Making WavesNewsletter of Oceanic Consulting Corporation

Winter 2002

Full-size Modular Ship Bridge

Full-motion Platform Base Actuated in Six Degrees ofFreedom (provides motion cues and special buffet effectsincluding engine vibration, wave impact and collision)

Simulation of Ship Hulls and Offshore Structures

Training in Ship Handling, Single Point Mooring and Station Keeping

Training in Advanced Navigation, Piloting and BridgeResource Management

Length 5m

Width 7m

Window Angle 15º

Visual Theater Diameter 20m (approx.)

Visual Theater Height 12m (approx.)

Visual Theater Field of View 360º Horizontal27º Vertical

• IMD Offshore Engineering Basin • IMD 200 Meter Towing Tank • OERC 58 Meter Towing Tank

• IMD 90 Meter Ice Tank • IMD Cavitation Tunnel • MI 22 Meter Flume Tank

• MI Centre for Marine SimulationSpecification sheets can be obtained from the Oceanic website or by contacting one of our offices.

MI Centre for Marine Simulation.

Specification Sheets are Available for all Major Facilities, Including:

Ship Bridge Simulator Specifications.

In this issue...• Computational Fluid Dynamics:

Applying Advanced Technology.• Charting the Course: Winter 2002.• Oceanic Opens Office in Houston.• Multi-Vessel Numerical Simulation

Applied to ATB Units.

The use of computational fluiddynamics (CFD) codes to simulate flowaround ships and marine structures is apowerful and cost effective way to analyzeand evaluate new designs. Numerical modelingof marine flows can be used alone or as acomplement to physical testing to aid in design andanalysis. To better meet our clients’ requirements fornumerical flow simulation, Oceanic has recently licensedCFX-5 from AEA Technology Engineering Software.

CFX-5 is a Reynold’s Averaged Navier-Stokes (RANS) based finite volumecode. The solver can handle unstructured hybrid grids which can be adapted,based on solution results, to better resolve areas of increased flow activity. This code isat the leading edge of commercial CFD technology and is used extensively in the automotive,aerospace and civil engineering industries as well as by several of the world’s largest navies. Recentadvances in CFX-5’s free surface modeling algorithms allow Oceanic to offer its clients some of the most accuratemarine CFD simulations available.

In one recent project, Oceanic used CFX to compute the wind forces on the FPSO for the Woollybutt Field, offshore Australia. In this study, the wind forces werecomputed for several combinations of wind heading, draft and heel angle. The model, shown here colored by pressure contours for a bow wind, included a detailedrepresentation of the process modules, hull and superstructure. To ensure accuracy of the simulations, wind loads for the flare tower were computed using a detailedmodel and then used to correct the results of the whole ship model. Thanks to Vanguard SPC (IOM) Ltd. for permission to print this image.

For more information in this area,contact Michael Doucet.

Computational Fluid Dynamics:Applying Advanced Technology.

E-mail: oceanic@oceaniccorp.com URL: www.oceaniccorp.com

95 Bonaventure Ave., Suite 401P.O. Box 28009St. John’s, Newfoundland, CanadaA1B 4J8Phone: (709) 722-9060Fax: (709) 722-9064

In Canada: 9801 WestheimerSuite 302Houston, Texas77042, USAPhone: (713) 917-6805Fax: (713) 789-5472

In the United States:

• Maneuvering Assessment of a Shuttle Tanker ATB Unit.• IMD Names New Director of Research.• The Marine Institute & Ice Navigation Simulation.• Consultant Profile: Tor Naess.• Modeling Podded Propulsors.• MI Ship Bridge Simulator Specifications.

• Roll Stabilization Options for a CoastalCruise Vessel.

• Numerical Modeling of Ice Forces ona Single Point Mooring System.

• The Institute for Marine Dynamics &Flexible Structures.

In this era of unprecedented national andinternational trade, Articulated-Tug-Barge (ATB) unitsare used increasingly to transport everything fromrail cars and truck trailers to oil and other liquids.Owing to the popularity of ATBs and the perceivedmarket for computational seakeeping analysis ofsystems of multiple vessels, a new version of theMOTSIM seakeeping code was developed to permitthe simulation of two vessels simultaneously with orwithout mechanical interaction forces between them.To assess the applicability of the new numericalmodel to ATBs, a validation study was undertaken atOceanic using data from ATB model experimentsperformed over the past several years.

A typical ATB features a barge with a notch in thestern which fits the bow of the tug. Pins extend fromeach side of the tug, thus locking the vessels

together while allowing them to pitch independently.The rigid constraints of the pinned joint weremodeled mathematically to simulate its effects onthe vessels’ motion and to allow computation of theconnection loads at the pins. Preliminary resultsfrom this study were compared with experimentaldata for relative pitch and net pin connection force(see Figures 1 and 2). These results indicate that themultiple-vessel version of MOTSIM is capable ofaccurately predicting the performance of a pinnedATB system including the pin loads. This allowsOceanic to offer ATB clients a cost-effective methodto establish performance attainment at the earlydesign stage.

In addition to ATB systems, validation efforts arecontinuing for side-by-side moored vessels such asFPSO/shuttle tanker systems, tanker lightering, or

heavy lift vessels. The continued development of itsnumerical simulation capability ensures that Oceaniccan offer timely, cost-effective services to clients.

For more information in this area,contact Michael Doucet.

Welcome to the Winter 2002 issue of ournewsletter! Here in Newfoundland, winter isupon us. Most of you are in much warmerclimates, but it is our harsh marine climatethat makes the Newfoundland communityand Oceanic Consulting Corporation expert inthe evaluation of marine systems with whichour clients challenge the world’s oceans.

This newsletter highlights some of thenumerical modeling initiatives that are at theforefront of our efforts in Newfoundland, bothwithin the firm and with our research partnersat the National Research Council of Canadaand the Memorial University ofNewfoundland. Through the application ofcommercial codes like CFX for the evaluationof wind loads on FPSOs, panel method codesfor the motion of coastal cruise vessels, andnumerical models for mooring loads due toice, Oceanic is using numerical models as analternative or support to physical modeling.In each case, our aim is to provide the mostcost-effective solution for our clients.

Once again, this newsletter gives me theopportunity of announcing another step in ourglobal marketing strategy. In another first, ourfirm is pleased to announce the opening ofour office in Houston, Texas. We are proud tohave Clint Gosse, originally from Dallas, Texas,join our team to lead our U.S. marketingefforts. Although Clint, who is retired from aVice President's position in a majorengineering company in the Houston area,was born in the U.S., he does have roots inNewfoundland. Welcome aboard, Clint!

The application of podded propulsorscontinues to increase in the shipbuilding

world and we have made considerableprogress in the evaluation of thetechnology over the past year or so.Modeling the propulsion performance of

vessels with pods is becoming a normal partof our design evaluation process and in thepast couple of months we have undertakensuch studies on vessels ranging from pipelaying ships to very shallow draft icebreakers.We are also participating in continuingresearch in this area with people fromboth the National Research Council andMemorial University. Under the leadershipof Dr. Brian Veitch, Associate Professor ofOcean and Naval Architectural Engineeringat Memorial, Oceanic’s consulting andengineering team are helping in an effort toimprove the modeling and evaluationknowledge of this technology. In the end, weaim to help expand the knowledge ofhydrodynamics and improve the service weoffer our clients.

I hope you find this newsletter helpful andinformative. If you have any questions onanything in this issue or on performanceevaluation of your own projects, please takethe opportunity to contact us. We would behappy to assist you.

For Oceanic Consulting Corporation,Best Regards,

Dan Walker, Ph.D., P.Eng.President

As part of our continuing international strategicinitiative, Oceanic is pleased to announce the recentopening of a business development office inHouston, Texas. Our aim is to establish a permanentpresence in a major engineering/design center inthe United States, and as a result increase our abilityto gain a precise understanding of client needs andbuild strong working relationships.

Oceanic has employed Mr. Clint Gosse as theDirector of Business Development of the Houstonoffice; he will manage client relations and highlightbusiness opportunities in the Houston area. Anative Texan and a registered Professional Engineer,Mr. Gosse has extensive international experience inbusiness development for engineering, procurementand construction firms, with a previous client list thatincludes the major players in the petroleum industry.He will concentrate his efforts on engineeringparticipants of the offshore industry and presentOceanic’s credentials to firms requiring marineperformance evaluation and optimization services.

Mr. Gosse brings market knowledge that will allowOceanic to better serve clients throughout theUnited States. In just a short time, he hasestablished relationships with new and previousclients and provided insight on future opportunities.As Mr. Gosse says, “There is great demand forcomprehensive expertise in physical and numericalmodeling of marine systems in the United States.Oceanic has that expertise and is right here in NorthAmerica. I am impressed with the awareness andreputation of Oceanic in the marketplace, and I amlooking forward to developing strong relationshipswith clients in my territory.”

Charting the Course: Winter 2002. Oceanic Opens Office in Houston.

Mr. Clint Gosse,Director of Business Development, Houston Office.

Multi-Vessel Numerical Simulation Applied to ATB Units.

Figure 1: Figure 2:

With its leading expertise in the performanceevaluation of Articulated-Tug-Barge (ATB) units,Oceanic has collected valuable data for input intotime-domain numerical simulations. In a recentstudy, Oceanic evaluated the use of an ATB as ashuttle tanker for transferring oil from deepwatersites to shore-based facilities. In the study,maneuvering force derivatives were obtained viaforced motion experiments using a planar motionmechanism (PMM); the data was used withOceanic’s in-house maneuvering software to verifythat the ATB would comply with the maneuveringrequirements outlined by the International MaritimeOrganization (IMO).

The maneuvering simulation program applied byOceanic is a time-domain numerical model used forsurface ship maneuvering. The program useshydrodynamic force derivatives, which can comefrom model tests using PMM data or from semi-empirical expressions based on basic hullcharacteristics, to model the forces acting on thehull. For the computer simulations of the ATB, morecomplex non-linear force models were used. Toproperly implement control force algorithms,additional information concerning the forces andmoments resulting from control devices such asrudders and propulsors was required. This data wasobtained from a PMM model test program, whichincluded a series of rudder and yaw sweep

experiments to determine the control device yawmoment and the sway force at various ruddersettings and vessel headings. To model the flow andforces resulting from the control devices, the modeltests were conducted with a propeller speedcorresponding to the ship’s self-propulsion point.

Using the hydrodynamic hull force derivativesdetermined from the PMM and a validated modelfor the control devices, the numerical simulationsassessed the vessel’s maneuvering characteristics asoutlined in IMO Resolution A.751(18) InterimStandards for Ship Maneuverability, including turningability, initial turning ability, 10/10 and 20/20 zig-zag maneuvers and crash stop maneuvers.

This application of model testscombined with the numericalassessment provided

Oceanic’s client with a cost-effectivemeans of assessing themaneuveringperformance of theproposed vessel.

For more informationin this area, contactDon Spencer.

Maneuvering Assessment of a Shuttle Tanker ATB Unit.Floating Production Storage and Offloading (FPSO)systems for offshore oil production have beenoperating for several years in the North and theSouth China seas, both areas of extreme weatherenvironments. Because of its mobility andversatility, the FPSO is an attractive option for bothof these locations. Single Buoy Moorings Inc. (SBM)recently designed an FPSO unit for an operation inBohai Bay, China. The FPSO is normally moored toa piled jacket structure through an articulated yokesuch that the vessel is free to move without inducingmoments on the mooring. At times, the FPSO maynot be present and the yoke is supported on afloating cylindrical buoy, potentially subjecting it toice loading. Oceanic was contracted to determinethe loading on the buoy from moving ice floes.

In this study, a three-dimension discrete elementcomputer program, DECICE, was used to assess theice loading. DECICE solves complex solid mechanics

problems involving multiple interacting bodies, someof which may fracture internally and produce newbodies. Each element, whether rigid or deformable,is considered a distinct body, which may or may notbe in contact with neighboring bodies; anyunbalanced forces acting on the elements governthe movement of each block. The deformability,frictional, and damping characteristics of the contactpoints are represented by spring-slider-dampersystems.

For the numerical simulations, the ice sheet wasmodeled as an isotropic elastic brittle material withMohr-Coulomb failure criteria and tension cut-off.The buoy was modeled as a single rigid elementconsisting of a twelve-sided cylinder with conesfitted to the ends. The ice sheet was moved againstthe cylinder at various speeds with the cylinder freeto heave and roll. Ice thickness and flexural strengthwere varied to represent thin new ice, and thicker,

but weaker, rafted ice. The effect of varying thecoefficient of dynamic friction between the ice sheetand the buoy was also assessed.

The simulations completed by Oceanic’s engineersindicated that the ice-induced loading could besignificantly reduced by the addition of a smallblister on the buoy at the waterline to help it ride uponto the incoming ice. Oceanic’s results will assistSBM in designing a system that is capable ofoperating in the extreme conditions of Bohai Bay.

For more information in this area,contact Don Spencer.

Numerical Modeling of Ice Forces on a Single Point Mooring System.

Passenger comfort is a critical consideration in thedesign of a cruise vessel, and designers can selectfrom various options in order to achieve a particularlevel of comfort. In 1999, Oceanic was contractedby Guido Perla & Associates of Seattle, Washingtonto assess roll stabilization options for the 300-footCoastal Queen Class cruise vessels they weredesigning for American Classic Voyages. Oceanicused the time-domain seakeeping simulationprogram MOTSIM to predict the vessel’s motion invarious seaways without roll stabilization, withbilge keels, and with the installation of active fins.

The vessel’s overall motions, as well as accelerationsin the dining room and selected cabins, werecomputed, allowing the assessment of passengercomfort in critical areas of the vessel.

A comparison of the motions and accelerations withand without the roll reduction systems indicated thatthe active fin system would yield the greatest rollreduction at the design speed. However, bilge keelswould provide a substantial reduction in roll motionin heavier seas. The bilge keels were eventuallyselected for their cost and effectiveness at all speeds,

whereas the active fin performance is degraded atlower maneuvering speeds. During the acceptancetrials in early 2001, the Cape May Light (see Figure 3below), built at Alabama Shipyard in Mobile,Alabama, was found to have the comfortable ridepredicted with MOTSIM (see Figure 4 below fornumerical image).

For more information in this area,contact Michael Doucet.

Roll Stabilization Options for a Coastal Cruise Vessel.

The Institute for Marine Dynamics & Flexible Structures.An important aspect of ocean engineering is theability to use flexible structures for surface or sub-sea intervention, operations or other marine work.Some of the primary marine applications of thisstructural element are the mooring of vessels, eitherfloating or submerged, and the towing of marine

systems. At the Institute for Marine Dynamics (IMD),Dr. Wayne Raman-Nair is developing mathematicalmodels for simulating the behavior of these flexiblestructures. The main research tasks are to classifyand model the dynamic behavior of mooring systemsand flexible risers, and to define appropriate solution

algorithms. The developed formulation assesseshydrodynamic effects due to environmental conditions(waves and current), models the flexible structure,and calculates dynamic effects due to stretching andbending. Non-homogeneous lines of variablecharacteristics are being considered in this research.

Centerlineof Rotation

Turret GantryStructure

Risers(Generic)

MooringLines

Figure 3: Figure 4:

Using the methods of multi-body dynamics, IMD hasbeen developing programs in the MATLAB™environment to simulate the 3D dynamics of multi-point mooring systems and risers, thus allowing forthe assessment of the effects of large motionscaused by waves and current. These numericalmodels will also be integrated in a hybrid modelingprogram that will allow the Institute to providecomputer controlled “surrogate moorings”.Surrogate moorings can be used in model test caseswhere the size or depth limitations of a test basin donot allow the full mooring or riser system to bephysically modeled.

The benefits of this research include greatereconomy of engineering design, greaterpredictability of system response, andultimately, safer systems that require lessalteration, repair and downtime after installation.Several companies involved in offshore researchand development have expressed interest inthe project, and IMD is now seekingcollaborative partners.

For more information in this area, contactDr. Wayne Raman-Nair, IMD.

Planing HullPressure Distribution

Oceanic Consulting Corporation’s newly appointedSenior Consultant for Business Development, Tor Naess,will coordinate business development activities with thefirm’s consulting group and regional offices in the U.S.and U.K., as well as provide direct consulting servicesto clients. Tor holds a Master of Science degree in NavalArchitecture and Marine Engineering from the NorwegianUniversity of Science and Technology, has 26 years ofengineering and management experience, and he is alsothe author/co-author of 30 technical conference papers.

In his early career as a research engineer athydrodynamics laboratories in Norway, Tor was engagedin working on ship afterbody vibrations and propellerinduced pressure fluctuations. He later joined a leadingEuropean shipbuilding and offshore construction group

and became involved in the design of ships and offshorevessels. Over time his focus shifted to the offshorepetroleum industry, where he gained hands-onexperience from working with oil companies, majorcontractors, vendors and service providers in this industry.During this stage of his career, Tor’s offshore backgroundencompassed design experience from floating structures,including semi-submersible drilling units, productionplatforms, diving support vessels, FPSOs, and tensionleg platforms. Tor’s understanding of the critical aspectsof offshore platform design is a valuable asset to theperformance evaluation services offered by Oceanic.

Consultant Profile: Tor Naess.

Tor Naess,Senior Consultant, Business Development.

Oceanic Consulting Corporation is pleased to reportthat the National Research Council of Canada’s Institutefor Marine Dynamics (NRC-IMD) has appointedDr. Stephen Jones to a one-year term as acting Directorof Research. In this role, Dr. Jones will direct theresearch efforts of the Institute’s scientists and engineers,encourage collaborative work with IMD partners, andoversee the hiring of new researchers as the Instituteexpands its scientific program.

Dr. Jones, who was named Principal Research Officer(NRC’s highest professional level) in 2001, hasconducted and supervised research in the field of ship-

ice interaction since joining NRC in 1984. He haspublished more than 100 papers and reports and hasserved as editor of several research journals. Inaddition to managing international projects, he haschaired numerous committees and has held NSERCawards and adjunct professorships.

For additional information,contact Derek Yetman, IMD.

IMD Names New Director of Research.

Modeling Podded Propulsors.Early in 2001, Oceanic embarked on the challenge ofdesigning and fabricating model sized poddedpropulsors to keep abreast of the innovations in themarine propulsion industry. Podded propulsion hasbeen in the marketplace for the past 15 years but wasnot initially considered a viable alternative to moreconventional forms of propulsion due to its inadequatepower-conversion efficiency. However, manufacturersof podded propulsors have made great strides inimproving the performance of their units in the pastfive years; this has resulted in a significant increasein the potential application in the shipping industry.It was important for Oceanic to address this trend inship propulsion in order to stay current with clientmodel testing requirements. Although accuratelyapplying podded propulsor technology to model testingwas seen as a challenging exercise, Oceanic begandesign earlier this year.

Creating a generic base unit that would be applicableas a conventional single propeller z-drive and a dualpropeller podded propulsor using modular “off the shelf”components was the goal of the development program.It was important that the units be as small as possibleto be applicable on a wide range of scale models.The units, in their first form, would consist of a strut,

double ended gearbox, and instrumentation unit.The instrumentation unit would be mounted on oneside of the gearbox and a nose cone on the other toform a conventional z-drive unit. To model a poddedpropulsor, an instrumentation unit would be placedon both sides of the gearbox. If required, the unitcould be fitted with fairings to accurately representthe geometry of commercially available z-drive andpodded propulsor units.

The first iteration of Oceanic’s modular poddedpropulsors made their model testing debut during aresistance and self-propulsion test program of a pipelaying vessel. The units were configured as z-drivesand fitted with ducted propellers. Following this testprogram, the units underwent minor modificationsand were installed in their z-drive configuration withopen propellers on a scale model shallow watericebreaker. This program evaluated the resistanceand self-propulsion of the icebreaker in both openwater and in various ice conditions at deep and shallowwater depths.

In both test programs the units have shown greatpromise. Oceanic is now designing and planning thesecond version of the units for installation in theirpodded propulsor form.

For more information in this area,contact Lee Hedd.

Dr. Stephen Jones,Director of Research.

The Marine Institute & Ice Navigation Simulation.The improvement of existing technology and thedevelopment of new approaches for dealing withchallenging ocean environments is often a functionof the research infrastructure available to support themarine industry. Within the Oceanic community, theMarine Institute of Memorial University continues tosupport this industry through the employment of newlydeveloped tools. The Centre for Marine Simulationof the Marine Institute recently signed a Memorandumof Understanding with Transport Canada to evaluatethe Ice Navigation Simulator developed by PhiloSoftand Sicom under contract to the TransportationDevelopment Centre.

While the Ice Navigation Simulator is intended toassist with the establishment of ice navigationtraining programs, the development of ice simulationcapabilities is also significant to commercial marineindustries as they develop vessel and structure designsfor more severe arctic environments. According toAnthony Patterson, the Director of the Centre forMarine Simulation, “The capability to simulatenavigation through ice is a significant leap forwardin training programs targeted at ice navigators.We expect to incorporate the simulator into ourtraining and research programs, and we expectto refine ice simulation over time using the

tremendous knowledge base on ice operations herein St. John’s, which is also significant to commercialindustries.”

For more information in this area,contact Anthony Patterson, Marine Institute.