What's the difference between Multibeam Echo Sounder (MBES), Side Scan Sonar (SSS), and Single Beam Echo Sounder (SBES)?

One question I hear quite often is:

"What's the difference between Multibeam Echo Sounder (MBES), Side Scan Sonar (SSS), and Single Beam Echo Sounder (SBES)?"

The truth is, there isn't a "best" system Each one is designed for a different purpose, and choosing the right tool depends on the project's objectives. Here's a simple comparison:

🔹 Multibeam Echo Sounder (MBES)

What it does Measures water depth across a wide swath beneath the vessel, creating a high-resolution 3D model of the seabed.

Advantages: ✔ High-density bathymetric data ✔ Excellent seabed coverage ✔ Ideal for detailed terrain mapping

Limitations: • Higher equipment and operating costs • Requires accurate calibration and sound velocity corrections

Best used for: Bathymetric surveys, offshore construction, pipeline routes, dredging, port development, and cable route investigations.

🔹 Side Scan Sonar (SSS)

What it does: Produces detailed acoustic images of the seabed, highlighting objects, textures, and features rather than measuring depth directly.

Advantages: ✔ Excellent target detection ✔ Identifies debris, wrecks, rocks, and pipelines ✔ Provides detailed seabed imagery

Limitations: • Does not provide accurate bathymetric depths on its own • Image quality depends on towfish altitude and survey conditions

Best used for: Pipeline inspections, UXO surveys, search and recovery operations, environmental assessments, and seabed feature detection.

🔹 Single Beam Echo Sounder (SBES)

What it does: Measures depth directly beneath the vessel using a single acoustic beam.

Advantages: ✔ Simple to operate ✔ Cost-effective ✔ Reliable for routine depth measurements

Limitations: • Limited seabed coverage • Can miss features located between survey lines

Best used for: Navigation surveys, river and canal surveys, reservoirs, small harbors, and projects where full seabed coverage isn't required.

The most important takeaway?

These systems don't compete with each other they complement each other. On many offshore projects, combining MBES for detailed bathymetry with Side Scan Sonar for target detection provides a far more complete understanding of the seabed than either system could deliver alone.