How Singlebeam and Multibeam Echo Sounders Differ and Which You Should Choose
The main distinction among systems lies in how many beams (or “soundings”) they can take per “ping” (per emitted pulse), and how widely they sample the seafloor. Single-Beam Echo Sounder (SBES) How It Works A single-beam echo sounder emits one acoustic pulse (or beam) straight downward (or nearly so) from the transducer. It listens for the return echo and measures the two-way travel time. It takes the fastest (shortest) return as the depth (i.e. the nearest point in that beam path) The beam typically has a certain angular width (e.g. 10°–30°) so that it covers a small footprint on the seafloor. Strengths of SBES Simplicity The system is mechanically and computationally simpler. Less hardware, fewer beams to manage. Lower Cost Because of the simpler design, single-beam systems are cheaper to procure, operate, and maintain. Easier Data Processing The data volume is far less. You get a single depth per ping, which is simpler to interpret, check, and edit. Good for Linear or Sparse Surveys If you only need spot depths, cross sections, navigation checks, or small-scale monitoring, SBES is often sufficient. Lower Power / Equipment Footprint Less demanding in terms of power, mounting, and vessel space. Limitations of SBES You only get a single depth point per ping. Meaning large gaps between lines if the survey spacing is coarse. You don’t get information about the seafloor adjacent to that point (i.e. sideways). For complex terrain or detailed mapping, you must run many survey lines, which takes more time. Terrain or features between your lines may be missed entirely. Multibeam Echo Sounder (MBES) How It Works A multibeam echo sounder emits a fan or swath of acoustic energy across a broad angle beneath the vessel (i.e., spanning side to side). On reception, it uses beamforming to split the returned echoes into multiple directional beams, each corresponding to a specific angle across track. Each beam yields a depth measurement. Thus, in a single ping cycle, you may get tens to hundreds (or even more) of individual soundings across the seafloor beneath and to the sides of the vessel. It also often collects backscatter data (i.e. intensity of echo) and sometimes water-column features. Strengths of MBES Wide Swath Coverage & Efficiency Because each ping covers a swath (often many times the water depth in width), you can map large areas faster and more completely. High Density & Redundancy Many overlapping beams mean more data points, more detail, and redundancy (helpful in removing bad data). Better Terrain Characterization You can detect slopes, features, ridges, valleys, obstacles, and more subtle morphology. Gaps between lines are minimized. Backscatter & Additional Data Backscatter allows inferences about seafloor composition (hardness, texture). Water column data can reveal objects like bubble plumes or fish schools. High Resolution in Shallow Water In shallower depths, MBES can resolve fine details because beam spacing is tighter. Limitations & Challenges of MBES Higher Cost The systems, support hardware, calibration, and maintenance are more expensive. More Complex Setup & Calibration You need careful calibration, sound velocity profiling, motion compensation (roll, pitch, heave, yaw), and more involved data processing. Data Volume & Processing Load Huge data sets that require powerful processing, storage, filtering, and quality control. Performance in Deep Water / Remote Areas In extremely deep water, the beam spacing becomes large, reducing resolution. Also, coverage diminishes with depth. Hardware Demands & Vessel Requirements Mounting, power, stability, motion sensors, navigation systems must be robust. Side-by-Side Comparison Feature / Metric Single-Beam (SBES) Multibeam (MBES) Beams per ping 1 depth point Many (tens to hundreds) across a swath Coverage per pass Narrow (just under track) Wide swath (across-track) Survey speed Slower for area coverage Faster, more efficient Data density Sparse (depending on line spacing) High density Terrain detail Limited Can capture slopes, features, morphology Backscatter data Usually none (just depth) Yes, often simultaneous Complexity Low High Cost Low to moderate High Suitable for Spot checks, linear transects, shallow, restricted budget Full bathymetric mapping, detailed surveys, large areas Calibrations & corrections Simpler More rigorous (motion compensation, sound velocity, etc.) Performance in deep water Good (for point depth) Coverage and resolution decrease with depth Which One Should You Choose? The ideal choice depends on your survey objectives, budget, vessel capability, and area size. Here are guidelines to help: Use Single-Beam If: You only need point depths (e.g. for navigation checks, depth verification, dredging checks, small channels). The survey area is small or your coverage needs are limited. Budget or equipment constraints are tight. You need something quick, simple, and easy to operate with minimal staff or processing infrastructure. The terrain is relatively flat and you don’t expect complex features. Use Multibeam If: You need comprehensive coverage — no gaps, high spatial detail. You are mapping a large area (coastal zones, offshore, seafloor mapping). You need terrain details, slopes, features, and want to detect hazards, ridges, channels. You want backscatter or water column data as extra information (e.g. substrate type, plumes, fish). Time is critical, you want to minimize survey time by covering more area per pass. You have the budget and capability to manage complex data and equipment. In many modern hydrographic and geophysical surveys, multibeam has become the preferred standard, especially for charting, marine construction, resource mapping, and scientific surveys. That said, single-beam still holds relevance in many use cases where full coverage or high resolution isn’t required. Hybrid / Complementary Use Often, surveys may combine both: Use SBES as a backup or verification tool. Use multibeam for broad mapping and SBES for deep channels or areas where MBES cannot reach. In shallow or constrained areas (e.g. very shallow water or near structures) where multibeam may struggle, a single-beam sensor may still be viable. Also, there’s a development of multispectral multibeam systems that combine capabilities across frequency bands to improve substrate discrimination, and better backscatter processing. Ready to Upgrade Your Survey Capabilities? Get the right echo sounder for your next hydrographic or dredging project.At Geossotech, we supply and support reliable Singlebeam and Multibeam Echo Sounders suited
