The southern sea of Indonesia faces the open ocean i.e., the Indian Ocean. This provides an initial hypothesis that the location has a ti potential for wave energy throughout the year. The current due to the breaking wave is estimated to have a high velocity. This study focuses on analyzing the velocity of current oceanographic survey due to breaking waves with a case study in Pacitan bay, East Java, Indonesia. The oceanographic survey method uses ADCP and a Current Meter to capture wave and current data sampling with the purpose of the research was for the electrical energy generation near the coast. ADCP is used to record the occurrence of waves and ocean currents before the wave break. The Current Meter is used to record current occurrences after the wave breaks. The instantaneous absolute current velocity, ca, and return current velocity, U, reach a value of 2-3 m/s.

A36 and A53 steels are low carbon steel with relatively similar carbon percentage, respectively 0,25-0,30% and 0,25-0,29%. Both steels are often used within the marine industry. The objective of this research is to figure out the effect of the variation of the groove angle and the heat input to the process of welding two different steel plates towards a metallography, tensile, and bending test with E71T electrode, as well as figuring out the groove angle and heat input to weld 18 mm thick steel plates. The variation of the groove angle used are 55°, 60°, and 70° with heat input variation of 140 and 180 A. Results of this experimental study shows that specimen with groove angle 70° and heat input 180 A with the largest sum of HAZ length, which is 8,4 mm, as well as the largest perlite phase, which are respectively, 67% within A36 base metal, 65% on A36 HAZ, 62% on weld metal,63% on A53 HAZ, and 66% on A53 base metal. The largest open defect value in bending tests is 1.87 mm owned by specimens with groove angle of 55° and heat input of 140 A.

Indonesia has enormous potential in the maritime sector, specifically in the tourism sector. Tourism in Indonesia is developing in several regions. There is one of the tourism destinations in Gresik Regency, that is Dalegan Beach. Dalegan Beach is located in Dalegan Village, Panceng District which has an area of 6.39 km 2 . Dalegan Beach has an area of about 2.3 ha and a beach length of about 180 meters. Dalegan Beach has a potential eco-tourism because of sloping beach topography, calm waves and white sand. However, to develop the Dalegan Beach as an eco-tourism have several obstacles. There are lack of infrastructure to support tourist attractions, unclear collaboration between the village community and the local government, and poor management so that the development of eco-tourism is not optimal. This study aims to improve the management of Dalegan Beach as eco-tourism, which involved all stakeholders include local governments, communities, regional consultative bodies and universities. The Analythic Hierarchy Process (AHP) method is applied on this study in order obtaining an integrated and sustainable beach management formula based on priority scale. There are five factors used for the criteria in this analysis process, those are environmental, economic, social, infrastructure, and legal. Furthermore, the Expert Choice software are used to process inputs gained from the stake holders. The result of analysis indicates the order of alternative priority management that must be carried out namely human resource empowerment of 0.336 or (33.6%), then the development of tourist destinations with a value of 0.256 or (25.6%), further development of tourism marketing of 0.238 or (23.8%) and finally industrial development of 0.170 or (17.0%).

Darrieus turbine has a vertical-axis configuration that is suitable for current from any direction. Placing a circular flow disturbance in front of the turbine can influence the performance. This study wants to investigate the positioning of the flow disturbance to find the best configuration. The study method used numerical simulation with Computational Fluid Dynamics (CFD) software. There are three variations of the cylinder position in front of the turbine with the angle of 0°, 60°, and -60°. As a result, the configuration can improve or disrupt the performance depending on the position installation. In position 0°, the performance was a decrease of 18%. The best performance is at the flow disturbance position of -60°. The maximum coefficient of power (Cp) value of the turbine was 0.19, with increasing of 27%. Therefore, it is recommended to use the position of -60° in front of the turbine.

Scope for of research publications on ocean current energy has increased, resulting in high innovation from ocean energy technology and available models for numerical equations in article publications. Reviews for mapping studies on the development of technology and numerical equations are still rarely carried out. This review refers to articles that use equipment used at sea and are based only on ocean currents for research. From a variety of results of the investigation, it can be expected to be used as material for further studies to find research materials that can be discussed collectively or need to be handled further. The objective of present review study is scanning condition of technology used for analysis and find out the types of numerical equations that are often used in papers in recent years. The result is that various areas of innovation have been investigated in current energy conversion technologies that increase performance and durability and reduce the impact on the environment and have summarised alternative numerical analysis commonly used for current energy conversion technologies.

Recently, harnessing the energy from low wave energy density areas is concerned to deal with renewable energy targets. The previous study proposed a pitch point absorber with a submerged sectional equivalent area as the design parameter. However, that parameter did not suggest the best sectional area and did not directly correlate with the theory of structure hydrodynamic. Thus, this research proposes the diameter-to-draft ratio as a design parameter for the pitch point absorber. The study was conducted numerically using Boundary Element Method software to investigate diffraction characteristics of the device and analyze structure response in irregular waves. The model was modified with five different diameters and ratios. JONSWAP Spectrum was used to generate wave elevation with a 2-m significant wave height and 10-second peak period. The time domain simulation was set at 10.800 seconds. The result of this study showed that the highest responses occurred when the diameter-to-draft ratio was 5 because it has the closest structure natural frequency to assumed wave frequency, which makes it easier to resonate. In all diameters, the higher ratio affects the range of the structure natural frequency getting farther from the assumed wave, so the responses become smaller.