Due to its high energy concentration, hydrokinetic energy from tidal and rivers flow provides great expectation. One of the effective ways to meet the energy production target is to reduce the installation and maintenance effort arranging turbines in such configuration, known as hydrokinetic turbine array. The performance of array configuration is affected by turbine position and rotational direction. This research provides a comprehensive analysis of the effect of turbine rotational direction and position on the array performance. The experimental study and URANS simulation were carried out to gain deeper information. This previous study proposed 3 side-by-side configurations, i.e. Co-rotating” (Co), “counter-rotating-in” (CtI) and “counter-rotating-out” (CtO) and the current study proposed 2 multi-row configurations, i.e. 3T-A and 3T-B. The comprehensive information is provided. Both experimental and numerical study confirmed that the velocity superposition in the interaction zone gives the constructive effect on turbine performance. All site-by-site configurations is able to enhance farm effectiveness. Co configuration is recommended to install in the resource having unpredictable flow direction. However, the CtI is for canal or river since it has better performance. The study for multi-row configuration shows that the downstream turbine has performance decrement due to the bad effect of the upstream turbine wake.

Abstract portable dynamic positioning system has not commonly applied to the vessel, especially on barge. Besides for dynamic positioning function, the system can be used as vessel's main propulsion. By using this system, the vessel able to not using anchors because the functions can be performed by the Portable Dynamic System. This research designed the vessels with main dimensions LWL 90.1 meters, 25 meters wide, 5.5 meters high and 4.2 meters draft. To generate the vessel with a maximum speed of 8 knots, it takes four thruster supplied with power 225 kW each, so that the total generated power is 1100 kW. This study analyzes three conditions of the vessel stability, there are the condition of full payload, empty payload, and maximum payload. The first is full payload conditions resulting payload in the amount of 5650 ton with a draft on the LCF at 4,181 meters. The second is the large empty payload condition displacement is 2809 ton and water draft on the LCF at 1,591. And the last is maximum payload conditions, resulting payload in the amount of 7450 ton with a draft on the LCF at 4,994 meters.Keywords flat top barge 300feet, portable dynamic positioning system, thruster, ship stability

⎯ Natuna Sea is one of the places in Indonesia, which has a high potency of fish up to one million ton per year. Fisherman in Indonesia relies too much on the fossil fuel, which has limited resources. The author wants to redesign the fishing vessel into the battery electric fishing vessel that can be recharge to reduce the use of fossil fuel and also to increasing the revenue of the fisherman. To minimize the capacity of the battery, the fishing activities concept is also change into centralized fishing activities which the activities is centralized in an open sea and has the offshore building as the fishing base that has power station to recharge the batteries and cold storage to collect all the fishes. As the object to redesign, it is used 10 GT purse seine fishing vessel. As the results of the calculation, it gets the total battery capacity 6000 Ah for operation 11 hours (4 hours travel time, 6.5 hours fishing activities, and 0.5 hours break). Based on the technical and economic analysis, it can be concluded that the battery electric fishing vessel has a better revenue and fewer expenses than the diesel-powered fishing vessel. Keywords⎯ batteries, electric propulsion systems, fishing vessels, Natuna Sea.

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Energy is an everlasting demand which sustains humanity and its activity throughout the world. The main problem energy for all country is still using fossil energy. Using fossil energy caused pollution and contaminate environment. Adopting Ocean wave energy we can convert the wave into eco-green energy. Wave energy in Indonesia very abundant, it’s coastal line is 95,181 km number 2 in the world after Canada. The device that used to convert ocean wave energy into electrical energy is called WECs (Wave Energy Converters). Latterly, there are many kinds of WECs that already developed by an engineer. Pendulum system is one sample of WECs, its has uncomplicated working principle. Zamrisyaf is The man who first invented the device in 2010. Recently, the researcher still haven’t found the parameter of pontoon geometry that can afford a good sea keeping for this WECs. In this research, the authors has been performed using experimental approach to test the pendulum system. The purpose of this study is to analyze the novel geometry of pontoon that identical to trimaran that can produce a large amplitude of pendulum oscillation through an experimental approach. The analyzed aspect is the combination of outrigger length, outrigger height, pendulum rod length, pendulum mass, and wave periods which have a maximum amplitude of pendulum oscillation. The analysis results show that the better solution is pontoon thus has outrigger height of 40 mm, pendulum rod length of 106.7 mm, outrigger length of 413 mm, pendulum mass of 20, and wave periods of 0.8 s have a maximum amplitude of pendulum oscillation as big as 60 degrees.