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IJOCE (International Journal of Offshore and Coastal Engineering)
Published by Institut Teknologi Sepuluh Nopember Surabaya
ISSN : -     EISSN : 25800914     DOI : -
Core Subject : Engineering,
Engineering
IJOCE, International Journal of Offshore and Coastal Engineering, is an academic journal on the issues related to offshore, coastal and ship science, engineering and technology. Published quarterly in February, May, August, and November.
Arjuna Subject : -
Articles 202 Documents
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Short Circuit Analysis due to Reconfiguration of AC to DC Electric Power System on Tanker Ship with Hybrid Energy Source Adi Kurniawan; Arialdi Almonda; Sardono Sarwito
International Journal of Offshore and Coastal Engineering Vol. 8 No. 1 (2024)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j25800914.v8i1.20464

Abstract

The conventional AC electric power distribution system on ships has a higher impedance than the DC system, thus providing more significant distribution losses. Due to the enormous losses in the distribution system, a larger power output is required to balance the power required by the loads, and the losses occur on the line between the sources and the loads. Therefore, reconfiguring the power distribution to the DC system is promising. However, analysis in other aspects needs to be performed, including for short circuit current. In this research, power system simulator software is used to analyze the amount of fault current that contributes to each type of distribution. The simulation is performed under four ship operation modes, including sailing, maneuvering, at port, and cargo loading-unloading. The results of the simulation show that the short-circuit current can be significantly decreased after the reconfiguration of the system. A similar phenomenon has occurred in other operation modes. The short circuit value decreases around ten times in the DC system compared to the AC system. Therefore, the DC system is safer than the AC system.
Analysis of the Effect of Sinker on Bearing Capacity of Anchor in Calm Buoy Mooring System: Case Study of SBM Pengapon Semarang Murdjito Murdjito; Eko Budi Djatmiko; Agnes Teresa Melani
International Journal of Offshore and Coastal Engineering Vol. 8 No. 1 (2024)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j25800914.v8i1.20465

Abstract

The addition of sinkers on the mooring line is generally used to support the anchor in maintaining its position in extreme environmental conditions. In this study, the author will analyze the effect of sinkers on the mooring line tension and the bearing capacity of the anchor. The sinker variations in this analysis are 10, 15, and 20 tons, which will be added to the asymmetric mooring line of CALM Buoy SPM Pengapon Semarang. The type of anchor SPM is Stevpris MK III on soft clay soil type. The author first analyses the line tension in each environmental loading condition and then analyses the anchor's bearing capacity. The analysis results show that the largest tension occurs in line 3 without a sinker in DEC conditions with an environmental load direction of 314.24 deg, 1301.19 kN (End A) and 1310.43 kN (End B). In the analysis of the holding capacity of the anchor, the author refers to the SOF ABS Class 2019 and the charts of Appendix D2 and D6 API RP 2SK. The results indicate that the gradation of weight and position of the sinker causes the line tension between the sinker and the fairlead to increase linearly, with an average percentage increase of 1.35%. Meanwhile, the bearing capacity of the anchor, which includes required holding capacity, anchor weight, and estimated drag distance/fluke length, decreased with an average percentage of 7.46%, 15.39%, and 4.79%. Based on the consideration of the End A tension analysis results in the DEC condition, it is stated that the 20-ton sinker in position 1 is a suitable variation of the sinker in this SPM Pengapon Semarang case study.
Risk Analysis of Equipment Loss During Marine Survey Operation by Integrating Fault Tree to Bayesian Network Dwitya Harits Waskito; Ahmad Muhtadi; Dimas Fajar Prasetyo; Indra Kurniawan; Dwi Haryanto; Adi Slamet Riyadi
International Journal of Offshore and Coastal Engineering Vol. 8 No. 1 (2024)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j25800914.v8i1.20466

Abstract

The process of deploying and towing the survey equipment for several marine survey activities is essential since it visualises the seabed and improves data accuracy. Since the equipment is deployed to an underwater level, the risk arises with the deployment. These risks include potential contact with submerged objects and the seabed, which can result in the loss of equipment and have detrimental environmental consequences. This study aims to analyse the risk-associated factors related to the loss of survey equipment using Fault Tree Analysis (FTA) and Bayesian Network (BN). The constructed FTA was converted into BN to find the relationship between Basic events and simulate the probability of updating Basic events. The sensitivity analysis results of the BN model indicate that "Procedure Failure" is the Basic contributor to the loss of survey equipment. The findings from this study will have practical implications for stakeholders, enabling them to enhance the safety of marine survey activities, particularly by mitigating the occurrence of equipment loss during operational procedures.
Analysis of Constraints in Implementing Inaportnet at Sorong Port Class 1 Arief Nashrul Firdani; Heri Supomo
International Journal of Offshore and Coastal Engineering Vol. 8 No. 1 (2024)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j25800914.v8i1.20467

Abstract

This research examines the challenges that arise when expanded logistics operations are conducted utilizing the Inaportnet program, which has been in place at KSOP Class 1 in Sorong City since 2017. This study examined a population using the inaportnet application at the Port of Sorong City. Using a qualitative descriptive methodology, The inaportnet application, which is currently being improved, users or stakeholders who need guidance with how to use the application, and the occasionally in-interfered-with signal in the Port of Sorong City are a few challenges that must be overcome. It is hoped that the findings of this analysis and discussion will provide information and recommendations for implementing Inaportnet at the Port of Sorong City to ensure service fairness (first come, first served), realize transparency of ship and goods services at the Port, hasten the completion of ship and goods services, and reduce costs associated with handling ship and goods services.
Analysis of Abrasive Materials dan Air Pressure Variations for Thermal Spray Aluminum Coating on Adhesion Strength and Corrosion Resistance in Seawater Environment Herman Pratikno; Raymond Danielle Mulya; Wimala Lalitya Dhanistha
International Journal of Offshore and Coastal Engineering Vol. 9 No. 1 (2025)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j225800914.v9i1.4467

Abstract

Marine structures must withstand the marine environment for a certain design life. However, corrosion causes a decrease in structural integrity before reaching the design life. Thermal spray aluminum coating becomes a protection method because of its resistance to corrosion in the long term. This study analyzed the effect of variations in abrasive materials and air pressure on thermal spray aluminum coating on ASTM A36 steel. The steel material will be blasted with two types of abrasive materials, namely garnet and aluminum oxide, then coated using the electric arc wire spray method at pressures of 2.5 bar, 3.5 bar, and 4.5 bar. Testing was carried out using the pull-off adhesion test and the three-electrode cell method. The results showed that the highest adhesion strength of 12.2 MPa occurred at 4.5 bar aluminum oxide, while the lowest was 6.3 MPa at 2.5 bar garnet. The lowest corrosion rate of 0.001 mm/year was obtained at 4.5 bar garnet, and the highest was 0.101 mm/year at 2.5 bar aluminum oxide. Based on the results of the corrosion rate test, it can be concluded that the increase in pressure is directly proportional to the increase in coating performance in resisting corrosion. Conversely, the increase in surface roughness is inversely proportional to the coating performance in resisting corrosion.
Lazy Wave Flexible Riser Dynamic Tension Analysis with Variation of Diameter and Buoyancy Module Configuration in Extreme Condition Muhammad Farhan; Eko Budi Djatmiko; Murdjito
International Journal of Offshore and Coastal Engineering Vol. 9 No. 1 (2025)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j225800914.v9i1.4502

Abstract

ABSTRACT Oil and Gas Production at floating offshore facilities is growing. It prompted the design of the Flexible Riser as a solution to channel exploration results to floating offshore facilities. In this final project, dynamic stress analysis of lazy wave flexible riser is carried out with variations in diameter and number of buoyancy modules under extreme conditions. This study discusses the maximum tension and minimum bending radius (MBR) on the flexible riser due to variations in diameter and number of buoyancy modules in extreme conditions with two system conditions, namely intact conditions and damage conditions. From the results of the analysis, the larger the diameter of the flexible riser, the greater the maximum tension at the SPM point. While it will be smaller at the PLEM point and the more buoyancy modules used, the smaller the maximum tension at the SPM point, the larger it will be at the PLEM point. The larger the diameter of the flexible riser, the smaller the MBR in the SagBend area. The larger the HogBend area and the more buoyancy modules used, the larger the MBR in the SagBend area, while the smaller the HogBend area.
Lazy Wave Flexible Riser Dynamic Responses Analysis with Variation of SPM Offset from PLEM on Operation Condition Muhammad Naufal Hawari; Wisnu Wardhana; Murdjito Murdjito
International Journal of Offshore and Coastal Engineering Vol. 9 No. 1 (2025)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j225800914.v9i1.4503

Abstract

The increasing use of flexible risers in oil and gas exploration projects is a big challenge for engineers to design better riser systems to improve further the efficiency and safety of exploration and production activities in offshore oil and gas fields. SPM is often used as an offloading facility connecting FSO or FPSO as recipients of oil and gas products from subsea templates or wells. Under operating conditions, SPM can move freely following the movement of environmental loads. Drifting or changes in position due to the load on the SPM can threaten the riser response, whereas the riser response can be different whether the SPM is moving or drifting in its stress or bending response. The results in this study also contain the effect of this phenomenon on their fatigue life. As a result, the difference in riser response due to the distance from SPM to PLEM is that the farther the distance from SPM from PLEM, the greater the stress response and bending radius it has. Fatigue life also follows the same results, where the farthest distance from the SPM configuration to PLEM has the lowest fatigue life compared to the closest distance from the SPM to PLEM configuration, with the highest fatigue life at 128.31 years and the lowest at 124.78 years.
Trunnion Structure Analysis with Rigging Variations at The Loadout Stage During Lifting Jacket Platform Process Muhammad Faris Pramudiansyah; Yoyok Setyo Hadiwidodo; Handayanu
International Journal of Offshore and Coastal Engineering Vol. 9 No. 1 (2025)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j225800914.v9i1.4504

Abstract

An offshore structure is a structure that is operated at an offshore base and has the general function of oil and gas exploitation and exploration. The making process of this structure is called the fabrication process. Fabrication is the process which is covered the whole activities to produce the structure. Lifting is a process that is included in this fabrication step.Many important lifting items correspond to the requirement to let the lifting process is working. A trunnion is a tubular member that helps lift the structure because it is where slings can be convoluted. Trunnion can be called lifting lugs, depending on the engineer at the company used.In this research, the trunnion that must be analyzed is the trunnion that has the general function for the jacket-to-lifting processes. In contrast, the researcher analyzed the effect of various rigging configurations. The considered variable of rigging configuration is the shape and amount of the spreader bar.
Replace Experimental and Numerical Study on Ocean Current Turbine Performance with Innovative Idea Using Toroidal Propeller Dendy Satrio; Mohammad Fahrur Riza Al Azizy; Deva Ery Aditya Putra; Sandi Jagat Pasma; Dio Alif Wahyudo; Zaidan Arsa Sulthana
International Journal of Offshore and Coastal Engineering Vol. 9 No. 1 (2025)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j225800914.v9i1.4505

Abstract

According to the HEESI, the share of renewable energy production is only 13.29% of the total energy production, with a target of 23% by 2025. One promising renewable energy source with a potential of 41 GW is ocean currents. To harness this potential, propeller turbines can be used. Propellers are a critical component of these turbines, typically designed based on the Wageningen B series. However, this series still exhibits issues such as cavitation and noise during operation. Toroidal propellers offer advantages by eliminating tip vortices, resulting in quieter operation, and reduced fatigue. This study aims to enhance the efficiency of propeller turbines through modifications using toroidal propellers. The study employs ANSYS Fluent for simulation and experiments. The process includes designing toroidal propellers with a maximum diameter of 3 meters, blade pitch angles of 60°, and blade counts ranging from 3 to 9. These designs are then simulated to analyze power and efficiency. Performance testing will measure RPM, and observe cavitation. The results are for blades ranging from 3 to 9 generates 42.6 to 63.2 kW. Therefore the best design is 9 blades that generate 63.7 kW of power with a maximum RPM of 89.9.
Analysis of the Pretension Angle of Mooring Lines SPM and Its Effect on the Tension and Strength of Subsea Marine Hose Rabiatul Muthi’ah; Murdjito Murdjito; Eko Budi Djatmiko
International Journal of Offshore and Coastal Engineering Vol. 9 No. 1 (2025)
Publisher : Department of Ocean Engineering

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j225800914.v9i1.4506

Abstract

The industry of oil and gas industry have developed along with advances in technology, so does the mooring system. Mooring system is a series that functions to keep the ship station or floating platform at all water depths. Currently, there are many types of moorings that can be used, one of which is Single Point Mooring (SPM). SPM itself consists of various types of mooring legs, as well as other supporting components such as subsea hose or riser. Subsea hose and mooring lines are closely related because in the application, the length of the mooring lines also determines the offset or limitation of motion of the SPM, while the subsea hose also has a maximum limit of pull caused by the movement of the SPM. In addition to the length of the mooring lines, another factor is the pretension angle. Therefore, in this study, an analysis was carried out by varying the pretension angle (45°, 50°, 55°, 60°) under extreme conditions and inline loading by reviewing the tensile forces on the mooring lines and risers. The larger the angle, the smaller the tensile force, so the offset would be larger, and vice versa. The results of this study indicate that the pretension angle applied must be appropriate so that the tensile force on the mooring lines that occurs can also be appropriate.

Page 19 of 21 | Total Record : 202

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