RADAR project sea trial

7 - 13 July 2006, Nazare, Portugal.

1. Objectives: the RADAR’06 sea trial fulfills the generic objectives of the RADAR project (contract FCT POCTI/CTA/47719/2002) namelly,

  1. engineering test of a network of light acoustic-oceanographic buoys (AOBs) developed under the proejct;
  2. acquire acoustic data to allow testing at the sea an integrated system of acoustic tomography for “Rapid Environmental Assessment (REA)”;
  3. acquire environmental, water column, sea bottom and meterological data before, during and after the sea trial to allow the validation of the inversion results  and allow their assimilation into generic models for REA.

In particular the RADAR’06 sea trial follows under task 3 of RADAR project and acoustic data acquisition , concurrent oceanographic data tu support tasks 1 and 4 of the technical annex of the project.

2. Means to be employed a board NRP Auriga: 2 AOB's with 16 hydrophones, CTD, Lubell 1424HP acoustic source, 3 thermistor chains, 3 ADCPs.

NRP Andromeda

3. Test area:

Work area
4. Operations day by day:

Thursday 6/July - leave SiPLAB with 2 vehicles and equipment at 14:00; arrive at port of Figueira da Foz at 19:00; unload equipment from van and load aboard NRP Auriga; start installation of communications mast, base station and heavy computation cluster computers.

mounting communication mast
Friday 7/July
- continue equipment installation and configuration; AOB2 deck testing; at sunset IH CTD finally arrives and is embarked and secured; meteo forecast for saturday July 8th is 2m wave height and 20 knots wind out of Figueira da Foz; NRP Auriga master takes the decision to not go out on saturday.

Saturday 8/July
- just wait;

Sunday 9/july - left port of Figueira da Foz at 06:30 and went straight out to the west; at 09:30 approximately 20 nm out of port, 1.5 to 2 m wave height with 15 knots; ship rolling very unconfortable for working or navigating; maneuvering obliged to keep ship upwind/wave constantly at least at 0.5/1 knot speed. Forecast saying that wind should get fresher in the afternoon at about 20 kn wind and 2 to 2.5 m wave height. 12:30 - return to port.

Monday 10/july - left port of Figueira da Foz at 07:30 and went to southwest to the working area; covered skies but 0.5 m wave height and 5 knots wind;

10:30 reached position for work;  start deploying AOB2-002 through the ships' stern A-frame, array first and then buoy, ship was keeping about 1 knot ahead in order to keep hydrophone array clear from propellers; when the buoy hits the water array is pulling heavily on buoy's bottom and buoy is horizontal: mast hits badly the ship's hull; buoy is released.

reaching the AOB2-002 with the workboat

11:00 buoy does not communicates and decision is taken to deploy the workboat for approaching the buoy (photo to the left).

recovering AOB2-002

11:30 after shunting the water sensor the buoy still does not communicate and decision is taken to recover the buoy onboard the workboat (photo on the left).

12:00 - wireless antenna is found to be broken during deployment and even after antenna replacement the already shunted water sensor is not working; the water sensor is found to be in open circuit and eliminated from the circuit and replaced by bare wires;

12:30 - deployment of AOB2-001; this time the buoy is deployed by starboard with the crane and the operation works out very well, smooth and well coordinated by IH; after a few minutes the buoy is found again to not responding to base station calls;

13:00 - the workboat is again deployed and the buoy is checked for its wireless antenna and water sensor; after shunting the water sensor the buoy is still not on; at this point the buoy is again recovered on the workboat and taken onboard; on the deck the buoy still does not work and cables are checked and found that the battery power cable is (probably) not well connected - after reconnection the buoy instantly works and responds to all commands;

reaching AOB2-001 with workboat

14:00 - decision is taken to redeploy AOB2-002 with the water sensor eliminated and therefore powered from the deck;

- the buoy is in the water, turned on and communicating; the HP1424 sound source is deployed from starboard side using the crane and maintained at approximately 10 m depth (left photo below); transmissions start; this time signals are received on the array hydrophones but strongly saturate; several alternatives are tested: increase dynamics, reduce signal power, etc...It seems that saturation happens at the pre-amplifier level at 3.8 Veff and is not signal dependent; saturation slightly varies from hydrophone to hydrophone; once in a while between two saturations a piece of LFM can be clearly seen (photo below). Decision is taken to recover the buoy and the HP1424 sound source.

deploying HP1424 sound source
repairing AOB2 wifi antenna
emitted signals
the lab aboard NRP Auriga

15:30 - leave working site and head to port; start packing equipment since meteo forecast gives 2.5 m height and 20 knots wind for next 3 days so, decision is taken to end radar'06 sea trial and pack all equipment.

18:00 - return to port of Figueira da Foz;

Thursday 11 July - load van and car and return from Figueira da Foz to SiPLAB

The RADAR'06 team (from left to right): Nelson, Fred, Celestino, Sergio and Cristiano (NRP Auriga behind)
the team

Test plan: version 1.1 (28jun06)  here
Cruise Report: here

Last update: September 3, 2006