Renewable energy technology has been developed to reduce use of fossil energy. It has two advantages namely environmentally friendly and renewable. For example the use of marine current as a source of electricity by using a turbine. Several studies have been done to improve performance of turbine, for example the use of a duct. The duct amis to reduce torque ripple so that power does not have high fluctuations that result in excessive vibration in the turbine. Therefore the subject of this study is how the effect duct on Darrieus-Savonius combination turbine to reduce torque ripple factor (TRF) with the analysis of CFD. The simulation was performed on duct type 1, 2 and without duct with result of TRF is 3,939; 3,489 and 4,930. The conclusion that the use of duct on turbine can decrease torque ripple, where type 2 produces a smaller TRF namely, 3.489.

The 2D numerical simulation of an underwater acoustic system undergoing VIV (Vortex Induced Vibration) which is in position parallel to 5 m distance with variation of hydrophone cable position. The diameter of the hydrophone cable in use is 0.04 m, with Reynold numbers (Re) variations of 13000, 15000, 17000, 19000, 21000, 23000, 25000, 27000 and 30000. Position variations are used to determine the flow pattern characteristics that occur behind the cylinder as well the maximum value of drag coefficient (CD) and lift coefficient (CL). The simulation results show that the characteristic flow pattern around a cylinder at each Re value indicates the release of the vortex behind the cylinder with different drag and lift coefficient values.  Keywords: Vortex Shedding, Hydrophone, Acoustic System

Wooden hulls have been damaged and overgrown by fouling have negative impact on the service life and also increase the resistance of ship thereby increasing fuel consumption. Therefore the ship have to repaired regularly. The problem discussed is how to repair wooden ships such as replacing plank, cleaning hull and coating; and hull analysis to determine resistance of ship. Therefore the object of this paper is to repair wooden ships and analysis of the hull. The method used is training that is followed by demonstration and also science and technology simulation that explains the form hull and resistance of the ship with use of software Maxsurf. The result is replacement plank on the keel, and the side; clean the hull, putty and coating. The ship is measured and the main dimension is obtained and then makes line plans and 3D ship models. The calculation of the ship's resistance shows that ship use main engine Honda GX 160 with 5.5 hp will produce 6.325 knots.ABSTRAKKondisi lambung kapal kayu yang rusak dan ditumbuhi biota laut (fouling) berdampak negatif pada umur pakai kapal dan juga menambah tahanan kapal sehingga meningkatkan konsumsi bahan bakar. Oleh karena itu kapal harus diperbaiki secara berkala. Permasalah yang diselesaikan adalah bagaimana reparasi kapal kayu seperti penggantian papan kayu, pembersihan lambung, pengecatan dan juga analisa bentuk lambung kapal kayu untuk mengetahui tahanan kapal kayu. Sehingga tujuan penulisan ini adalah melakukan reparasi kapal kayu dan juga analisa lambung kapal. Sendangkan metode penelitian yang digunakan adalah adalah pelatihan yang diikuti demonstrasi dan juga simulasi ipteks yang menjelaskan bentuk lambung dan tahanan kapal dengan bantuan software Masurf. Kapal yang reparasi dilakukan pergantian papan pada lunas kapal, dan sisi kapal, pembersihan lambung, pendempulan dan pengecatan. Selanjutnya dilakukan pengukuran kapal untuk mendapatkan ukuran utama dan pembuatan gambar rencana garis dan model kapal 3D. Pada perhitungan tahanan kapal dengan menggunakan motor penggerak Honda GX 160 dengan daya 5,5 HP akan menghasilakan kecepatan 6,325 knot.

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The purpose of this study was conducting a risk assessment of the environment due to the implementation of ballast water management on vessel operations. Environmental risk assessment was based on the pertaining laws and regulations of the government of Indonesia Republic and international laws, as well as the sample comprising vessels operating in Indonesian waters. The data used for the analysis were based on the visits of the vessels operating in the operation territory of Inaport I - Inaport IV. The analysis was carried out based on the number of vessels that unload the ballast water at the port and IMO regulation MEPC 56/23 ANNEX 2. The amount of ballast water unloaded measurement used statistical method to determine the probability of risk occurrence. Using a risk matrix, the ranking of environmental risk due to the implementation of ballast water management would be achieved. In 2016, the numbers of ship visited in International route were 30.843 ships and the assumption was the ships conducted deballasting was 60% from the ship numbers in each time throwing ballast water around 25 tons, so, the total water discharged was 450.000 tons.