Bathymetry
Surveyor 240-16 MBES Multibeam Echosounder
Surveyor 240-16 - the multibeam head
The Surveyor 240-16 is a 16-channel multibeam echosounder that maps a continuous swath of seabed rather than a line of depth points.
One cable, a spare penetrator and a housing that opens
Every figure here is from the specification table on this page. Hover or tap a number to trace it to the hardware.
- 01Power10–30 V5 W typical idle, 15 W typical maximum while pinging, on tinned wires.
- 02Spare penetratorM10An auxiliary hole to relocate an I²C sensor, such as a BlueROV2 Bar pressure sensor, off the vehicle hull.
- 03Data interface100BaseT EthernetJST GH (4 pos), the Blue Robotics connector standard. JST GH to RJ45 adapter included.
- 04Mounting holesM4-0.7On the top, bottom and sides of the housing.
- 05Housing300 m depth ratingAluminium. It opens for inspection - not potted or oil-filled. 790 g in air, 145 g in water.
Every Surveyor 240-16 MBES Configuration
The same multibeam head. The second build adds a pressure sensor so the sounder has its own depth reference.
- In most situations points are detected up to 50 m slant range from the sensor; in ideal conditions substantially further.
- Even in compromised conditions you can expect reliable performance up to 30 m from the target plane.
- 10–20 points are detected per ping. Point density rises if you slow the vessel or run overlapping passes.
- Maximum ping rate, per Cerulean's specification table: 16 pings per second at 200 range steps, 10 at 400 and 6 at 800. It falls as range grows, because of the speed of sound.
- Built-in 9-axis IMU handles pitch and roll compensation. Heading and position come from the vessel.
- Aluminium housing, 300 m rated, external status LED, M4-0.7 mounting holes on top, bottom and sides. It opens for inspection - it is not potted or oil-filled.
- An auxiliary M10 penetrator hole lets you relocate an I²C sensor (such as a BlueROV2 Bar pressure sensor) off the vehicle hull.
What differs between the configurations▾
| Specification | Surveyor 240-16 MBES | With Bar30 pressure sensor |
|---|---|---|
| In the box | Multibeam head | Multibeam head + Bar30 pressure sensor |
| Own depth reference | No - depth comes from the vessel | Yes - Bar30 fitted |
Everything else on this page is common to both configurations; which vehicle each one is cut for is on the cards above.
Key specifications16 rows▾
| Acoustic frequency | 240 kHz |
| Along-track TX beam width | 4° |
| Cross-track TX beam width | 80° |
| Receive array elements | 16 |
| Cross-track beam width | 7° (conventional beamforming) |
| Cross-track angular resolution | 1° (angle of arrival) |
| Range resolution | up to 1/800th of range setting |
| Maximum suggested range | 100 m |
| Maximum depth rating | 300 m |
| Power supply | 10–30 V, 5 W typical idle, 15 W typical max pinging |
| Data interface | 100BaseT Ethernet |
| Electrical connection | JST GH (4 pos) for data - Blue Robotics connector standard. Tinned wires for power. JST GH to RJ45 adapter included. |
| Weight in air | 790 g |
| Weight in water | 145 g |
| Max bandwidth | 450 kbps |
| Max ping rate | 16 @ 200 range steps · 10 @ 400 · 6 @ 800 |
Where a figure here differs from one you have seen on another listing, this table is the current revision; some resellers are still publishing an earlier one.
Published by Cerulean - specification page
What's in the box▾
Cerulean’s own packing list for this product.
What’s in the box
- Surveyor 240-16 multibeam head
- JST GH (4 pos) data cable - Blue Robotics connector standard
- Tinned wires for power
- JST GH to RJ45 adapter
Kit contents vary by supplier - some ship a platform-specific mounting bracket and cabling in the same box, and some do not. This is the list for the unit as we supply it. If you are comparing quotes, check you are comparing the same box.
Downloads▾
Surveyor 240-16 MBES, and what it produces
Photographs of the hardware - not renders.
Sixteen channels, and why the resolution beats the beam width
The Surveyor transmits a fan 4° along track by 80° across track, then listens on a 16-element receive array. Conventional beamforming on sixteen elements would give a cross-track beam about 7° wide. Instead of beamforming, the Surveyor estimates the angle of arrival of each return, which resolves position across the swath to about 1°.
That distinction is the whole product. Seven degrees tells you something is there. One degree tells you its shape.
Each ping yields 10–20 detected points across the swath - not hundreds. Point density is built up by slowing the vessel and running overlapping passes. A built-in 9-axis IMU corrects pitch and roll; heading and position come from the vessel, and SonarView combines the three to place every point geographically.
New to this decision? Single-beam or multibeam for shallow-water survey?Three range figures, and which one to plan against
300 m is the housing depth rating - how deep the unit survives. An AUV can carry it there; it will not map the bottom from the surface at 300 m.
100 m is the maximum suggested range setting. A ceiling on the control, not a promise of detection.
50 m is where Cerulean says points are detected in most situations, falling to about 30 m from the target plane when conditions are against you - soft bottom, heavy pitch and roll, acoustic interference.
Plan against 30–50 m. Some listings for this unit quote “depths up to 100 metres”, which repeats the setting ceiling as if it were a capability, and at least one still carries an older Cerulean revision showing 50 m as the maximum suggested range.
Range also costs ping rate, and that is acoustics rather than a product limitation - a ping cannot go out until the last one is back. Cerulean's specification table gives 16 pings per second at 200 range steps, 10 at 400 and 6 at 800. Fewer pings over the same ground means fewer points, so extend your range setting and you will want to slow down to hold density.
Capture in SonarView, process where you already work
SonarView is Cerulean's free cross-platform application - Windows, macOS, Linux, or as a BlueOS extension on the vehicle. It is required: the Surveyor has no onboard logging, so a computer or companion computer must be connected to run the sonar and record. Budget about 5 GB of log per hour at the maximum ping rate.
Exports are CSV point cloud, GSF, and SVLOG (SonarView's native format).
Hydromagic (Eye4Software) supports the Surveyor directly through its multibeam plugin and imports SVLOG natively, with vessel offsets, calibration and heading configured in-package. Contractors running this unit for dredging work report it as the shortest path from capture to a gridded deliverable.
Reefmaster imports the CSV export and generates charts and contours in a handful of steps, exporting to KML - a sensible entry point if you do not already own a survey package.
CSV point clouds also open in CloudCompare, MeshLab or Blender for viewing and inspection.
Running SonarView as a BlueOS extension on the vehicle is worth doing on a BlueBoat: the sonar link never drops even if you lose the boat's radio, raw sonar data stops competing with piloting for telemetry bandwidth, and settings follow the vehicle rather than the laptop.
Two settings to check before you mobilise
- QGroundControl message rates, if you use it. QGroundControl overrides the vehicle's MAVLink message rates by default, and Cerulean's own documentation is blunt that this badly degrades data quality. Enable “All Streams Controlled By Vehicle Settings”, then set
SR0_POSITIONandSR0_EXTRA1to 50 Hz and reboot the vehicle. Two minutes on the bench; a wasted day if you find out on site. Source - A current SonarView build, if you survey slopes. Position arriving through the ArduPilot EKF can carry an apparent delay of a couple of hundred milliseconds. On flat ground it is invisible. On a steep slope it shows as an offset between the up-slope and down-slope passes over the same seabed. Cerulean added fixed-time-delay compensation in SonarView after a user reported it in March 2026. Harbour floors and dredging basins are unaffected; quarry walls and channel banks are not. Ask us and we will confirm the build you need. Source
What operators report
Collected from the Blue Robotics community forum and from Cerulean - these are users' accounts and the manufacturer's, not SepcoTech references.
A dredging contractor running a Surveyor on a BlueBoat alongside a Norbit multibeam on the same site reported matching XYZ results, with slightly less detail in the fine data - immaterial once interpolated to the gridded matrix their excavators and cranes work from.
Blue Robotics reported a customer covering 80 acres in a single morning, and close to 40 units sold as of January 2026 without a performance complaint reaching them.
A retired Boeing 737 sunk as an artificial reef in about 25 m of water in British Columbia was surveyed in full by one operator with a BlueBoat and a Surveyor.
Reported on the Blue Robotics community forum, January–May 2026.
Three details worth knowing
- The housing opens. It is not potted or oil-filled, so it can be inspected or serviced rather than replaced. Unusual at this price.
- A spare M10 penetrator on the housing lets you relocate an I²C sensor off a vehicle hull that has run out of penetrations - the Bar30 depth sensor on a BlueROV2, for instance.
- An Omniscan 450 SS can share the Surveyor's mounting holes on a BlueBoat, giving side-scan imaging and bathymetry from the same pass.
All three are published by Cerulean - product documentation.
Common questions
Answers Cerulean publish, plus operators’ reports from the Blue Robotics community forum - each linked back to the source it came from.
Does the Surveyor have its own GNSS?
No. It has no GNSS receiver - SonarView takes position from an external source and logs it. On a BlueOS vehicle that is MAVLink2Rest; otherwise a GNSS device with NMEA output. Source
Does it have an IMU?
Yes, a built-in 9-axis IMU used for roll and pitch compensation. Heading comes from the vehicle. There is a compass on board too, but Cerulean recommend using the vehicle's heading. Source
What NMEA messages does it need?
NMEA 2000: 129025 and 127250. NMEA 0183: RMC or GGA, plus HDT. 10 Hz or better. If you have the choice, use NMEA 2000 - converting to 0183 tends to slow gateways down badly. Source
How much data will a survey produce?
Budget about 5 GB of log per hour at the maximum ping rate. If you are logging to a Raspberry Pi, 128 GB is a good card. Source
Where is the acoustic phase centre?
In the receive elements inside the array module on the front of the unit. Cerulean publish a dimensioned drawing. Source
Will it work with my hydrographic software?
Directly with Hydromagic, which has a plugin for the Surveyor and imports SonarView's SVLOG format natively. Otherwise via CSV point cloud or GSF export, both of which import into most hydrographic packages. Reefmaster is a low-cost option if you do not own one. Source
Do I need RTK?
For survey deliverables, effectively yes - depth accuracy is capped by position accuracy. Users running this unit for dredging report an RTK correction stream, commonly an Emlid receiver with the NTRIP extension on BlueOS. For reconnaissance and rough bathymetry, standard GNSS is workable. Source
Do I need a sound velocity profiler?
Not always. In shallow fresh water at near-constant temperature, correcting from a measured water temperature is often enough - the Surveyor's spare penetrator takes a Celsius temperature sensor for exactly this. SonarView defaults to 1500 m/s and fresh water can sit nearer 1445 m/s, so the correction matters. In stratified, deeper or saline water, or where the contract requires it, take a profile. Source
Surveyor 240-16 MBES on video
Published by Cerulean Sonar on their own channel.
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