2 – 4 O c t o b r e O H I MACHC Seminar - Acapulco Hydrographic surveys « Instrumentation and methodology » Serge Allain - SHOM

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Strategy adopted for a survey depends on objective… Several criteria : - reconnaissance surveys - systematic coastal surveys - traffic lanes - searches for wrecks - type of survey: topography, landmarks, currents, bathymétry What users? What draughts? Navigation threshold? Ocean bottom changes? Knowledge a priori?

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco An example : strategy for bathymetric surveys by SHOM hydrographic vessel (1100T) 140+ standardizing documents, guides, procedures, user manuals for hydrographic surveys S-44

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Strategy adopted for a survey depends on objective… The strategy adopted a survey depends on the means actually available… Several criteria: - platforms (launches, vessels) - instruments, sensors (calibrated) - logistics (vehicles, radiocom., maintenance), - and… IHO trained, qualified, certified personnel!

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Strategy adopted for a survey depends on objective… The strategy adopted for a survey depends on the means actually available… Objectives + Means + Duration + Hazards (weather, frequency of breakdowns of equipment, obstructions, etc.) Optimization Organization Methods

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco The various phases Preparatory Work Execution Monitor time actually spent onshore or at sea Data processing ashore (UKHO)

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Preparatory work (1/2) Positioning geodetic systems, search for geodetic points, GPS targets, radiopositioning, interference, masks, projections Tide measurements of water height, models available for reduction of soundings offshore, observatories Sound velocity depending on the zone, the depth

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Preparatory Work (2/2) Exploitation of existing documents charts, fair sheets, local guides, sailing directions, aerial photographs, satellite images Preparation of plotting sheets drawing of sounding lines, identification of narrow zones, coverage Writing particular instructions « how? » : sensor parameters, associated, measurements, spacing of sounding lines, adjustments, applicable references

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Execution Calibration, Deployment of instruments (mooring, positioning beacons, tide gauges) Monitoring of defined routes Possible deployment of towed sensors Navigational warnings Measurements (bathymetry, oceanography, sedimentology…) Inspection of landmarks, coast views, buoys Topography, Toponymy …

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Instrument type (1/2) Multibeam and vertical echosounders for bathymetry, Side scan sonar for detection of obstructions and wrecks Magnetometer for detection of metal objets Tide gauges and current meters Grabs for bottom sampling Classification system for the superficial layer of sea bottom Sub-bottom profiler Broadcasting stations of GPS differential corrections (port and offshore soundings) GPS receivers and other measuring instruments for geodetic work (theodolite, level)

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Instrument types (2/2) Computer system PC and UNIX stations set up in real-time networks (data collection) And offline (processing) linked to a server - A0 plotter, A4 printer Data collection and processing software HYPACK for the preparation, collection and processing of single beam and sonar soundings CARIS HIPS/SIPS for processing multi-beam soundings (shallows / VH) CIRCE for processing multi-beam soundings (medium depths / BH) CARAÏBES for the display of MBS data

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Vertical echo sounder

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Vertical echo sounder z = 0.5 c dt Calibration at the helm Geometry of the beam e = 2z tg (  /2)

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Defects and corrections heave Lateral echo

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Sound Velocity measurement Sound Velocimeter

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco GPS Differential GPS

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Tides Pressure tide gauge

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Principle h = (Pgauge - P atm) / Rho.g Rho= voluminal mass of water g= gravity acceleration h Instrument zero

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Adjustment of tide gauge h Instrument datum Chart datum H

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Current meters Doppler effect Rotor

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Detection of obstructions Objective To detect obstructions between the regular sounding lines Means Side scan Sonar Magnetometer for detecting metal wrecks

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Side scan sonar

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Sounding Monitoring of sounding lines Evenly spaced out, corrected if uneven Direction of sounding lines Perpendicular to isobaths Cross lines of sounding Checking of consistency of measurements at intersections Interlines Increase the density of soundings by bringing lines closer together if the sea bottom is very uneven

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Verification at sea and on land Follow-up the first results in practically real time (exploitability, obstructions, wrecks, shallows)… in order to react before leaving the zone! Exploitation of predicted tide for checking at crossing points of the lines of sounding Positioning checks Checking of archiving of data (AND back-ups) Checking of calibration documents Analysis of raw measurement data

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Positioning validation reprocessing Positioning of soundings Link-up to antenna base Attitude corrections Reduction of soundings Velocity immersion of the base tide Processing

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Compiling Sheet papers Track lines bathymetry Obstruction research Files Wrecks Obstructions Tidal observations Current observations Surveys Chart marked up Technical Report

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Conclusion To ensure the quality of a survey it is necessary to: Define what is required To adapt the methodology and means to the requirement Assess what has been done Soundings Detection Measurements accuracy

2 – 4 O c t o b r e O H I MACHC Seminar - Acapulco Hydrographic Surveys « New Developments »

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Main methodology principles Systems qualification Mastering the configuration Quality control Bathymetry at SHOM ISO 9001:2000 certification SMF system

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Conclusions AlgorithmeContexte Historique Tests «BH1 l’Espérance » «BH2 : Lapérouse, Borda, Laplace » 2000 «VH 90 » Simrad EM12D Simrad EM1002S Atlas FS20 «BHO Beautemps Beaupré » Simrad EM1002S EM Fassmer launches Simrad EM m à 12000m 10m à 400m 0m à 100m 50m à 11000m 0m à 150m

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Conclusions AlgorithmContext Reviews Trials Multibeam data capature Several measurements per cycle Almost 100% coverage

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Example : Europa – May 2003 « Beautemps Beaupré » Data collected in Conclusions AlgorithmContext Rewiews Trials Data Volumes EM M soundings 16 hours Challenges Advantage Management, interaction, display, validation Statistical Exploration of the sea bottom relief 10.1 M soundings EM hours x25 EM 1002S M soundings 2 hours x2

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Conclusions AlgorithmContext Reviews Trials Improvement of display tools

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Conclusions AlgorithmContext Reviews Trials Types of errors Noise of the sounder Systematic Errors Occasional errors Performance estimation of the sounder x y z Pitching axis Heave axis Head ing MBS attitude P GPS Relative Position of the various sensors Time evolution of the orientation and of the position of the sensors

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Quality control – system integrity Calibration and specific SHOM sea trials at the time of installation Trials on flat sea bottom to serve as a reference : verification of the calibration in roll, calculation of the accuracy to 95% of the sounder, detection rates :

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Quality control – system integrity Trials on uneven seabed – wreck identification Trials on detection capacity on submerged targets

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Inclusion of an SMF system Attitude control unit Hull velocimeter Sound velocimeter GPS positioning Synchronisation

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Inclusion of an MBS system MBS EM 3000 POS/MV GPS Receiver AQUARIUS 5002 Hull velocymeter Smart SV Signaux GPS MBS system Actions inertielles Sounded area Environnement Réel Computing system LECTEUR DAT ? Sound velocymeter SV 5 XX GPS Antenna Application VH Fassmer Roll, Pitch, heading control + GPS

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Thales Navigation Aquarius Special Order Bathymetry (PS44) Geodesy, Topography WAAS/EGNOS, L1/L2, DGPS, LRK©, RTK Quantity : 25 Cost : 30 k€ Return

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Applanix POS/MV Attitude and heading control unit Corrects heave and roll for MBS WAAS/EGNOS, L1/L2, DGPS, RTK Quantity : 10 Cost : 80 k€ Return

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Future developments linked to main development and integrated coastal zone management Bathy-topography laser MBS Photogrammetry, spatial imagery hydrodynamic digital models

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco

2 - 4 O c t o b er O H I MACHC Seminar – Acapulco Conclusion La technologie au service de l’hydrographie…et des navigateurs Maîtrise totale de la qualité car responsabilité de l’Etat est engagée It is better not to know where you are and know that you don’t know, than to be convinced you know where you are when you are not Cassini