 January 2014
N. de Hilster, The Inverted Heading Calibration: a field case
7/18

8. Autocollimation Set
2D prism target
Alignment accuracy: 0.002°
15 January 2014
N. de Hilster, The Inverted Heading Calibration: a field case
8/18

9. Autocollimation
Rotating bases for FOG and T2
15 January 2014
N. de Hilster, The Inverted Heading Calibration: a field case
9/18

10. Procedure
dFOG for initial pitch and roll
B
15 January 2014
A
N. de Hilster, The Inverted Heading Calibration: a field case
10/18

11. Procedure
Physical heading alignment
15 January 2014
N. de Hilster, The Inverted Heading Calibration: a field case
11/18

12. Procedure
dFOG for final pitch and roll
B
15 January 2014
A
N. de Hilster, The Inverted Heading Calibration: a field case
12/18

13. Procedure
dFOG on the weather deck
15 January 2014
N. de Hilster, The Inverted Heading Calibration: a field case
13/18

14. Procedure
Create Master Training Datum
Markers
15 January 2014
N. de Hilster, The Inverted Heading Calibration: a field case
14/18

15. Procedure
Repeated on the other side
15 January 2014
N. de Hilster, The Inverted Heading Calibration: a field case
15/18

16. Result
15 January 2014
N. de Hilster, The Inverted Heading Calibration: a field case
16/18

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)
15 January 2014
N. de Hilster, The Inverted Heading Calibration: a field case
17/18

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
15 January 2014
N. de Hilster, The Inverted Heading Calibration: a field case
18/18