Oficina Oceanográfica Naval Instalación de Sistema Multihaz en Botes de Oportunidad

1. Oficina Oceanográfica Naval Instalación de Sistema Multihaz en Botes de Oportunidad

2. International Division’sMultibeam Equipment Data Acquisition Computer Freewave Data link Trimble MSGR Digiboard Seabird Sound Velocity Profiler Applanix POS/MV Attitude Sensor Reson 9001 Reson 8101

3. Recent Multibeam Operations in Latin America Instituto Oceanográfico de la Armada del Ecuador • Vessel - LAE Rigel • Length - 19.96 m • Draft - 1.5 m • Speed - 12 knots • Twin Screw Dirección General Adjunta de Oceanografía, Hidrografía y Meteorología de la Armada de México • Vessel - ALACRAN P-301 • Length - 16.7 m • Draft - 0.959 m • Max. Speed - 30 knots • Twin Screw

4. Razones para seleccionar instalación de Multihazsobre el costado • Instalación menos costoza • Montura fácilmente modificada • Uso en multiplicidad de lanchas • Más propenso a ruido (ya sea mécanico o eléctrico) y vibración • Reducción de rendimiento de haces más cercanos al casco de la lancha

5. Pre-requisitos para operaciones de levantamientos Multihaz • Características ambientales del área de trabajo • Tipo de levantamiento • Capacidades y limitaciones de • Sistema de sonar a usar • Sensores de movimiento y sistema de posicionamiento • Software de colección de datos • Hardware y software de procesamiento de datos

6. Vessel Suitability Mount Design Installation Test and Evaluation Calibrations Quality Assurance Data Collection Data Cleaning Data Analysis Keys to SuccessfulOver-the-Side Multibeam Surveys

7. Vessel Suitability • Size • Small vessels • Desirable for high frequency systems • Maneuverable in shallow and restricted areas • Large vessels • More difficult to design mount • Longer poles required to clear draft of the vessel • Vibration and movement are increased

8. Vessel Suitability LAE RIGEL • Size ARM ALACRAN P-301 20 meters Andrés Diaz 16.7 meters 9 meters

9. Vessel Suitability • Construction • Wood, Fiberglass or Aluminum require • Rigid hulls and gunwales for pole support • Bolt-through-hull installation • Inside Bulkhead access at waterline • Steel Hull Construction. • Hull-side brackets can be welded to hull • Care must be exercised to avoid internal fuel tanks.

10. Vessel Suitability • Propulsion and Maneuvering • Single screw v/s Twin screw • if twin screw - synchronized and balanced • Track-keeping capabilities -Slow/Fast • Top speed matching capabilities of sonar system • Work Space • Room for equipment and personnel • Climate controlled

11. Vessel Suitability • Suitable location for mounts • Transducer • Away from noise sources - electrical/mechanical • Hull characteristics - water flow • Close as possible to pitch axis • Attitude Sensors (POS/MV) • IMU - CoG or near transducer • GPS- POS / MV Antenna (heading) multi-path, movement, vibration free • If vessel is suitable, make measurements for the type on mount to be used

12. Vessel Suitability Mount Design Installation Test and Evaluation Calibrations Data Collection Data Cleaning Data Analysis Quality Control Over the Side MultibeamPresentation

13. POS/MV Mount Over-the-side Transducer Mount Side view Mount Design • Material -aluminum • Anti-corrosive • Easy to machine • easy on drill bits

14. Mount Design • Requirements • POS/MV • Both antenna on same rigid plate • Minimum 1 meter Phase Center Separation • Minimal movement and vibration Design or Modify support as needed 1 meter Antenna Plate • POS/MV Mount • Location • Highest object on vessel (preferably) • Firmly attached to stable superstructure

15. Transducer Mount Design

16. Hull Hull side Mounting Bracket Mount Design Vessel Measurements for Side-mounting w Dimensions (L x d x w) and  of hull-side mounting brackets are determined by the Internal Vessel Construction and External Hull Geometry Measurements between Stiffeners d  L

17. Reson-Style Over-the-Side Design Mount Design Backing Plates • Plate Thickness • minimum 3/8 ” (1/2 ”preferred ) • Brackets - depends on length of bracket Sleeve Hull Transducer Pol e Plate Slotted holes for fine adjustments Plate-side Bracket Mounting Collars Hull- side Bracket Mounting Brackets

18. Mount Design Not shown in diagram Plate as close to hull as possible or against Maximum separation of sleeves and placement close to water-line: Increases Stability of pole Plate and Pole Length After assembly Drill hole and insert bolt to prevent slippage of mount Top Sleeve close to Gunwale Bottom Sleeve close to water line as possible Water Line Max Pole thickness for increased rigidity Pole length determined by draft and beam width of sonar

19. Mount Design

20. Vessel Suitability Mount Designs Installation Test and Evaluation Calibrations Data Collection Data Cleaning Data Analysis Quality Control Over the Side MultibeamPresentation

21. Installation requires vessel • to be removed from water • Smaller vessels = Reduced costs Installation

22. POS/MV Mount

23. Transducer Mount Installation Verify all measurements Verify mount design before drilling the first hole

24. Transducer Mount Installation

25. Equipment Installation • Equipment Installation Install Transducer Head on pole • Use all isolation bushings and washers • Fully connect transducer cable and tie-wrap • Route cable along pole and attach (duct tape) • Install GPS and/or POS/MV Antenna • Direct POS/MS antenna to same orientation • Attach cables and route to controller

26. Interface Survey Equipment • Connect survey systems to data collection computer

27. Vessel Suitability Mount Designs Installation Test and Evaluation Over the Side MultibeamPresentation • Calibrations • Data Collection • Data Cleaning • Data Analysis • Quality Control

28. Navigation System Tide gauge Verification Sound Velocity Profiler Data collection Attitude/ Heading sensor Sonar System Test and Evaluation

29. Navigation Systems Test • Purpose • Accurate navigation for Sonar calibrations and Quality Control • IHO Standard Horizontal Accuracy for minimum horizontal position errors. • Methodology • 24-hour Static tests conducted over 1st Order Geodetic Station with 10 cm accuracy @ 2 • Data collected compared to benchmark to 95% confidence level (2) • Results • Static DGPS 24 hour test @ 95% level = 0.19meters • Insert static result into Error Budget Model for final horizontal accuracy error • 0.50 m total modeled error for horizontal sounding position ONLY • desirable for calibrations and survey operations • Errors random about the known point

30. Tide gauge EvaluationPredicted vs. Real17 day period • New installation or existing • Level • Check staff & time • Compare predicated • Real • Predicted • Check tide gage for accuracy Max Variation .27 m

31. Sonar System Test • Purpose • Verify proper installation and operation of Over-the-side Reson 8101 MB system • Methodology • Static (dock-side) Testing • Mount stability in down-locked position - passed • full swath return - passed • Minimal side-lobe interference with hull

32. Sonar System Test • Dynamic Testing • Mount stability at survey speed • Swath return at survey speed • Sonar System failing speed test demonstrated on next slide

33. Sonar System Dynamic Test RESON Display Center beams Only Missing outer beams Noise - ?

34. Sonar Dynamic TestFailure Analysis • Possible Causes • Cavitations • Electrical Noise • Mechanical Noise • Transducer Cable • Sonar System

35. Failure Isolation • System functions when not moving • Conducted following tests • Vessel to full speed and shut-down all engine and electrical • Eliminated flow related problems • Full throttle-dead in water - screws not engaged • Eliminated electrical problems • Engage screws • Noise immediately evident

36. Failure Isolation • Confirmed mechanical vibrations • Possibilities • Harmonics induced by unbalanced twin screws • Vibrations from engines • Weakened hull structure • Temporarily lowered sonar head using line and saw improvement in signal

37. Sonar TestSolutions • Local machinist milled extension pole to insert inside original with 1 mm tolerance image • Damped vibrations using wood bracing image and sand bags image • System received full beam coverage and survey commenced image

38. Sonar Dynamic Test Resumed Maximum Survey Depth Loss of outer beams at depth

39. Sound Velocity Increasing Sound Velocity Reflection Critical Angle Outer beam without Correction Outer beam with Correction Nadir

40. Sound Velocity ProfilerField Test • Multibeam systems require accurate sound velocity profiles • Sound velocity profilers must be properly calibrated, maintained and operated • Two profilers deployed and compared as a confidence test of systems

41. Seabird SBE-19Microsystems SVP 16Comparison

42. Final Evaluation • After all problems are defined and resolved • Develop reference surface DTM using beams close to nadir • Cross check lines run across this surface can be compared beam by beam for a full swath analysis Pre-Survey Stats • This will give you qualitative analysis of the quality of your survey data

43. Conclusions • All movement during multibeam surveys is undesirable • Unmeasured movement between reference frames can render data unusable • These are minimized by • Proper vessel selection • Mount design • Installation

44. Conclusions • All equipment must be tested for operation within the parameters of specifications • The environmental characteristics of the water that was ensonified during the survey, can not be determined post-time • The solution is • Calibration and testing of profilers prior to data collection

45. MR. ERIC L. VILLALOBOS HYDROGRAPHIC ENGINEER SHOA CAT A INTERNATIONAL DIVISION TEL: 228-688-4529 DSN: 828-4529 e-mail : villalobose@navo.navy.mil NAVAL OCEANOGRAPHIC OFFICE 1002 BALCH BLVD. STENNIS SPACE CENTER, MS 39522-5001 TEL : 228-688-4203 FAX : 228-688-5357