Mechanical Scanning Sonar

Multibeam Echosounder vs Mechnical Scanning sonar: What is the difference?

One question we often find ourselves answering is the difference between a traditional multibeam echosounder and a Mechanical Scanning Sonar (MSS).

A Mechanical Scanning Sonar (MSS) is a very high-frequency Multibeam Echosounder mounted on a stepper motor, allowing the echosounder to rotate during a scan. The system creates high-resolution, laser-like imagery of underwater structures or objects of interest - even in areas of reduced or zero visibility. The system is ideally suited to surveying manmade structures that are perpendicular to the seafloor; scanning sideways rather than downwards.

What about tilting the multibeam head?

It is now common practice to perform structural inspections by tilting a conventional multibeam head to transmit sideways. However, in most infrastructure inspection situations, a higher frequency MSS is preferable, due to the higher resolution that the MSS provides.

When performing asset integrity surveys of critical structures such as bridges or dock walls, any interpolation could potentially mean missing damage that can affect the overall integrity of the asset.

3D Mechanical Scanning Sonar data can be combined with other datasets

Mechanical Scanning Sonar data can be seen as the underwater version of laser scan data

' Pulsar', SEP Hydrographic's dedicated road transportable survey vessel.

The key benefits offered by the 3D Mechanical Scanning Sonar include:

Provision of highly detailed data, enabling targeted visual inspection if required, or removing the need for it altogether.
Production of a baseline BIM compatible 3D point cloud.
Removal of subjectivity in interpretation.
Allows accurate monitoring of any integrity changes over time.
Improved QHSE when compared to traditional inspection methodologies, including diving services.
Quantitative measurements of change over time from damage to siltation levels.
Helps to safeguard and extend the lifespan of the asset.

Applications

Survey repeatability and change monitoring
Following the production of a high-resolution 3D point cloud with centimeter resolution, subsequent survey results can be loaded into the same database allowing for easy comparison between data sets over the same asset.

Ports/Harbours
Our services are focused mainly around routine monitoring, damage inspection, and as-built surveying. Our offering is flexible and responsive, and we are comfortable working with various deployment techniques to reduce cost, in line with project specific requirements.

Inland Waterways
We can perform surveys of canals and other inland waterways to provide information on debris and other hazards in the water column, structural integrity, scour around structures, and volume calculations for dredging, flood risk mapping, as well as positioning of marine and terrestrial assets, such as bridges.

Bridges
Combining both marine and land-based survey techniques, we can offer a complete monitoring and inspection solution both above and below the waterline. Our vessels and equipment are ideally suited to working in shallow water, and we can react to provide emergency survey information following events that threaten asset integrity.

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SEP Hydrographic offers comprehensive high-resolution BIM-compatible 3D asset inspection services. Combining marine and terrestrial survey techniques utilising a range of high- specification positioning, marine survey, scanning and photogrammetry equipment, SEP Hydrographic provides high-resolution 3D point cloud imagery of structures for monitoring and inspection both above and below the waterline.

If you have any comments or feedback on this topic, please get in touch with one of the team.

Related Pages: Pulsar Asset Inspection Surveys

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