Planing Hull Research Articles

Enhancing Efficiency in Deep-V Planing Hull Ships: A Study on The Design of Spray Strips to Minimize Resistance

Spray strips are deflectors installed on the hull to decrease the wetted surface area (WSA). By reducing the WSA, the overall resistance of the ship is lowered because it lessens the friction of water flowing against the hull. The purpose of this research is to predict the function of spray strips in an effort to improve ship performance. In this study, the numerical methodology employs the Finite Volume Method (FVM) along with the Reynolds-averaged Navier-Stokes equation (RANS) for resolving fluid dynamics issues. The modeling of the two-phase flow involves the utilization of both the Volume of Fluid (VOF) model and the Eulerian model. The results of this study show that spray strips can reduce the total resistance by about 2.7%. Increasing the number of spray strips can reduce the drag shear value by 3.5%. Spray strips are effective in reducing total drag when the Froude number (Fr) is greater than 1 or when the vessel is in the planing phase. The profile shape of spray strips with dimension 2:1 shows the best performance on ship resistance.

Speed dependence, sources, and directivity of small vessel underwater noise.

Small vessels (<10 m) radiate underwater noise in sensitive coastal environments, but there is insufficient knowledge of their noise radiation. Through detailed measurements of seven small boats and a jet ski in a shallow water environment on the Swedish west coast, this study presents results on the speed dependence of small vessel underwater noise, its sources, and its directivity. For vessels with planing hulls, broadband source levels increase with speed until planing is attained. When planing, source level dependence on speed is weak. A detailed noise source analysis of one vessel showed that at low speed, tonals from the engine dominate the noise radiation, whereas at higher speeds, propeller tonals and broadband noise dominate. Noise radiation into different horizontal angles shows little angle dependence, and noise levels relative to the closest point of approach show a similar pattern across all investigated vessels. Received noise levels at approximately 100 m range are not high enough to cause hearing impairment in marine animals, but fast-moving small vessels may cause behavioural reactions or stress responses across several marine animal groups.

Experimental Study of Damage Energy on the Bow of a Vessel with Second-Generation Viscoelastic Layers for the Galápagos Islands

Experimental study of the damage energy is a reproduction of the GFRP vessels’ slamming in the sea. The investigation was carried out to the laboratories by the construction of two types of GFRP panels: viscoelastic and non- viscoelastic modified. Through a bending test, the data collection was developed to get the measurement of the variables in key points. The obtained results showed an expected behavior because the modified specimens were able to spread the force induced from the center to the edges. Besides, the damage energy in the modified panels return in bigger amounts than the unmodified. Flexibility demonstrated a higher rate of increase in the unmodified panels, indicating that the viscoelastic layer contributed to the stiffness increment in the modified panel. In conclusion, viscoelastic materials help to dissipate the energy absorbed by the structure, elongating the lifetime. Also, this study expands the basic knowledge of viscoelastic materials’ behavior in the GFRP planing hull vessels.

Effects of yaw angle on hydrodynamic performance for an oblique planing hull

Effects of yaw angle on hydrodynamic performance for an oblique planing hull

Investigating the effect of underlying angle, width, and number of spray rails on the performance of planing hull and their optimization using the Taguchi method

Investigating the effect of underlying angle, width, and number of spray rails on the performance of planing hull and their optimization using the Taguchi method

Investigating the Effects of Cargo Weight and its Distribution on the Dynamic Performance of a High-Speed Planing Hull

The aim of this article is to evaluate the effects of cargo relative weight and its distribution along the boat’s length in addition to the relative water wavelength on the dynamic performance of a high-speed planing hull. Here, the dynamic performance is measured by the intensity of the boat’s heave and pitch motions. The Zarnick’s strip theory, which divides the vessel’s hull into equal lateral sections, is used to study the applied forces on the vessel, and a MATLAB code is provided based on it. It is demonstrated that increasing the cargo weight and its distribution result in more heave and pitch, and the maximum amount of them are observed in the wave with a length of about 5 times the length of the boat. In addition, the interactive effects of cargo weight and its distribution on the heave and pitch motions are affected by the relative wavelength. Therefore, the more centralized cargo distribution is preferred to increase the dynamic performance of a heavy planing boat with cargo weights more than 50% of the boat’s weight, while moving in short waves (λ⁄L&amp;lt;4); and for light cargo weight, less than 50% of the boat’s weight, the favorite cargo distribution is broad. When the boat sails in long waves, the desired distribution is reversed.

Matching of propulsion system components for a planing hull model

ABSTRACT This study specifies propellers for a main engine and transmission system to reach 20 knots for a vessel of certain dimensions. Propeller designs for 16-20 knots were examined using Fn and speed-resistance prediction. Twenty-four propeller variants are created with a 110 kW main engine and varied reduction rates. Twelve propellers that meet design specifications are CFD analysed. The data show that the P6 propeller consistently generates the most thrust and the P3 the least. Margins of error analysis show that propellers P4, P7 and P9 are closest to performance charts' values. As the advance ratio exceeds thresholds, open water diagram-CFD solver error rates rise. As long as advance ratios are followed, the P4 propeller produces reliable results, limiting error rates. Future studies should include propellers at different speeds further propellers, engines and transmissions. For researchers, professionals and mariners interested in ship propulsion design and effectiveness, this article is crucial.

Moving air-water interface on no-slip solid walls for high-speed planing hulls

ABSTRACT In this study, the classical ‘moving-contact-line’ problem associated with the no-slip boundary condition (BC) is examined, with a particular focus on large-scale, high Reynolds number turbulent ship flows. Numerical ventilation is one of the main issues reported for the computational prediction of the high-speed small planing craft using the Volume-of-Fluid (VOF) method. A numerical strategy is presented to resolve this issue with a wave blanking distance defined and used when solving the VOF equations, which is chosen based on the y + values and the velocity profiles in the boundary layer. A series of numerical tests are conducted using a slamming plate and a stepped high-speed planing hull. The numerical experiments show that if the blanking distance is y + < 30 (inside the buffer and viscous sublayers), the air-water interface on the wall will be unstable and numerical ventilation will occur. For the blanking distance y + > 30 (outside the buffer layer), the air-water contact line is smooth and air entrainment can be avoided. It is suggested that the blank distance needs to satisfy 30.0 < y + < 200.0 in consideration of accuracy and stability, and a value of y + ∼ 100.0 can be used in practice.

Dynamic motion analysis of stepless and stepped planing hulls in random waves: A CFD model perspective

Predicting the dynamic responses of planing hulls in real sea conditions is important for identifying how basic design factors influence their seakeeping performance. Hence, there is a pressing need to provide high-fidelity models for predicting the motions of these hulls in random waves, representing actual seas. In this article, a computational-based model for solving viscous fluid flow around the vessel is built to address this problem. Three different planing hulls, denoted as C, C1, and C2, each distinguished by the number of steps incorporated on their bottom surfaces (1 and 2 indicating the respective step count, with case C being the stepless hull), are modeled in a Computational Fluid Dynamics (CFD) tank, allowing for analysis of the effects of steps on dynamic responses of a planing surface operating in random waves. CFD data is compared against those collected in towing tank tests, revealing a satisfactory level of accuracy. Extreme value and gamma distributions are shown to give probabilities of maxima/minima of displacements and vertical acceleration at the center of gravity (CG) for all three hulls. It is shown that the stepless boat may be exposed to lower vertical acceleration at an early planing speed, but at higher planing speeds, a double-stepped design mitigates the vertical acceleration. Nevertheless, the double-stepped hull would experience more significant extreme heave responses across all speeds and may be exposed to less significant extreme pitch responses during the ride at the highest speed compared to the stepless and one-stepped hulls. The skewness of heave and pitch is evaluated, and it is found that the heave response tends to skew toward positive values (upward). This skewness becomes more noticeable with increasing speed but remains insensitive to wave steepness. Additionally, the pitch response at lower planing speeds shows a partial skew towards negative values (bow-down), but eventually, they may also be partially skewed towards positive values at higher speeds. Moreover, a correlation is observed between the kurtosis of responses of different hulls and the occurrence of the 1/100 highest responses, indicating that a kurtosis greater than 3.0 would result in more extreme responses. Overall, this analysis offers practical insights into planing hull behavior in actual sea conditions from a CFD model perspective, highlighting the potential of CFD in simulating this complex problem.

Prediction of the impact of biofouling roughness on a full-scale planing boat performance using CFD

This study investigates the crucial role of surface roughness caused by biofouling in contributing to increased drag in fast planing vessels. Through rigorous computational fluid dynamics (CFD) simulations using a full-scale reference hull, the impact of surface roughness on planing hull performance is examined. The results show that heavy slime roughness on the hull surface causes a significant increase in total resistance, ranging from 10% at low speeds to 80% at high speeds. Skin friction was identified as the most affected component of resistance, with additional changes in residual resistance. Although the change in residual resistance is relatively small, they give rise to dynamic phenomena such as variations in pressure distribution, wave elevation, and wave making formation. The study also explores the influence of surface roughness on dynamic lift forces, observing an increase in upward friction forces but ultimately concludes that overall hull performance was hampered due to the disproportionately higher increase in resistance caused by roughness (biofouling). Changes in dynamic trim, dynamic sinkage, and dynamic wetted surface area due to this roughness are also discussed.

A revisited verification and validation analysis for URANS simulation of planing hulls in calm water

Verification and Validation (V&V) is the foremost analysis which is carried out for evaluation of the accuracy level and dependability of computational fluid dynamic (CFD) simulations. The present study investigates the V&V of CFD models in predicting the dynamic trim and hull resistance of high-speed planing hulls with an aim to provide a deeper understanding of V&V analysis in this specific field of application. Two different planing hulls, namely the C05 stepped hull and the C1 interceptor hull, are analyzed with four different grids and time-steps using two mesh motion techniques, namely overset and morphing approach. The discretization (grid) and time-step uncertainties for each CFD simulation are estimated using the least squares method. The results indicate that the overset mesh approach performs better than the morphing grid method in terms of numerical uncertainty and validation achieved for both hulls. The error of both techniques in the prediction of resistance and trim angle of the boat shows an acceptable range of accuracy. The findings provide valuable insights for simulation-based designing and optimizing high-speed planing hulls, specifically by identifying the optimal mesh technique, cell number, and time-step for accurate prediction of wetted surface shape, ventilation formation, running attitude, and resistance.

CFD Analysis of the Influence of Marine Fouling on the Performance of High-Speed Planning Craft

Marine fouling, such as heavy slime, is the result of algae and other invertebrates settling and growing on the surfaces of planning hulls that are immersed in water. This may result in a range of serious and costly economic problems. The amount of resistance that planning hulls encounter when operating in maritime settings is an important aspect that considerably impacts the performance, energy efficiency, and operational expenses associated with these hulls. Because of this, the focus of this investigation will be on high-speed planning craft ships. In recent years, there has been a rise in the number of instances in which this sort of ship has been used for military, commercial, and recreational purposes. With the use of CFD analysis, the purpose of this study is to conduct an exhaustive investigation into the effect that the surface roughness of heavy slime has on the resistance of planing hulls. The results will be compared to a reference scenario, including a hydrodynamically smooth hull, to determine how much heavy slime affects resistance. According to the findings of this research project, the presence of heavy slime on the surface of a high-speed planing ship had a significant impact on the performance of the ship, particularly on the friction resistance, which saw an increase of up to 65% as a consequence of the presence of the slime. The results of this study will have substantial repercussions for ship designers, naval architects, and operators. The findings will provide them with useful information that will allow them to improve hull designs and devise effective tactics for fouling management.

Experimental and computational fluid-structure interaction analysis and optimization of Deep-V planing-hull grillage panels subject to slamming loads – Part II: Irregular waves

The paper presents a comprehensive experimental and numerical study of the structural response of a planing hull in irregular waves. Two grillage panels are investigated: a traditionally designed grillage panel based on current structural design methods and an optimized grillage panel based on loads evaluated by computational fluid dynamics (CFD) in regular waves and mathematical optimization methods. The structural response of these two grillage panels in irregular waves is investigated both experimentally and numerically. Experiments and numerical simulations show that the largest impacts do not necessarily occur when the wave height is largest, but rather when there is a deep trough and the wave height is low. Comparing the structural response in irregular waves with the structural response in regular waves shows a reasonable correlation. Nevertheless, a more severe regular wave condition is needed to capture the wave impacts needed for structural design. Numerical simulations show that they can better predict the vertical acceleration of the center of gravity than current structural design methods. It is discussed how American Bureau of Shipping practices lead to safe but conservative structural designs and how current computational methods lead to more efficient design solutions.

Numerical Investigation on the Motion of a High-Speed Planning Hull in Calm Water Condition using RANSE Method

Planing hulls were commonly used in both civilian and military situations. The prediction of the motion of the planing hull was complicated due to the trim angle and sinkage oscillations caused by the lift variations and complex hydrodynamic interactions at high speeds. To evaluated the motion of the planing hull, it was essential to analyse the hydrodynamic performance of the planing hull at high speed. This paper presented a CFD method for calculating the hydrodynamics of a planing hull in calm water conditions at different Froude numbers. The numerical method was based on the Reynolds-averaged Navier-Stokes equation (RANSE). The volume of fluid (VOF) and two degrees of freedom equations were utilized. An efficient procedure was introduced to solve numerical divergence in numerical simulations. Resistances of the planing hull in numerical results were compared with experimental results to verified and validated the used RANSE method.

Predefined-Time and Prescribed-Performance Control Methods Combined with Second-Order Terminal Sliding Mode Control for an Unmanned Planing Hull System with Input Delay and Unknown Disturbance

In this study, we investigate a terminal sliding mode control (TSMC) system combined with predefined-time and prescribed-performance control methods for an unmanned planing hull (UPH) system in the presence of a control input delay at the heading axis and a porpoising motion due to pitching-moment disturbance. A second-order TSMC system is adopted to bypass the unstable heading-angle response of the conventional first-order TSMC system caused by the control input delay of the hydraulic rudder actuator system. Next, predefined-time and prescribed-performance control methods are proposed to enhance the disturbance rejection performance of an uncertain UPH. The results of sequential comparative simulations show that the disturbance rejection performance of the proposed hybrid disturbance rejector using both the predefined-time and prescribed-performance control methods for a porpoising motion is superior to those of conventional controller systems without introducing disturbance observers.

Experimental analysis of a planing monohull model during forward acceleration: part II – evaluation of an indirect method for applying thrust angle in the experiments

ABSTRACT Most towing tank model tests conducted on planing hulls are not performed under self-propulsion conditions, and it is often not feasible to directly apply towing force at the corresponding point of action and along the thrust of the full-scale vessel. Therefore, it is essential to establish a well-defined method for accurately applying the thrust line in bare hull model tests using alternative loading solutions, such as CG shift, and understand how any deviation affects the model’s running attitude and performance. This article presents an analysis of the dynamic equilibrium equations of motion for the model, considering various variables that can be used to adjust the thrust line in towing tank tests. The proposed formalism can aid in determining the external loading requirements in resistance tests. Finally, the article discusses the challenges and provides an error estimation for a simplified method of applying a constant thrust angle in the accelerated tests.

Numerical Study on Resistance of Stepped Planing Hull

A stepped planing hull, also known as a step hull, is a hull modification that reduces the wetted surface area. Although this type of hull has proven effective in several ships, it is still rarely used. The step hull possesses numerous advantages that make it ideal for activities involving small and fast boats. However, regrettably, its full potential remains untapped at present. The purpose of this study was to identify the effect of variations in the angle of the step hull on resistance or drag. The study utilized the CFD method, and three hull configuration models were used at each change in hull step angle of 180º, 210º, 240º, and 270º. Configurations 1 and 2 have similarities in terms of rear hull length (600 mm), hull height (20 mm for configuration 1 and 30 mm for configuration 2), and deadrise angle (15° for configuration 1 and 20° for configuration 2). Configuration 3 has similarities with an 800 mm rear hull, 20 mm hull height, and 15° deadrise angle. It was found that as the Froude number increases, the coefficient of total resistance decreases. Conversely, as the Froude number increases, the resulting resistance also increases. The configuration with the highest resistance value corresponds to the alteration from configuration 2 with a hull step of 180°, and that the alteration from configuration 2 with a hull step of 270° corresponds to the configuration with the lowest resistance value. This study concludes that deadrise angle and the height of the step hull are the main factors that require careful consideration when designing ships that use a step hull. Therefore, this research provides an understanding of the step hull and can serve as a basis for the development of the step hull.

Numerical simulation of planing hull motions in calm water and waves with overset grid

This paper presents simulations of planing hull motions in calm water and waves with the unsteady RANS solver and the overset grid in Star-CCM+. The calm-water simulations were performed for the Fridsma planing hull model at Froude numbers from 0.59 to 1.78. Convergence studies were first carried out on dimensions of overset domain, grid resolution, time step and turbulence model, including k–ɛ, Realizable k–ɛ, k–ω, and SST k–ω models. Uncertainties in numerical solutions due to spatial discretization were examined. The best-practice settings were summarized and used for simulations of the Fridsma planing hull with calm water and regular waves, as well as the investigations of scale effect. For the calm-water simulations, resistance, sinkage and trim of the Fridsma planing hull and LRI-II hull were compared with experimental data and empirical results based on the Savitsky method. Additionally, the recommended settings were also applied to two full-scale planing hulls, LRI-II and OTH-Vp, in irregular waves. Convergence studies were also carried out on wave generation. Predicted motions and vertical accelerations were compared with sea trial data. Validation studies show that the predictions are in good agreement with experimental data.

Analysis of the double steps position effect on planing hull performances

Along with developing high-speed craft technology, the planing hull is growing with modifications for better performance. One such technology is stepped hull, both single and double. Planing hull with steps allows the boat to run at a relatively low drag-lift ratio with lower frictional resistance due to reduced wetted area. In this study, the hull was modified with variations in the position of the double steps, which aimed to determine the effect of the first and second step positions on the total resistance, dynamic trim, and dynamic sinkage generated by computational fluid dynamics (CFD). Based on the analysis results, variations in the position of the stepped can change the hull performance. Shortening the distance between the two steps and moving both rearwards toward the transom can lower the total resistance. The dynamic trim and dynamic sinkage decreased as the position of the two steps was shifted further forward. An equation created in a non-dimensional form relates the positions of two steps to the desired results of total resistance, dynamic trim, and dynamic sinkage, namely: {(x1-x2)/L + (x1x2)/(LB)} × Fr∇, where x1 is distance the first step from transom, x2 is the distance of the second step, L is the length of the boat, B is the beam of the boat, and Fr∇ is the volume Froude number.

Numerical parametric assessment of the effects of stern wedges on the pressure and friction resistance of high-speed craft

ABSTRACT In the current study, wedge effects on a planing hull's friction and pressure resistance components have been numerically investigated. This study also assesses how the variation of pressure and friction resistance components can be predicted by trim angle variation. The obtained results indicate that at F r b < 0.9 , stern wedges slightly increase the vessel's pressure resistance. By increasing the speed, pressure, and friction resistance components of the wedge-mounted model descends and increases, respectively, compared to the baseline model. The results indicate that the wedge-mounted planing hull experience a decrease in pressure resistance of up to 27% and an increase in friction resistance of up to 34%. After F r b = 2.15 , some interaction effects between the wedge length and height on the total and pressure resistance appear. The findings also indicate that wedge effects on the planing hulls' pressure and friction resistance components are much different from those of displacement hulls.