Keywords : focus

Focus on the smf

the multibeam sounders on the Pourquoi pas ?

The R/ V Pourquoi pas? will be equipped with two multibeam sounders provided by the Danish company RESON for surveying the seabed and under sea cartography:

  • a 100kHz system: Seabat 7111, dedicated to coastal hydrographic surveys and exploration of the continental shelf and the top of the continental slope.
  • a Seatbat 7150 12/24kHz dual-frequency system. This sounder will have two operating modes:
    • a "wide coverage" (12kHz) mode for general exploration surveys at great depths (200/12000 metres), covering a wide swathe (20km),
    • a "high resolution" mode (24kHz), for detailed exploration: sites where submersibles will be used, for example surveying sites.


Main characteristics

Expected performance

5 x P if P<1000m

20km if P>1000m

Max (1m, 0.3% P)

Seabat 7111 antenna

Seabat 7150 antenna


The acoustic antennae will be installed in a pod suspended under the ship's hull, called a "gondola". This is a heavy structure, independent of the hull, sited a few dozen centimetres from the keel and connected to the hull with streamlined struts.

The shallow-water multibeam sounder will be installed in a fairing infront of the gondola.

The gondola also houses the transducers for the ship's other acoustic equipment:

  • Eramer / Triton Elics sediment penetrator (2 to 8kHz)
  • Simrad EA600 single-beam sounder (12/38/200kHz)
  • RDI Ocean Surveyor doppler current profiler (38/150kHz)

The shape and underside of the gondola of the Pourquoi pas? have been approved during tests on a scale model at the naval dock in the Netherlands.

Data acquisition / processing

In real-time, the bathymetry and reflectivity data will be acquired and stored using TECHSAS software. It will be displayed using the SUMATRA software.

In batch processing, the data will be processed using the CARAIBES software package.