Penggunaan Marking Table Untuk Pengukuran Dimensi Model Uji Kapal Tipe V-form

Kapal patroli merupakan kapal cepat yang digunakan untuk tugas inspeksi, monitoring dan pengawasan. Pembuatan model uji kapal patroli tidak mudah mengingat bentuk haluan kapal yang cenderung pipih (V-form). Keakurasian pembuatan model kapal sangat penting untuk mendapatkan hasil uji model kapal yang rasional dengan tingkat validitas yang dapat dipertanggungjawabkan di laboratorium hidrodinamika. Dalam tulisan ini dibahas mengenai pembuatan model kapal Patroli yang didesain dengan skala model 1:21,19 dengan bahan kayu laminasi. Pemeriksaan model kapal terdiri dari pemeriksaan permukaan dan konstruksi lambung, dengan beberapa parameter pengukuran yang perlu diperhatikan: frame spacing 1 sampai dengan frame spacing 20 station, pemeriksaan point AP (After Perpendicular) ke bagian paling belakang dan pemeriksaan point FP (Fore Perpendicular) ke bagian paling depan model kapal. Pengukuran dilakukan dengan meletakkan model kapal diatas marking table untuk melakukan pengukuran dan pemeriksaan dimensi baik pada arah x, y maupun z. Alat waterpass digunakan untuk mengetahui pelurusan posisi model kapal. Setelah itu dilakukan penandaan frame station, waterline dan draft serta nomer lambung model uji kapal. Kualitas keakurasian pengukuran sangat ditentukan oleh alat ukur dan prosedur yang digunakan.Tinggi rendahnya tingkat ketelitian hasil suatu pengukuran dapat dilihat dari harga deviasi hasil pengukura

Analisa Kecepatan dan Karakteristik Pola Gelombang pada Kapal Bantu Hidro-Oceanography

Kapal hidro-oceanography dituntut mampu melaksanakan operasi diberbagai medan perairan, oleh karena itu penting merumuskan technical requirement yang didasarkan pada pertimbangan teknis yaitu dengan mengkaji kecepatan, power dan karaktristik gelombang permukaan yang terjadi pada kapal bantu hidro-oceanography dengan menerapkan teknik numerik untuk menghitung kecepatan, power dan menganalisa gelombang. Metode yang dipilih untuk menghitung besarnya tahanan dan power dari beberapa variasi metode. Dari metode Holtrop diperoleh tabel input untuk hullspeed, tabel output untuk hullspeed pada rentang kecepatan 12-14 KNOTS. Dari tabel-tabel tersebut dapat kita analisis gelombang untuk kecepatan 12 KNOTS dan 14 KNOTS

Analisa Ketidakpastian Pengujian Resistance Model Kapal LCT 1000 DWT

Uji tahanan yang dilakukan di tangki tarik memiliki kesalahan (ketidakpastian) pada hasil. Analisa ketidakpastian dapat digunakan untuk mengevaluasi kualitas data percobaan dan menyediakan perkiraan kuantitatif kesalahan percobaan. Metodologi analisa ketidakpastian, prosedur, dan hasil disajikan untuk uji tahanan model kapal LCT 1000 DWT skala (λ) 15 dengan ukuran model kapal L = 3,997 M, B = 1000 M, T = 0,167 M, WSA = 4,089 M2, Prosedur dirangkum dan mengikuti International Towing Tank Conference (ITTC) Kualitas Manual Prosedur. Hasil penelitian menunjukkan nilai ketidakpastian sebesar 1,27% dari kecepatan 1,3271 m/s dan nilai ketidakpastian sebesar 4,79% dari tahanan 1,2771 kg.Keywords : Uncertainty analysis, Procedures, Ship model test

Optimizing Ocean Energy Harvesting: The Significance of Natural Frequency in Piezoelectric Generator Device Electrical Output

This study explores the significance of the natural frequency parameter in enhancing the electrical performance of a piezoelectric generator device, mainly when deployed in ocean energy harvesting. While natural energy harvesting aims to establish affordable and sustainable renewable energy sources, piezoelectric devices capitalize on the inherent piezoelectric effect derived from natural movements. Despite the abundance of constant natural movements in the Earth's environment, the application of piezoelectric devices in ocean energy remains relatively understudied. The experimental setup involves a cantilever-designed piezoelectric device made from polyvinylidene fluoride (PVDF). The study investigates the relationships between vibration frequency, initial distance, and electrical output. Findings indicate that higher setup parameters may lead to increased electrical output, but the relationship is not linear. Notably, the resonance between the vibration frequency and the device's natural frequency emerges as a critical factor in optimizing electrical performance. Detailed experimentation, visualized through figures and graphs, demonstrates the nuanced interplay of setup parameters and electrical output. The study emphasizes that the initial distance, while important, does not singularly determine the device's electrical performance. It challenges conventional beliefs by showcasing that piezoelectric devices can operate efficiently in tight spaces. Furthermore, the study delves into the non-linear relationship between vibration frequency and electrical output. Examining natural and resonant frequencies reveals that resonance occurs most prominently at the device's natural frequency, emphasizing the importance of precise tuning for optimal performance. The findings offer valuable insights for the strategic deployment of piezoelectric technology in ocean energy harvesting, paving the way for more efficient and effective devices in real-world condition

Representative application of LNG-fuelled ships: a critical overview on potential GHG emission reductions and economic benefits

The shipping industry is the primary and most significant mode of international cargo transportation. The ship must comply with strict rules regarding reducing greenhouse gas (GHG) emissions as a dominant transportation mode. Liquified Natural Gas (LNG) is the primary alternative fuel option for several shipping companies. In essence, many studies recommend LNG as a transitional and alternative fuel because its emission characteristics are cleaner than other fossil fuels. Several previous investigations have been carried out to develop an action plan for integrating the use of LNG as a ship fuel. However, there have been few discussions on the estimation of GHG emission reduction and the economic efficiency of a representative LNG-fuelled ship. The recent progress on LNG-fuelled ships is systematically reviewed to summarize the pathways and highlight the core technological concepts, technical issues, current LNG-fuelled ship applications, and future outlooks regarding integrating LNG energy resources into ship power systems to measure GHG emission reductions and cost savings estimations. The report will discuss the current development in the maritime sector and the effects of the macroeconomic scale. The result reveals that future research on ship-based LNG energy systems will probably concentrate on integrating new energy source generating strategies with existing ship power systems to improve energy efficiency. Several potential research areas for future outlook were also discussed to anticipate future challenges