Over the past decade, sub-bottom imaging has remained a niche technique in marine geophysical surveys. However, recent advancements in survey platforms and computational processing have lowered the barrier to entry for Synthetic Aperture Sonar (SAS) systems that rely on these technologies. One beneficiary of these advancements is EdgeTech’s Buried Object Scanning Sonar (eBOSS). By utilizing low Frequency Modulated (FM) acoustic pulses and SAS processing, eBOSS generates 3D volumes of the water column and sub-seabed in real time. Sulmara has successfully integrated eBOSS on various platforms, including Remotely Operated Tow Vehicles (ROTV), traditional Work-class Remotely Operated Vehicles (WROV), and Uncrewed/Autonomous Surface Vehicles (U/ASV). These integrations are supported by Real Time Kinematic (RTK) positioning systems at the surface, inertial navigation systems, and acoustic positioning systems subsea, often complemented by high-frequency sonar and magnetics for seafloor mapping and target definition.

Both sidescan sonar and MultiBeam EchoSounder (MBES) are used to detect the seafloor and prominent targets for Unexploded Ordnance (UXO) survey applications. Uniquely, eBOSS can also detect, locate, and image buried targets as well as prominent ones. Sulmara’s Discover system employs a vessel-mounted MBES and an EIVA scanfish equipped with a magnetometer spread and eBOSS, all surveyed in a single pass. To validate the system, Sulmara recently deployed and imaged a Surrogate Item Trial (SIT) that mimics the acoustic and electromagnetic properties of a WWII Luftmine B (LMB). Correlating detections from the full sensor suite provide highly reliable deliverables for marine surveys, reducing the uncertainty of interpretation of pUXO and raising confidence in UXO identification. 

Depth of Burial (DOB) survey tenders are tailored to traditional WROV specifications. Sulmara has proposed this can be achieved directly from a single ROTV hosting a co-located sensor suite. For post lay and verification surveys the system operates at ten times greater speed and ten percent cost of standard WROV survey. Examples of both deployment methods in varying geologies off the coast of New England highlight the adaptability of the platform. The seafloor and buried targets imaged with all sensors provide unique multifrequency and multi-physics insights into the geology and target composition. This approach enables advanced geophysical interpretation, allowing for observation of the exterior surface, and the interior, of targets and the seabed using both low-frequency acoustics and electromagnetics.