Global maritime defence company Forcys is building on its recent merger with a keystone contract award. Reaffirming its focus on the defence sector, Forcys will deploy its Sentinel Intruder Detection System (IDS) across multiple sites for a close allied nation to protect vital elements of their Critical National Infrastructure (CNI).
In an ever-shifting sociopolitical landscape, the ability to counter unseen underwater threats grows more critical by the day. For over two decades, Sentinel has provided global peace of mind, becoming the world’s most deployed intruder detection sonar. The system detects, tracks, and classifies divers and uncrewed underwater vehicles (UUVs) approaching a protected asset from any direction, providing security teams with the early warning needed to react.
Paul Badger, CEO of Forcys, stated: “This contract demonstrates our enhanced capacity to deliver large-scale projects. By integrating our teams, we’ve matched world-class engineering and program management with global outreach. This synergy is exactly why we brought Forcys, Chelsea Technologies, and Wavefront Systems together.”
Ioseba Tena, CCO of Forcys, added: “Following a year of high-volume expeditionary deliveries providing ‘protection on the move’, 2026 sees Forcys scaling to meet the world’s most significant CNI challenges to deliver ‘protection that stays’. Our expanded team is now rolling out permanent IDS installations where permanent vigilance is the only option.”
Capable of identifying divers at ranges up to 1,000m and UUVs at 1,500m, Sentinel sets the standard for reliable, long-range underwater detection. It is currently utilized for defence, CNI, vessel, and VIP protection duties worldwide.
Powered by the Navy League of the United States, Sea-Air-Space 2026 is the premier maritime exposition in the U.S., bringing together defense industry leaders and top military decision-makers from around the world to share the latest advancements in the maritime domain. With industry leading speakers and events featured across three impactful days, Sea-Air-Space is a must-attend for anyone invested in the future of U.S. maritime strength and innovation.
The Combined Naval Event (CNE) 2026 returns as Europe’s leading forum for naval and maritime collaboration. Taking place from 19–21 May 2026 at the Farnborough International Exhibition Centre, this flagship event brings together over 2,200 senior naval leaders, government officials, industry representatives, and international partners from more than 85 nations including key participation from NATO and allied maritime forces.
CNE 2026 will feature six focused theatres, delivering a comprehensive agenda that explores the full spectrum of naval operations—from fleet readiness and maritime domain awareness to shipbuilding, undersea warfare, and evolving multi-domain challenges. With a programme shaped by operational needs and strategic priorities, the event provides a unique opportunity to share insights, align approaches, and strengthen partnerships across the global naval enterprise.
Whether you’re shaping policy, advancing capability, or supporting mission success, CNE 2026 is where the maritime community comes together to define the future of naval power
The UK Government has recognised the need for nature-based solutions to climate change as part of the UK’s target of reaching Net Zero emissions by 2050. Understanding the location and extent of subtidal seagrass beds (Zostera Marina) is crucial to determining their contribution to ecosystem services. Therefore, we need to accurately define the extent of the known seagrass beds and prospect for new seagrass beds in areas where they may occur, using methods that are accurate, efficient, and repeatable.
During sea trials of Solstice Multi-Aperture Sonar (MAS®), we found that Solstice was very good at mapping subtidal seagrass. To understand this capability better, we mapped the seagrass beds in Plymouth Sound in October 2023 and August 2024 to assess the suitability of this new sonar system for wide-area seagrass and ecosystem mapping. Solstice MAS was mounted on a small, shallow-draft survey vessel and run over the many seagrass beds in Plymouth Sound. Solstice generates wide-area, repeatable, and georeferenced seabed images and bathymetry, enabling the precise mapping of features such as seagrass beds and capturing areas of the seabed as small as 1.5cm x 3.75cm. Solstice can be used for mapping areas of 1m2 and above, but there is no limit to the largest area of seabed that can be mapped.
Figure 1: Solstice MAS displays showing bathymetry and texture over an area of rock and sand seabed.
During the surveys, we found that seagrass was visible on the sonar record as a well-defined texture different from other seabed types such as rock, sand waves, and kelp. Seagrass grows in depths less than 5m in Plymouth Sound, and in some places it grows between rock reefs and right up to the low water mark. These areas are difficult to map safely using drop cameras or echo sounders because the boat must be directly over the area being recorded. Using Solstice, we could safely map these difficult areas using the sonar’s 100m range capability. The boat could be in deeper water offshore and still image the seagrass in amongst the rocks and shallows 100m away.
Figure 2: A single 200m wide sonar image of the seagrass bed off Drake’s Island in Plymouth Sound.
This method is an efficient and accurate way of mapping seagrass beds. Solstice is designed for survey speeds of up to 6 knots, achieving a maximum seabed coverage rate of 1.6 km² or 160 ha per hour. For example, the largest seagrass bed in Plymouth Sound is 1300m long, but this can be mapped in just 9 minutes. Post-processing and analysis can be conducted back in the office using standard sonar processing software, further minimising expensive vessel time. Unlike conventional side scan sonar, the image quality does not depend on tow speed. The sonar is also unaffected by poor underwater visibility.
Figure 3: A detailed image of the seabed off Drake’s Island showing seagrass, kelp, sand and rock reef.
Solstice records details about the type and texture of the seabed around a seagrass bed, illustrating the seagrass in context. This information helps us to understand why the seagrass grows where it does and can provide invaluable information about a site before any restoration work begins. Solstice images provide detailed insights into the spatial variation of seagrass beds, which is essential information for planning detailed investigations using divers, drop cameras, or ROVs. The Solstice sonar images are georeferenced and spatially accurate, so relocating significant features on the seabed using divers is straightforward.
Figure 4: Solstice creates images of the seabed that show variations in seagrass coverage and density over large areas.
We also used Solstice to prospect for seagrass in areas where it may grow. Solstice detects small, sparsely distributed patches of seagrass that are difficult to locate and even harder to accurately map using other methods. We used it to find an area of potential new growth in Cawsand Bay that was beyond the extent of the known seagrass bed. We also identified several previously unknown seagrass beds in Jennycliff Bay on the east side of Plymouth Sound, the largest being 390m2 in area. The results of these surveys have revealed significant differences between the previously known extent of the seagrass beds in Plymouth Sound and those defined by Solstice MAS.
Measuring Change in Seagrass Beds
Understanding the health of seagrass beds is crucial to determining their contribution to ecosystem services. Accurately measuring change is an important part of understanding and monitoring seagrass. The actions we need to take depend on knowing if the seagrass is improving or getting worse, and if the changes are a trend or temporary. The efficiency, wide area coverage and inherent spatial accuracy of Solstice MAS® makes it ideal for assessing changes in seagrass beds over time.
The state of a seagrass bed may change for many reasons. Seagrass is affected by annual cycles of growth, die-off, and senescence, which are currently not well understood. We know that seagrass beds can also change due to storm events and other impacts such as water quality incidents and agricultural run-off. Variations in the plants themselves tell us something about the health of the seagrass at a small scale, but larger scale measurements provide different information: is the seagrass bed spreading or receding, has the seabed sediment changed, is the seagrass being damaged by boat anchors or moorings?
We used Solstice MAS to generate detailed, accurate and repeatable measurements required to determine changes in seagrass beds. For example, we found a sonar image from Solstice tests in April 2018 that showed the southern end of the seagrass bed in Cawsand Bay in Plymouth Sound, and we then mapped the same area in October 2023. The picture below shows Solstice sonar images of the same area of seabed taken five years apart. The brown stripe across the pictures is the area imaged by the sonar, and the same large rock is visible at the bottom of both pictures that we can use as a reference when comparing the images.
Figure 5: Comparison between Solstice sonar images from 2018 and 2023 for the southern end of the seagrass bed in Cawsand Bay, showing significant changes to the coverage
The seabed around the rock is flat sand, and the white ‘fluff’ on the sand is how seagrass appears on the Solstice sonar. The upper picture from 2018 shows the southern end of the large seagrass meadow in Cawsand in the upper left corner, and there are a few patches of seagrass between that and the rock. By 2023, the seagrass had spread, covering much of what was once bare seabed and covering ground further west beyond the rock.
Notice how the seagrass forms clumps and patches with bare or sparse areas in between. Measuring seagrass coverage in this area using diver transects would give very different results depending on where the transect was laid. Solstice provides a much wider view of the seagrass from which we can calculate more accurate and representative measurements of coverage.
A change was also noticed in the seagrass bed at Ramscliff on the east side of Plymouth Sound, this area was mapped in detail using Solstice MAS sonar in October 2023 and again in June 2024.
Figure 6: Variation in seagrass coverage at Ramscliff between October 2023 and June 2024
The change in eight months is noticeable. The overall extent of the seagrass bed was similar, but the coverage was much less and had become very patchy. The coverage was 1.33 hectares in 2023, but eight months later it was just 37% of the 2023 area.
Figure 7: Solstice sonar images showing a variation in sediment depth at Ramscliff between 2023 and 2024 in an area of seabed approximately 50m x 55m
The picture above shows one possible cause for this significant loss in coverage. A close inspection of seabed rock features near the seagrass shown on the Solstice sonar image suggests that there were changes to the sediment levels at the site. The picture on the left shows the seabed in 2023; note the small rock in the lower left corner, marked with a white arrow. The same rock is shown in the picture on the right when seen in the summer of 2024, and now far more of the same small rock is visible. More of the rock would be visible if the sediment level around it dropped, which suggests that the level of seabed sediment reduced at the Ramscliff site between 2023 and 2024, perhaps taking some of the seagrass with it.
Habitat Suitability Models
The UK Government has recognised the need for nature-based solutions to climate change as part of the UK’s target of reaching Net Zero emissions by 2050. Seagrass is one of the key species that contribute to a wide range of ecosystem services, so restoration of seagrass beds is a priority. Subtidal seagrass needs a particular environment in which to grow, and we can predict where reseeding may be successful using a habitat suitability model.
The ability for subtidal seagrass to grow depends on several factors. There needs to be sufficient light reaching the seabed, which is defined by the water clarity and water depth. Water clarity varies according to location; in some places where the water is clear seagrass can be found down to 10m depth, but the maximum depth range is usually 5m in Plymouth Sound where we are doing this research. Seagrass grows on sand and mud sediment and in places where there is not too much water current and not too many waves to scour the seabed. There are other factors, such as water quality, but this must be good enough because seagrass already grows in Plymouth Sound.
We used Solstice MAS® to help create habitat suitability models in Plymouth Sound. We used its bathymetry capability to make a 3D model of the seabed and from that identified the flatter areas that are less than 5m deep. The seabed texture information from Solstice is good for identifying different types of seabed, like sand and rock, and it can often be used to identify marine life such as seagrass and kelp. Published models exist that show the type of seabed in each port of the UK coast, but in some areas, such as Plymouth Sound, the models are too coarse to be used for accurately planning rewilding projects. Solstice can provide the detailed and accurate spatial information needed before planning restoration work. In some cases, it can also say if restoration work is feasible. Solstice was used to help create a suitability model for seagrass off Drake’s Island at the northern end of Plymouth Sound. The sonar records were interpreted to identify areas of sand/mud, rock, and kelp that were shallower than 5m depth. The model showed that the existing seagrass bed is bounded on both sides by kelp-covered reef and that there was little room for expansion to the sides.
Figure 8: Habitat suitability model for Drake’s Island in Plymouth Sound with unoccupied suitable areas shown in red. The existing seagrass bed does not cover the predicted area, suggesting that some other factor is limiting growth.
The Drake’s Island seagrass bed does not extend northward as far as the expected 5m depth limit, which suggests some other factor is limiting growth. We can test the assumptions used for the habitat model using the detailed seabed models created using Solstice. We can compare the theoretical coverage of seagrass with the actual cover as seen on the sonar, and any difference will highlight some other factor not yet considered (Fig. 1). The north side of the island faces the Tamar River channel and is subject to strong tidal currents, so these may be limiting the spread of the Drake’s Island seagrass bed. Further work to test this idea will be done shortly using a Sonardyne Origin ADCP to measure the actual water current inside and outside of the seagrass bed.
The habitat model for Cawsand Bay on the west side of Plymouth Sound shows that an area to the north of the existing seagrass meadow is suitable for seagrass. Solstice sonar surveys and observations by divers suggest that the seagrass is expanding northwards beyond Sandway Point (Fig. 2). Within a few years, the seagrass in Cawsand may have naturally expanded to cover all the suitable real estate in that area.
Figure 9: Habitat suitability model for subtidal seagrass in Cawsand Bay, Plymouth. The unoccupied areas suitable for seagrass are shown in red.
Detecting Seagrass Damage
The UK Government has recognised the need for nature-based solutions to climate change as part of the UK’s target to reach Net Zero emissions by 2050. Seagrass is one of the key species that contribute to a wide range of ecosystem services, so the restoration and maintenance of seagrass beds is a priority. Subtidal seagrass is easily damaged, so accurate monitoring is required to ensure that the seagrass is in good condition. This requires detailed records of the seabed at high spatial accuracy so subsequent records can be directly compared. Damage can come from several sources; seagrass beds can be physically damaged by storms, small boat moorings and anchoring, as well as large marine litter.
Seagrass usually grows in sheltered environments, but these areas may occasionally be affected by severe storms that disturb the seabed over large areas. The edges of seagrass beds can also be eroded by variable riverine currents, such as the bed on the north side of Drake’s Island in Plymouth Sound. Here, the spread of the seagrass appears to be limited by the outflow of the Tamar River, and the northern extent of the seagrass expands and retreats over time.
Figure 10: Solstice waterfall image of an area off Drake’s Island in Plymouth Sound. The edge of the seagrass affected by riverine currents is on the left. Inset is a bare patch in the seagrass caused by the presence of large marine litter.
Damage to the seagrass will occur if a small boat deploys its anchor in a seagrass bed. Once on the seabed, the anchor digs into the sediment and displaces the seagrass by its roots, while the anchor chain drags across the seagrass, damaging leaves over a wide area. This continues while the boat swings on its mooring as the chain drags across a swathe of seagrass. When the anchor is later recovered, more seagrass roots are disturbed as the anchor breaks out of the seabed.
Small boat chain moorings in tidal areas can damage seagrass. Simple moorings have a metal chain attached to a heavy mooring block on the seabed at one end and a floating buoy at the other. Here, the chain can drag over the seabed around the mooring block when the tide goes out. This is a problem in areas where the depth of water is small, but the range of tide is large, such as Cawsand Bay in Plymouth, where the depth and the tide range are the same at approximately 5m. The action of the chain leaves a bare patch around the mooring where seagrass cannot grow. Alternative mooring designs replace the chain or use floats to lift it clear of the seabed so the seagrass can grow around the mooring block.
Figure 11: An image of the seabed created by Solstice MAS showing damaged areas in a seagrass bed caused by small boat moorings.
During recent surveys of seagrass beds in Plymouth Sound using Solstice MAS, we found that large marine litter can also damage seagrass beds by creating a bare patch of seabed around the object. The reason for this is not clear, but it may be due to localised seabed scouring around the object caused by tidal currents.
We are using Wavefront Solstice MAS® to record and monitor damage to seagrass beds in Plymouth Sound:
Solstice can locate features in the seabed, such as mooring blocks, bare patches and anchor scours.
- Solstice produces high-resolution, scaled images that can be used to accurately measure damaged areas of seagrass.
- The efficiency and spatial accuracy of Solstice data make it ideal for assessments of change in seagrass beds over time, improvements after damage is mitigated.
- Solstice is efficient and can cover up to 160 ha per hour, so it can be used for rapid assessments of large seagrass beds.
We are using Solstice to accurately record the position, size and shape of any damage to the seagrass in Plymouth. Repeat surveys will highlight changes in the damaged areas to see if they are improving, particularly where yacht moorings have been upgraded or marine litter has been removed.
Figure 12: Marine litter can also damage seagrass. This image from Solstice MAS shows bare patches in the seagrass caused by large marine litter on the seabed.
A comprehensive report has been published on this work, please click here to download a copy.
An interview with Dr. Rob Crook, Research Director, Sonar Systems here at Forcys.
Solstice Multi-Aperture Sonar, or as we call it, Solstice MAS is a product of a rethink of side scan technology from the bottom up.
It aims to blend the high resolution of Synthetic Aperture Sonar (SAS) with the robustness and the reliability of side scan. The high-quality imagery is dependent on more than just high resolution. Solstice is therefore designed to provide not just high resolution but high SNR and contrast too. To achieve this, Solstice is built around five key technologies. In this interview, we’ll concentrate on Multi Ping Multi Look (MPML) and how this distinguishes Solstice MAS from SAS.
Q. Before we look at Solstice MAS and its advantages over traditional sidescan and synthetic aperture sonar systems, could you please briefly explain what these two actually are?
Sidescan sonar dates back to the 1970s and it’s become a workhorse technology used for commercial surveys or for search, classification, and mapping type MCM operations. It creates useful imagery of the seabed and objects which lie on it.
The longer the array of hydrophones or aperture used by the sidescan sonar, the better the picture resolution. Higher operating frequencies create higher resolution imagery, but that’s at the expense of range. Synthetic aperture sonar, or SAS, seeks to improve this resolution by synthesizing an aperture in the signal processing far longer than the actual physical sonar array. Also, SAS tends to operate at a considerably lower frequency, which helps extend its range.
Q. What experience do Forcys have in this technology?
Our engineers at Forcys have considerable experience in designing and developing synthetic aperture sonar systems. Two of our principal designers led the hardware development for NATO’s so-called MUSCLE SAS program and also led the development of a SAS system for a major international defense company.
Forcys, through Wavefront Systems, acted in a design consultancy role for several other SAS projects over the past decade. From this experience, we’ve learned that SAS can be very effective, but it is not without its drawbacks. It’s relatively expensive, heavy, and power-hungry, and in some fairly commonplace scenarios, SAS can be fragile.
Q. What do you mean when you say SAS can be fragile?
SAS can produce impressive results in the right conditions, such as deeper deployments away from the surface effects or when deployed on larger, more stable platforms. However, SAS can struggle in very shallow water—less than 40 feet deep—or when deployed on smaller, say 9 or 12-inch diameter AUVs. In these situations, feedback from users suggests SAS performance can degrade significantly.
Q. And what would that degradation look like and why does it occur?
Some SAS systems can compromise as much as 50% of their claimed swath in shallow water, or default to the poor resolution associated with its real aperture length when the coherent processing fails. The quality of this data is rarely of operational use and missions have been compromised as a result.
As to the why: SAS performance is adversely affected by higher-order multipath interference commonly encountered in shallow water scenarios. Its performance is degraded by unknown or dynamic sound velocity profiles. It demands high-accuracy bathymetry, without which non-linear platform trajectories will not produce focused images, and it struggles to provide reliable performance, particularly in high cross-currents, due to the impact these have on the SAS micro-navigation.
Now, some of these issues aren’t unique to SAS, of course, but because SAS seeks to extend the range of conventional sidescan sonar, they have a far greater significance for SAS.
Q. And what are the associated operational issues with SAS?
Large, heavy, power-hungry systems; complex mission planning due to its achievable range being dependent upon its speed—with higher speeds reducing available ranges—and often unmanageable quantities of real-time data making real-time processing problematic.
Q. Okay, so tell us, what did you do?
We decided to completely rethink the sidescan tech from the bottom up with the aim of developing a sensor which blended the high resolution of SAS with the robustness and reliability of sidescan.
Q. So, tell us more about Solstice.
Well, high-quality imagery is dependent on more than just high resolution. Solstice is therefore designed to provide not just high-res, but high SNR (signal-to-noise ratio) and contrast. To achieve this, we designed Solstice around five key technologies: MSAT (Multipath Suppression Array Technology), RAC (Real-time Auto Calibration), Motion Compensation, Pixel Perfect Imaging, and last but certainly not least, multi-ping multi-look.
Q. Is this last core technology the one that most clearly distinguishes MAS from SAS?
Yes, it’s what makes MAS unique and distinct from SAS for sure. Our multi-ping multi-look tech incoherently combines returns from multiple pings to greatly enhance the image signal-to-noise ratio, which in turn greatly reduces the distracting speckle-type noise so common in SAS imagery.
This ability to integrate incoherently allows our multi-aperture processing to be far less affected by navigational inaccuracies. This makes Solstice’s imaging performance in shallow water environments on smaller, less stable vehicles far more robust.
Of course, design decisions like this come with trade-offs. In this case, incoherent multi-aperture processing doesn’t increase the image resolution as the multiple apertures are processed, but MAS largely offsets this effect by using a much higher operating frequency than a typical SAS. Its natural real aperture resolution is therefore much better—a better starting point, you might say.
Q. Just to be clear, can you explain precisely what you mean by coherent and incoherent processing, and how are they different?
So, SAS coherent processing uses both the signal phase and amplitude information. Multi-ping multi-look uses incoherent processing, meaning only the amplitude is used for processing of the multiple apertures.
Q. Now what are the operational advantages of Solstice MAS?
Solstice has the ability to image large areas of the seabed at significantly higher ground speeds than SAS. Its low 20-watt power draw dramatically extends search, classify, map mission durations for AUVs, and this allows the sonar to be used alongside identification systems such as Voyis’s laser line scan in our latest L3Harris IVER4 Recon module.
Mission planning is simplified due to the constant range swath, and that all the advanced MAS processing can be performed on board the vehicle itself in real time, producing manageable quantities of data that are available for third-party software packages such as automated target recognition algorithms.
Q. Are you continuing to develop Solstice and can you share any future developments?
We pride ourselves on maintaining relationships with our end customers, listening to their real-world experiences of sensor tech, and using this information to help guide our development and improve our products.
The latest addition to the Solstice family is a bigger brother, Solstice MAS 4000. It’s now being sea trialled and has already achieved SAS-like along-track resolution within a power budget of just 24 watts.
