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Unit 2.b. Phases of a Hydrographic Survey Captain M K Barritt RN

Unit 2.b. Phases of a Hydrographic Survey Captain M K Barritt RN. Phases of a Hydrographic Survey. Preliminary Liaison Establishment of control and calibration of equipment Area search Investigations Ancillary observations. Preliminary Liaison.

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Unit 2.b. Phases of a Hydrographic Survey Captain M K Barritt RN

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  1. Unit 2.b. Phases of a Hydrographic SurveyCaptain M K Barritt RN

  2. Phases of a Hydrographic Survey • Preliminary Liaison • Establishment of control and calibration of equipment • Area search • Investigations • Ancillary observations

  3. Preliminary Liaison • Before a survey commences, liaison with other authorities is essential. • Fishery Liaison Officers for de-confliction. • Port Control Offices. • Coast Guard for Navigational Warnings.

  4. Preliminary Liaison • Before a survey commences, liaison with other authorities is essential. • Fishery Liaison Officers for de-confliction. • Port Control Offices. • Coast Guard for Navigational Warnings.

  5. Establishment of control • Horizontal: How will I fix my position, and preferably with more precision than the subsequent chart user? • Vertical: How can I make allowance for change of tidal height?

  6. Calibration of equipment • Performance of equipment must be validated before and during survey: • Static and dynamic validation of navigational aids used for position-fixing. • Target or patch tests of sonar devices. • Constant monitoring of sound velocity. • Sampling of seabed.

  7. Error Budget - Example

  8. Tidal Reduction

  9. Comparison with previous work • What did previous surveyors find, and have we relocated or disproved their findings?

  10. Area Search • What tool is best: MBES +/- DCSS, SBES +/- DCSS? • What sort of traffic will navigate in this area? Who are the customers? • What are the general depths? • What sort of topography is expected? • Are many wrecks and obstructions expected?

  11. 6½ Knots s.o.a. in direction of strongest tidal streams Magnetometer Sidescan Sonar c.15 m Up to 1,200 metres

  12. SONAR COVERAGE

  13. TIME Sea surface return First seabed return SEABED DEPRESSIONS & ELEVATIONS Seabed depression identified by shadow preceding hard return Seabed elevation identified by shadow following hard return

  14. HAND-COMPILED SEABED TEXTURE TRACING

  15. SWATH WIDTH SWATH WIDTH MULTI-BEAM ECHO SOUNDERS Beam angle Depth

  16. Investigations

  17. Survey line 1 Survey line 2

  18. Ancillary Observations

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