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Frequently Asked Questions

Our FAQ is a growing resource of information on subsea operations including marine survey and underwater inspections 

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Underwater Inspection Technology

Marine Data

  • Marine data encompasses a variety of measurements and information gathered about the ocean and seabed, including:

    Bathymetric Data: Measures the depth and topography of the seafloor

    Geophysical Data: Includes seismic data, magnetic and gravitational data, which help in understanding the geological features under the seabed

    Oceanographic Data: Concerns ocean currents, temperature, salinity, and water column properties

    Biological Data: Involves biodiversity assessments and the distribution of marine species

    Chemical Data: Includes data on the water's chemical composition, pollutants, and nutrient levels

    Meteorological Data: Related to weather and atmospheric conditions over the ocean.

  • The main users of bathymetric data include a diverse range of sectors that rely on detailed underwater terrain information for various applications. These users depend on accurate and up-to-date bathymetric data to support safety, operational efficiency, scientific research, and environmental management.

    Hydrographic Offices: National and international bodies use bathymetric data to produce nautical charts and ensure safe navigation in coastal and offshore waters.

    Maritime Navigation: Shipping companies, maritime pilots, and port authorities utilise bathymetric data for route planning and to avoid underwater hazards.

    Coastal Engineering: Engineers use bathymetric data for the design and construction of marine and coastal structures, such as ports, harbors, and coastal defenses.

    Offshore Oil and Gas: Energy companies and offshore engineering contractors uses bathymetric data for exploration, drilling site selection, pipeline routing, and the installation of oil platforms and underwater structures.

    Renewable Energy: Developers of offshore wind farms, tidal power, and other marine renewable energy sources require detailed bathymetric data for site selection and infrastructure development.

    Marine Science and Research: Researchers study bathymetric data to understand oceanography, marine geology, and ecosystem dynamics. It's crucial for habitat mapping and environmental impact assessments.

    Environmental Monitoring and Conservation: Organisations involved in marine conservation use bathymetric data to monitor habitats, manage marine protected areas, and conduct biodiversity assessments.

    Military and Defense: Naval operations use bathymetric data for submarine navigation, amphibious operations, and strategic planning.

  • Final data is often stored in data repositories, which are centralised hubs such as national hydrographic office databases, and international repositories like the Marine Geoscience Data System. Common formats include standard geospatial data formats such as GeoTIFF for raster data and Shapefile or GeoJSON for vector data. Data will likely adhere to international standards such as those from the International Hydrographic Organization (IHO) to ensure its accuracy for use in i.e., navigational products or engineering planning.

    Within the marine survey part of chain, while the industry still uses portable hard drives to store and share data, digitalisation has started to offer a more dynamic alternative. Online platforms and services that facilitate the sharing of data across different stakeholders, including public and private stakeholders have the potential to introduce significant financial and operational value, as explained in this white paper we created with our partner TrueOcean.

Subsea Europe Services

  • No. Subsea Europe Services is an integrator of hydroacoustic technology, including MBES. We take the very best, field-proven MBES models from manufacturer R2Sonic and unify them in a single integrated package, which includes everything needed to acquire the highest quality marine data. We call it the integrated Hydrographic Survey System, or iHSS for short.

  • The integration of all components needed to conduct MBES-based hydrographic surveys simplifies the marine data acquisition workflow. This can open the door to organisations without permanent, in-house expertise to collect their own marine data using owned vessels or vessels of opportunity.

    Trained experts are still required to operate the iHSS safely and effectively, and the Subsea Europe Services support team is ready to join users with little or no experience during installation and throughout a survey campaign, helping our clients to maximise performance. Our vision, however, is to make MBES operation simple and automated enough that familiarisation training only will be enough to get the best results from a hydrographic survey campaign using the iHSS.

  • The MBES ownership model is suited to those users that are confident of the need for continuous usage over several years. It’s no secret that purchasing MBES technology is a significant investment but for many MBES owners, this investment can be severely under-utilised. The rental model is much better suited in the case of users with no fixed utilisation rates. And while availability in the rental market can be challenging, Subsea Europe Services has looked closely at stocking and logistics to ensure that we can meet client requests within 1-2 days of first contact.

  • A system is essentially the result of integration between sensors, equipment and user interfaces. This becomes a solution when the survey platform is also part of the delivery. At SES we provide access to a wealth of high-quality sensors such as R2Sonic Multibeam Echo Sounders and AML sound velocity instruments. We combine these sensors to create survey-ready packages such as the Integrated Hydrographic Survey System (iHSS). Through our partnerships with Unmanned Surface Vessel (USV) manufacturer Martac Systems and our relationship with several Remotely Operated Vehicle (ROV) suppliers, Subsea Europe Services provides complete turnkey solutions. This is the combination of integrated survey technology and the actual survey platform as a single delivery, with expertise and support also included as part of the solution.

Uncrewed Platforms

  • AUV: Autonomous Underwater Vehicle

    Usually torpedo-like in shape, AUVs have been in operation since the mid-nineties. While labeled autonomous, the current generation of AUVs still need full mission guidance and do not generally operate without a human in the loop, in the context of real-time decision-making at least. AUV applications are payload-specific but bathymetric and sub-bottom data acquisition are common uses, in addition to environmental monitoring and some mine-hunting operations.

    HAUV: Havering Autonomous Underwater Vehicle

    An HAUV can be viewed as a tetherless ROV or a more intelligent, agile and flexible AUV. The term was coined by the Singapore-based autonomous vehicle specialist, BeeX, for the state-of-the-art A.IKANBILIS platform. A.IKANBILIS is a state-of-the-art HAUV used for underwater inspection operations of diverse infrastructure, from floating solar farms to offshore wind turbines. The latter was demonstrated in a live context by Subsea Europe Services and wind farm owner Northland Power during a pilot project in July 2023, which took place at the Deutsche Bucht offshore wind farm located in the German North Sea.

    MASS: Maritime Autonomous Surface Ship

    Larger commercial vessels with part, or so-called full autonomy for operation on set routes including ferries and coastal transport. This is due to the lack of international regulations on autonomous ships, leaving it up to national bodies to decide what is allowed in their waters only. Few MASS’ are in operation so far, but new-generation technologies will make them a more common sight in the decades to come.

    ROV: Remotely Operated Vehicle

    Usually tethered to a cable for power, as well as control, data transfer, and maneuvering, ROVs are operated by pilots sitting on either the launch vessel or in some cases at facilities ashore. ROVs often feature manipulator arms and specialised tools and are used for diverse engineering and underwater intervention applications.

    USV: Uncrewed Surface Vehicle

    Alternatively referred to as ‘Unmanned Surface Vehicles’, USVs are essentially boats without anybody on board. They make excellent marine survey platforms as they can be used to safely operate in areas that may not be suitable for manned vessels. USVs also provide excellent payload flexibility, which ensures the right hydrographic instruments can be chosen for the job at hand. They come in many shapes and sizes, although many still adhere to manned vessels paradigms. It’s the USV designs that move away from this – with electric power and high-speed operation – that are set to break down application barriers and truly realise the operational and economic potential of USVs.

  • Simply put, de-manning marine survey and underwater inspection operations can lower the cost of data collected while enabling much faster working. Smaller, more environmentally friendly, battery-powered USVs can take over from diesel and petrol-burning survey platforms and do their job better while unlocking new more effective practices. For instance, small, fast, and agile USVs can be launched from any vessel of opportunity that has even the lightest of cranes on board. These USVs could reside permanently on service vessels and be put into action as soon as they are needed. USVs can even operate in swarms, with multiple units working in perfect harmony to map large areas in a fraction of the time that manned survey vessels would take for the same survey. The freedom for new vessel designs and methodologies that removing the human from the loop introduces will transform the subsea survey industry sooner rather than later. 

  • The autonomy computer in any unmanned vehicle has a complete view of its surroundings to provide real-time situational awareness for instant decision making. We’ve already seen this so-called ‘sensor fusion’ in action on Tesla cars, and autonomous marine vehicles are using the same approach. By combining Lidar, radar, sonar, navigational maps, CCTV and countless other underwater and above the surface sensors, the uncrewed vehicle can take the action that its programming demands very quickly no matter what the current conditions throw at it. Through machine learning, such a vehicle continuously improves its decision making, making both survey operations and navigation even safer and more efficient.

  • This was also a big question when robotics started to take over some jobs in industrial sectors decades ago, and fears of massive job losses were proven to be unfounded. We believe it is the same for marine survey. USVs won’t ‘take over’ anything, but they will increase capacity and augment current capabilities. There will be fewer professionals operating at sea in the future, as they will be working from central operations rooms, with responsibility for multiple projects. Rather than employing fewer people though, the next generation of USV and AUV technologies could become the enablers of new job types and more opportunities to work in the world of subsea data acquisition. Already we see the potential for new business and operational models made possible by USVs making it faster and lower cost to collect more quality data within the same time frame.

  • Sometimes referred to as the ‘umbilical cord’ an ROV cable is multi-use. Firstly, it provides power to the vehicle and its instruments. This is an important aspect as ROV mission endurance is practically open-ended because they do not rely on internal batteries (and pilots can operate on rotating shifts). The cable also enables remote control of the vehicle using a joystick or the pilots preferred method of operation in addition to live sensor data and visual feeds to provide complete awareness for safe and effective operation. Further, the cable can provide live sensor data to other members of the mission team who can suggest changes to the original plan based on what they see in real-time.

  • The regulations governing the use of Unmanned Surface Vehicles (USVs) in marine surveying vary by region and are still evolving. Generally, USVs must comply with:

    COLREGs: The International Regulations for Preventing Collisions at Sea, to ensure USVs can safely navigate in compliance with rules applicable to all vessels.

    National Maritime Authorities: Local maritime laws that might specify operational limits, crewing requirements, and safety standards specific to unmanned vessels.

    Classification Societies: Bodies such as Lloyd’s Register or the American Bureau of Shipping (ABS) provide standards and frameworks that include the design, construction, and operational maintenance of uncrewed vessels to ensure safety and reliability.

    International Maritime Organization (IMO) Regulations: The international regulations for smaller uncrewed vessels have yet to be established, though generally, such platforms operate only within national waters.

  • ‘Resident’ refers to systems designed to be deployed for extended periods directly in the marine environment without the need for frequent retrieval. Resident uncrewed platforms, such as AUVs or ROVs, are stationed underwater at or near their operational sites and can perform tasks like inspections, maintenance, or data collection autonomously. They often operate from a subsea docking station, where they can recharge, transfer data, exchange payloads, and receive commands. This setup reduces the need for surface support vessels, cutting operational costs and increasing the efficiency of marine operations.

Marine Survey Operations

  • There are several aspects to this but one of the most important consideration for survey speed is how your multibeam echosounder transducer is mounted. Any kind of pole mounting can cause vibration which can then affect the data quality. However, a hull mounted transducer suffers from much less vibration so its possible under some circumstances to acquire data as fast as 20 knots. A further consideration of survey speed is the along-track coverage, which is a topic that our multibeam echosounder partner R2Sonic explains well here.

  • The best approach for ensuring data quality is to have an expert marine surveyor on board, but if you are interested in what can be controlled when using a multibeam echosounder, our technology partner R2Sonic has written a handy guide. Simplifying the acquisition of marine data is an area that Subsea Europe Services is currently working on however. Our goal is to make it easy for any organisation to carry out marine surveys regardless of in-house expertise. Today we achieve this by providing fully integrated, survey-ready systems (integrated Hydrographic Survey System) and the support of our own expert team during client surveys. In the coming years and decades, together with our partners we want to bring more automation and autonomy in order to simplify the data acquisition process.

  • Swarm surveying is the idea that multiple USVs can be dispatched to a survey location quickly and acquire more data faster than traditional survey vessels, and at a lower cost with reduced risk. Working in tandem with a crewed or uncrewed mothership overseeing the operation, multiple smaller USVs carrying full hydroacoustic payloads capable of acquiring data to S-44 standards can ‘cover’ much more ground than a manned survey platform. Subsea Europe Services’ USV partner MARTAC has already successfully demonstrated this with the use of hydrographic Mantas T12 USV ‘swarms’ in multiple exercises, showing a future where synchronised unmanned platforms can survey an area of the seafloor many times faster than a single manned platform.

  • The ‘mothership concept’ in marine surveying refers to the use of a larger vessel that acts as a central platform supporting the operation of smaller uncrewed vessels or vehicles. Typically, the mothership will already be working on site, therefore the charter cost of a dedicated survey vessel can be avoided. The mothership provides logistical support, power, data processing capabilities, and acts as a control center for the smaller vessels which can be unmanned surface vehicles (USVs), autonomous underwater vehicles (AUVs or Hovering AUVs), or remotely operated vehicles (ROVs). This arrangement allows for extended missions, increased data collection efficiency, and operational flexibility, as the uncrewed platforms can be launched, monitored, and recovered from the mothership while it goes about it’s primary work (such as transporting engineers to turbines at offshore wind farms),

  • There are five ‘orders’ described in the current industry standards, which are detailed in IHO Standards for Hydrographic Surveys (S-44) 6th Edition. These are:


    Special Order

    This is the most rigorous of the orders and its use is intended only for those areas where under-keel clearance is critical. Because under-keel clearance is critical a full sea floor search is required and the size of the features to be detected by this search is deliberately kept small. Since under-keel clearance is critical it is considered unlikely that Special Order surveys will be conducted in waters deeper than 40 metres. Examples of areas that may warrant Special Order surveys are: berthing areas, harbours and critical areas of shipping channels.


    Exclusive Order

    Introduced in the 6th edition of IHO Standards for Hydrographic Surveys (S-44), Exclusive Order hydrographic surveys are an extension of IHO Special Order with more stringent uncertainty and data coverage requirements. Their use is intended to be restricted to shallow water areas (harbours, berthing areas and critical areas of fairways and channels) where there is an exceptional and optimal use of the water column and where specific critical areas with minimum underkeel clearance and bottom characteristics are potentially hazardous to vessels.


    Order 1a

    This order is intended for those areas where the sea is sufficiently shallow to allow natural or man made features on the seabed to be a concern to the type of surface shipping expected to transit the area but where the under-keel clearance is less critical than for Special Order above. Because man-made or natural features may exist that are of concern to surface shipping, a full sea floor search is required, however the size of the feature to be detected is larger than for Special Order. Under-keel clearance becomes less critical as depth increases so the size of the feature to be detected by the full sea floor search is increased in areas where the water depth is greater than 40 metres. Order 1a surveys may be limited to water shallower than 100 metres.

    Order 1b

    This order is intended for areas shallower than 100 metres where a general depiction of the seabed is considered adequate for the type of surface shipping expected to transit the area. A full sea floor search is not required which means some features may be missed although the maximum permissible line spacing will limit the size of the features that are likely to remain undetected. This order of survey is only recommended where under-keel clearance is not considered to be an issue. An example would be an area where the seabed characteristics are such that the likelihood of there being a man-made or natural feature on the sea floor that will endanger the type of surface vessel expected to navigate the area is low.

    Order 2

    This is the least stringent order and is intended for those areas where the depth of water is such that a general depiction of the seabed is considered adequate. A full sea floor search is not required. It is recommended that Order 2 surveys are limited to areas deeper than 100 metres as once the water depth exceeds 100 metres the existence of man-made or natural features that are large enough to impact on surface navigation and yet still remain undetected by an Order 2 survey is considered to be unlikely.

    To be fully compliant with an S-44 Order, a hydrographic survey must comply with all bathymetric and feature detection requirements. This means that only an entire survey solution, from vessel to equipment and process to expert surveyors can be classified, which is why Subsea Europe Services pays attention to the entire hydrographic value chain.

    Our multibeam system manufacturer partner R2Sonic looks into why it’s impossible for a multibeam echosounder to classified under s-44 in more depth here.

Marine Survey Technology

  • Multibeam echosounders are the common standard technology for acquiring the marine data needed to map the topology of the seafloor. MBES use the physics of sound in water to measure water depth. Unlike single beam echo sounders, MBES use a wide swath made up of multiple acoustic ‘beams’ or ‘pulses’ for optimal coverage, which makes hydrographic surveying faster and more efficient.

  • In addition to the acquisition of data for the creation of high-resolution seafloor maps, an MBES can also be used for geological and oceanographic research, offshore oil and gas exploration and seafloor cable routing, among many more applications including post-dredging and construction reports, as well as underwater object or UXO (Unexploded Ordinance) search.

  • An echosounder measures the round-trip time it takes for an acoustic pulse to bounce off an object on the seafloor in order to record a ‘depth sounding’. These soundings are then combined with corrective data logged from other instruments and used to create an accurate chart of the seafloor topology for navigation or underwater construction purposes.

    There are two primary types of echosounder; a single beam echosounder fires one pulse at a time in one direction (usually directly below the boat), while a multibeam echosounder generates multiple pulses at a wider angle, usually to port or starboard. While this results in better coverage for improved raw data, it makes MBES surveys more complicated to plan and harder to carry out.

    The complexity of the MBES survey workflow requires an expert marine surveyor to be on board and a highly experienced helmsman to keep the survey vessel on the planned lines. Subsea Europe Services GmbH is working on ways to simplify the process however, using technology integration to empower more automated marine survey operations.

  • It's no secret that multibeam systems are costly, so if you are looking to buy your own, knowing how to maintain it is a must. Our multibeam echosounder partner R2Sonic has a great guide on looking after transducers.

    Of course, if you prefer to rent or subscribe for access to the latest technology with Subsea Europe Services, you can be confident that all equipment delivered has been maintained thoroughly and fully tested before it leaves the warehouse

  • You don't need to know this directly, but you do need to be able to communicate what you need to achieve from a survey. With this information, the Subsea Europe Services team can spec the exact product or integrated ready-to-survey-system for you. We'll take into account everything from your budget and vessel configuration, to water depth and required operating frequencies in order to ensure the technology we deliver is the ideal fit to acquire the data you need. Find out more about preparing to get a multibeam echosounder at our technology partner R2Sonic's website.

  • The patch test measures the alignment between the multibeam transducer to the motion sensor and gyro. This data is critical to the acquisition of precise seafloor data and to negate image ‘ghosting’ on objects. Our multibeam partner R2Sonic covers the patch test in it’s knowledge hub and in even more detail in relation to it’s own Sonic 2024/2022 multibeam echosounders here.

  • The integrated Hydrographic Survey System (iHSS) is designed to simplify marine data acquisition so that users of any experience can select the right configuration for the job, quickly install and calibrate the system on almost any type of vessel available and collect outstanding subsea survey results under even the harshest conditions.​ Subsea Europe Services has handpicked the most accurate and reliable sensors from our partners to make the iHSS a cornerstone in the reducing complexity and helping a wider range of end-users to collect their own marine data on diverse vessels of opportunity.

  • As the name suggests, the iHSS is delivered to you as a complete survey system, so you only have to work with one supplier – Subsea Europe Services. The benefits of our integration work can be seen at each phase of the hydrographic survey workflow:


    Planning: Our hydroacoustic technology experts help to select the correct configuration for your specific needs.

    Logistics: We deliver the preconfigured system and can have it with you within 24-48 hours if your requirement is urgent.

    Installation: The iHSS comes with everything you need and is easy to install and calibrate. Our experts can help over the phone or be there to assist on the day.

    Operation: We ensure that all hardware and software work in harmony making operation simpler and possible even for non-experts.

    Postprocessing: With a choice of three R2Sonic echosounders, the iHSS will always provide the best raw data as a foundation for high quality end products.

  • Both multibeam echo sounders and interferometric sonars are types of sonar systems used for underwater mapping and imaging, but they work on different principles.

    Multibeam Echo Sounder (MBES)

    MBES works based on the principle of acoustic echolocation. It sends out multiple beams of sound waves at different angles and receives the echoes reflected back from the seafloor or underwater objects. By measuring the time taken for the echo to return, along with other parameters, it can calculate the depth and position of the objects on the seafloor.


    Multibeam systems cover a wide swath of the seafloor in a single pass due to their multiple beams, providing good area coverage and bathymetric data. Data processing involves merging data from different beams to create a comprehensive map of the seafloor.

    Interferometric Sonar

    Interferometric sonar, also known as interferometric synthetic aperture sonar (InSAS), or bathymetric sonar, uses a different principle called interferometry. Instead of multiple beams, it employs two or more closely spaced transducers, and by measuring the phase difference between the signals received, it can calculate the seafloor's depth and shape. It is often used in towed or autonomous underwater vehicles (AUVs) for high-resolution seafloor imaging.

    Interferometric sonar provides high-resolution imagery of the seafloor and can generate detailed 3D bathymetric maps. It captures the seafloor's complex topography with high precision, but also collects more data points which must be processed to ensure accuracy. While this has been done by skilled human operators in the past, new artificial intelligence systems can now automate much of the processing to a point that quality controlled data can be provided in real-time as the survey happens.

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