High-speed Boats Research Articles

Spatial identification of public spaces’ functions: a case study of Bach Dang Wharf Park in Ho Chi Minh City, Vietnam

Abstract Urban public spaces serve various functions and roles, such as physical, symbolic, ecological, economic, political, social, psychological, and aesthetic. Each function has specific design requirements and holds different meanings for space users. This study aims to identify the location of various functions within Bach Dang Wharf Park, one of the famous central riverside parks of Ho Chi Minh City, Vietnam, and test hypotheses about the concentration of hotspots for each function. To achieve these, we combined participatory GIS methods and face-to-face interviews using quantitative questionnaires and then used SPSS software to examine the relationship between park users’ identification of functions and other factors. We conducted two surveys, each lasting one week, in June 2022 and April 2023, with a total of 223 respondents and 1,413 marked points for park functions. The results showed that how people perceive park functions significantly relates to the characteristics of their park visitation rather than personal information. The hotspots of physical, symbolic, ecological, economic, and political functions appeared with high confidence levels and differed in size and location between the survey times. Meanwhile, in the 2022 survey, hotspots of social function appeared at the old pier near the high-speed boat station and opposite Nguyen Hue walking street. Later in 2023, these areas were mostly concentrated by markers of psychological function. At the same time, hotspots of aesthetic function were recorded in the space in front of the ASEAN flagpole. This approach effectively promotes community involvement in urban planning by better understanding citizens’ needs for public space.

The future and technique challenges of high-speed ground effect vehicle enrolled in maritime transportation

This paper presents a high-speed ground effect vehicle (HS-GEV) used specifically for maritime transportation. Given the limitations of current vessels, including various types of watercraft and high-speed boats, in fulfilling of needs in different maritime transportation scenarios, the HS-GEV emerges as a promising solution to address unmet requirements. To efficiently accomplish maritime transportation missions with quickness and safety, several critical features are emphasized, including short take-off on water, flight maneuverability and flight stability. The key techniques required to achieve these features, as well as recent progress highlights, are introduced. Following and promoting these crucial techniques is also suggested as a future step to improve HS-GEV performance. With its predominant features, the HS-GEV holds immense application value in enhancing a high-speed maritime transportation system that aligns with the evolving needs of the real world.

Effects of a long-drive shaft on flow field around a high-speed boat propeller in Thailand using CFD

The Long-Tail Boat (LTB) is a high-speed boat in Thailand. The propulsive system has a long-drive shaft that holds the propeller on the end of the shaft. It is used under inclined shaft conditions because of shallow water draft. Thus, the fluid flow into the propeller blade area is unsteady due to the cross-flow component. Therefore, the long-drive shaft is an important parameter in generating the flow field before entering the propeller blades, which affects propeller efficiency. This paper presents a numerical analysis of the flow field around a long-drive shaft and propeller blade areas in a full-scale propeller size using the Reynolds-Averaged Navier-Stokes (RANS) solver. The unsteady propeller performance is carried out by considering inclined flow conditions. In addition, the computational results of fluid flow in terms of the pressure distributions and wake fields around a long-drive shaft and propeller are investigated, which influence the propeller performance and the generating drag forces by a long-drive shaft. The results can be applied to modify the long-drive shaft of boats. Highlights The Long-Tail Boat (LTB) is a local vessel in Thailand that has a high speed Computational fluid dynamics (CFD) code ANSYS Fluent to study the effect of a long-drive shaft propeller with inclined shaft angles The long-drive shaft should be designed in suitable for operating the inclined shaft conditions because it will directly affect the propeller efficiency

Nonlinear mechanical behavior and stress amplification effect correction of thin plate welded structure considering initial deformation

With the continuous development of light weight of ships, thin plate welded structures are widely used in superstructure of large hull structures and high-speed boats. However, the thin-plate welded structure has a special nonlinear mechanical behavior because of its small stiffness, more complicated welding deformation. The nonlinear mechanical behavior of thin plate welded structure is mainly caused by large slenderness ratio and complex initial buckling deformation, which can be characterized and quantified by defining global deformation angle αG and local deformation angle αL. Because of the welding angle deformation and welding dislocation, there is obvious stress amplification effect at the welding corner, but the traditional stress amplification correction formula is only suitable for thick plate welding structure. Aiming at the nonlinear mechanical behavior and secondary bending moment effect of thin plate welded structure, an analytical model of thin plate welded structure with initial deformation is established by combining theoretical derivation and numerical method. The results show that the additional bending moment effect caused by local welding deformation angle cannot be ignored. Finally, combined with a series of fatigue tests, the additional bending moment caused by bending deformation and angular deformation of typical welded joints is analyzed, and the notch stress field and fatigue strength correction of thin plate welded structures with initial defects are realized.

Calculation of Hydrodynamic Coefficients of a High-Speed Boat in Surge Motion Using Numerical Simulation

Calculation of Hydrodynamic Coefficients of a High-Speed Boat in Surge Motion Using Numerical Simulation

Comparison of Performance of Straight- and V-shaped Vanes Applied as Energy Saving Device to High-speed Boats

Hull Vane® is a device, generally utilizing a straight vane, installed horizontally near the stern of a vessel below the water surface and oriented in the transverse direction of the vessel with the purpose to save fuel consumption and to increase the vessel’s comfort. Because the bottom-hull form of a ship is generally curved, a non-straight vane may be more effective than a straight one when applied as Hull Vane®. The purpose of this study is to investigate the effectiveness of a V-shaped vane when applied as Hull Vane® on a 31 m high-speed crew boat. The study utilizes a computational fluid dynamics (CFD) method. CFD results show that the Hull Vane® decreased the bow-up trim of the boat, affected the boat’s wetted surface area, and decreased the height of the waves generated by the boat. The wave-height reduction due to the V-shaped Hull Vane® is larger than the straight Hull Vane®. Further, the Hull Vane® significantly reduced the total resistance of the boat at Froude number Fr = 0.34 with a larger reduction resulted from the V-shaped Hull Vane® (25.09% reduction for the straight vane and 30.75% reduction for the V-shaped vane). The observed resistance reduction decreased with increasing speed, ascribed to a too-large vane’s lift. The V-shaped Hull Vane® is more effective than the straight Hull Vane® in reducing the total resistance of the boat.

Operational interactions between humans and Indo-Pacific Finless Porpoises, Neophocaena phocaenoides: An integrated spatial model in the northern Strait of Hormuz

The Indo-Pacific Finless Porpoise (Neophocaena phocaenoides) is a little-known cetacean under human pressure in the Persian Gulf and the Gulf of Oman. In Iran, most sightings have been reported from the northern coasts of the Strait of Hormuz. We invested the spatial overlap between finless porpoise habitats and human activities in the Harra Protected Area and Biosphere Reserve in the north of the Strait of Hormuz. Suitable porpoise habitats were modeled using the Maxent model, employing 112 presence points and an array of physical seascape variables. A detailed (30 m) Landsat 8-derived depth layer was found as the most important factor determining porpoise distribution. The multi-criteria evaluation procedure was calibrated using a set of pairwise weighted and fuzzified layers including ship routes, and distance from main boat routes, coastal and port cities, and fishing zones to determine the intensity of human sea use. Results showed a significant spatial overlap of over 3,500 ha (8.7% of the region) between highly suitable porpoise habitats and human sea use areas, covering the whole entrance of the estuary where high-speed boats sail between northern and southern cities. Since the porpoise population is found in the study area only within the borders of the Harra Protected Area, limited fishing activities and low-speed boat movement inside the zone of overlap are suggested to lower the human-porpoise interaction in the region.

Research on the Shape Optimization of Three-Dimensional Bow

Boat is mainly composed of hull, ship frame, deck, cabin and ship deck building. When people are designing the boat, one key consideration is the shape of the bow in order to decrease the resistance and fuel-consumption. In this paper, theoretical analysis of resistance to bow and the optimization aimed for lower resistance were produced by using COMSOL Multiphysics 6.0. Firstly, a simple and ordinary model of bow is presented. Then, the mathematical and physical model are established by COMSOL. Afterwards, after I exam whether the computational model is effective enough for the further optimization, the calculating results are worked out and I compare them with the common bow’s experimental data, with the purpose of the optimization, the lower resistance, in different conditions such as different ship speed and draft. The polynomial expression of several important section is used to construct the basic outline of the three-dimensional bow with different width, bow length, angle of bow top and the possible maximum and its position. Then, I choose the bow length, angle of bow top and the possible maximum and its position as the optimization parameter. Finally, I reach the conclusion of a better-performing bow design for newer high-speed boat requirements and future studies are discussed.

Numerical Modeling of Surface-Piercing Flexible Hydrofoils in Waves

_ Hydrofoils made of metal alloys were broadly used on high-speed boats in the past. Nowadays, much lighter hydrofoils made of composite materials are finding increasingly more applications on sailing yachts and powerboats. However, these hydrofoils are usually rather flexible, and their design requires computationally demanding analysis, involving hydroelastic calculations. In this study, exploratory high-fidelity simulations have been carried out for surface-piercing hydrofoils in unsteady conditions with help of a computational fluid dynamics solver for fluid flow coupled with a finite element solver for the foil structure. To model unsteady foil deformations, the morphing mesh approach was utilized, and the volume-of-fluid method was applied for multiphase flow simulations. The computational setup, as well as verification and validation study, is described in this paper. Three hydrofoils of different stiffness, including a perfectly rigid foil, were simulated in both calm water conditions and regular head waves. Representative examples of foil deflections and wave patterns, as well as time-dependent structural and hydrodynamic characteristics, are presented. Introduction Hydrofoils are efficient lift-generating devices intended for application in water flows. Hydrofoils have streamlined shapes, and when operating at small incidence angles, they can produce high lift forces at relatively low drag, when moving in a certain speed range. Due to this ability, hydrofoils and their derivatives are commonly used as control and propulsive devices, e.g., as rudders, fins, and propeller sections. In the second half of the last century, hydrofoils found broad applications on fast boats, such as passenger ferries and military ships (McLeavy 1976; Matveev & Duncan 2005). These craft were able to achieve high speeds at lift–drag ratios (LDR) around 12–15, significantly higher than LDR of other hulls, such as planing boats. However, due to rather limited favorable operational conditions with regard to speed and payload, popularity of hydrofoils somewhat receded. One of drawbacks was that hydrofoils were usually made of metal alloys, thus being relatively heavy and difficult to service.

Study on the influence of artillery recoil on the lateral stability of patrol boat

To solve the problem of lateral instability of a high-speed law enforcement patrol boat caused by the recoil of artillery fire, this paper adopts the method based on EFD (Experiment Fluid Dynamics), the dynamic stability of a high-speed patrol boat model under the impact of an external force is simulated by a percussive test. First, the model of the patrol boat is tested by dragging on the surface of still water, and then the percussive test is carried out with different centers of gravity height, different external impulses, and different speeds, the influence of the above factors on the transverse stability of patrol boat is studied. The results show that the higher the height of the center of gravity, the higher the external impulse and the lower the speed, the worse the transverse stability of the model will be. The results show that the EFD method is feasible, which is of great significance to the shape optimization design of high-speed craft and the selection of artillery systems.

Does Military High-speed Boat Slamming Cause Severe Injuries and Disability?

Many operators of professional high-speed boats suffer severe, acute, and permanent injuries caused by slamming-induced hull impacts. As the number of professional high-speed boats and their speed capabilities increase, operators are reporting increasing numbers and severity of injuries. However, the actual incidence rate of acute injuries and the prevalence of chronic musculoskeletal disorders are still unknown. We sought to investigate, among professional high-speed boat operators, (1) the self-reported incidence rate of impact-induced injuries, (2) the most common types of injuries or injury locations, (3) what impact characteristics were reported, and (4) the prevalence of self-reported sick leave, disability, and medical or orthopaedic treatment. This study was an internet-based survey among retired military high-speed boat operators. The survey was given to members of the Combatant Craft Crewman Association online user group (360 members). Participants answered questions on demographics, service branch, service years and capacity, boat type, types of events, injury location, severity, pain, disability, and need for treatment. Values are presented as the mean ± SD and proportions. Incidence rates are presented as injuries per person-year. A total of 214 members of the Combatant Craft Crewman Association participated in the survey (213 men, mean age 50 ± 9 years, mean BMI 29 ± 4 kg/m 2 ). A total of 59% (214 of 360) of those we surveyed provided responses; all provided complete survey responses. The self-reported incidence rate of impact-induced injuries was 1.1 injuries per person-year served onboard. A total of 32% (775 of 2460) of respondents reported injuries that affected the back, and 21% (509 of 2460) reported injuries that affected the neck. Among those who responded, 33% (70 of 214) reported loss of consciousness onboard, and 70% (149 of 214) reported having experienced impaired capacity to perform their job onboard because of impact exposure. A total of 49% (889 of 1827) of the reported injuries were attributed to impacts containing lateral forces, 18% (333 of 1827) to frontal impacts, and 12% (218 of 1827) were attributed to purely vertical impacts. Finally, 67% (144 of 214) of respondents reported at least one occasion of sick leave from training or missions. Seventy-two percent (155 of 214) applied for a Veterans Affairs disability rating, and 68% (105 of 155) of these had a rating of 50% or higher. Additionally, 39% (84 of 214) reported having had surgery during active duty, and 34% (72 of 214) reported surgery after leaving active service. The results suggest that in the investigated military population, exposure to slamming-induced impacts onboard high-speed boats may cause more injuries than previously reported. Most reported injuries are musculoskeletal, but the high number of reported slamming-induced events of unconsciousness is concerning. Level IV, prognostic study.

Analysis of the Behavior of Fiberglass Composite Panels in Contact with Water Subjected to Repeated Impacts.

One of the most common applications of glass fiber composite materials (GFRP) is the manufacturing of the hulls of high-speed boats. During navigation, the hull of these boats is subjected to repetitive impacts against the free surface of the water (slamming effect), which can cause severe damage to the material. To better understand the behavior of the composite material under this effect, in the present work, an experimental test has been carried out to reproduce the slamming phenomenon in GFRP panels by means of a novel device that allows this cyclic impact to be obtained while the panels are always in contact with water. By means of non-destructive ultrasound inspection in immersion, it has been possible to establish the evolution of the damage according to the number of impacts received by each panel. Destructive tests in the affected zone, specifically shear tests (Iosipescu test), allow determination of the loss of mechanical properties experienced by the material after receiving a high number of impacts in the presence of water (up to 900,000 impact cycles in some panels). The behavior of the material was found to be very different in wet and dry conditions. Under dry conditions, the material loses stiffness as the damage density increases and its shear strength also decreases, as does displacement at maximum load. For wet conditions, the material shows higher displacements at maximum load, while the shear strength decreases with increasing stiffness.

A Study into Surface-Piercing Propellers at Different Immersion Depths using a Towing Tank and a Numerical Method

Surface-Piercing Propellers (SPPs) are essential categories of high-performance propulsion systems usually used for high-speed boats, which are designed to operate in semi-submerged conditions. In such conditions, a propeller performs in a two-phase mixed environment, consisting of water and air concurrently. Due to the intrinsic complexity of the working environment, describing the performance of an SPP is complex and cannot be recognized with the traditional submerged propellers. The present study aims to assess the effect of immersion depth on semi-submersible propellers. Accordingly, experimental tests in a towing tank were used along with a numerical method to achieve reliable results. In the numerical method, a sliding mesh was used to simulate the propeller's motion, and the volume of fluid was used to model the free surface. The hydrodynamic coefficients of the SPP, measured in the towing tank, were used to validate the numerical method. The outcomes of the numerical method were revealed to be in good agreement with the experimental data. The results showed that the critical advance coefficient decreased with the rise in the immersion depth. In detail, altering the immersion depth from 0.4 to 0.75 reduced the critical value of the advance coefficient from 0.8 to 0.7. The ventilation pattern also changed with increasing the immersion ratio. For a constant advance coefficient, the amount of ventilation increased at shallower depths of immersion.

Dynamic of Tunneled Planing Hulls in Waves

A tunneled planing craft is a high-speed boat with two tunnels over the hull bottom that are designed to improve the vessel’s performance. Hydrodynamic performance of tunneled planing hulls in calm-water is well-known, however, current information on wave conditions is limited. In this study, two different tunneled planing hulls with two degrees of freedom in heave and pitch motions are studied in regular waves by using the computational fluid dynamics (CFD) method based on the Unsteady Reynolds Averaged Navier-Stokes Equations (URANSE) in conjunction with k−ϵ turbulence model. The results demonstrate that tunneled planing hull motions in waves are nonlinear. In addition, it is found that the dynamic responses of heave and pitch motions as well as occurrence portability of the fly-over phenomenon significantly increases as the Froude number grows. Fly-over motions resulted in vertical motions and acceleration up to 5g, high impact pressure, and large induced drag. At a very high planing speed, after flying over the water surface, when the vessel re-enters the water, the resulting hydrodynamic load leads to a second fly-over motion. Since the fly-over is an unwanted movement with adverse effects, these results can provide a better understanding of the fly-over motion that one may consider in future design for improving the planing hull performance.

Swarms of Pirates: Red Team Exercises Using Autonomous High-Speed Maneuvering Surface Vessels

We present a final overview of the efforts by the Naval Air Warfare Center Weapons Division (NAWCWD) and the Jet Propulsion Laboratory to automate the operation of the largest fleet of autonomous maritime vehicles. The vehicles are intended for large-scale demonstrations and tests of US Navy systems or tactics. This review covers a preexisting distributed architecture for human-in-the-loop control of several autonomous high-speed boats with a main focus on the planning, formation assignment, and formation switching pipeline. Algorithm capabilities are described and validated in simulation and field tests using real-world vehicles. Theoretical lower bounds on the time required to change formations are also derived and used to bound our experimental performance. We are able to present data from the 2019 “final exam” that pitted this architecture in a head-to-head competition, which was won after a perfect run with no hazardous maneuvers recorded under autonomous control. The effort concluded successfully on December 31, 2020, with the delivery of code and documentation after successful integration and testing exercises in 2019 and 2020. We conclude the paper with discussions of limitations, extensions, and suggestions for future work.

Investigation on the Lift Force Induced by the Interceptor and Its Affecting Factors: Experimental Study with Captive Model

An interceptor is an appendage widely used for high-speed planing boats to reduce resistance and modify hull attitude by the lift force-induced, but the relationship between the induced lift force and the factors affecting it are still not clear, especially for the vessels other than the planing hull. In this paper, a model test of a series of models is performed to investigate the lift force induced by an interceptor and the influence of the affecting factors systematically. The lift forces induced by the interceptor are tested in the conditions of different velocities, interceptor heights, angles, and drafts in the towing tank. The effects of each factor and the coupled effects are analyzed. It is found by the experimental results that the lift coefficient of the induce lift force in the present investigation is approximately proportional to the square of the non-dimensional velocity and interceptor height, but the effect of the interceptor height is of a limited extent. The influence of angle and draft on the lift force induced by the interceptor cannot be ignored in the present study. The induced lift force is decreased when the angle of the plate is reduced and is enhanced when the draft is increased.

Effect of Ventilation on Cavity Formation on Stepped Planing Hulls

_ A stepped planing hull is a type of high-speed boat with a transverse break in the bottom of the hull. The step allows the hull to run at a higher trim angle, and also reduces the wetted surface area at planing speeds because of a pocket of air that forms aft of the step, often reducing the frictional resistance. This paper summarizes model tests that were conducted on a prismatic planing hull, with two adjustable stern sections, to form either a single- or twin-step planing hull. Measurements were made of the resistance, heave, wetted lengths, and cavity pressures behind the steps for various speeds at fixed trim. The ventilation cases included natural ventilation, augmented ventilated by means of vent tubes located behind the step, and reduced ventilation, where the flow was blocked off from the step by closing the vent tubes and adding longitudinal fences to either chine to prevent air inflow. Blocking off the ventilation causes negative pressures to form and increases resistance. Tests conducted in waves showed that the size of the ventilation cavity behind a step is not affected significantly by small waves, indicating a shielding effect of the hull. Introduction Stepped hulls are becoming increasingly commonplace in high-speed craft for both military and recreational purposes. A stepped hull is a type of planing boat, in which there is a discontinuity in the bottom, resulting in flow separating from the step and reattaching father aft along the hull. This feature can reduce resistance in some cases. Although they’ve been in use for over a century, they remain a challenge to design and to physically model.

SIMULASI NUMERIK KENDALI KAPAL CEPAT TAK BERAWAK DUA PROPELLER TANPA RUDDER

This paper discusses the simulation of automation control and hull manufacturing on a fast boat. This high-speed boat that will be carried out for fish mapping. This study uses a numerical simulation to predict its motion. The experiment was carried out 3 times in forward motion, and 3 times in turn motion. The ship’s time and movement in ideal conditions will be recorded for each experiment. With the PID value for forward overshoot with values such as: 8.94%, 30.86%, and 40.60%, while turning overshoot is obtained, among others: 25.77%, 49.82%, and 61.15% Then the advanced settling time obtained includes: 0.91 seconds, 3.84 seconds, and 5.31 seconds. The settling time for turns is: 1,022 seconds, 0.85 seconds, and 0.84 seconds These values are obtained from the simulation graph of the three-dof formulas for surge, sway, yaw.

BENCHMARK TESTS OF FINETM/MARINE CFD CODE FOR THE CALCULATION OF SHIP RESISTANCE AT HIGH FROUDE NUMBERS

Benchmark tests of FINETM/ Marine CFD code were performed to verify the ship-resistance calculation results at high Froude numbers. The CFD code solves the Reynolds-averaged Navier-Stokes (RANS) equations with modelling of the free surface effects, that is, the generation of waves due to the ship movement on the water surface. A high-speed OSV boat was considered at three speeds (17, 20 and 26 knots), which correspond to the Froude numbers based on the volume of displacement FrV = 1.29, 1.52, and 1.98.The CFD results show a good agreement with the results of Savitsky’s formula and the numerical results obtained from Maxsurf Modeller. Further, a reasonable agreement was found between the CFD results and available experimental data. Flow visualisations show that the wave pattern behind the boat consists of transverse and divergent waves. As the boat’s speed increases, the wave height increases, and the wave pattern becomes more dominated by the divergent waves. These observations are consistent with the classical analytical predictions.

A CFD Study of the Resistance Behavior of a Planing hull in Restricted Waterways

The demand for high-speed boats that operating near to shoreline is increasing nowadays. Understanding the behavior and attitude of high speed boats when moving in different waterways is very important for boat designer. This research uses a CFD (Computational Fluid Dynamics) analysisto investigate the shallow water effects on prismatic planing hull. The turbulence fl ow around the hull was described by Reynolds Navier Stokes equations RANSE using the k-ɛ turbulence model. The free surface was modelled by the volume of fl uid (VOF) method. The analysis is steady for all the ranges of speeds except those close to the critical speed range Fh=0.84 to 1.27 due to the propagation of the planing hull solitary waves at this range. In this study, the planing hull lift force, total resistance, and wave pattern for the range of subcritical speeds, critical speeds, and supercritical speeds have been calculated using CFD. The numerical results have been compared with experimental results. The dynamic pressure distribution on the planing hull and its wave pattern at critical speed in shallow water were compared with those in deep water. The numerical results give a good agreement with the experimental results whereas total average error equals 7% for numerical lift force, and 8% for numerical total resistance. The worst effect on the planing hull in shallow channels occurs at the critical speed range, where solitary wave formulates.