The speed of the ship and its effect on optimal trim

Abstract

The optimal ship trim produces the least amount of resistance for any given speed and draft. Even a small variation in it would result in a significant variation in resistance and Specific Fuel oil Consumption (SFC- g/kwh) that plays a key role in Ship Energy Efficiency Management Plan (SEEMP). There are several factors that affect the optimum trim of the ship after cargo loading has been disrupted during her passage. These factors include consumption of fuel, environmental dynamics, cargo shifting, speed, and so on. Besides directly affecting the total resistance, speed also affects dynamic trim and sinkage, which change the static trim of a vessel when it is moving. The purpose of this paper is to provide a concise overview of the factors affecting SFC and thereby reducing exhaust emissions. It focuses on the significance of optimal trim as an operating measure, which is influenced by speed through the creation of a pressure field on the hull's surface while in motion. The subject of the investigation is a Handy Max size bulk carrier with a deadweight of 45,193 tons, equipped with a MAN B&W 6S50MC-C7 engine with a Maximum Continuous Rating (MCR) of 9,480 kW at 127 RPM. Using data from the vessel’s General Arrangement and the line plans to form the model of the vessel and then implementing Computational Fluid Dynamics simulations under dynamic conditions. Rhinoceros 7 was followed by Ansys Fluent in the creation of vessel 3D models, then it attempted to analyze the dynamic conditions, at post- processing phase due to limitation in student version, the data from the ship’s manual, the sea trail results and results from similar articles and naval architect book use to analyze. The figures indicate that optimal trim with minimal resistance and consequently lower power demand, resulting in minimum specific fuel consumption, can be achieved when the vessel is near an even keel or have zero static trim when stationary. At an ECO speed, dynamic trim would be approximately 0.5 meters aft.