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Fishing boats are a means of transportation used by fishermen to go to fishing grounds as well as bring home the catch. Most fishing boats in Pantura, East Java Indonesia, still use diesel engines as propulsion. Excessive use of diesel engines can result in air pollution due to exhaust gas particles from the combustion of diesel engines. In order to address this issue, fishing vessels' hulls have been modified or combined with those of Nusantara ships. The reason for choosing the two hulls is that the modified results will be developed into fish boats using sails, so that they require the hull of the Nusantara ship that has sail propulsion. Modifications have been made so that the resistance produced by the hull has been lower. Therefore, the fuel consumption produced is smaller and can reduce exhaust emissions. One model is tested in this study, namely a combination of ship models from the archipelago ship, the Golekan ship with a fishing boat currently operating in the East Java Pantura. Testing of resistance has been carried out by experimental methods in towing tank and numerical method using Maxsurf software. In addition, flow patterns have been also analyzed in this study. The results of the comparative comparison have showed that the resistance tested by the experimental method has been lower than the one tested by using numerical method at a speed of 7-10 knots. Meanwhile, at speeds of 11-12 knots, the resistance tested by the experimental method is higher than the one tested using numerical method. However, the difference is very small. The flow pattern at each speed of the ship is turbulent. The higher the speed of the ship is, the more the Reynolds number increases, so the water flow pattern tends to increase in turbulence. [ABSTRACT FROM AUTHOR]

Dynamic processes in the coastal waters play an important role in regulating the marine pollution distribution caused by riverine inputs and are relevant for coastal management. Here, the coastal water properties were investigated from field measurements and modeling hydrodynamic processes in the northeastern coast of Sumatra. The present study found that the river discharges affect a low salinity of 28–29 psu in the surface waters along near the coastal line. The river discharge might influence by strong La Niña with high rainfall in December 2010. However, the authors suggested that the effect of tidal mixing is stronger than the freshwater discharges, resulting in vertically well-mixed coastal waters in the region. The observed tidal range of 200 cm indicates a strong tidal mixing in the waters. The tidal elevation contributes more than 70% of the total measured sea elevation. The tidal current signal in which the flow pattern simulations show no significant differences among tide and wind-tide driven currents, is also dominant (77%). [ABSTRACT FROM AUTHOR]