PENGARUH POSISI CENTERBULB BERBENTUK FOIL TERHADAP KOMPONEN HAMBATAN KAPAL IKAN KATAMARAN MV. LAGANBAR

Catamarans are double hull ships which have many advantages over single hull ships with the same displacement. To increase catches, fishermen in Cilacap converted ships from the original single hull with outrigger to double hull (catamaran). Displacement of ships has doubled. But the ship's resistance increased to almost 4 times. To reduce the resistance of catamarans, some researchers use the concept of center bulb. In this study, the center bulb form used foil. The purpose of this study was to determine the effect of center bulb position on ship resistance components by comparing 9 center bulb positions. The results stated that of the nine center bulb position configurations, Model 6 is the best model because at Fr 0.35 it can reduce ship resistance by up to 33%. For the viscous resistance component it is not significantly affected by the use of the center bulb. But on the wave resistance component, the use of this center bulb can reduce wave resistance by 47% at Fr 0.35.

Download Full-text

Influence of the transom immersion to ship resistance components at low and medium speeds

Journal of Naval Architecture and Marine Engineering ◽

10.3329/jname.v17i2.48494 ◽

2020 ◽

Vol 17 (2) ◽

pp. 165-182

Author(s):

I. Z. Mustaffa Kamal ◽

A. Imran Ismail ◽

M. Naim Abdullah ◽

Y. Adnan Ahmed

Keyword(s):

Froude Number ◽

Wave Resistance ◽

Hull Form ◽

Ship Resistance ◽

Resistance Components ◽

Ranse Solver

The transom stern offered some advantages over the traditional rounded cruiser stern reducing the resistance of a ship. This can only be achieved if the transom stern is carefully designed with suitable transom immersion ratio. In this study, the influence of different transom area immersion ratios on the resistance components was investigated for a semi-displacement hull and a full displacement hull. The base hull was based on NPL hull form and KCS hull form for a semi-displacement and full-displacement hull respectively. The transom immersion ratios for the NPL hull were varied at a ratio of 0.5, 0.7, 0.8 and 1.0. The resistance of each of the NPL hull form was simulated at Froude number 0.3 up to 0.6. The transom immersion ratios for the KCS hull were varied at a ratio of 0.05, 0.1, 0.15 and 0.3. The resistance of each of the KCS hull form was simulated at Froude number 0.195, 0.23, 0.26 and 0.28. The transoms of both hulls were modified or varied systematically to study the influence of the transom shape or immersion on the total and wave resistance components. The investigation was carried out using a CFD software named SHIPFLOW 6.3 based on RANSE solver. These results on the NPL hull shows that the larger the transom immersion, the higher the resistance will be for a semi-displacement vessel. The increased resistance is contributed by additional frictional and wave resistance components. The results for the KCS hull seems to contradict with the results obtained from the NPL hull. The larger and deeper transom for the case of KCS hull form sometimes can be beneficial at higher Froude number.

Download Full-text

ANALISA KOMPONEN HAMBATAN KAPAL IKAN TRADISIONAL DI PERAIRAN CILACAP

Jurnal Kelautan Indonesian Journal of Marine Science and Technology ◽

10.21107/jk.v9i1.958 ◽

2016 ◽

Vol 9 (1) ◽

pp. 1

Author(s):

S Samuel

Keyword(s):

Water Resistance ◽

Frictional Resistance ◽

Slender Body ◽

Resistance Components ◽

Fishing Boat ◽

Calm Water ◽

Double Hull ◽

Traditional Fishing ◽

Body Method ◽

Resistance Component

RESISTANCE COMPONENT ANALYSIS OF TRADITIONAL FISHING BOAT IN CILACAP Monohull fishing boats used to catch fish is modified into a catamaran boat. The purpose of this modification is to get more fish. Catamaran ship has a double hull, but with the double hull ships resulted in increasingly complex resistances. It is interesting to study in depth about the resistance components of Catamaran boat. Resistance Components not only consist of surge resistance, frictional resistance, and the form resistance but with the distance between demihull causing interference waves. There are many research results of Catamaran boat in that aspect, but the data and information obtained from the experiment is still inadequate. In addition, there is still lack of accuracy particularly in predicting interference resistance component in calm water (calm-water resistance) as a result of the distance between the demihull. This study aims to describe the resistance component at Catamaran boat by using slender body method. Keywords: catamaran, Cilacap, slender body method ABSTRAK Kapal ikan monohull yang biasa digunakan untuk mencari ikan dimodifikasi menjadi kapal catamaran. Tujuan modifikasi ini untuk mendapatkan muatan ikan yang lebih banyak. Kapal Catamaran mempunyai dua lambung, tetapi dengan adanya dua lambung mengakibatkan hambatan kapal semakin kompleks. Menarik untuk dikaji lebih lanjut tentang komponen hambatan kapal Catamaran. Komponen hambatan tidak hanya terdiri dari hambatan gelombang, hambatan gesek, dan hambatan bentuk namun dengan adanya jarak antar demihull sehingga menimbulkan interferensi gelombang. Sudah banyak dijumpai hasil riset kapal Catamaran pada aspek tersebut, tetapi data dan informasi yang diperoleh dari eksperimen masih kurang memadai. Disamping itu, masih ditemukan ketidak-akurasian khususnya dalam memprediksi interferensi komponen hambatan pada air tenang (calm-water resistance) akibat dari adanya jarak antar demihull tersebut. Penelitian ini bertujuan untuk memaparkan komponen hambatan pada kapal Catamaran dengan menggunakan slender body method. Kata kunci: catamaran, Cilacap, slender body method

Download Full-text

Convergence of a Sequence of Slender-Ship Low-Froude-Number Wave-Resistance Approximations

Journal of Ship Research ◽

10.5957/jsr.1984.28.3.155 ◽

1984 ◽

Vol 28 (03) ◽

pp. 155-162

Author(s):

Francis Noblesse

Keyword(s):

Froude Number ◽

Wave Resistance ◽

Beam Length ◽

Remarkable Property ◽

Ship Hulls ◽

Low Froude Number ◽

Vertical Cylinders ◽

Elliptical Cylinders ◽

Double Hull ◽

Special Case

Convergence of the sequence of slender-ship low-Froude-number wave-resistance approximations /"/, n > 0, obtained as a particular case of the slender-ship theory of wave resistance recently proposed by the author, is proved for the special case of ship hulls in the form of vertical cylinders with elliptical waterlines. Specifically, it is shown that we have where b is the thickness (beam/length) ratio of the cubical cylinder, Fis the Froude number, and r lf(b,F) is the Guevel-Baba-Maruo-Kayo low-Froude-number wave-resistance approximation associated with the exact zero-Froude-number (double-hull) potential. Vertical elliptical cylinders thus have the remarkable property that the ratio iipj{b,F)/rpp(b,F) is independent of the Froude number, that is, depends only on the thickness ratio of the cylinder.

Download Full-text

Study of Prismatic Planing Model Spray and Resistance Components

Journal of Ship Research ◽

10.5957/jsr.1983.27.3.187 ◽

1983 ◽

Vol 27 (03) ◽

pp. 187-196

Author(s):

Robert Latorre

Keyword(s):

Frictional Resistance ◽

Total Resistance ◽

Wide Beam ◽

Resistance Components ◽

Turbulent Transition ◽

Measured Resistance ◽

Pressure Resistance ◽

Resistance Tests ◽

Resistance Component ◽

Good Agreement

The results of a study of prismatic planing model spray and resistance components are presented. The calculated total resistance values are shown to be in good agreement with the measured resistance. The features of the whisker spray and spray blister are discussed along with an experimental technique using wide-beam prismatic models for measuring the spray thickness. A derivation based on energy considerations of the prismatic planing hull pressure resistance component and the spray thickness is presented. The spray thickness values calculated from this formulation are in qualitative agreement with the measured spray thickness. The frictional resistance component obtained from the resistance measurements indicated an extensive laminar flow on the planing model bottom. An acetanilid film was sprayed on the planing model bottom which tripped the laminar-turbulent transition. The CF-values estimated from the acetanilid film pattern were found to be 75 to 90 percent of the CF-values estimated from the corresponding resistance tests.

Download Full-text

Effect of Wake on Wave Resistance

Journal of Ship Research ◽

10.5957/jsr.1972.16.2.93 ◽

1972 ◽

Vol 16 (02) ◽

pp. 93-112

Author(s):

Sander Calisal

Keyword(s):

Boundary Layer ◽

Froude Number ◽

Wave Resistance ◽

Survey Method ◽

Viscous Resistance ◽

Total Resistance ◽

Ship Model ◽

A Value ◽

Design Speed ◽

Minimum Resistance

Suction is applied to the boundary layer of a ship model designed to be of minimum resistance for a Froude number V/(Lg)1/2= 0.289. The total resistance with suction is measured and the wave resistance is calculated by a wave-survey method. For the design speed the wave resistance is observed to remain almost constant up to a certain suction value and then to increase linearly with suction. The remaining viscous resistance, calculated by subtracting the directly measured wave resistance from the total resistance, decreases by the application of suction to a value lower than the values given by ITTC 57 and Schoenherr curves.

Download Full-text

A Dissipative Green's Function Approach to Modeling Gravity Waves Behind Submerged Bodies

Journal of Ship Research ◽

10.5957/josr.08170054 ◽

2020 ◽

pp. 1-14

Author(s):

Mirjam Fürth ◽

Mingyi Tan ◽

Zhi-Min Chen ◽

Makoto Arai

Keyword(s):

Green’S Function ◽

Green's Function ◽

Gravity Waves ◽

Potential Flow ◽

Wave Resistance ◽

Damping Term ◽

Early Design ◽

Resistance Components ◽

Rayleigh Damping ◽

Early Design Stages

Potential flow-based methods are common in early design stages because of their associated speed and relative simplicity. By separating the resistance components of a ship into viscous and wave resistance, an inviscid method such as potential flow can be used for wave resistance determination. However, gravity waves are affected by viscosity and decay with time and distance. It has, therefore, long been assumed that the inclusion of a damping parameter in potential flow would better model the wave resistance. This article presents a Kelvin–Neumann dissipative potential flow model. A Rayleigh damping term is inserted into the Navier–Stokes equations to capture the decay of waves. A new 3D Green's function based on the Havelock–Lunde formulation is derived by the use of a Fourier transform. An upper limit for the Rayleigh damping term is found by comparison with experiments and a possible improvement on conventional potential flow models for the wave making resistance prediction of a submerged ellipsoid is proposed. 1. Introduction To accurately determine the resistance is of great importance when designing a ship. Therefore, steady ship motion in calm water is a classical problem in ship hydrodynamics. Potential flow modeling is a common method to predict the wave resistance of ships. One benefit of potential flow is its computational speed. Speedy determination of the wave resistance is of great importance in early design stages. Because all ship properties are intertwined, it is not beneficial to dwell too much on one parameter. Potential flow-based models are, therefore, used for a wide range of industry applications during early phases of ship design (Wilson et al. 2010). A potential model using image sources to fulfill the free-surface condition and an exact body condition is known as a Kelvin–Neumann model. The Kelvin– Neumann problem is well known and well described, but it continues to be a topic of interest (Kuznetsov et al. 2002). Developments of Green's functions for resistance predictions is continuing to be of interest long after Michell (1898) developed his theory on the wave resistance of a ship. Recent Green's function applications include wave resistance determination (Taravella & Vorus 2012) and the calculations of forces acting on a submerged ellipsoid (Chatjigeorgiou & Miloh 2013). Doctors (2012) used a linearized potential flow method to determine the resistance components of a marine cushion vehicle.

Download Full-text

Design 30 GT Catamaran Fishing Boat with Variations of Hull Type and Inter-Demihull Length for Minimum Resistance

International Journal of Innovative Technology and Exploring Engineering - Special Issue ◽

10.35940/ijitee.c8147.019320 ◽

2020 ◽

Vol 9 (3) ◽

pp. 1126-1133

Keyword(s):

Wave Resistance ◽

Original Model ◽

Fishing Gear ◽

Viscous Resistance ◽

Total Resistance ◽

Optimal Form ◽

Fuel Savings ◽

Fishing Boat ◽

Resistance Value ◽

Minimum Resistance

Fuel savings are closely related to ship resistance. Research on reducing resistance continues to be done in various ways, ranging from hull modification, optimization of the propulsion system and the addition of polymer substances. Resistance are also influenced by ship’s velocity and variations of inter-demihulls length. This challenge has been widely discussed by experts, especially the variety of inter-demihull length. This research aims to analyze the 30 GT catamaran fishing boat resistance with variations in hull type and inter-demihull length. The main aim is to get the obstacle characteristics of these variations. The advantage of this research lies in the more varied shapes and inter-demihull lengths of each model where the characteristics of the obstacles will also vary, so that this research can later be an alternative for the community in the use of catamarans to increase fishing productivity. The study was conducted using CFD (Computational Fluid Dynamics). From the results, one of the most optimal form of the model is the type of hull Symmetrical Hard Chine with a variation of S / L 0.5 at maximum speed.Tthis model has a wave resistance value of 9.87 kN, a viscous resistance of 5.04 kN, and a total resistance value of 14.92 kN. Where there is a reduction of the wave resistance of 12.1%, viscous resistance of 1.5%, and a total resistance of 8.779% from the original model. Another advantage of this type for the Purseseine Boat is the use of a fairly wide deck for the laying of fishing gear.

Download Full-text