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INDONESIA
KAPAL Jurnal Ilmu Pengetahuan dan Teknologi Kelautan
Published by Universitas Diponegoro
ISSN : 18298370     EISSN : 23019069     DOI : 10.14710/kapal.
Core Subject : Science,
Earth & Planetary Sciences
Jurnal ini merupakan Jurnal Ilmiah untuk mengembangkan ilmu dibidang Ilmu Pengetahuan & Teknologi Kelautan. Jurnal ini diterbitkan oleh Teknik Perkapalan Universitas Diponegoro 3 (tiga) kali dalam 1 tahun pada bulan Februari, Juni dan Oktober.
Arjuna Subject : -
Articles 408 Documents
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Vertical Motion Optimization of Series 60 Hull Forms Using Response Surface Methods Utomo, Budi; Iqbal, Muhammad
Kapal: Jurnal Ilmu Pengetahuan dan Teknologi Kelautan Vol 17, No 3 (2020): October
Publisher : Department of Naval Architecture - Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/kapal.v17i3.33212

Abstract

There are many aspects to analyze seakeeping performance, one of which is the ship's vertical motion. As well-known, vertical motion and its derivatives, vertical velocity and acceleration, will be related to other aspects of seakeeping performance, such as slamming, deck wetness, and MSI. This study discusses optimizing the hull shape with small vertical motion using the Response Surface Methods (RSM). This research aims to minimize the ship's vertical motion so that the ship's performance is better than the initial one. Besides, this research was conducted to apply the RSM in the naval architecture field. The hull's shape used in this study is Series 60 hull form with a length of 31 m. The variables used for the optimization process are the ratio of L/B (X1) and B/T (X2) in the range of ± 10% with fixed displacement. Seakeeping analysis was carried out at a speed of 6.78 knots (Fr 0.2), a heading angle of 180°, and a significant wave height of 0.77 meters. The results show that the optimum model is found in Model 9 where the value of X1 = -2.94 or L/B = 6.71 and X2 = 5 or B/T = 2.75. Model 9 can reduce the vertical motion of the ship by 16.38%.
Experimental Investigation of Bow Slamming on a Ship: The Effect of Weight and Impact Angle Baso, Suandar; Himaya, Andi Nadia; Samman, Faizal Arya; Anggriani, Andi Dian Eka; Rosmani, Rosmani
Kapal: Jurnal Ilmu Pengetahuan dan Teknologi Kelautan Vol 18, No 1 (2021): February
Publisher : Department of Naval Architecture - Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/kapal.v18i1.35663

Abstract

The impact pressure induced by slamming can imply physical damage on a ship. The high probability of the slamming impact is on the bow part in the actual sea state. In this present study, the slamming induced pressure on the bow flare of a ship have been investigated through the experiment. The experiment was schemed by the dropping test based on free-falling body in the wave tank, wherein the bow of the ship model was inclined in several impact angles 0° to 30° to the free-water surface. To measure slamming impact pressure acting on the bow flare, the piezoelectric sensors S1, S2, S3, S4 were attached to the bow section and installed on a computer. As the obtained results, the impact pressure on bow flare occurred in a short time duration caused by slamming. The discrepancy of the peak impact pressure between ship model weight of 2.42 kg and 7.29 kg for the impact angle 0° is 70.36% S1, 69.52% S2, 68.97% S3, and 68.34% S4. For the relative impact angle of 30°, the discrepancy is 67.02% S1, 65.73% S2, 58.51% S3, and 48.21% S4. The tendency of the peak pressure coefficient at the sequenced impact points S1, S2, S3, S4 is similar for all impact angles 0°, 10°, 20°, and 30°. The peak pressure coefficient due to the full load condition is highest in the nearest bottom part, and the peak pressure coefficients due to the lightship condition highest in the nearest bottom part caused by the small impact angle.
Study on Implementation of Activity-Based Costing (ABC) System on Determination of Indirect Costs in Ship Production Wahidi, Sufian Imam; Virmansyah, Vialdo Muhammad; Pribadi, Triwilaswandio Wuruk
Kapal: Jurnal Ilmu Pengetahuan dan Teknologi Kelautan Vol 18, No 1 (2021): February
Publisher : Department of Naval Architecture - Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/kapal.v18i1.33000

Abstract

Currently, business development, especially in the maritime sector, has quite rapid progress in Indonesia. Recently, the shipbuilding industry's development is an effort to improve competitiveness with the global market. With the increasing development of the shipbuilding industry in Indonesia, cost accounting as a cost information system is challenged to develop the shipbuilding industry, requiring high product quality. This matter requires the company to decide on proper budget planning not to experience losses. Activity-Based Costing (ABC) System is a system to determine costs using activities to classify costs to produce indirect costs that are more systematic and relevant. Activity-based costing systems identify resources in each department's activities to provide information about a product's cost. It collects indirect costs and allocates them to various products in proportion to the product volume. Therefore, activity-based costing can estimate the product costs and individual activity costs used in the production well. The first step is classifying activities, associating various costs with various activities, determining homogeneous cost groups, and determining group rates. The second step of this stage is the determination of overhead prices selected from each cost group. This research compares indirect costs to the construction of 2x1800 HP tugboat ships according to traditional cost accounting methods with the Activity-Based Costing System method. The first method's result is 3,432,920,043 IDR and the second method is 2,231,760,472 IDR.
Effect of the Addition of Hydrofoil on Lift Force and Resistance in 60 M High-Speed Vessel Ismail, Izzuddin Nadzir; Manik, Parlindungan; Indiaryanto, Mahendra
Kapal: Jurnal Ilmu Pengetahuan dan Teknologi Kelautan Vol 17, No 3 (2020): October
Publisher : Department of Naval Architecture - Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/kapal.v17i3.28772

Abstract

The development of sea transportation technology is needed to meet the demand for ships that can carry heavier loads and operate at high speeds. Modifications in the form of additional hydrofoil variations were conducted to produce higher lift and reduce the resistance generated by the ship so that the ship can go more efficiently at high speed. This study aims to obtain the effect of adding hydrofoil to ships with variations in the type and shape of foil and find out which types and shapes can reduce resistance on the ship. This research was conducted with several model analysis tests using Computational Fluid Dynamic (CFD) based software, namely Tdyn, at several different speeds. The results of this study show that of the six variation models analyzed, rectangular fully submerged foil models can reduce the total resistance value of the ship by 17.822% from the original ship on Froude Number (Fr) 0.670. The type and shape of the foil is very influential on the lift and resistance produced by the ship.
The TLP 2-DOF as an alternative model for extreme wave application Akmal, Jamiatul; Lubis, Asnawi; Tanti, Novri; Nuryanto, Nuryanto; Murti, Adam Wisnu
Kapal: Jurnal Ilmu Pengetahuan dan Teknologi Kelautan Vol 18, No 2 (2021): June
Publisher : Department of Naval Architecture - Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/kapal.v18i2.37187

Abstract

Tension Leg Platform (TLP) is an offshore platform structure used for deep-sea oil and gas exploration. The main structure of the TLP consists of a deck, pontoon, mooring system, and foundation. TLP operates in a balance of buoyancy, structural weight, and mooring tension. The problem is the construction of TLP in the deep sea, where sometimes extreme waves appear could damage the TLP structure. This paper proposes a new model of TLP that is more stable to extreme waves. The method is to separate the mass of the deck and the mass of the pontoon into two flexible parts, which are connected by a cantilever spring system. Thus the TLP motion becomes two degrees of freedom (TLP 2-DOF). Using the dynamic vibration absorber (DVA) method, the ratio of the deck mass, pontoon mass, and spring stiffness are adjusted so that the primary mass movement is minimal. Furthermore, the ratio of the amplitude of the deck movement as the primary mass to the wave amplitude is analyzed, which is known as the operator response amplitude (RAO). The results showed that the TLP 2-DOF model was more stable. As an illustration, at resonance conditions, this model can reduce RAO to about 67%.
Comparative Analysis of Taper and Taperless Blade Design for Ocean Wind Turbines in Ciheras Coastline, West Java Madi, Madi; Tuswan, Tuswan; Arirohman, Ilham Dwi; Ismail, Abdi
Kapal: Jurnal Ilmu Pengetahuan dan Teknologi Kelautan Vol 18, No 1 (2021): February
Publisher : Department of Naval Architecture - Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/kapal.v18i1.32486

Abstract

The blade is the most critical part of turbine design because it is used to convert kinetic to mechanical energy. In general, the blade types used for ocean wind turbines are taper and taperless blades, like those operated at Ciheras Coastline. Previous research has been analyzed the type of airfoil used in designing taper blades for ocean wind turbines using NACA 4412, which was selected as the optimal foil configuration at sea wind speeds of 12 m/s. In this study, the comparison of taper and taperless blade designs using NACA 4412 at a wind speed of 12 m/s is analyzed. The comparative study with previous research has been carried out and resulted in the same graphical patterns and performance results. In this study, the focus is on investigating the performance coefficient of power, mechanical power, and electrical power. The final result shows that taper blade designs are highly recommended for use in ocean wind turbines compared to taperless blades. In general, the performance produced by taper blades is more significant than taperless blades at relatively high wind speeds. The maximum performance coefficient of power, mechanical power, and electrical power generated by the taper blades in sequent are 0.47, 1535 watts, and 786 watts, while the taperless blades have 0.44, 1437 watts, and 736 watts.
Effect of Current on Mechanical Properties and Microstructure of Aluminum 6061 with Gas Tungsten Arc Welding Process Tarmizi, Tarmizi; Sianturi, Kevin Daniel; Irfan, Irfan
Kapal: Jurnal Ilmu Pengetahuan dan Teknologi Kelautan Vol 17, No 3 (2020): October
Publisher : Department of Naval Architecture - Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/kapal.v17i3.30054

Abstract

Aluminum 6061 is an aluminum alloy that is widely used in various industrial fields, which heat treatable. However, it can be joined using a welding process. Aluminum joining using the Gas Tungsten Arc Welding (GTAW) process has become the option to produce good quality joints. This research aims to get optimum welding parameters by knowing the mechanical properties and microstructure of the welding results. The GTAW process uses a 25-volt voltage, Argon protective gas flow rate of 15 liters per minute with filler rod ER 5356 with 2.4 mm diameter and electrodes tungsten 2.4 mm in diameter. This process uses a single V butt joint and groove angle of 60° with variations in the current of 100, 110 and 120 A. The results indicate that specimens with a variety of current of 110 A give better results in the absence of defects, have a tensile strength of 152 MPa, and get a hardness value of 87.55 HV, which is the highest compared to the other two specimens. Whereas specimens with the current variation of 100 and 120 A have defects in the weld area. The optimum parameters of the 6061 aluminum GTAW process with a thickness of 6 mm using a current of 110 A bring on better outcomes and mechanical properties than the use of currents of 100 and 120 A.
The Effect of Trim on Tanker, Container and Bulk Carrier Ship Toward the Reduction of Ship’s Exhaust Gas Emission Undap, Robin; Fadillah, Arif
Kapal: Jurnal Ilmu Pengetahuan dan Teknologi Kelautan Vol 18, No 2 (2021): June
Publisher : Department of Naval Architecture - Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/kapal.v18i2.33877

Abstract

Emission is one of the few environmental problems, and ships are one of the modes of transportation that produce it. This study aims to define the impact of using optimal trim during the cruising phase, so it can decrease the resistance and the fuel consumption, which will lead to less emission produced by the ship. The type and amount of ships used in this study are three tanker ships, three container ships, and two bulk carrier ships. The methodology used in this study is by using Holtrop’s resistance calculation method with the help of Maxsurf software. The resistance, the power needed, and the fuel consumption is calculated on 22 trim variations and seven speed variations. This study determined that the average decrease in fuel consumption caused by trim optimization for tanker, container, and bulk carrier ships is 5.641%, 8.269%, and 15.704%. Furthermore, the average decrease of emissions produced by tanker, container, and bulk carrier is 6.494%, 11.317%, and 13.775%, respectively. These results are narrowed down to conclude that trim optimization can reduce fuel consumption by up to 9.871% and decrease the emission produced by up to 10.529% for the three types of ships used in this study.
Material Effectiveness Model for the Construction of Aluminum Hull Suwasono, Bagiyo; Darmawan, Mochammad Rizky; Baroroh, Intan
Kapal: Jurnal Ilmu Pengetahuan dan Teknologi Kelautan Vol 18, No 1 (2021): February
Publisher : Department of Naval Architecture - Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/kapal.v18i1.29974

Abstract

Construction of a hull generally requires several plates and profile material. Early indications for shipbuilding indicate that in manner, the linear function approach for installed material was 75% to 90%, and waste material was 10% to 25%. This study is conducting an assessment of the area of installed material and waste material on small vessels made of aluminum with variations in ship length and the method of approach trend lines both linear and nonlinear. Secondary data retrieval in the form of an aluminum cutting plan for plate material and profile from the AutoCAD application, which is then reprocessed through the FastCAM application to obtain results in the form of identification of installed material and waste material area. Based on variations in ship length and material area results, a scatter plot process was carried out through the Excel application to obtain results in the form of trend line functions with an R-squared determination coefficient of more than 0.9 and the results of the calculation of the intersection between the function of installed material and waste material, and the waste material function with the x-axis uses the balance method. The final result showed that the linear function gives an indication of the effectiveness of the material located in the range of 6 to 23 meters in length of the boat and polynomial function of order 2 in the range of 6 to 18 meters in length, while the waste material area in the two functions maximum 22%.
The Wave Heights Distribution of Random Wave Based on Ocean Basin Firdaus, Nurman; Ali, Baharuddin; Nasir, Mochammad; Muryadin, M
Kapal: Jurnal Ilmu Pengetahuan dan Teknologi Kelautan Vol 17, No 3 (2020): October
Publisher : Department of Naval Architecture - Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/kapal.v17i3.31021

Abstract

The wave height parameter in ocean waves is one of the important information for a marine structure design. The present paper investigates the results of wave heights distribution from laboratory-generated for single sea state. Data of the random wave time series collected at the ocean basin are analyzed using the wave spectrum and compared with the theoretical spectrum in this study. The random wave data is varied with four sea states consisting of sea states 3, 4, 5 and 6 obtained from laboratory measurements. The parameter conditions of generated sea waves are represented by a value of significant wave height and wave peak period in the range of sea states. The individual wave heights data in each sea state are presented in the form of exceedance probability distribution and the predictions using a linear model. This study aims to estimate the wave heights distribution using the Rayleigh and Weibull distribution model. Furthermore, the accuracy of the wave heights distribution data's prediction results in each sea state has been compared and examined for both models. The applied linear models indicate similar and reasonable estimations on the observed data trends.

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