Pengaruh hasil sumber daya listrik yang dihasilkan dari mesin genset yaitu kemungkinan terjadinya lubang cacing dan retak, dan apabila arus yang terlalu rendah akan mengakibatkan kurangnya penembusan dan kemungkinan terak terperangkap tinggi, sehingga dapat mengakibatkan kekuatan dari sambungan lasan yang rendah. Pengujian pada sambungan pengelasan  yang berbeda diameter elektroda dengan menggunakan mesin genset, akan diperoleh kekuatan tarik dan kekuatan impak maksimum dari masing-masing material uji dan dapat diketahui pemilihan diameter elektroda yang paling baik digunakan untuk masing-masing pelat. Pengelasan menggunakan jenis sambungan butt joint (single V-groove) dengan sudut 600, dengan diameter elektroda 3,2 mm dan 4 mm dengan tebal masing-masing material uji 8 mm dan 10 mm. Hasil pengujian didapatkan kuat tarik dari diameter elektroda 3,2 mm tebal material 8 mm adalah rata-rata 443,747 N/mm2, diameter elektroda 3,2 mm tebal material 10 mm adalah rata-rata 435,187 N/mm2, diameter elektroda 4 mm tebal material 8 mm adalah rata-rata 447,23 N/mm2, dan diameter elektroda 4 mm tebal material 10 mm adalah rata-rata 447,07 N/mm2. Hasil penelitian, modulus elastisitas dan tegangan luluh sama-sama memiliki kenaikan nilai, serta nilai pada regangan menurun. Sedangkan hasil pengujian impak didapatkan energi impak dari diameter elektroda 3,2 mm tebal material 8 mm adalah rata-rata 90,67 Joule, diameter elektroda 3,2 mm tebal material 10 mm adalah rata-rata 295,9 Joule, diameter elektroda 4 mm tebal material 8 mm adalah rata-rata 44,91 Joule, dan diameter elektroda 4 mm tebal material 10 mm adalah rata-rata 273,83 Joule.

No abstract

The propeller was one of the main propulsors in ships that consumed a lot of fuel due to the viscous force acting in the ship. Therefore many studies have been carried out to increase the performance of ship propellers. One of the ways is using Energy Saving Device (ESD) to improve propeller performance. One of the ESD is Propeller Boss Cap Fins (PBCF). PBCF was used to improve the propeller performance by reducing the hub vortex during propeller rotation. In this study, we compare the propeller performance before and after PBCF installation without changing propeller dimensions. The variations of PBCF fins were made in 0,1D, 0,2D, and 0,3D with a combination of the angle of the propeller cap were 15° and 20°. The propeller performance is carried out with the computational fluid dynamics (CFD) method. It was made in the open water assumption to reduce of wall effect. B-series propeller is used in the present study. The validation of propeller performance is made using empirical results. This study aimed to determine the effect of the installation of PBCF on the performance of B-Series propellers on the Ro-Ro 1000 GT ship. The results show that variation with a fin diameter of 0,2D and a propeller cap of 20° can increase propeller efficiency by 0.03%. It can be concluded the addition of PBCF can improve propeller performance.

No abstract

Abstrak Bambu laminasi merupakan bahan bangunan rekayasa yang dibentuk dengan sistem perekatan beberapa bilah bambu sehingga memiliki kelebihan dapat dibuat dalam berbagai ukuran dan sifat mekanika yang lebih uniform dari bahan bambu alami. Teknik laminasi dari bahan bambu menjadi solusi untuk mengembangkan sebuah produk kayu yang memiliki struktur dan sifat mekanik lebih kuat dan awet. Prosedur pembuatan dan pengujian spesimen kayu laminasi bambu petung dan bambu apus mengacu pada SNI-03-3958-1995, SNI-03-3399-1994 dan SNI 03-3959-1995

⎯ towing hook is one of the important components of a tugboat. Its function is to tow various types of ships, namely containers, tanker ships, and even barges. This activity affects the components to undergo failure and crack, especially the support structure of the hook. Earlier research has analyzed various types of stress characteristics, namely fatigue crack, maximum stress, and maximum factor of safety aimed both at the support structure and the whole profile of the tug. The research aim is to determine the value of stress in the support structure and the safety factor brought by tensile load transferred from the towing hook. The analysis is done using finite element method in Altair Hyper Works 2019. Structural strength of the towing hook support structure is analyzed in 2 loading conditions, namely lightweight barge and full load barge. Two different approaches are used for comparison. The first approach is using barge resistance, and the second is by utilizing maximum tug horse-power to speed ratio. Maximum stress acquired in both loading conditions and both approaches is 118.64 MPa; 121.80 MPa; 230.90 MPa; 329.86 MPa respectively. The safety factor is measured using 2 criteria, BKI permissible stress criterion and BKI Material Strength criterion. Results of safety factors based on BKI permissible stress are 1.644; 1.601; 0.845; and 0.591. According to BKI Material Strength, the safety factors on both loading conditions are 3.371; 3.284; 1.732; and 1.212.

Reducing fuel consumption and carbon emissions in the development of ship propulsion systems following the required Energy Efficiency Design Index (EEDI) has become a concern for the fishing industry as determined by the International Maritime Organization (IMO). This study analyzes the suitability of using a 30 GT fishing vessel propeller and propulsion engine for optimum efficiency. The analysis focuses on developing a propulsion system selection model, studying the characteristics of the ship's resistance, loading propellers, and selecting the appropriate engine. The propeller-engine matching procedure predicts the propeller and engine suitability. Furthermore, the Analytic Hierarchy Process (AHP) method determines the suitability level for the propeller and diesel engine. The results showed the highest level of suitability for the Yanmar 6CH-HHTEC engine versus the A.30X34 type propeller with 31.7%. Then the Deutz BF06M1013MC engine versus the B.30X28 propeller type, the Yuchai YC6A170C engine versus the B30X28 propeller type, and the Volvo D7ATA engine versus the B30X28 propeller type with percentages of 26.6%, 26.4%, and 15.3%, respectively. The high level of SP2 selection is due to the propulsion system having minimal noise levels, dimensions, and engine weight but having maximum power.

The buckling phenomenon for imperfect pipe under bending has been investigated by nonlinear FEA, considering the effect of a cross sectional oval deformation by changing the variables of pipes, that is, L/D varying from 2.5 to 20, D/t varying from 50 to 200, and imperfection (d o /t) varying from 0.05 to 0.5. As well as the elastic buckling, the elasto-plastic buckling was investigated. From the calculation results, the followings were found. The reduction of buckling moment due to imperfection is larger in short pipe than in long pipe. The effect of imperfection for pipes with large values of D/t is larger than those with small values of D/t if L/D of both pipes is same. The effects of imperfection for elastic analysis are larger than elasto-plastic analysis. The buckling moment reduces more by the imperfection of buckling mode than by that of oval mode.