Friday March 19th 2010
8:00-8:30 Opening Remarks
8:30-9:00 Dr. Daniel Savitsky
John G. Hoyt, Naval Surface Warfare Center, Carderock Division, Betheda, MD
Seakeeping
9:00-9:30
Seakeeping of a Systematic Series of Planing Hulls
Luke Soletic, Davidson Laboratory, Stevens Institute of Technology, Hoboken NJ
It has been over three decades since seakeeping research on a systematic series of planing hulls has been conducted at Davidson Laboratory. Past studies have tested prismatic planing hulls, which have become increasingly less common. In this paper, a seakeeping study of a systematic series of four warped-bottom, United States Coast Guard designed planing hulls is presented. The 47 foot motor lifeboat serves as the parent model in the series; the three variants exhibit differing L/B ratios and deadrises. The models were tested in Pierson / Moskowitz spectral seas at sea states 2 and 3. Speed to length ratios of 2, 4, and 6 were tested. Each model was tested at four load cases corresponding to combinations of two displacements and two LCG locations, respectively.
The primary objectives of the study were to determine which hull form exhibited the best seakeeping performance and to compare the data to results from previously established seakeeping prediction methods. Performance trends with respect to series geometry parameters as well as model loading and speed were noted. The parent model was found to generally exhibit the best seakeeping performance of the series. The seakeeping performance trends observed by the author agreed favorably with those found by Gerrard Fridsma in his 1971 seakeeping study of prismatic planing hulls in spectral seas. Agreement of the series’ experimental acceleration and added resistance data with the Savitsky / Brown prediction was found to be reasonable. Furthermore, agreement of the experimental acceleration data with the exponential distribution was investigated. It was found that the acceleration data did not match the exponential distribution using the selected time history buffering method. A discussion of the effects of acceleration buffers on seakeeping statistical data is included. Efforts were made in acceleration time history processing to isolate and record only genuine wave-induced accelerations while excluding extraneous noise. Statistical results of several processing methods are provided.
9:30-10:00
Dynamic Performance of the NTUA Double-Chine Series Hullforms in Regular Waves
G.J. Grigoropoulos, National Technical University of Athens, Greece
D.P. Damala, National Technical University of Athens, Greece
T.A. Loukakis, National Technical University of Athens, Greece
A systematic Series of double-chine, wide-transom hull form with warped planing surface has been developed at the Laboratory for Ship & Marine Hydrodynamics (LSMH) of the National Technical University of Athens (NTUA) during the last 15 years. The series, inspired by a proposal of Savitsky et al (1972) provide a handy and suitable base for the design of medium and large modern monohull ships and pleasure craft, which operate at high but pre-planing speeds. The series consist of five hull forms with L/B ratios equal to 4.00, 4.75, 5.50, 6.25 & 7.00s. The non-dimensional displacement-length coefficient CDL = Δ/(0.1 LWL)3 , where Δ is the displaced volume and LWL the waterline length at rest, is used to represent the loading condition. Two scaled models for each hull from has been constructed and tested at six displacements, including very light ones. The resistance characteristics of the series were presented by Grigoropoulos and Loukakis (2002). Furthermore, their seakeeping behavior is expected to be attractive since the parent hull of the series showed a superior performance over several competitive hull forms (Grigoropoulos and Loukakis, 1995). This fact has been observed in real life by Dan Savitsky many years ago. Thus, it was decided to carry out a systematic investigation of their dynamic performance in waves. Model tests have been carried out in regular waves while an ambitious and time-consuming experimental investigation is underway to test the hull forms of the series in random waves.
In this paper the dynamic performance of the hull forms in regular waves is presented in a systematic way. Tests have been carried out for two level keel displacements and at two speeds corresponding to Fn = 0.34 and 0.68. The RAO curves for heave, pitch, acceleration as well as added resistance are presented. Furthermore, the ongoing program of the model tests in sea states is described.
10:00-10:15 Break
10:15-10:45
U.S. Coast Guard Response Boat – Medium (RB-M)
David M. Shepard, USCG, Washington, DC
Jeffrey M. Curtis, USCG, Washington, DC
The U.S. Coast Guard’s 45’ Response Boat – Medium (RB-M) is replacing the Coast Guard’s fleet of 41’ Utility Boats that have been in service for more than 30 years. Used for a wide range of missions including Search and Rescue (SAR) and Ports, Waterways and Coastal Security (PWCS), the RB-M provides vastly improved capabilities including increasing speed from 26 knots to over 42 knots, improved seakeeping, self-righting stability, and enhanced crew accommodations.
In June 2006 the Coast Guard awarded a contract was awarded to Marinette Marine Corporation (MMC) in partnership Kvichak Marine Industries (KMI) and CAMARC Ltd. for the detailed design and construction of a planned fleet of 180 boats.
Starting with the projects initiation in 2001, a very detailed systems approach has been used in the RB-M procurement. This has included the evaluation of three test boats, a very detailed 3-D design development that included a full scale mock-up, and the development of a very robust logistics system that includes electronic technical manuals and on-line maintenance and parts tracking.
The first production RB-M was delivered in March 2008, and Low Rate Initial Production continues at a delivery rate of approximately 1 boat per month.
The first 6 boats have undergone extensive Operational Testing and Evaluation (OT&E), and the results of OT&E are being incorporated into the final production design.
Once approval is received, full production will ramp up to approximately 30 boats per year with parallel production in Kent, WA and Green Bay, WI.
This paper will cover all aspects of the RB-M acquisition from the initial requirements development through full production.
10:45-1:00 Lunch
Stability
1:00-1:30
Practical Dynamic Stability Evaluation for Planing Boats
Edward M. Lewandowski, CSC Advanced Marine Center, Washington, DC
Evaluation of the transverse stability of planing hulls at speed is complicated by the presence of dynamic forces and by coupling of roll motion with yaw and sway, and indirectly with trim and heave. A method will be presented to evaluate the coupled dynamic roll-yaw-sway stability, using only craft geometry and loading, and results available from a standard "Savitsky method" resistance prediction. The method applies data obtained from a series of straight-course and rotating-arm maneuvering tests conducted at Davidson Laboratory. The counter-intuitive effect of appendages on stability will be discussed. Sample calculations will be provided.
The model test program mentioned above also contained some unique tests to evaluate the roll damping of unappended planing hulls in the planing regime. The simple (and somewhat obscure) equations developed from these results will also be presented.
1:30-2:00
Tank Tests to Estimate onset of Dynamic Instabilities of High-Speed Planing Craft
Toru Katayama, Tomoki Taniguchi and Kazuya Habara, Osaka Prefecture University, Department of Marine System Engineering, Osaka, Japan
In 1994, a high speed towing system (the maximum speed of which is 15m/s) was developed to investigate the performance of high-speed planing craft at Osaka Prefecture University. Nowadays, the system has many experimental devices, and resistance and propulsion test, seakeeping test, maneuvering test and so on can be carried out.
In this paper, for dynamic instability as one of important performance of high speed planing craft, the experimental techniques using above-mentioned devices and the analyzing procedures, that were developed to estimate the occurrence possibility of some dangerous motions, are explained. And some results are also shown.
2:00-2:30
On the Stability of Powerboats
Chris Barry, SNAME Small Craft Committee Administrator, Jersey City, NJ
Traditionally small powerboats have only had to meet simple intact and damaged stability requirements, principally those in 33 CFR 183, (also promulgated by ABYC as Project H-8) or 46 CFR 178.33 (for small passenger vessels), or in many cases, none at all, depending instead on successful experience based on proven traditional designs. More sophisticated standards were also hampered by the difficulty of performing the requisite stability calculations.
Recently, however, ISO published ISO 12217, promulgating international standards for boats under 24 meters. In addition, there have been a couple of accidents involving small passenger vessels that have resulted in new standards, and new vessel types, such as RIBs have required new criteria. Other countries have also developed standards for small craft. Earlier 46 CFR 28.500 promulgated more sophisticated analyses of fishing vessels (over 24 meters) and other international standards for smaller fishing vessels are being developed. Finally, many small, fast power craft are being procured by governmental agencies for security applications which result in more severe exposure than is traditional for recreational craft, so there is a search for applicable stability standards. Many of these new standards require righting energy calculations and similar “ship-like” stability analyses.
This paper summarizes, discusses and compares a number of old and new standards and explains some of the key concepts that underlie these analyses and suggests other voluntary criteria that might improve safety. It also presents techniques for using available software for performing these analyses.
2:30-2:45 Break
Model Testing
2:45-3:15
Recent Advances in Radio Controlled Model Testing
Barry Deakin, Wolfson Unit MTIA, University of Southampton, Southampton, UK
Self propelled models under radio control have been used for many years to assess the maneuvering and handling of ships, and occasionally small craft. The limitations for testing small, fast craft have been linked to the low model weight required and the ability to install enough power, as well as the cost of modeling.
Recent advances in motor and battery technology, the availability of model water jet drives, and developments in small data logging and GPS systems have enabled cost effective modeling of very fast craft. Their handling characteristics can new be accurately assessed at an early stage of the design. This helps to ensure a successful boat, determine the acceptable boundaries of the design, or modify it to eliminate any problems found.
At the Wolfson Unit we have successfully tested boats up to 55knots, with single and twin screw, and single, twin and triple water jet drives.
3:15-3:45
The Use of Small Model Testing and Full Scale Trials in the Design of Motor Yachts
Joe Snodgrass, Viking Yachts, New Gretna, NJ
Michael Morabito, Stevens Institute of Technology, Hoboken, NJ
The use of data from many years of carefully conducted full scale trials, combined with towing tank tests on concept designs can be of great assistance to designers. The paper discusses how the Davidson Laboratory conducts model tests of motor yachts, describes the methods that Viking Yachts uses during their full-scale trials, and demonstrates how these methods were used to in the design of the Viking 82.
3:45-4:15
Model Studies of High Speed Catamaran Hull Forms
Richard Neff , Davidson Laboratory, Stevens Institute of Technology, Hoboken NJ
Today, high speed catamarans are becoming very prevalent in offshore racing and in fast recreational boats. Typically, the demi-hulls of these craft feature an asymmetrical hull form, which reduces spray drag inside of the tunnel. In order to predict the performance of these vessels using the Savitsky method, designers must make an assumption for the lift of asymmetric hulls as well as the interaction effects associated with tunnel width. This paper summarizes the results of recent student-lead systematic studies conducted at the Davidson Laboratory, as well as earlier published studies pertaining to performance prediction for high speed catamaran hull forms.
4:30pm Adjourn for Friday
Saturday March 20th 2010
Advanced Hulls
8:00 – 8:30
Power Catamarans: Design for Performance
Albert Nazarov, Albatross Marine Design, Thailand
The experience of power catamaran design and research is presented, covering planing and displacement catamarans 6 to 24m in length developed by ‘Albatross Marine Design’ during last years. The perspectives of power catamarans as pleasure and special craft for different markets and applications are reviewed.
The dynamics of power catamaran is discussed, differences between multihulls and monohulls are noted. Classification of hull shape is provided in respect to mode of operation, desired speed and applications. Recommendations are given for hull shapes particulars selection, namely for LCG, CP, CB, deadrise, submersed transom area, static load factor, etc. in forms of diagrams.
It is noted that catamaran’s arrangement is designed around tunnel and thus special attention is given to finding a compromise between tunnel proportions and general functionality of boat.
Tunnel shaping is studied in terms of performance and seakeeping, approaches are reviewed. Recommendations for vertical and horizontal tunnel clearance are given, based on calculations and tests. Special attention paid to hulls interaction and slamming areas. Photographic record of tunnel flow is provided for different speeds.
Components of resistance are discussed and review of available methods of catamarans performance predictions is given, with recommendations to their areas of application. Diagram is proposed for estimation of required power versus speed at early stages of design.
Seakeeping is discussed in terms of operational safety and ride comfort. Results of measurements of vertical accelerations with acceleration gauges are presented for series of power catamarans. Comfortable speeds of operations are recommended for different catamaran size and sea state conditions. Maneuverability is discussed based on GPS track measurements, where dependence of turning circle from beam is noted.
Study of weight of composite structure is presented for several options of 10m power catamaran, starting from basic CSM laminates to high-tech solutions. The importance of weight reduction is emphasized, cost efficient methods discussed.
Samples designs are presented, reflecting company’s experience in the field for rescue, work and pleasure catamarans. Results of sea trials are presented and discussed in terms of further improvements. The perspective directions of research are specified along with proposed methods.
8:30-9:00
Efficient Power Boat Concepts
Lou Codega, Naval Architect, Smithfield, VA
Power boats in today's marketplace, particularly those built for recreation, make the term “efficient design” almost an oxymoron. And they are rapidly becoming unaffordable. We'll look at current designs and compare them to other means of transportation. Then we'll present two conceptual designs, one paying homage to the past and one looking to the future, that address many of the current boats’ shortcomings.
9:00-9:30
Development and Experimental Evaluation of the Transonic Hull
Alberto Calderon, Transonic Hull Company, La Jolla, CA
Lee Hedd, Oceanic Consulting Corporation, St. John's, NL, Canada
A new hull form has been developed by the Transonic Hull Company of La Jolla, California with the primary goal being to significantly reduce hull wave making resistance and motions in seaway. An extensive research and development program has resulted in a new monohull shape code named Transonic Hull (TH) and this paper presents the principal results attained to date.
Hydrodynamic theory establishes that wave making of displacement hulls primarily originate from curvatures of their waterplane. These curvatures create bow waves, midbody troughs, and stern waves, which generate a “hull speed” problem when the distance between bow and stern wave equal the boat’s length (speed/length ratio 1.34). Near and above hull speed, resistance due to wave making grows at a high exponential rate. Development of the TH technology is focused on reduction of wave making resistance across a broad speed range by significantly altering the wave profile along the hull by using a slender triangular waterplane with rectilinear sides free of curvatures extending from bow to maximum beam at the stern. Tow tank experiments indicate a large reduction of drag of more than 20% at operational speeds is attainable when compared to some conventional hull forms. The TH’s forebody is shaped with minimum volume and this and other features provide negligible pitch response in large significant sea states. In addition, the TH form has been shown capable of operating at high speeds in a seaway without significant slamming events. Performance predictions and comparisons of the TH vessel in a seaway are based on experimental data at model scale and sea trials from a 20 foot prototype.
This paper demonstrates that the TH technology is not size dependent, has simple shapes easy to fabricate, can be constructed with conventional methods, provides smooth riding greatly decreasing voluntary and involuntary speed reductions, and offers very large fuel savings. Therefore it has a transformational potential for ship building and maritime transportation, much like swept wings of jet transport aircraft displaced propeller driven transport aircraft and transformed airlines and aircraft building industries.
9:30-10:00
On High Speed Monohulls in Shallow Water
Dejan Radojcic, University of Belgrade, Belgrade, Serbia
Jeffrey Bowles, Donald L. Blount and Associates, Inc., Chesapeake, VA
Dejan Radojcic, University of Belgrade, Belgrade, Serbia
Jeffrey Bowles, Donald L. Blount and Associates, Inc., Chesapeake, VA
The hydrodynamic performance of marine craft has long been known to be influenced by water depth. When operating in shallow water at displacement speeds, they slow down at constant power. On the contrary, when planing in shallow water, vessel speeds increase at constant power. Additionally, surface waves generated by the hull vary radically with vessel speed and water depth. In recent years, mega yachts are being designed for length Froude numbers (FL) greater than 0.4, with many operating between 0.5 and 1.0; and some have even higher speeds. As these modern mega yachts being delivered have overall lengths up to and exceeding 100 meters, shallow water effects are being observed by their captains in relatively deep water. Thus, it is the intent of this paper to refresh, for the mega yacht community, what defines shallow water, the impact on performance and a general discussion on the responsibilities for hull-generated waves and wake occurring in shallow water both near and remote from the vessel.
10:00-10:15 Break
Safety
10:15-10:45
Fire Protection
John McDevitt, Consultant, Drexel Hill, PA
On March 31st, 2008, a Monday morning at 4:52AM the Miami Beach Fire Department was dispatched for a serious fire aboard a 76 foot late model motor yacht at the Miami Beach Marina. The boat was occupied by seven people who were all asleep at the time. Five of the people barely escaped the fire but with fractures, burns and cuts. Two people didn’t escape with the others and were trapped in a stateroom below decks.
The trapped occupants slept in a port stateroom that had only a small porthole, too small for a human to escape. While people assembled outside, the two occupants still inside the vessel, frantically screamed and waved from the small porthole to gain the attention of those now gathering on the dock.
The trapped occupants attempted to exit but their route was blocked by the fire now consuming the salon. They put on several layers of clothing and jumped into the shower with the intention of running through the burning salon. When they reopened the door to their room, the fire was making its way to the lower levels of the boat. Realizing they were trapped, they retreated back to their stateroom without a way out.
The Miami Beach Fire Station is a short distance from the marina. Even more importantly, a local fisherman boarded a small boat that he realized could fit between the bow of the vessel and the bow piling. Two Miami fire fighters also boarded the small boat and through the small porthole, they armed the trapped people with a breathing apparatus and hose line. The fire fighters then cut a hole in the side of the vessel and barely extracted the two trapped people before the boat sank.
The basics of effective fire protection are simple: Prevention, detection, egress and suppression. Although boating safety standards offer valuable information that supports good fire prevention practices, I will not give the industry good marks when it comes to egress, detection and suppression.
Egress - Most vessels 45 feet and larger have at least one stateroom with only one way out. If a fire enters the common area outside this stateroom, there is no other means of escape. Appliances such as washers and dryers are frequently found in this same common area, further complicating escape should a fire occur in one of these devices.
Egress is also frequently compromised by the design of the vessel and desire to keep deck spaces free and clear of hatches.
Detection - Smoke alarms are required everywhere we sleep, but smoke alarms are typically not found or even required aboard a pleasure boat – despite the compromised egress conditions. The fire vessel in Miami was not equipped with any early warning device to alert the occupants of the fire. Had there been, the outcome would have likely been very different.
The cause of the fire has not been officially determined due to the condition of the vessel after it sank. It can be assumed that careless smoking may have been the possible cause based upon the testimony of the occupants. Thankfully (and barely) there were no fatalities, there were various injuries, some serious, to all of the occupants and the losses to the fire vessel and two other boats totaled well over $10,000,000.
It is difficult to provide adequate egress in all staterooms aboard a boat. It is neither difficult nor expensive to install fire detection devices in a boat with sleeping quarters. The RV industry has required fire detection since 1982.
Had working smoke alarms been in place, the fire likely would have been discovered a couple of hours earlier and extinguished by the occupants who would have then gone back to bed to awake and enjoy another great day on the water.
Effective fire detection has proven itself all over the world for over four decades. Smoke alarms allow for safe egress by alerting the occupants in a timely fashion. When detection alerts the occupants of the fire early on, suppression is usually much less of a challenge. Smoke alarms in boats with sleeping quarters are a no brainer!
Why don’t we require and install smoke alarms in a boat? That’s what the people in Miami are wondering!
10:45-1:00 Lunch
1:00-1:30
Research Plan for the Investigation of Injury and Fatigue Criteria for High Performance Craft
Dean M. Schleicher, Donald L. Blount and Associates, Chesapeake, VA
Recently developed injury and fatigue criteria hold the promise of providing high performance craft with improved safety characteristics while operating in a seaway. SED8 criteria has been proposed and accepted as an injury model. Epidemiology is currently being gathered using the CACTUs system which should correlate SED8 measurements with long term injury reports. ICI has been proposed as a potential metric for motion induced fatigue. Limited testing and measurement has been performed which has led to a proposed criteria for minimizing motion induced fatigue. These criteria can be used to evaluate existing high performance craft through full scale trials. However, significant work is needed to quickly assess early design decisions with regard to these criteria. Fundamental craft characteristics are decided early in the design process. The ramifications of these decisions with respect to these criteria are not clearly understood. The effect of the operational environment on the performance of a given craft with regard to these criteria is also not clearly understood. Thus, in order to truly protect operators of high speed craft in a variety of sea states and operational conditions, further understanding with regard to the response of a given design to a wide variety of sea conditions is needed. The primary objective of this paper is to focus attention on this design problem, describe these criteria and present a long-range research plan that will lead to the definition of operability envelopes in a seaway for high performance craft.
1:30-2:00
Personal Watercraft Safety
Paul Kamen, Surface Propulsion Analysis, Berkeley, CA
With an estimated 1.55 million personal watercraft (PWC) in use, these vessels account for only 8.6% of the U.S. recreational fleet. Yet in 2005, annual PWC accidents accounted for 1,007 out of 3,451 total serious boating injuries (29.2%) and 44 of a total of 163 non-drowning fatalities(27.0%). Hazard level per hour of operation is even more striking: A 2007 study by the California Dept. of Boating and Waterways found that for every hour of operation, a PWC is 24 times more likely to be involved in a serious accident than a canoe or kayak.
While cultural and lifestyle issues correlated with PWC operation may be a factor, there is also considerable evidence that certain design characteristics may also contribute to the relatively high accident and fatality count.
This paper explores two important elements of PWC control: off-throttle steering and emergency stopping.
Off-throttle steering refers to the absence of steering control when there is no thrust from the waterjet propulsor. A common accident scenario involves sudden release of the throttle control when a hazard appears or is first noticed, followed by an unsuccessful attempt to turn out of the way. Most PWC's also lack effective reversing buckets, as found on waterjet propulsion applications for conventional boats.
Although manufacturers have addressed these problems in various ways, considerable debate remains over the effectiveness of their efforts. The debate extends to the role of various testing and advisory organizations in setting standards which may or may not be adequate. Specifically, we evaluate the SAE and UL test protocols, and compare to real and theoretically achievable maneuvering performance.
We also suggest techniques that may be useful to the forensic naval architect in reconstructing PWC collisions.
2:00-2:30
Biomechanical Assessment of Small Craft Collisions
Scott R. Lucas, Exponent, Inc., Philadelphia, PA
Joseph C. McGowan, Exponent, Inc., Philadelphia, PA
Robert S. Salzar, University of Virginia, Charlottesville, VA
Christopher Planchak, U.S. Navy, Norfolk, VA
James E. Getz, National Association of State Boating Law Administrators, Lexington KY
Six staged watercraft collisions were performed to assess the corresponding boat dynamics and boat operator kinematics. Each boat was operated remotely through a series of handheld radio transmitters capable of controlling steering, throttle, and a master kill switch. The impact angles varied and the differences in traveling speed between the target boat and bullet boat just prior to impact was approximately 20 knots. Triaxial accelerometers mounted to the deck of each boat provided sensor data that was measured and recorded using several MotionMaster EDR-6DOF recorders. Hybrid-II anthropomorphic test devices (ATDs) were placed in occupant positions and their resulting kinematics recorded. Deck triaxial acceleration data was used as input to a lumped-mass human dynamics model (MADYMO) to understand occupant kinematics and potential for injury. Noted results include the presence of large vertical (z-axis) deck accelerations. Results were analyzed to assess expectations regarding occupant kinematics as a function of speed, attitude, positions of target and bullet craft, as well as boat design parameters. The role of grip strength in the ability of an occupant to hold on to available railings in the face of an imminent collision was assessed. The collision geometry was analyzed in terms of USCG Rules requirements and expectations regarding operation in extremis. Within the impact velocities and angles studied in this test series, results indicated a low risk of head and neck injuries during the first phase of the collisions. The staged collisions provide insight to aspects of crash avoidance and protection of the operator and crew.
2:30-2:45 Break
Computational Fluid Dynamics Vari
ation on Steady Planing Hull Performance
2:45-3:15
The Effects of Deadrise and Deadrise Variation on Steady Planing Hull Performance
Biomechanical Assessment of Small Craft Collisions
Scott R. Lucas, Exponent, Inc., Philadelphia, PA
Joseph C. McGowan, Exponent, Inc., Philadelphia, PA
Robert S. Salzar, University of Virginia, Charlottesville, VA
Christopher Planchak, U.S. Navy, Norfolk, VA
James E. Getz, National Association of State Boating Law Administrators, Lexington KY
Six staged watercraft collisions were performed to assess the corresponding boat dynamics and boat operator kinematics. Each boat was operated remotely through a series of handheld radio transmitters capable of controlling steering, throttle, and a master kill switch. The impact angles varied and the differences in traveling speed between the target boat and bullet boat just prior to impact was approximately 20 knots. Triaxial accelerometers mounted to the deck of each boat provided sensor data that was measured and recorded using several MotionMaster EDR-6DOF recorders. Hybrid-II anthropomorphic test devices (ATDs) were placed in occupant positions and their resulting kinematics recorded. Deck triaxial acceleration data was used as input to a lumped-mass human dynamics model (MADYMO) to understand occupant kinematics and potential for injury. Noted results include the presence of large vertical (z-axis) deck accelerations. Results were analyzed to assess expectations regarding occupant kinematics as a function of speed, attitude, positions of target and bullet craft, as well as boat design parameters. The role of grip strength in the ability of an occupant to hold on to available railings in the face of an imminent collision was assessed. The collision geometry was analyzed in terms of USCG Rules requirements and expectations regarding operation in extremis. Within the impact velocities and angles studied in this test series, results indicated a low risk of head and neck injuries during the first phase of the collisions. The staged collisions provide insight to aspects of crash avoidance and protection of the operator and crew.
3:15-3:45
T-Splines: A New Timesaving Technology for Designing Hulls with Minimal Control Points
Matt Sederberg, T-Splines, Inc., Provo, UT
T-Splines is a NURBS-compatible technology used to design smooth, freeform surfaces. T-Splines was invented in 2003, and is already used commercially in many industries, including consumer product design, freeform architecture, jewelry, and marine. T-Splines is also used as the basis for active research in many universities. Specifically in the marine industry, the ability of T-Splines to create complex, freeform, watertight surfaces provides enhancements to both hull and superstructure design. In hull design, T-Splines does not have some of the restrictions of NURBS, the current industry standard, and can use much fewer control points to describe a hull. This makes the hull easier to fair. In superstructure design, T-Splines allows large sections of the superstructure to be defined as a single, smooth surface, which greatly simplifies form finding and complex intersections.
3:45-4:15
Use of Commercial CFD Codes to Enhance Performance Prediction Capabilities for Planing Boats.
John Scherer, Mercury Marine, Oshkosh, WI
Scott Morton, Mercury Marine, Oshkosh, WI
Neal Patil, Mercury Marine, Oshkosh, WI
Commercial CFD codes have become common tools for evaluating hydrodynamic performance of marine components such as propellers and appendages. The codes have traditionally been limited to submerged, single-phase flow and displacement vessels. New modeling capabilities within these codes have extended their potential application to free surface problems and cavitating or ventilated flows. Mercury Marine has been evaluating the use of these codes for analyzing planing boat performance with the inclusion of appendages, propellers, tabs/interceptors, and their interactions. Validation cases and results of this investigation will be presented with recommendations for the application of these codes.
4:30 Adjourn for Saturday
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