This study aims to analyze of tidal in the Eastern Bintan Island waters, including the harmonic constant value, water level elevation and type of tidal. This study used tidal observation data obtained from the Badan Informasi Geospasial (BIG) during 2015-2019. The tidal harmonic constant value is calculated using the Admiralty method, which is one of the harmonic methods that calculates the mean sea level and the sinuoidal function. Admiralty calculations used schemes and tables which are operationalized by Excel software. The water level field observation was carried out in August 2020 with the Tide master instrument. The analysis results obtained 9 harmonic constants which are then used to determine the Formzahl number and water level elevation. Furthermore, the calculation results of harmonic constants and water level elevations are used in tidal forecasting for the next 8 months using Worldtides software. The results showed that the Eastern Bintan Island waters had a tye of Mixed Tide Prevailing Semi Diurnal. Meanwhile, the water level elevation has a

The aim of this research was to investigate the performance of a banana weevil ash catalyst for biodiesel production at varied methanol to oil ratio. The method is the ash catalyst prepared through the simple burning of banana weevil in an open room. The powder is crushed by mortar and calcined at 600 °C for 5 hours. The crystallinity and the morphologies of the powder were analyzed by XRD, SEM, and EDX. The biodiesel production was carried out in a batch reactor for 90 minutes using stirrer at 65 °C. The molar ratio of methanol to oil was varied of 6:1, 8:1, 10:1, 12:1, and 14:1 with catalyst loading of 4.0 wt.%. The results showed that the highest yield was reached 96% at methanol to oil ratios of 12:1. The density and viscosity of biodiesel were reported of 0.85 gr/ml and 3.04 cSt, respectively. The properties of biodiesel showed conformity in the range of SNI standard. Based on these results, it can be concluded that, banana weevil ashes can be a promising heterogeneous catalyst for biodiesel production.