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Multibeam bathymetry has historically meant a crewed boat, a pole-mounted sonar, and a survey team exposed to swift current, thin ice, or contaminated water. The Cerulean Surveyor 240-16 MBES collapses that footprint into a 2.4 kg payload you can fly on a mid-size UAV or mount on a USV, capturing dense, full-coverage seabed data without putting a crew on the water. This guide explains how the system works, how multibeam compares with single-beam, and where it delivers the clearest safety and efficiency gains for hydrographic and dredging teams.
Why drone-borne bathymetry changes the survey calculus
Conventional hydrographic surveys require a manned vessel, a calibrated pole or hull mount, and trained personnel operating in conditions that are often hazardous: fast-moving rivers, tailings ponds, near-shore surf zones, or partially frozen reservoirs. Mobilizing a boat is slow and expensive, and every hour on the water carries risk. Mounting a compact multibeam echo sounder (MBES) on an uncrewed surface vessel (USV) or a UAV removes the crew from the danger zone while increasing the density and repeatability of the data you collect. For water-resource and dredging teams, that translates directly into faster mobilization, lower day-rates, and the ability to survey sites that were previously off-limits.
The Cerulean Surveyor 240-16 MBES is built for exactly this workflow. It is a 240 kHz multibeam system weighing 1.8 kg for the sensor and 2.4 kg as a complete system, optimized for integration on mid-size platforms such as the DJI M300 RTK, M350 RTK, M400 RTK, and Pixhawk-class drones. Explore the full lineup in our drones for bathymetric surveys collection.
Multibeam vs single-beam: what the difference buys you
A single-beam echo sounder fires one narrow acoustic pulse straight down and records a single depth directly beneath the transducer. To build a surface model you fly tightly spaced, overlapping lines and interpolate between them. The EchoLogger ECT-400S is a strong example of this class: a 450 kHz single-frequency sounder with a 5-degree conical beam, a 0.15 to 100 m measurement range, and a sensor weighing just 275 g. For deep, simple profiles or a low-cost first deployment, single-beam is efficient and dependable.
Multibeam, by contrast, transmits a wide cross-track fan and resolves many soundings per ping across that swath. The Surveyor 240-16 uses an 80-degree cross-track transmit beam and a 16-element receive array with angle-of-arrival (AoA) processing to detect 10 to 15 targets per ping across the swath. That means full-coverage bathymetry on a single pass instead of dense interpolated lines, capturing channel walls, scour holes, and structure that a single downward beam would miss entirely.
| Parameter | Surveyor 240-16 MBES | EchoLogger ECT-400S (single-beam) |
|---|---|---|
| Operating frequency | 240 kHz | 450 kHz |
| Coverage | 80° cross-track swath, 10–15 targets/ping | Single 5° conical beam |
| Measurement range | 0.5 – 50 m | 0.15 – 100 m |
| Angular resolution | < 1° (AoA) | Not applicable |
| Range resolution | 0.5% of range setting | — |
| System weight | 2.4 kg | 1.6 kg (standard housing) |
If your work centres on volumetric change, structure mapping, or full-coverage hydrographic charts, multibeam is the right tool. For straightforward depth profiling on a budget, browse our echo sounders for drones collection to compare options.
How the Surveyor 240-16 achieves resolution at depth
The 240 kHz operating frequency gives the Surveyor strong bottom definition in the shallow-to-moderate band where most inland and near-shore hydrographic work happens, from 0.5 to 50 metres. Rather than relying solely on conventional beamforming, which yields roughly a 7-degree beam, the system applies angle-of-arrival estimation to achieve sub-degree angular resolution (less than 1 degree) across the full 80-degree swath. Combined with a range resolution of 0.5% of the range setting, this produces tightly positioned soundings suitable for engineering-grade surfaces.
Built-in motion compensation
A multibeam sounder is only as accurate as its attitude data. The Surveyor 240-16 includes a built-in inertial measurement unit (IMU) that compensates for pitch and roll, keeping soundings stable as the platform moves on a wake or in light chop. Position and heading are supplied by the drone's GNSS, so the payload inherits the RTK accuracy of the host aircraft without a separate positioning system.
Integration: Ethernet, SkyHub, and clean payload management
The Surveyor connects over Ethernet with a SkyHub connector, which keeps integration straightforward on supported DJI and Pixhawk-class platforms. SkyHub handles payload power, data logging, and terrain-aware automation, and the same ecosystem supports a range of advanced sensors. To understand how this fits a broader multi-sensor program, see our pillar guide on advanced drone surveying with SPH Engineering and our breakdown of the role of SkyHub in integrating complex drone payloads. Teams running mixed payload fleets often pair bathymetry with subsurface work such as airborne ground penetrating radar with ZondAero.
Safety and efficiency gains over crewed boats
- No crew in the hazard zone. Surveying swift rivers, tailings ponds, or thin-ice reservoirs from shore eliminates the most serious exposure of traditional hydrographic work. Our case study on surveying hazardous tailings ponds illustrates the point.
- Faster mobilization. A 2.4 kg payload and a host drone replace a trailer, a boat, and a launch ramp, cutting setup from hours to minutes.
- Full-coverage data in a single pass. The 80-degree swath means fewer survey lines and less time on station versus single-beam interpolation.
- Repeatable volumetric monitoring. Consistent flight lines and RTK positioning make pre- and post-dredge surveys directly comparable for accurate volume calculation.
Dredging-volume calculation
For dredging teams, the value is in the difference. A baseline multibeam surface captured before dredging, compared against an as-built surface afterward, yields cut-and-fill volumes with confidence. Dense full-coverage soundings reduce the interpolation error that erodes volume accuracy with single-beam data, which matters when payment or environmental compliance hinges on the cubic-metre figure. Repeating the survey on a fixed cadence also tracks sedimentation and scour over time without remobilizing a vessel each cycle. To scope a system for your sites, request a quote and our team will help match the platform to your depth range and host drone.
Key Takeaways
- The Surveyor 240-16 is a 240 kHz multibeam echo sounder weighing 2.4 kg as a complete system, optimized for mid-size UAV and USV platforms.
- It covers an 80-degree cross-track swath and resolves 10 to 15 targets per ping, delivering full-coverage bathymetry on a single pass.
- Angle-of-arrival processing achieves sub-degree angular resolution with a range resolution of 0.5% of the range setting over a 0.5 to 50 m depth range.
- A built-in IMU compensates for pitch and roll, while position and heading come from the host drone's RTK GNSS.
- Multibeam captures channel walls and structure that a single-beam sounder like the ECT-400S would miss between lines.
- Flying or floating the sensor keeps crews out of swift current, contaminated water, and thin-ice hazards.
- Dense before-and-after surfaces enable accurate, repeatable dredging-volume calculation without remobilizing a boat.
