The Sentinel

  • The study of extreme wave events in the ocean has become a popular area of research in recent years. Aside from seafarers, extreme waves impact coastal communities and are of great interest to marine renewable energy companies. This is particularly prevalent in the face of coastal erosion, rising sea levels and uncertainty in how the wave climate will change in a warming world. However, much of the current research is based on modeling and experiments. Extreme wave events – including storm waves, rogue waves, storm surges and tsunamis – are rare, and as such are difficult to observe and measure. Usually the wave categories are divided into two streams: long waves and short waves. Generally, the ratio of depth to wavelength is used as a parameter to differentiate between long and short waves. Tsunamis and storm surges are typically very long waves, so they are considered shallow water waves. Storm waves and rogue waves are much shorter in wavelength relative to ocean depth.

     
    The west coast of Ireland is a perfect location to observe extreme waves, especially when it comes to storm waves and rogue waves. Indeed, Atlantic swells propagate eastward toward the coastline of Ireland. Depressions from the Atlantic regularly bring very unsettled weather across Ireland. A few weeks ago, post-tropical cyclone Ophelia towered waves to the coast of Ireland, with a number of record breaking wave heights. 
     
    Definition of rogue waves: Oceanographers describe the sea state with a statistical measure called the significant wave height. This is the average height of the one-third highest waves. A rogue wave is one that is more than double the significant wave height. Rogue waves are sometimes called freak waves, but this is misleading: although they are rare and extreme, rogue waves are part of the normal behavior of the oceans.
     
    Ocean wave measurement usually uses spectral approaches developed in the 1950s. Surface waves are recorded with a fixed length time series (usually 20 minutes) from which are derived nominal wave spectra. Hardware is based on wave staffs, wire gauges, buoys or underwater acoustic sensors, but device cost means that measurements are made at a single point. These existing techniques have deficiencies: (i) many of the most dangerous wave classes on the ocean either cannot be measured at all or are inaccurately recorded because of sampling deficiencies; (ii) existing wave buoys cannot reliably measure processes such as wave breaking or rogue waves which are all better characterized as instantaneous phenomena and which do not appear in average wave spectra; (iii) sensor cost precludes wide area deployment and inhibits measurement of full spatio-temporal wave evolution dynamics. Buoys only measure accelerations, and a double integration provides displacement. Also, the buoy sensor in the case of a usual Datawell is gimballed in the buoy and can produce spurious large values if the buoy is rotated. Satellite measurements (altimetry) only provide significant wave heights. 
     
    The Irish winter of 2013-2014 was severely affected by many storms due to the atmospheric jet stream extending right over Ireland carrying successive storms. This exceptional weather combined with high tides resulted in serious coastal damage and widespread flooding. An altimeter pass in the Eastern Atlantic detected phenomenal significant wave heights near 19m just west of Ireland. 
     
    Prof. Frederic Dias from University College Dublin then decided to organize a measuring campaign for the following winter (2014-2015). He concluded that the best instrument to capture extreme wave events off the west coast of Ireland was an Acoustic Doppler Current Profiler (ADCP). In collaboration with Teledyne RD Instruments (TRDI), a Sentinel V ADCP was deployed in 36m of water at a site off the west coast of Ireland during the winter of 2015 (the experiment was repeated during the winters of 2016 and 2017), with the aim of gathering accurate wave measurements in extreme conditions. 
     
    The Sentinel V was gimbal-mounted and housed within a trawler-resistant frame and secured to the seabed in an upward-looking configuration. The Sentinel V is one of the latest in a line of ADCP developed by TRDI. It utilizes sonar pulses along five beams to gather measurements of both orbital velocity and echo intensity at predetermined distances (bins) along each beam. The five beams are arranged in the so-called Janus configuration, with beam five in the vertical and beams one-four offset at some predefined angle from the vertical. For this deployment, the Janus angle was 25 (degrees) and 34 bins, each separated by 1.2 m from center to center, were selected along each beam. 
     
    The nominal vertical distances from the ADCP transducer head to the centers of the first and last bin were approximately 26m and 66m, respectively, giving an effective range of measurement from about 10m below to 30m above the Mean Water Level (MWL). In addition to Doppler readings, pressure was recorded by the Sentinel Vs onboard sensor. The Sentinel V had on board a 16GB memory card. Pitch and Roll readings were recorded by the ADCP’s onboard micro electromechanical systems (MEMS) accelerometers.
     
    Velocities and backscatter intensity were recorded along the five beams continuously at 2 Hz for three months. Continuous sampling enabled the capture of details of several giant events with crest-to-trough heights more than 22m. Several theoretical explanations have been proposed for such extreme waves, in particular modulational instability and directional focusing. Typical oceanic wind seas are short-crested, or multidirectional, wave fields and their dynamics is more ‘free’ than the 1D ‘long-wave-guide’ counterpart. Indeed, energy can spread directionally and as a result nonlinear focusing due to modulational instability is diminished. The recorded extreme wave is 22m peak to trough, but does not show any characteristic nonlinear features such as depleted adjacent waves or unusual steepness. Instead it appears more like a standard wave group produced by superposition. What we saw during this extreme event is a group of waves that is moving and grows in amplitude to reach a maximum before it decays. 
     
    A key quantity to understand the formation of extreme waves is the wave directional spectrum. While traditional statistical approaches have been developed to derive wave directional spectra, the array of five direct surface tracking beams provides an opportunity to construct directional estimates for short time scales or even individual events. A successful investigation into the directional properties of groups of large amplitude waves was performed using time-frequency decomposition methods applied to the surface-track and subsurface velocities measured by the Sentinel V.
     
    An independent measure of wave direction was produced through a concept created by Brandon Strong, an engineer at TRDI. This new measure compared well to proven methods. 
     
    Time frequency decomposition revealed details in wave direction on short time scales necessary to isolate a wave group. Short time scale directional distribution shows that the 22m wave group had a particular direction but that the directional grouping in and around the peak was not different than the rest of the storm. Measurements also showed that the directional variability of this storm was significant making it unlikely that nonlinear models like modulational instability are responsible for this event because they require a quasi-single direction.
     
    These figures provide an overview of the entire deployment in 2015, where a significant wave height greater than 10m and maximum wave height greater than 22m was measured, and the extreme wave direction.
     
     
    The Authors
    Frederic Dias received a PhD in Civil and Environmental Engineering from the University of Wisconsin in 1986. He started his career in the U.S. before coming back to France to join CNRS in 1990. In 2000, he moved to Ecole Normale Superieure de Cachan and has been a Professor of Applied Mathematics since. 

    In 1984 Darryl Symonds started his career at Teledyne RD Instruments (TRDI) located in San Diego. During this career he has worked as an assembler, technician, customer service manager and, starting just over 17 years ago, he became the Director of the Marine Measurements Product Lines (MMPL).
     
     
    (As published in the November/December 2017 edition of Marine Technology Reporter)
  • Basin survey is being acquired by the MV Oceanic Endeavour deploying Sercel’s next-generation Sentinel RD solid streamer and started in January 2014. The Sentinel RD has a reduced diameter and a 15% weight reduction, compared to the original Sentinel, providing reduced cable drag and increased storage capacity

  • Teledyne RD Instruments  announced two updates to its Sentinel V ADCP. The enhancements include a complete update to the firmware and the user software interface program, ReadyV, and an update to the post-processing Velocity software package. These two releases provide for added flexibility in the setup of

  • The Company: Beier’s integrated engineering department and installation team specializes in retrofit projects, providing custom-designed systems for clients, reducing vessel downtime, and achieving the highest level of performance on the open water. Beier Radio, LLC and its subsidiaries (Beier Integrated

  • The rapid loss of Arctic sea ice is a sentinel. Most of us will never venture into the Arctic, but it can and does provide us with a forewarning of impacts coming to our parts of the Earth – and some of the most significant impacts will directly affect the maritime industry.   In earlier times, coal

  • Beier Radio, Inc. marks 70-years of providing engineering, sales and service for marine electronics around the globe. During its 70 years in business, Beier Radio has grown from being one of the first marine electronics distributors in the southern United States to a leader in integrated vessel control

  • Aluminum Boats, Inc. of Crown Point, La., recently delivered the Baltimore Sentinel, a 63- foot-long by 20-foot beam, 150-passenger excursion boat, to Maryland Tours, Inc. of Baltimore, Md. The new vessel made the 2,000-mile delivery trip from its south Louisiana shipyard " ... absolutely trouble-free

  • Tideland Signal Corporation of Houston, Texas, has introduced the new SAB-12 Sentinel Articulated Buoy. According to the manufacturer, the buoy has outstanding station- keeping capabilities and may be deployed where water depth makes placement of a fixed structure impractical. The SAB-12 consists

  • When the world's largest vehicular floating bridge was completed recently at Seattle, a newly built, Cummins-powered vessel—Driftwood II—was on hand to begin serving as the concrete structure's tender. Performing bridge maintenance, backup firefighting and environmental cleanup chores is a 46-foot

  • U.S. firms leverage Netherlands-based Damen Shipyard’s vessel designs and technical support. For nearly 40 years, Damen Shipyards Group in the Netherlands has licensed its vessel designs and technical support to yards owned by other companies. The business practice showcases not only the depth, variety

  • are scheduled to be delivered in 2017. In June 2014, Bollinger Shipyards delivered the USCGC Raymond Evans, the 10th FRC to the USCG in Key West, Fla. The Sentinel-class is replacing the Coast Guard’s Island-class 110-ft. patrol boat. The FRC uses an in-service parent craft design based on the Damen Stan Patrol

  • in the 1980’s,” Socha said. Defense budget cuts have not yet affected  Bollinger’s FRC backlog. Socha said 13 FRCs remain, plus any additional awards. The Sentinel-class FRC is a new patrol boat capable of deploying independently to conduct missions that include port, waterways and coastal security; fishery

  • MR Aug-23#53 IN THE SHIPYARD
Brix Marine
BRIX Marine Delivers Artemis:)
    August 2023 - Maritime Reporter and Engineering News page: 53

    IN THE SHIPYARD Brix Marine BRIX Marine Delivers Artemis: Rede? ning Bayonne Drydock Wildlife Adventuring on the Kona Coast BDD Completes BRIX Marine delivered Artemis from its custom PaxCat portfolio, designed for Hawaiian Adventures, a provider of immersive wildlife experiences on the USCG Cut er

  • MT May-23#21  that, years later, would put the Partridge fam-
sea circles)
    May 2023 - Marine Technology Reporter page: 21

    he story of Covelya Group is a familiar one in sub- to a connection that, years later, would put the Partridge fam- sea circles, the story of a man with a dream and ily on the acquisition path. the gumption to start his own company operating Fast track to 2006, when Sonardyne’s cooperation with Wave- T

  • MN Apr-23#35 2025 and 2026; and the Polar Security Cutter program)
    April 2023 - Marine News page: 35

    2025 and 2026; and the Polar Security Cutter program underway at Bollinger Mississippi Shipbuilding (previously VT Halter Marine) in Pascagoula, Miss.—the series’ ? rst vessel Polar Sentinel is scheduled to be launched in 2025. In June last year, Mobile, Ala. shipbuilder Austal USA was awarded a

  • MR Jun-22#45  Cmdr. Aja 
Kirksey said the option of sending an FRC)
    June 2022 - Maritime Reporter and Engineering News page: 45

    UNITED STATES COAST GUARD Deputy Sector Commander for Sector Honolulu Cmdr. Aja Kirksey said the option of sending an FRC with a WLB to- gether as a surface action unit (SAG) has proven to be success- Sentinel Class Fast ful. But these long deployments have risk, and we shouldn’t assume that because

  • MR Apr-22#35 Inside the “Largest Coast Guard 
Shipbuilding Effort Since)
    April 2022 - Maritime Reporter and Engineering News page: 35

    Inside the “Largest Coast Guard Shipbuilding Effort Since WWII” At his fourth, and last “State of the Coast Guard” speech held earlier this year at USCG Air Station Clearwater, Admiral Karl Schultz gave a rundown of the physical maritime assets being built to power the United States Coast Guard for the

  • MN Mar-22#36  a 70-foot pilot 
boat for the Galveston Pilots. 
stage)
    March 2022 - Marine News page: 36

    Feature Shipbuilding Gladding-Hearn Shipbuilding Gladding Hearn is currently building four pilot boats, including a 70-foot pilot boat for the Galveston Pilots. stage of the build program and is believed to be competing Austal USA has four Independence-class LCS currently with yards such as Bollinger

  • MT Mar-22#17 The 2017 paper “Undersea Cables In-
dispensable, insecure)
    March 2022 - Marine Technology Reporter page: 17

    The 2017 paper “Undersea Cables In- dispensable, insecure,” by Rishi Sunak, a member of Parliament, and published by the British think Tank Policy Exchange, states that the world is totally dependent on the half-million-mile undersea net- work. But as dependency rises, so do the Photo courtesy US

  • MR Mar-22#17 The 2017 paper “Undersea Cables In-
dispensable, insecure)
    March 2022 - Maritime Reporter and Engineering News page: 17

    The 2017 paper “Undersea Cables In- dispensable, insecure,” by Rishi Sunak, a member of Parliament, and published by the British think Tank Policy Exchange, states that the world is totally dependent on the half-million-mile undersea net- work. But as dependency rises, so do the Photo courtesy US

  • MN Nov-21#68  CTV
and design of the vessel would occur during)
    November 2021 - Marine News page: 68

    Vessels Hybrid-electric CTV and design of the vessel would occur during 2022-2023, set- ting the stage for building and launching the hybrid CTV in the mid-2020s, timing that would ? t well with the start of operation of wind turbines by May? ower Wind. Incat Crowther is the designer of the vessel

  • MR Jun-21#30  be submitted by June 11, 2021. The keel for the 
lead ship)
    June 2021 - Maritime Reporter and Engineering News page: 30

    USCG CUTTERS with offers to be submitted by June 11, 2021. The keel for the lead ship, USCGC Argus (WMSM 915), was “authenticated” in April of 2020.The second OPC, USCGC Chase (WMSM 916),is currently in production. The Coast Guard recently mod- i? ed the contract to begin construction of the third OPC

  • MN Jun-21#35  trade than in the U.S. On international sea)
    June 2021 - Marine News page: 35

    Captain Bernie Egan, Supervisor of Marine Operations, Prince Rupert Port Authority Prince Rupert Port Authority maritime trade than in the U.S. On international sea trade routes, particularly in Europe, shippers use what van Ryn- bach described as modern versions of older style cargo ves- sels: ships

  • MT Mar-21#52  from scratch, it comes 
quiring the seismic data for high-reso-)
    March 2021 - Marine Technology Reporter page: 52

    , a ‘compact’ marine seis- graded underwater acoustic positioning mic solution specially designed for ac- software. Rebuilt from scratch, it comes quiring the seismic data for high-reso- with a more powerful and ef? cient data lution 3D imaging of targeted offshore engine with improved positioning accu- areas

  • MN Oct-20#54  ad-
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    October 2020 - Marine News page: 54

    VESSELS USCG National Security Cutter Stone Passes Acceptance Trials class NSCs with two more under construction and one ad- ditional under contract. The technologically advanced Legend-class NSC enables the Coast Guard to meet the demands required for mari- time and homeland security, law enforcement

  • MT Jul-20#16  and impact of future mi- of the Sentinel-2 Multi-Spectral Instru-)
    July 2020 - Marine Technology Reporter page: 16

    will signi? cantly reduce way it leverages the near infra-red band directs it to a permeable conveyer belt. the quantity and impact of future mi- of the Sentinel-2 Multi-Spectral Instru- At this point, the waste is transferred croplastics. Dr. Lauren Biermann of the ment (MSI) to ‘see’ things that don’t

  • MN Aug-20#62  Point 
Navigation Systems 
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    August 2020 - Marine News page: 62

    one hundred Comms, Controls & Electronics Rose Point Navigation Systems RHOTHETA Ventura Rigol RHOTHETA International, Inc. Often used for navigation before the adoption of GPS, radio direction ? nders continue to function today as safety equipment for all types of vessels. RHOTHETA radio di- date

  • MR May-20#49  up ships
periods of time are therefore likely to  to rely)
    May 2020 - Maritime Reporter and Engineering News page: 49

    SHIp MAINTENANCE Biofouling & layed up ships periods of time are therefore likely to to rely on in water husbandry will require become fouled. As the organisms grow, the services of a diving company with Acknowledgements: so will the forces required to remove the method to match the fouling and the

  • MN Apr-20#37  American Marine 
will take over the construction of a ferry)
    April 2020 - Marine News page: 37

    SHIPBUILDING REPORT All American Marine Once up and running again, All American Marine will take over the construction of a ferry power by hydrogen fuel cells. Blount Boats The 56-foot icebreaking tugboat being built by Blount Boats for N.Y. Power Authority (NYPA). Photo: Blount Boats Photo: All

  • MT Jan-20#43 lent due to their proven performance.  puter models and)
    January 2020 - Marine Technology Reporter page: 43

    lent due to their proven performance. puter models and data from the gliders, al communities. Taking weather forecasts into account, researchers from Rutgers University researchers directed the gliders towards determined that strong winds on the Measuring the Changing Ocean a storm’s anticipated

  • MT Jul-19#60 .sonardyne.com
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    July 2019 - Marine Technology Reporter page: 60

    MTR 100 Sonardyne Hampshire, UK John Ramsden, Managing Director Staff: 290 www.sonardyne.com Sonardyne From the day it was founded close to 50 years ago, Sonar- instrument of choice for subsea resident vehicles and is sup- dyne’s focus has been customer-driven innovation in our porting the most demanding

  • MT Jun-19#14  project, ‘3D live habitats for the full 
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    June 2019 - Marine Technology Reporter page: 14

    Case Study Great Barrier Reef Great Barrier Reef’s 3D Habitat he mapping project, ‘3D live habitats for the full extent of the Great Barrier Reef,’ will provide maps of the predicted coral types and underwater landscape for the more than 3,000 reefs within Tthe 350,000 sq. km of the GBR. EOMAP’s technolog

  • MT Jun-19#8  computing. phones in the Sentinel streamer. 
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    June 2019 - Marine Technology Reporter page: 8

    or navigation systems, with the capability to run WFS Extre- and are incorporated with the hydro- Image Courtesy Sercel meEdge computing. phones in the Sentinel streamer. June 2019 8 MTR MTR #5 (1-17).indd 8 5/28/2019 9:11:17 A

  • MT Sep-18#61  Celeb- and development grant by the National 
shipping ? rms)
    September 2018 - Marine Technology Reporter page: 61

    Marine was awarded a research Shipping Firms Recognized NOAA presented awards to 13 global port Corp.; Polar Tankers Inc.; Celeb- and development grant by the National shipping ? rms for their commitment rity Cruises Inc.; Hamburg Sud; Exxon- Science Foundation (NSF) to enhance in helping prevent ship collisions

  • MT Jun-18#54  offshore wind farm project in the  to one of the world’s)
    June 2018 - Marine Technology Reporter page: 54

    a unique grillage design as part of a TCarta said it delivered satellite derived bathymetry (SDB) collaborative scope for an offshore wind farm project in the to one of the world’s largest oil and gas producers, Total SA, U.K. and one of the biggest in the world. who will use the water depth data for preparing

  • MT Mar-18#49 selected to pro? le the full water column. Thus a 75 kHz)
    March 2018 - Marine Technology Reporter page: 49

    selected to pro? le the full water column. Thus a 75 kHz Long nection, these ADCP data are available in near real-time and Ranger sits at the deep site while a 300 kHz Sentinel is at the for a long duration—two years so far. This has led to innova- inshore location. tive use of the ADCP data. Housed in a