Deep Trekker Diver Profile: Mike Fletcher

<p>Exploring with the Deep Trekker systems, travelling the world, adventuring among wrecks, visiting customers and meeting industry professionals  are by far the biggest perks working at Deep Trekker. We experience so many unique situations and meet so many amazing personalities.</p>
<p>Among the incredible people we encounter working at Deep Trekker, are a number of professional and commercial divers who  have a passion for marine exploration as well as working beneath the waves. In this mini-series we are going to feature some of the amazing divers we meet through our Deep Trekker contacts. Keep checking back for our Diver Profile series on our blog.</p>
<img class="wp-image-5002 size-full alignleft" src="//images.ctfassets.net/sr1t8a9wvxz9/1tfVS0AW65TCD9cw6gjocV/f1fffe88272e7010409215b862835972/diving6.jpg" alt="Commercial Diver Mike Fletcher" width="435" height="474" />

<p>The first diver we are featuring is a close friend of Deep Trekker’s. He’s been diving for over 30 years and has helped to film, produce and been a part of numerous diving broadcasts and television shows. <span class="il">Mike</span> <span class="il">Fletcher</span> began diving professionally in 1977 and has spent thousands of days in the water since then.</p>
<p>I first met <span class="il">Mike</span> last summer when he joined Sam and I on the water in Port Dover, Ontario to explore with the Deep Trekker DTG2 and DTX2 ROVs. He was extremely humble and laid back. It was impossible to tell the degree of success <span class="il">Mike</span> has encountered over the years without knowing beforehand. His love of diving was obvious as <span class="il">Mike</span> spoke about various underwater adventures and encounters.</p>
<p>It is clear to me that <span class="il">Mike</span> does what he does because of his passion for the water and exploration. That’s why after years of successful endeavors, <span class="il">Fletcher</span> continues to dive regularly and partake in expeditions particularly within the Great Lakes.</p>


Find out how ROVs can assist in a variety of diving applications

<p>Growing up on a dairy farm near Port Dover, <span class="il">Fletcher</span> certainly wasn’t born into a diving life. At age 13 his father sold their farm and bought land on Lake Erie. This, mixed with the debut of a number of dive related shows on television sparked an interest in diving within <span class="il">Mike</span>. He explains that he used to lay in bed at night listening to the sounds of the oil rigs and platforms off the coast and imagine the sort of work available for divers out there.</p>
<p>In 1975 <span class="il">Mike</span> <span class="il">Fletcher</span> began his career in the marine construction and offshore oil and gas industries. He was hired on as part of a crew building an oil refinery. While in that position the crew was in need of a diver to perform tasks underwater and <span class="il">Mike</span> volunteered. From there he became their commercial diver. In 1977 he was hired by Place Gas and Oil as a full time commercial diver.</p>
<p>When he wasn’t spending his hours working in the water, you could usually find <span class="il">Mike</span> in the water exploring the many shipwrecks that lay on the beds of Lake Erie and surrounding Great Lakes. As his dives grew longer and deeper, <span class="il">Mike</span> acquired more certifications and further developed his diving capabilities.</p>
<img class="size-full wp-image-5003 alignright" src="//images.ctfassets.net/sr1t8a9wvxz9/4QE74UH2vk8T2EI7Napq5f/db896739273fdfb6d880a8611a114a70/Punta-Arenas-Chile.jpg" alt="Punta Arenas, Chile Fletcher" width="375" height="268" />

<p><span class="il">Mike</span> obtained his certifications for operating decompression chambers and also became a licensed dive medic and captain. From there he began to explore the world of underwater cinematography. <span class="il">Mike</span>’s first cinematic endeavor was Sea Hunters where he was the diver coordinator on the National Geographic Series. In addition, <span class="il">Mike</span> has been an integral  part of a number of History Channel and Discovery Channel broadcasts.</p>
<p>Today, <span class="il">Mike</span> can be found diving with his son Warren on their new series Dive Detectives. The description for the series is as follows:</p>
<p>“The series covers a wide range of stories involving war, hidden treasure, disaster, science, and archaeology. The Fletchers travel the world, from the murky depths of the Mekong River to the warm, clear seas of the Caribbean to the frigid waters of the Canadian Great Lakes, shaping a dramatic, action-packed narrative that features real people and real missions unfolding in gripping actuality.”</p>
<p><span class="il">Mike</span> continues to strengthen his relationship with Deep Trekker and attends a number of our demos. He uses our ROVs regularly on his expeditions searching for missing wrecks and exploring those already found.</p>
<p>Be sure to check back to hear of any updates regarding <span class="il">Mike</span> <span class="il">Fletcher</span>’s excursions and Deep Trekker.</p>
<p>Sources Used:</p>
<p><a href="http://www.divedetectives.com/" target="_blank">http://www.divedetectives.com/</a></p>
<p><a href="http://www.imdb.com/name/nm1828943/" target="_blank">http://www.imdb.com/name/nm1828943/</a></p>
<p><a href="http://www.xray-mag.com/content/mike-fletcher-%E2%80%94-dive-detective-depth" target="_blank">http://www.xray-mag.com/content/mike-fletcher-%E2%80%94-dive-detective-depth</a></p>
<p>Personal encounters with <span class="il">Mike</span></p>


Learn all about remotely operated vehicle pilots: how to become one, job descriptions, and job salary.

You may have always known you want to work in or around the water. You may already be a scuba diver, joined the Navy, or just liked to find the unknown in the depths of the sea. There is a job you may have never heard about that will satisfy your craving for adventure while also challenging your intellectual skills and steady strength when dealing with unknowns.

Becoming a Remotely Operated Vehicle (ROV) pilot allows you to be in charge of a complex and challenging piece of robotic equipment. The ROV is a submersible craft that helps various industries, from search and salvage, oil, and gas to scientific exploration. As an ROV pilot, you can perform data collection that <a href="https://www.deeptrekker.com/news/how-underwater-data-collection-is-made-easy-with-a-deep-trekker-rov" target="_blank">monitors invasive species for scientific endeavors</a> or detect underwater environments from topside until safety determinations are made. 

Read on if the thrill of the unknown intrigues and challenges you. The informational guide below will tell you all you need to know so you can have the future you always wanted but never knew you could have.

<figure>
<a href="https://www.deeptrekker.com/products/underwater-rov/dtg3"><img src="//images.ctfassets.net/kzewhs8e6cvu/5RaHJjyUFiaVailbhu34K4/dabefd099cb69b7aa7407e06d1679027/dtg2-dtg3-differences.jpg" alt="deep trekker dtg3 underwater rov drone" width="578" height="462"/></a><figcaption><a href="https://www.deeptrekker.com/products/underwater-rov/dtg3" target="_blank" rel="noopener">Deep Trekker DTG3</a>
</figcaption></figure>

## What's an ROV Pilot?
<a href="https://www.bls.gov/oes/current/oes172121.htm" target="_blank">There no one degree or route</a> to becoming an ROV pilot technician. Most ROV pilot technicians do have degrees in mechanical, electrical, or electronic engineering, but not all of them do. Some ROV pilot technicians have Bachelor Degrees in Earth Science or Biology. Other ROV pilot technicians have military service qualifications with the appropriate levels of vocational qualifications.

If you want to work offshore, you do have to complete a necessary offshore safety induction and emergency training (BOSIET) course, STCW-95, or courses that are equivalent. There are times when ROV's like Deep Trekker is used for identifying targets of interest, including a victim and evidence recovery or deployed in a rapid search response. In both cases, it's the versatility of the ROV and ROV pilot technicians that are so beneficial to the search team process.

The Center for Ocean Sciences Education Excellence (COSEE) provides training for ROV pilots. Other titles COSEE says are used by those who work as ROV pilots are:

<ul>

  <li>Pilot technician</li>
  <li>Pilot</li>
  <li>Co-Pilot</li>
  <li>Electronic Technician</li>
  <li>Handling System Operator</li>
  <li>ROV Maintenance Operator</li>
  <li>ROV Technician</li>

</ul>

Many times ROV pilots are called System Technicians and more. 

<img src="//images.ctfassets.net/kzewhs8e6cvu/1rLJd4nytFncIYm4EFK1bs/964bf646045ae76ff395f9602536630f/rov-pilots-lake.jpg" alt="ROV Pilots performing underwater inpection in a lake"/>


## ROV Pilot Job Description Trends

There are eight core ROV pilot job duties that comprise the job description of every ROV pilot. 

### 1. Operator of ROV equipment
The ROV pilot will operate ROV equipment as needed, and many times this includes things like videos and still cameras. ROV equipment also features <a href="https://www.sciencedirect.com/topics/engineering/acoustic-positioning-system" target="_blank">acoustic positioning systems</a> and <a href="https://www.deeptrekker.com/news/sonar-systems" target="_blank" rel="noopener noreferrer">SONAR.</a> What that means is an ROV's submersible-mounted transducer is an acoustic positioning system that will be able to calculate range from an ROV to other transducers at known locations giving the known spacing. 
As an operator of ROV equipment, once you know the accurate range calculation, you can adjust for tangibles like water temperature, the density of water, salinity, etc. by computing the one-way or both way timing. It's the bearing that gives the triangulation of the timing difference across the transducer array. 

### 2. ROV Supervision of Launch and Recovery
As an ROV pilot, you can be called upon <a href="https://www.marinetechnologynews.com/blogs/understanding-rov-launch-and-recovery-systems-e28093-part-1-700531" target="_blank">to deploy, recover, and safely</a> operate ROV equipment. That means you need to perform efficient ROV Launch and Recovery Systems (LARS) and the Tether Management System for the ROV (TMS). Both LARS and TMS are how ROVs are deployed from the surface by support vessels.

The preferred method using LARS in an ROV launch is composed of an A-frame. Almost all work class ROVs are used <a href="https://www.deeptrekker.com/news/rovs-for-offshore-energy-operations" target="_blank">by the oil and gas industries</a> for deepwater operations and have at least one video camera and light you're in charge of managing. TMS is used when ROV pilots need to deploy the ROV to a depth that uses a strong and heavy umbilical cable due to the depth or varying intensity of the currents. 

### 3. Preventative Maintenance on ROV Associated Equipment and Actual Vessel
Every ROV pilot needs to know how to perform diligent preventative maintenance on their ROV associated equipment and on the ROV itself. You should always have fresh water supplies ready to go and close by when you're at an ROV landing point. Every landing point gives you an opportunity to wash the ROV equipment and the ROV after you use it, which is considered part of the planned preventative maintenance needed for this vehicle.

### 4. Ensure You Perform and Utilize Test and Calibration Equipment
As an ROV pilot, you need to prepare and test your ROV and related equipment for any mobilization or demobilization. You will be monitoring the R&M of the ROVs as well as determining your damage repair or modifications that are needed. Often you're in charge of arranging or performing the life-extending repairs so certification can be uninterrupted. It's essential you're confident in performing workshop repairs that include but aren't limited to the testing and calibration of the ROV equipment.

<img src="//images.ctfassets.net/kzewhs8e6cvu/4T5qAWOnCmLrNKPGzTvcDI/c9d15420aaed596dd8254b9e3082655d/rov-maintenance.jpg" alt="ROV Pilot performin Underwater ROV Calibration and Maintenance"/>

### 5. Perform Basic Rigging and Be Able to Operate Small Boats
ROV pilots can carry out technical tasks like rigging and operating small boats and then write the technical reports that detail their</a> log activities. This is rigging as you've never seen before because you have to be able to knot, gear, and use the rigging equipment properly. Then you have to be able to use rigging in a safe and timely manner while providing the correct hand signals and keeping all items you're moving secure and without damage.

### 6. - Perform Basic Electronic and Hydraulic Construction 
ROV pilots should be able to perform basic electronic and hydraulic construction repairs and order spare parts when needed. This means you work with engineers when needed to perform modification to an ROV system. You must also be able to build and design the mechanical, electrical, and hydraulic construction systems for ROV use. 

### 7. Maintain ROV Technical Documentation
As an ROV pilot, you maintain any technical documentation needed. But the technical documentation you keep as an ROV pilot includes detailed reports on mission accomplishment, mission training, technical issues, and technical solution reports. Your logs and reports have to be current and be recorded with legible accuracy. 

### 8. Post-Mission ROV Flight Reports
It's not always the case, but sometimes you need to write ROV reports post-mission when needed. This includes writing mission success or failure as well as if you accomplished mission objectives. Try to keep your reporting at a high baseline standard. 

### 9. Environmental Safety Condition Interpretation  
Evaluating and interpreting the environmental conditions and then interpreting them is one of the most complex and challenging tasks any ROV pilot has to be able to perform. The safe deployment and recovery of an ROV depend on interrelated factors you must be able to read. This includes things like determining the vessel heading, wind speed, wave direction, surface current, visibility, and being able to understand basic weather forecasting models.

<img src="//images.ctfassets.net/kzewhs8e6cvu/4fFjJWDrrYrViEVYpVzsJI/ddb70ce834b16557bf3614144df85f0d/rov-deployed.jpg" alt="ROV Been deployed for a tactical mission"/>

<h2> How To Become an ROV Pilot? <h2>

Every ROV pilot will have training in the below areas. Each area targets a percentage of time it is expected you will have to work within the work activity category.

82% of your time is spent documenting and recording information as an ROV pilot. This includes maintaining your technical documentation related to your test results, procedures, or inspection data.

79% of your time is spent on average collecting scientific or technical data. As an ROV pilot, you then take the statistical data and provide calibration information along with the statistical report.

Approximately 73% of your time is spent in communicating with your supervisors, team members, peers, or subordinates. You will have to feel at ease coordinated and communicating with crew members as well. Equal to your communicating percentage, you also will spend 73% of your time on average, maintaining very dependent interpersonal relationships with your peers and customers of your employer. 

72% of your time is working on computer models that you're inputting, accessing, reading, retrieving, or maintaining. This means you have to be comfortable when using spreadsheet software and desktop publishing software that your employer uses.

69% of your time is spent compiling statistical data so you can better interpret calibration data as well as craft performance data. You will also have to be able to make decisions based on scientific or statistical information regarding problems with the ROV or troubleshooting ROV mission concerns. 

In addition, your ROV time percentage performing tasks include also being able to communicate effectively and efficiently with people like scientists and engineers that don't work for your ROV employer. More importantly, you have to be able to evaluate information to determine ROV compliance based on industry standards. 

<img src="//images.ctfassets.net/kzewhs8e6cvu/2rAykAXu5JBxMxT44EJD5e/b5120916bf1e25c36e8bc5bebc5272ae/rov-pilots-search.jpg" alt="Two ROV pilots training for Search and Resuce operations"/>

<h2> What Is the Job Outlook and Salary of An ROV Pilot? <h2>

ROV pilots can work in civil engineering fields, the defense industry, environmental sciences, marine archaeology, oil and gas industries, academic scientific endeavors, and more. Depending on what industry you choose to work for and what specific ROV job you want to embark on, your future can be filled with adventure, challenges, good salary, healthy growth, and international travel. Some ROV pilots love the experience of operating the robotic arm while others want to learn and use the video and sonar displays to calculate positioning and SONAR capabilities. 

The ROV pilot salary ranges from $91,920 to over $110,020 to start, although some industries pay more or less than the average mean salary. The national employment estimate for an ROV pilot is <a href="https://www.bls.gov/oes/current/oes_nat.htm" target="_blank">only about 11,360</a> people. That is the reason the average salary range is a bit higher than the national average.

Plus, becoming an ROV pilot is no easy task to undertake with the training and skills needed regardless of what your degree is in or what military or vocational training you have. If you want to work offshore as an ROV pilot, you must pass a medical exam at least every two years and take a Minimum Safety Training course (MIST) no matter what degree or training you already have completed.

Learn more about which underwater ROV is best for your application.

## Trainee ROV Pilot
You don't start out as an ROV pilot no matter what skills or education you have, so when you're a trainee ROV pilot, there are certain skills and tasks you must perform. You will start at the bottom rung of the ladder as an ROV Technician level 3 (which is the trainee designation). You will progress through to an ROV Pilot and even beyond, but you must meet every ROV trainee goal and objective before that happens.

The International Marine Contractors Association has guidelines for the ROV operational objectives, and most companies want to ensure you have the training and development competency you need before you ever can work with or around an ROV as an ROV pilot. There may be nothing more exciting than a search and rescue mission, but to get there, you have to prove you can be an asset to the mission, the team members, and the objective of the employer.

Your shifts can be as many as 12 hours long, and you have no way of knowing what the conditions or weather environment will be if you're operating offshore. You usually have to work off the deck of a ship regardless of weather in cold weather gear or thermal boiler suits. There is almost always heavy lifting involved at some point during your day to day operations.


## The Way Forward in Becoming an ROV Pilot
There's actually no other job quite like it, and there's not another vocation that gives you an opportunity to do so much for so many different industries. That is by itself one of the greatest reasons for becoming an ROV pilot. But the training is rigorous, and the job tasks are never easy because each day will be different than the last one.

DeepTrekker provides some of the best ROV equipment to some of the biggest corporations in the world. They offer the most innovative and affordable underwater ROV, which has made them a favorite of industries looking to develop innovative solutions for their submersible needs. 

DeepTreeker knows where the industries are that need your skills and what's more, they offer the equipment that most of those industries are using. There's never been a better merger between what you seek and what's being offered by DeepTrekker.

As Deep Trekker’s resident Technical Trainer Alexander Gold is dedicated to helping people achieve their goals. Trained as a high school teacher at the University of Western Ontario, Alexander brings his experience as a teacher in Thailand, England and Ontario to his Deep Trekker clients. 

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All You Need to Know About Becoming an ROV Pilot

ROV Pilot 101: All You Need to Know

Learn more about what sonar is and its many uses. Read about its applications, technologies, principles, and more. 

Sonar systems serve a wide range of purposes. This guide covers key aspects of sonar technology, including its use in underwater inspections, search and recovery operations, bathymetric surveys, and more.

<div> <div style="position:relative;padding-top:56.25%;"> <iframe src="https://www.youtube.com/embed/79aapAgRURA" frameborder="0" allowfullscreen style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe> </div> </div> <br>

The video above is an example of how sonar can help with underwater target identification and navigating toward it. 

Sonar is often the favourite tool in the toolkit for those that work underwater. Utilizing sonar can be more of an art than science in many cases, so it can be challenging for those initially exposed to it. 

It is a powerful option to have though, as it can provide position information, context for the environment around you, and imaging capabilities in even the murkiest water.

There are different types of sensors that utilize acoustic technology:

- Echosounders / Altimeters
- Mechanical Scanning (CHIRP, Sector Scanning)
- Doppler Velocity Logs
- Ultra Short Baseline Positioning
- Side-Scan sonars
- 2D Imaging sonars
- 3D Imaging sonars

While each of these technologies serves a unique purpose, this article specifically highlights how sonar is used for underwater inspections and surveys.

![Sonar Canoe new UI (2024)](//images.ctfassets.net/kzewhs8e6cvu/6HXbe9aMmMlWI9xEjol7uU/3cd28491e55f14f1bea490afe6cc74c3/sonar1__1_.png)

Sonars help with:

- Navigation in murky water or large, open spaces
- Identification of key targets
- Helping measure features such as sediment levels or defect size
- Situational awareness

Underwater applications for sonar include:

- Bathymetric surveys
- Pipeline inspections
- Explosive Ordnance Disposal (EOD) & Mine Countermeasures (MCM)
- Search and Recovery
- Marine salvage
- Infrastructure inspections
- Offshore wind installation support surveys
- Ocean science, discovery, & academic research

Discover how sonar makes search and recovery missions safer and effective, and explore the benefits of integrating Deep Trekker ROVs with side-scan sonar.

<h2> What Is Sonar and How Is It Used? </h2> 

Since GPS is ineffective underwater and capturing quality imagery with a camera can be difficult in murky conditions, sonar is a valuable technology for underwater tasks.

Sonar (sound navigation and ranging) uses sound waves to map and detect objects. Sound waves are emitted, some bouncing off objects and returning to the emitter. By measuring the time it takes for the sound to return, the distance to the object can be calculated.

Although often attributed to Leonardo Da Vinci, sonar has been used by animals like whales and bats for millions of years. [Whales, for example, can detect objects as small as rocks from over 60 feet away](http://www.actforlibraries.org/how-sonar-affects-whales/) and rely on sonar more than their vision.

Sonar can tell us the following information about the seafloor:

- The ocean's exact depth
- Seabed and sediment type
- Unique topographical features
- Fish species inhabiting the area
- Foreign objects lying on the seafloor

<div>
  <div style="position:relative;padding-top:56.25%;">
    <iframe src="https://www.youtube.com/embed/S-ZogPdX0sA" frameborder="0" allowfullscreen
      style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe>
  </div>
</div>


<h2> How Does Sonar Work? </h2> 

An active sonar system consists of a display, transducer, transmitter, and receiver. The transmitter sends an impulse, converted into a sound wave by the transducer. When the wave hits an object, it reflects back. Depending on the system, sonar can detect objects up to 7,000 meters away.

The transducer converts the returning echo into an electrical signal, amplified by the receiver and displayed on the screen. Multiple hydrophone sensors then measure the sound’s intensity and phase to determine the distance.

Sonar performance varies with ocean conditions, and scattering from small particles in the water can interfere, similar to [light scattering in fog](https://www.vedantu.com/physics/scattering-of-light). Regular studies of ocean environments help improve acoustic range estimations.

﻿Talk to us about which ROV sonar system is best for your application

<h2> Types of Sonar Systems </h2> 

Human ears and voices represent the simplest form of sonar, similar to how we hear echoes. Modern sonar systems, however, offer high resolution and range, with military sonar capable of covering 80% of ocean floors from just four vantage points.

Despite light’s speed and [RADAR’s velocity](http://www.bom.gov.au/australia/radar/about/what_is_radar.shtml), only sonar can map seafloors, create nautical charts, and locate hazards and shipwrecks. After the Titanic disaster, sonar technology advanced significantly, particularly during the World Wars, leading to two main types: 

- Active 
- Passive

<h3>Active Sonar</h3>

Active sonar uses a projector to send sound waves that bounce off objects and return to the receiver, helping determine range, bearing, and motion. Submarines use active sonar to detect nearby objects by measuring the time delay between transmission and the echo. Advanced modern tools can also identify an object’s size, shape, and orientation in detail.

Deep Trekker ROVs (remotely operated vehicles) utilize active sonar which sends out a sound wave at a particular frequency and then listens for how long it takes for that sound wave to return after bouncing off objects in the water and the seafloor. Multibeam imaging sonar uses multiple beams of sound to paint an image of what’s in front of the ROV.

<h3>Passive Sonar</h3>

Passive sonar doesn’t emit sound but listens for signals from other objects, such as sea life or ships. These are also referred to as [Hydrophones](https://www.deeptrekker.com/shop/products/ocean-sonics-rb9-hydrophone). They are used for surveillance and can only determine the sound source location with the help of additional listening devices. They must work together to determine the transmitter location without having their presence known (in a military setting).

<h3>CHIRP Sonar</h3>

CHIRP (Compressed High-Intensity Radar Pulse) sonar is used for bottom-tracking and fish-finding. It sends a sweep of frequencies, offering more detailed imaging than traditional 2D mechanical sonar. With each pulse, the transducer starts vibrating at a low frequency, which is then modulated upward to a high frequency over the duration of the pulse.

<div>
  <div style="position:relative;padding-top:56.25%;">
    <iframe src="https://www.youtube.com/embed/FbBSpxXAKN8" frameborder="0" allowfullscreen
      style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe>
  </div>
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<h2> Categories of Sonar Devices </h2> 

Sonar devices can be classified into different categories based on their applications and capabilities. Two noteworthy categories are:

- Echosounders
- Imaging Sonars

<h3> Navigating with Echosounder Sonars </h3> 

Echosounder sonars are instrumental in conducting bathymetry studies. They are widely used in various maritime applications, including navigation for ships, charting for safe passage, underwater mapping for scientific research, and assessing potential hazards beneath the water's surface.

There are two main types of echosounders commonly used for these surveys: single beam and multibeam. Through the application of these echosounder technologies, operators can gain valuable data to improve navigation safety, understand underwater topography, and enhance their knowledge of marine environments.

![ Italy ballast tank challenge hull inspection](//images.ctfassets.net/kzewhs8e6cvu/6DyaS4aUGDNOeqSHIZtR3c/049788d83994eea087eecae6d666cf52/2024-03-22_05-11-24__1_.png)

<h4>Single Beam Echosounder Sonars</h4>

Single beam echosounders (SBES) emit a single sound beam vertically down to the seafloor, commonly used for basic depth measurements on marine vessels and in fish finders.

When piloting ROVs, echosounders can be used for measuring altitude above the seafloor and avoiding obstructions. Typically they come in dual frequency configurations, allowing for adjustments in the range of the sonar in real-time. Low frequency offers a longer range, with a sacrifice in resolution, while high frequency is ideal for close range and produces a higher resolution result. 

Because single beam echosounders are relatively simple, they are the most cost-effective and easy to operate option for bathymetric surveys, and are particularly useful for small-scale hydrographic surveys, environmental monitoring, and research in shallower waters. 

However, their narrow coverage area requires multiple survey lines for larger areas, and data accuracy can be influenced by factors like temperature and salinity. As a result, data acquisition with single beam echosounders can be incredibly time-consuming for extensive bathymetric mapping. 

<h4>Multibeam Echosounder Sonars</h4>

Like single beam, multibeam echosounders (MBES) measure water depth, but with much more detail, utilizing multiple beams to cover a wider area, allowing for a more detailed and efficient mapping of the seafloor or lakebed. 

This high resolution bathymetric data shows details that are instrumental for accurate hydrographic surveying, underwater mapping, oceanographic research and exploration, and navigation for all types of marine vessels.

The ability to see shapes and detect objects on the seafloor reveals details about the seafloor, such as seamounts, trenches, and valleys; as well as objects such as sunken ships. However, the extra complexity comes at a higher cost, and requires advanced data processing and specialized software to extract the information from the raw data. 

The extra complexity can also yield unwanted results, since it’s more likely to pick up things like marine life, water bubbles, or particulate matter, which can affect the accuracy of the results and require more granular processing and filtering of the data. 

<h3>Visualizing with Imaging Sonar</h3> 

Unlike echosounders, which provide depth information, imaging sonar produces detailed visual representations of the underwater environment. These devices emit sound waves and capture the reflections to create images, allowing researchers, divers, and marine scientists to study marine life, locate wrecks, and map the seafloor or lakebed accurately. 

The high-resolution images provided by imaging sonar enable the exploration of underwater structures and environments with remarkable clarity, making it a valuable tool for scientific research, underwater archaeology, and various marine applications such as 2D and 3D modeling.


Discover how remote visualization using ROVs enables efficient monitoring, and maintenance of underwater assets by exploring the capabilities of advanced modeling techniques.

<h4>Scanning Imaging Sonar</h4>

Scanning imaging sonar devices utilize a rotating transducer to emit sound pulses in multiple directions, creating a comprehensive 3D image of the underwater surroundings. These devices excel in revealing underwater structures, marine life, and complex terrains, serving scientific research, construction projects, and underwater inspections. Particularly valuable in low-visibility conditions, scanning imaging sonar aids in navigation, object detection, and detailed imaging.

<h4>Multibeam Imaging Sonar</h4>

Multibeam imaging sonar devices, also known as “forward looking sonars”, are advanced systems that emit multiple sound beams to cover a wide area simultaneously, providing accurate and efficient mapping of large areas. 

They also update the image multiple times per second, which is much faster than scanning sonar, making it an invaluable tool for hydrographic surveys, oceanography, search and recovery, and underwater mapping projects.

Multibeam imaging sonar devices conveniently mount to Deep Trekker ROVs or Utility Crawlers for effective target identification in turbid waters. Below are the models available through Deep Trekker:

- [M370S](https://www.deeptrekker.com/shop/products/blueprint-oculus-multibeam-sonar-m370s):  Designed for long-range navigation and low-resolution imaging, this sonar is ideal for __open-ocean surveys__ and __shipwreck hunting__ with an operating range up to 200 meters.

- [M750D](https://www.deeptrekker.com/shop/products/blueprint-oculus-multibeam-sonars-m750d): A versatile dual-frequency sonar, combining high-resolution imaging for short-range tasks with an extended range for navigation. It is __well-suited for both short and long-range operations__, making it a best-selling model.

- [M1200D](https://www.deeptrekker.com/shop/products/blueprint-oculus-multibeam-sonar-m1200d): Operating at a peak frequency of 2.1MHz and equipped with a 2.5mm range resolution, this sonar is ideal for detailed close-range inspections, including __search and recovery, EOD (Explosive Ordnance Disposal), and MCM (Mine Countermeasures)__.

- [M3000D](https://www.deeptrekker.com/shop/products/blueprint-oculus-multibeam-sonars-m3000d): The highest frequency sonar in its class, specifically designed for precise short-range imaging and inspections. It is optimal for detailed examinations of __tunnels, tanks, walls, and ship hulls__.

- [C550D](https://www.deeptrekker.com/shop/products/oculus-multibeam-sonar-c550d): A compact and cost-effective option with a maximum range of 100 meters, the C550D offers lower resolution than higher-end models but __delivers essential imaging capabilities for budget-conscious operations__.

![Sonar comparison GIF](//images.ctfassets.net/kzewhs8e6cvu/4U9q4KoDqP0s6iSGkNDWHq/d7a99ed43dcd8a447ebfcf54373c58be/4_SONAR_.gif)

<h4>Side Scan Imaging Sonar</h4>

Side scan sonar is specifically designed to produce detailed images of the seafloor or lakebed along a transect line, and can be mounted on the hull of a ship or ROV for submerged object detection. It emits sound waves perpendicular to the direction of travel and captures the reflections from the seafloor. 

This type of sonar provides information about the shape and texture of the seafloor by creating black and white, or grayscale images - where lighter shades represent hard, reflective surfaces, and darker shades indicate softer, less reflective areas. 

Side scan sonar is widely used for large areas of seafloor imaging, underwater search and recovery operations, maritime construction, and archaeological explorations. Best suited for large-area searches when deployed on an Autonomous Underwater Vehicle (AUV) or surface vessel. On ROVs, side scan sonar is particularly useful for scanning larger areas in confined or hard-to-reach spaces, covering more area than standard imaging sonar.

Deep Trekker offers side scan sonar options for both the [REVOLUTION](https://www.deeptrekker.com/shop/products/side-scan-sonar-revolution) and [PIVOT](https://www.deeptrekker.com/shop/products/side-scan-imangenex-pivot) ROVs.

![SideScan - PIVOT](//images.ctfassets.net/kzewhs8e6cvu/4rdnX6FccNZn2fCGbiQ15Q/b5424f7d1b5c1e1e6db28bf59157f527/JCD04739-Edit.webp)


<h2> What Can Sonar and USBL Do For You?</h2> 

One powerful option to consider is USBL (Ultra-Short Baseline), which integrates seamlessly with sonar systems. USBL and sonar technologies make it simple for operators to determine their location and understand what they’re observing underwater, making them indispensable for ROVs. From search and recovery to salvage operations and defense, these technologies offer precision and reliability across a range of applications.

USBL uses triangulation to pinpoint the ROV’s position, with a transducer at the surface and a transponder on the ROV itself—essentially creating an underwater GPS. This positioning information can be displayed in real-time on mapping software, such as Google Earth, and provides an impressive 20 cm accuracy. By combining this data with a GPS coordinate at the transducer’s location, operators can estimate the ROV's position with high precision.

Real-time map overlays simplify positioning and navigation, which is especially valuable in industries like search and recovery, where USBL systems assist with navigating large or complex search areas. USBL is also invaluable in maritime applications, helping operators know exactly where their ROV is in relation to their target. In underwater inspections, USBL guides pilots with accurate location data, enabling them to remain oriented with respect to the structures they’re assessing.


Explore our comprehensive guide providing invaluable insights of sonar technology and its diverse applications.

<h2> Operating Principles of Sonar </h2> 

Sonar systems use fan-shaped sound beams with narrow horizontal and broad vertical ranges, effectively mapping cross-sections in the environment. This technology requires a deep understanding of acoustics to make accurate readings.

<h3>Sound Speed</h3>

Sonar calculates distance by multiplying the speed of sound in water by the time for an echo to return, using the formula: 

> Distance = known sound speed in water x (calculated sound delay upon return / 2)
> 
Variations in temperature, depth, and salinity affect sound speed, typically around 1500 m/s in saltwater. Calculators are often used to refine accuracy in changing conditions, as scanning sonar systems cannot directly measure sound speed.

<h3>Target Reflectivity & Sound Beam Patterns</h3>

Reflectivity varies by material; objects like rocks and metals give strong echoes, while softer surfaces like sand, mud, silt, and plants absorb more sound. Sonar echoes are displayed in bright colors for strong reflections and darker tones for weaker ones. 

Using rotating transducers, sonar systems scan the environment in an arc, similar to a flashlight, capturing slices of the surroundings for a complete image. If you take pictures of the area as the light sweeps across the room, you will capture slices of the room that are illuminated. While you won’t see the entire room lit up at once, combining these slices will provide a complete view of the area that was illuminated.

![Sean Royal Interview.00 19 48 17.Still001-topaz-enhance ](//images.ctfassets.net/kzewhs8e6cvu/m6tXocsnofiSkG7opwwJi/a497301204235fa705bae9199c77fb43/Sean_Royal_Interview.00_19_48_17.Still001-topaz-enhance__1_.jpg)

<h3>Object Visibility, Slant Range, Arrival Angle</h3>

Sonar only visualizes objects within its beam, and cannot distinguish between overlapping objects at the same slant range (vertical arrival angle).

For example, if two objects are positioned one above the other at the same slant range in front of the sonar, they will appear as a single object on the display due to the overlapping of their echoes.

<h3>Bottom Visibility</h3>

For those surveying the bottom of a body of water, understanding that signal strength decreases over longer distances, sonar systems can be mounted at specific angles to improve image clarity. This positioning produces clearer sonar images of the seabed on the display.

If the system is angled steeply downward at a low altitude, only a narrow area will appear on the display. As altitude increases, the sonar system will illuminate a broader expanse of the seabed.

When a human operator searches for objects on the seabed, optimal sonar results are achieved by adjusting the altitude and angling the system downward. This positioning maximizes the imaging range and signal strength for clearer bottom visuals.

Learn about different methods used to perform surveys of the seafloor & the bottom of various water bodies. Plus, learn how ROVs are a useful tool to underwater studies.

<h3>10% Rule</h3>

For effective coverage, both mechanical and side-scanning sonar systems should follow the "10% rule," achieving around 70% seabed coverage. This rule suggests that the sonar's altitude should be 10% of its range. For example, if the range is set to 10 meters, the sonar should be positioned 1 meter above the seabed; for a 20-meter range, the altitude should be 2 meters.

While there are several guidelines in sonar usage, the 10% rule is one of the most reliable.

![10-percent-rule-sonar graphic](//images.ctfassets.net/kzewhs8e6cvu/43cPWWctN6rJBGcBOsHkhh/98a0f2a69682373eb132f4cf6892cfee/10-percent-rule-sonar.jpg)

<h3>Acoustic Shadow, Distance, and Altitude</h3>

Similar to how visible light creates shadows, objects in sonar imaging cast "acoustic shadows."

When the sonar is positioned at a steep angle and high altitude, shadows are shorter and harder to distinguish, making object assessment more challenging. A lower altitude and shallower angle create longer shadows, aiding in better object detection.

Objects farther from the sonar cast narrower shadows due to beam geometry, with shadow width increasing as the sonar approaches. Wider shadows, however, can obscure other nearby objects, as these areas receive no direct acoustic signal. When inspecting crowded areas, adjusting to a steeper angle and higher altitude for shorter shadows improves object distinction.

![BRIDGE console with sonar on screen](//images.ctfassets.net/kzewhs8e6cvu/7wzH1hY76yO5pqe6liEMsX/ffda8752093796cf3901ad7a90d0d87a/BRIDGE_console_with_sonar_on_screen.jpg)

<h2> Echoes in Sonar </h2> 

As demonstrated in earlier sections, sonar systems often illuminate objects at an angle, displaying only surfaces and edges that are closer to the system. Surfaces directly facing the sonar will produce the strongest echoes, while angled surfaces will deflect acoustic waves away from the system, reducing echo clarity.

These principles apply broadly to large environments. For example, when inspecting boat hulls or dock fingers, sonar reveals prominent features within the direct line of sight as bright returns, while obscured areas appear as shadowed zones with no return.

<h2> ROV Navigation </h2> 

While sonar systems offer a unique approach to acoustic interpretation, they are particularly valuable when mounted on an ROV. Without sonar, an ROV pilot must rely solely on visual feedback from a camera, which can be limiting in low-visibility conditions, often with a reduced range of view that can be less than a meter.

Sonar significantly extends detection range, allowing the pilot to detect objects from further away. Instead of going over the seabed to find objects, the ROV can remain stationary and scan the entire environment. This approach allows the pilot to gain a clear understanding of the area, including the locations of man-made structures, natural features, and areas to avoid.

However, due to the low mass of ROVs, they are prone to unintended vertical and horizontal movement. For sonar imaging, any ROV shift during the transducer’s rotation can smear the image. To minimize this, narrowing the scan plane or positioning the ROV on the seafloor can help increase refresh rate and improve image clarity. When interpreting the sonar display, it’s essential to understand relative bearings, with objects positioned according to clockwise angles from 000 degrees R, allowing for precise readings.

<div> <div style="position:relative;padding-top:56.25%;"> <iframe src="https://www.youtube.com/embed/6qTtY_W6b9I?si=-WUTe7YjjHGKO_zX" frameborder="0" allowfullscreen style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe> </div> </div> 

<h3>Polar Scan</h3>

A polar scan encompasses a full 360-degree continuum, making it ideal for gaining environmental awareness around the ROV, especially in low-visibility conditions. 

<h3>Sector Scan</h3>

A sector scan is defined as any scan that covers less than a full 360 degrees. These scans are effective for improving the refresh rate while imaging the environment or tracking an object. However, the drawback of using a sector scan is that it may result in a loss of visual information from the areas behind or to the sides of the scanned sector.

![GPS Sonar](//images.ctfassets.net/kzewhs8e6cvu/3dbqIafrgJVTOVMCQvi9yo/37194ba6a8298054f3bd4f4c5e22dc6b/GPS___SONAR-min.jpg)

<h2> Object Location With a Mounted Scanning Sonar </h2>

Sonar can be used to locate targets in the water column or on the seabed. However, effectively utilizing the sonar system to find objects, especially small ones, requires practice.

To optimize object detection with an ROV, it is essential to maneuver slowly, allowing for the generation of clear sonar images without smear. The first step is to position the ROV on the bottom or in a stable orientation.

Once stable, initiate a polar scan to capture a comprehensive view of the surroundings. Following this, calculate the relative bearing to the target object. The ROV should then be aligned with the object at a zero bearing.

Next, employ a sector scan, narrowing the angle to about 90 degrees to improve the refresh rate of the images. Finally, maintain contact with the target using sonar as the ROV follows its movement.


<h2> Leveraging Orthomosaics and SoundTiles Software for Detailed Imaging </h2>

For complex underwater inspections, creating high-resolution orthomosaics with [SoundTiles](https://iquarobotics.com/soundtiles) software enables users to achieve precise, large-scale visual mapping. Orthomosaics are composite images generated from multiple sonar or camera captures, stitched together to create a continuous, top-down view of a surveyed area. This technique provides a cohesive, detailed visual reference, invaluable for monitoring asset condition, tracking changes over time, or mapping expansive underwater structures.

SoundTiles software, which integrates with Deep Trekker ROVs, automates the generation of these acoustic mosaics by piecing together sonar images captured during inspection. Using SoundTiles, operators can create a seamless, geo-referenced map, which is particularly beneficial for inspecting infrastructure like dams, tunnels, and ship hulls where a comprehensive view is crucial.

![orthomosaic GIF](//images.ctfassets.net/kzewhs8e6cvu/5gGjGKOpmvVXFAmkoZlMy/522e68092cf3ea9e582a69007449b7ec/orthomosaic-gif__1_.gif)
<figcaption>A field test at a hydroelectric dam showcases how sonar data captured by our PIVOT and REVOLUTION ROVs can be leveraged to generate orthomosaics of underwater assets.</figcaption>

Key Benefits of Orthomosaics and SoundTiles Integration:

- __Enhanced Visualization__: By combining multiple sonar captures into a single, high-resolution image, orthomosaics offer a detailed view of expansive or hard-to-navigate underwater areas.

- __Improved Accuracy__: SoundTiles software accounts for variations in sonar data, aligning images precisely to produce a highly accurate spatial representation.

- __Change Detection__: For routine inspections, orthomosaics serve as baseline references, allowing operators to compare images over time and identify any emerging structural issues.

Through the integration of SoundTiles with Deep Trekker ROVs, users can leverage orthomosaics for meticulous monitoring, enabling a comprehensive view that surpasses what individual sonar or visual captures can offer on their own.


<h2> Applications of Sonar Systems </h2> 

Each type of imaging sonar has its unique strengths, allowing researchers and marine experts to gain a comprehensive understanding of the underwater world. These technologies play critical roles in ocean exploration, marine conservation, and various industries that depend on accurate underwater mapping and imaging.

Let's take a look at some examples:

<h3>Bathymetric Studies</h3>

Bathymetry is the study of the "beds" or "floors" of water bodies, including oceans, rivers, streams, and lakes. Sonar is used on ships to measure the depth of the ocean floor, enabling safe navigation. This technology is also responsible for the depth readings found on nautical charts.

<h3>Pipeline Inspections</h3>

Pipeline inspections can be difficult in murky water with high-frequency sonar. Gas and oil companies use sonar to detect damage, spans, and rock dump integrity.

[![H20 Drones pipe inspection with sonar](//images.ctfassets.net/kzewhs8e6cvu/6r43IeM2sbgENwcFJxLZER/902d0deb1d5132bf5a98f7ac41c9b2d8/vloer_binnenpand_voorhaven_na_middenhoofd.jpg) ](https://www.h2o-drones.com/en/)
<figcaption>Source: Image courtesy of H20 Drones, pipe inspection with sonar</figcaption>

<h3>Explosive Ordnance Disposal / Mine Countermeasures</h3>

Sonar is also used for detecting unexploded ordnance (EOD) and conducting mine countermeasures (MCM) underwater. As seafloors are increasingly exploited, it becomes essential to identify cables, pipes, and potential hazards. Locating unexploded bombs, mines, and torpedoes is critical for safety. Sonar systems are also integrated into submarines and ships for underwater communication. Commonly, side-scan sonar, either towed or boat-mounted, is used to scan large areas for anomalies. Once detected, an ROV equipped with imaging sonar is deployed to re-identify and approach the target to confirm if it's an explosive.

<h3>Search and Recovery (Public Safety/Law Enforcement)</h3>

Sonar technology is often used during Search and Recovery missions to make it easier and more efficient to locate evidence or victims of boating accidents or potential drownings in unclear waters. Side-scanning systems help locate bodies and guide the divers to the site of the recovery. ROVs with imaging sonars offer a safe alternative to verify and recover the victim instead of divers.

![REVOLUTION Police Demo (Delaware, NJ, and Virginia State)](//images.ctfassets.net/kzewhs8e6cvu/1gPrjU22KaFlHxsT6VCa3u/b6f15224561d2ba453a0070e6e730d26/JCD06471.jpg)

<h3>Marine Salvage Efforts</h3>

Sonar technology also has the ability to help locate underwater objects in deep salvage operations where murky waters may hinder camera visibility. Identifying a shipwreck or other large structure from up to 200m (656’) away isn’t a stretch for some ROV mounted imaging sonars.

![shipwreck sonar](//images.ctfassets.net/kzewhs8e6cvu/7CBkhS09CChzHNAHaXWkE9/26dae5d80c28834a212bbf57e008cdca/2020-09-21_13-45-02_DEEP_TREKKER.jpg)

<h3>Offshore Wind Installation Support Surveys</h3>

Powerful sonar systems are used for the assurance of safe installation of wind turbines. These sites must be subject to survey with great accuracy to ensure the foundation of the turbine is secure in the water.

<h3>Infrastructure Inspections</h3>

Inspecting large structures like bridge pilings, dock piers, quay walls, and dams can be challenging due to their size, making it difficult for divers or ROV cameras alone to provide a comprehensive view. Sonar offers a wider perspective, enabling inspectors to better assess the structure, identify major defects, and track changes over time by comparing results with previous sonar surveys.

<h3>Ocean Science, Discovery and Academic Research</h3>

The addition of sonar technology is invaluable to underwater discovery and research by helping academics and researchers to monitor aquatic life or environmental conditions below the surface.

![Handheld controller with sonar on screen](//images.ctfassets.net/kzewhs8e6cvu/3vZ3kQ6Txp1PSeXZf3Nafg/141bcd7539431fb95e467e1c5bb11766/Handheld_controller_with_sonar_on_screen.jpg)

<h3>Tunnel Inspections With An Imaging Sonar</h3>

2D imaging sonars are an excellent option for various applications. By sending out hundreds of beams within a 120-degree horizontal and 20-degree vertical band, they produce higher image quality compared to single-beam, sector-scanning sonar. This type of sonar is featured in the channel survey video at the beginning of the article, as well as in the tunnel inspection video directly above.

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<h2>Underwater Remote-Operated Robots for You</h2>

With a foundational understanding of sonar systems and their applications, you're well on your way to determining whether sonar technology suits your needs. There's no rush to make a decision; taking the time to conduct further research will only benefit you.

![C550d Sonar mounted on PIVOT ROV](//images.ctfassets.net/kzewhs8e6cvu/6mIi0gevX8CqEpQdAUYL6J/19f53ac91fc58463f8b49f89d4c74556/IMG_5283.jpg)

Sonar systems come in various types and can be integrated with a range of tools, software, robots, and vehicles. Given the broad applications of sonar in sectors such as energy, infrastructure, defense, commercial diving, municipalities, maritime operations, ocean science, and underwater exploration, it's important to understand the specifics of what you're considering.

By adding [sonar](https://www.deeptrekker.com/shop/categories/rov-sonar-positioning), you can significantly enhance your ROVs ability to detect hidden objects that might otherwise evade detection by a camera system. These attachments allow for both side and forward scanning capabilities.

If you're interested in learning more about sonar or you would like to consult about the appropriate system for you, [get in touch with us](https://www.deeptrekker.com/contact-us) and we will happily accommodate your needs. 


Industry Related Articles

sonar-body-on-controller-screen 1

Infrastructure

Municipalities

All You Need To Know About Sonar Systems

Sonar Systems: All You Need to Know

ROVs and sonar can be used to inspect underwater structures such as tunnels. Learn how this inspection technique is used to ensure the safety of underwater structures.

<h2>What are underwater Tunnel and Infrastructure Inspections?</h2>

There are many structures that run through our cities that are not seen by most.  Structures are required to deliver our wastewater, stormwater, and drinking water to and from treatment facilities and source locations.  These structures need inspections to determine their long term viability and condition, to make educated repair decisions.  Repairing these structures is not quite as easy as repairing buildings and roads, since these are under many other structures, and involve many moving parts to perform these repairs.  Inspections are conducted to determine structural condition, sediment levels, and more.  The inspections can be conducted by divers, confined space entry, excavation, or robotic vehicles. 

![Revolution ROV being deployed down a submerged tunnel](//images.ctfassets.net/kzewhs8e6cvu/7e8Ia1Iprz0F0S0AwC0SCF/656d81f26cd6f1d8369e1026edf0f95d/ABH_1854__1_.jpg)

<h2>Why use an ROV for underwater infrastructure inspection?</h2>

For fully submerged pipe and tunnel inspections, an <a href="https://www.deeptrekker.com/resources/underwater-rovs" target="_blank" rel="noopener">ROV</a> is an excellent tool.  In some environments, such as when the water is murky or the diameter of the tunnel is large, it is difficult to rely on just a camera to perform a thorough inspection.  Limited visibility can make it difficult to identify defects.  An operator can drive the ROV closer to the walls, top and bottom of the tunnel to get a clear enough image, but that may mean multiple passes and may not provide adequate data such as understanding the sediment levels in the tunnel. 

These are some of the factors to consider when choosing an ROV for tunnel inspection

- <h3>Length and Diameter of the tunnels</h3>
  - Smaller diameter, smaller vehicle
  - Larger diameter, more likely to need imaging sonar (lights and camera alone will not provide enough context to the operator to perform thorough inspections)
  - Longer tunnels may require more powerful vehicles or imaging sonars to help make the inspection more efficient
- <h3>Access Points</h3>
  - Size of access points (Size of Vehicle)
  - Number of access points (Length of tether required)
  - Location of access points (How portable of a system is needed)
- <h3>Condition of the Tunnel</h3>
  - Sediment Levels (Tracked vehicles and swimming vehicles are better when there are significant amounts of debris in the pipe)
  - Submerged vs. Partially Submerged vs. Empty (Crawling vehicle vs. Swimming vehicle)
- <h3>Type of Data Required</h3>
  - General Visual Inspections can be done with a simple camera and lights
  - Sonars help get a general visual in murky water
  - <a href="https://www.deeptrekker.com/shop/products/cygnus-thickness-gauge-integration" target="_blank" rel="noopener">Thickness Gauge data in steel pipes</a>
  - Position in the pipe (USBL does not work, tether  length counter required)
  - Sediment Levels require a sonar


Read our article about sonars to learn what the technology is in more detail

<h2>Benefits of using a Sonar with an ROV for underwater Infrastructure Inspections</h2>

Adding an imaging sonar to the ROV enables operators to have a better understanding of the tunnel’s condition as a whole and allows for the following defects to be identified:

- <h3>Tunnel Condition</h3>
  - Deformation
  - Ovality
  - Corrosion
- <h3>Size and Types of defects</h3>
  - Cracking & Pitting
  - Collapses
  - Disjoints and Separation
- <h3>Obstructions</h3>
  - Sediment Levels, can hide deformations, reduce flow rates, increase risk of overflows
  - Foreign objects (building materials, tree rooting, cross bore pipes or cables)
  - Protruding Laterals

Finding these defects enables repair decision-making to happen.  Not all defects require immediate attention.  Often, these become points of interest for later evaluation.  The goal is to identify changes over time, to see if a defect is getting worse quickly or slowly.  If the defect is at a critical point and is growing in severity, then repair actions need to be immediate.  However, equally as important from a cost perspective, being able to narrow down which defects do not require attention helps reduce unnecessary repair spending. The benefit of an easy to operate ROV in your fleet is that the revisiting of these defects can be taken on by virtually any operator.


Need an ROV for submerged infrastructure inspections?

<h2>Submerged Tunnel Case Study - PipeTek</h2>

In this video, our team supported Pipetek, a pipe inspection contractor, on inspections of submerged tunnels and other structures for Toronto Water.  

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<h3>Mission Objective</h3>

The goal of this particular mission was to evaluate the condition of a combined sewer and storm tunnel for Toronto Water.  PipeTek needed to provide a report of the tunnel and associated pump and intake structures to determine the best next steps for managing the structure.  Since this was a 530m long, fully submerged tunnel, the REVOLUTION ROV was chosen for the task.  Longer tunnels with sediment in the bottom proved to be more difficult for pipe crawlers, robots that PipeTek had significantly more experience with at the time.  
The problem with pipe crawlers is that their wheels or tracks stir the sediment, obstructing the view of the tunnel.  They also have a shorter range of view, because their cameras can only raise so far from the bottom of the tunnel.  Human entry in this long of a tunnel would be far too dangerous.  By utilizing a free swimming ROV with an imaging sonar, PipeTek was able to capture a thorough report of these tunnels and structures.

<h3>Equipment Used</h3>

- <a href="https://deeptrekker.com/products/underwater-rov/deep-trekker-revolution" target="_blank" rel="noopener">Deep Trekker REVOLUTION ROV</a>

  - The REVOLUTION ROV is an underwater robot, equipped with a sonar device that lets operators see, even though the water was so turbid that the camera was essentially useless. The sonar enabled operators to visualize the environment around them in a way which is so much more than what you'd imagine with the traditional side scan or even a mechanical scanning sonar.

- <a href="https://www.deeptrekker.com/shop/products/blueprint-oculus-multibeam-sonars-m3000d" target="_blank" rel="noopener">Blueprint Subsea Oculus M3000d Multibeam imaging sonar</a>

  - The “d” in the M3000d sonar model name means it is a dual-frequency sonar, so you can switch between the low range, high frequency, high-resolution mode, and the wider-angle view, which is the low-frequency mode. The low-frequency mode provides more range and a wider field of view.  The high-frequency mode is best for up-close inspection of defects for precise measurements, the low-frequency mode is best for general views of the tunnel.  Switching between the two modes is just a single button press.  In this inspection, there were a handful of passes through the tunnel, both at higher speeds to get a quick general idea of the condition, looking for large artifacts or obstructions.  The slower passes at high frequency and resolution to focus on smaller defects

<h2>Interpreting Sonar Images</h2>

The REVOLUTION ROV is unique for the rotating camera head that also rotates the sonar head. As you rotate your camera up and down, that sonar also rotates up and down. In this image, the camera is actually pointed straight down negative 90 degrees.

<h3>Rotating Sonar to Face Straight down to View Shaft</h3>

![SS1 - Imagine Sonar facing down on shaft entrance](//images.ctfassets.net/kzewhs8e6cvu/sryg3QuNZKZFuJHF1jYL6/87f19efb0125091365e94a6ae5f9876d/SS1_imaging_sonar_facing_down_on_shaft_entrance.JPG)

The 20-degree sonar beam is spread along the wall in front of the ROV. The nose of the ROV is up against the wall, and so you are seeing the texture of that wall as if someone was shining a bright flashlight straight down.
When you point the sonar straight up and right at the edge of the tunnel, you can see the tether and a little bit of its shadow, as well as those bubbles coming up out of the mouth of the tunnel. Bring the sonar back down to zero degrees at that angle, and you get a cross-section of the walls that are around the ROV. Angle it up a little bit, you see the roof of the tunnel in front of the ROV.  If you go past 90 degrees, you can see right at the edge of the shaft. There are those bubbles going up the shaft coming out of the tunnel and my tether again will bring that sonar back down.

<h3>Seeing Small Artifacts (Bubbles) with Imaging Sonar</h3>

![SS2 imaging sonar identifying small artifacts bubbles](//images.ctfassets.net/kzewhs8e6cvu/47fP8chGh7kO91e8TguyF8/c74fd3b5d6694dbf90261115bc8cd4b0/SS2_imaging_sonar_identifying_small_artifacts_bubbles.JPG)

Now, the other thing that's interesting with the rotating sonar is that you could point that sonar slightly down and see the bottom of that tunnel. Unfortunately, it's covered in sediment, so this didn't give the operators as good an idea of the structure.  In this inspection, they focused on the crown. You can see there those two lines inside the tunnel are the edges of that sediment layer. As we moved along, looking at the roof of the tunnel, you could identify cracks where there's a bit of a shadow cast behind that, so it means that there's something elevated and they found it had a lot of the cracks.

<h3>Using Imaging Sonar to take Cross Section of Pipe and see Sediment Levels</h3>

![SS3 Imaging sonar identifying sediment levels](//images.ctfassets.net/kzewhs8e6cvu/67t6tdmu9FtEaZfFqhwjAq/8808932b6279070d8b5cd07d5f75c632/SS3_Imaging_sonar_identifying_sediment_levels.JPG)

There is some sediment built up as water pushed its way out of the crack and that sediment stuck to the wall of the tunnel. Another interesting application here is you can point this sonar straight down, as you saw earlier, but because they are inside the surround structure, they are getting a cross section of the tunnel. So that line at the very bottom that's crossing what you would expect to be a perfect circle. That's the surface of the sediment. From there, you could take regular sediment depth measurements while driving through a tunnel.

<h4>Identifying a protruding lateral in the tunnel</h4>

![SS4 imaging sonar captures lateral protruding](//images.ctfassets.net/kzewhs8e6cvu/362hWn0EBddY1y03R1Qjps/36f91c294f510a1ba3fbeed2ef367784/SS4_imaging_sonar_captures_lateral_protruding.JPG)

Another example of an interesting structure that was found is pictured below. Tilt the sonar up, and you see there's a long shadow. Any time you see a long shadow, it means that the object is tall. There’s something projecting downwards out of the roof of the tunnel. By maneuvering the ROV and sonar head around, you can get a better look from different angles. As they get close and sort of slightly adjust the angle, you can see there's a cylindrical object.  This is a lateral pipe that's projecting into the roof of the tunnel. You can see there's a little bit of debris sticking off the end of it, so they mark the location of that lateral.

<h3>Identifying small defects with an Imaging Sonar</h3>

![SS5 imaging sonar identifies and measures pits](//images.ctfassets.net/kzewhs8e6cvu/2Q19VzYhdEGsOg6y8DWGT8/869d6da636208f497ed03e9ee7c54882/SS5_imaging_sonar_identifies_and_measures_pits.JPG)

Interestingly, it was the only one seen in this 530-meter-long tunnel. Here's another interesting artifact and you'll see two instances of it. There are bubbles down the middle, with a bit of an oval, along with the other end of that oval. This oval crack is something not uncommon in tunnels like these. By rotating side to side, you’re able to get a slightly better visual of its shape.  Using the sonar software either live during the inspection or after the inspection when reviewing, you can use the ruler tool to measure these artifacts.
When they popped up at the other end of one of these tunnels, they were in a large reservoir base, which collects water so there isn’t excessive outflow. There were three pumps in this section, off to the right, some of those vertical structures with the thicker material at the bottom.  Using the sonar, not only are operators able to see the general structure looking for obstructions or debris, but they can get a sense of the texture of the wall, identifying obvious cracks or breaks crumbling.  Even with the sonar set to 10m range, you can see clear detail within 50 cm of the sonar head.  Having these visuals is also useful for having situational awareness near the pumps, understanding where not to drive to avoid tether entanglements. 

<h3>Scanning Complex Structures with an Imaging Sonar</h3>

![SS6 imaging sonar scanning pumps and complex structures](//images.ctfassets.net/kzewhs8e6cvu/7uvXvuj1Zk2lN3ED7mbEFz/2ef5de00eec7e225dc8b1d72db8944b0/SS6_imaging_sonar_scanning_pumps_and_complex_structures.JPG)

<h2>Imaging Sonar Operation Tips </h2>

In these environments, it is best to set the gain low, move slowly, and rotate your sonar around to get a better idea of your surroundings.  A calm and careful approach will not only prevent tether entanglements, which are really only a worry near complex structures such as a pump, but it will also produce clearer sonar footage.  This is especially important if other stakeholders are viewing the inspection after, it will make it easier for them to add notes and digest what was inspected.

<h3>Using Imaging Sonar to measure pit size</h3>

![SS7 imaging sonar identifying pit size](//images.ctfassets.net/kzewhs8e6cvu/7jBeoueeTsk70YbaIV1tep/51de7d6c090640b3c8ece8bd19b61d0a/SS7_imaging_sonar_identifying_pit_size.JPG)

In this shot, they did an outward-facing orbit with the sonar pointing down, looking for artifacts in a shaft wall. You can see a pit, so they get close, take some measurements of its location and its size.
One last part of this survey involved using the ROV to help with the retrieval of a tripod mounted scanner.  The tripod broke and the scanner fell to the bottom of the shaft.  The grabber on the ROV is typically able to assist in retrievals of tools, but this scanner’s heavy weight combined with smooth shape made it difficult to grip with our manipulators.  Other objects, whether it is drowning victims, concrete slabs or even e-scooters, have proven to be perfect targets for Deep Trekker’s manipulators to retrieve.

<h3>Recovering Lost Equipment with a Drop Claw monitored by the Imaging 
 Sonar</h3>

![SS8 Imaging Sonar monitoring cable grabber for equipment retrieval](//images.ctfassets.net/kzewhs8e6cvu/4OLAZzblcKbZy85Aiqmmzb/3164ce9373f04e29b0d5d7f00d9f0c9a/SS8_Imaging_Sonar_monitoring_cable_grabber_for_equipment_retrieval.JPG)

A large claw on the end of two ropes was used to retrieve it. When they pull on one rope, the claw closes around an object, and you pull the other one to retrieve the target.  The ROV with the sonar positioned near the target was able to monitor this process and help with where and when to pull the large claw shut. 

<h2>Summary of Mission</h2>

Overall, this survey was a complete success despite having zero visibility for the camera.  Using the imaging sonar combined with the flexibility of the rotating camera head on the REVOLUTION, PipeTek was able to identify several points of interest for Toronto Water to evaluate and plan to reinspect, such as protruding laterals, pits, cracks, and sediment levels.  Not only were these points of interest located and photographed, they also were able to measure these with the sonar tools available. 


<h2>Deep Trekker for Tunnel and Infrastructure Inspections</h2>

Imaging sonars are an extremely versatile and capable option for many different applications, not just tunnel inspections.  They are often referred to as the most important sensor on an ROV by ROV pilots.  The Blueprint Subsea imaging sonars are an excellent tool for tunnel inspections but are not the only option.  We have seen <a href="https://imagenex.com/products/831l-pipe-profiling" target="_blank" rel="noopener">Imagenex 831L Pipe Profilers</a> and <a href="https://imagenex.com/products/852-ultra-miniature-imaging" target="_blank" rel="noopener">mechanical scanning sonars</a> used to provide valuable tunnel inspection data as well.  These scanning sonars do not provide the level of detail required to make condition assessment decisions on small defects, but are excellent tools for determining the general condition of pipes, gathering data on ovality, sediment levels, and identifying major defects.

Using this type of technology can seem daunting at first, but it is easier once you have even a little bit of first hand practice. The important part of determining the right tool for your project is to know what the end goal of the inspection is.  

If you need help finding the right technology for your missions, reach out to our robotics experts to find the right option for your applications and budget.  <a href="https://www.deeptrekker.com/contact-us" target="_blank" rel="noopener">We are happy to help</a> – even if it means choosing a technology that isn’t Deep Trekker!

<h3>This project is not the only tunnels that Deep Trekker ROVs have been deployed on.</h3>  

- <a href="https://www.cspect.com/en/news/cspect-inspected-a-800meter-long-duct-with-their-rov" target="_blank" rel="noopener">Cspect performed multiple 800m duct inspections with their REVOLUTION ROV, utilizing a custom bracket to hold cameras above the water line in the partially submerged environment</a>.
- <a href="https://skyebase.be/projects-references/sweco-inspection-sewage/" target="_blank" rel="noopener">Skyebase Inspection Services used their REVOLUTION ROV to build 2D CAD models of underground pipelines</a>.
- <a href="https://www.deeptrekker.com/news/offshore-wind" target="_blank" rel="noopener">Asset Insight used their DTG3 ROV to perform up to 700m long cable landfall ducts</a>


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