Development of an algorithm for the prediction of ship resistance using the holtrop-mennen method
Sirin Atikah Safie
Date of Issue2016
School of Mechanical and Aerospace Engineering
The maritime industry has advanced and developed over the years. Now, ships are bigger in size and run faster. Similarly with other engineering division, naval engineering has made speedy progress in areas such as ship design, shipbuilding and ship service. A ship requires power to run through water, and this power is depended on the resistance experienced by water and air, the efficiency of propulsion gear supported and the connection between them. Due to this connection, it is important to take into consideration the hull design and the propulsion gear as a unified structure. In the case of choppy water, complication arises due to elevated resistance and by the propulsion gear running in detrimental circumstances. The ship experiences a driving force formed by the propellers or sails. This driving force is up against resistance, which can be termed as the drag of the vessel. When these forces are in equilibrium, the system is stabilize and the ship runs at a constant speed. To derive the ship’s resistance precisely by straight arithmetic is so complicated that it is not commonly used in ship design. Practically, quite a few methods have been developed to calculate ship resistance. These methods can be classified into: Experimental, Numerical and Empirical. This paper will discuss the relationship between effective power of a ship and resistance encountered at a range of speed. In various sea environments and conditions, the ship will experience different magnitude of resistance thus affecting the effective power. Following that, we will discuss the fluid dynamics aspect when ship is in operation. When in operation, a ship encounter forces from air and water. These fluids have their respective physical properties that affect the resistance of the ship. Next, we will discuss the various types of resistance the ship will experience. The total resistance of a ship consists of residuary resistance and frictional resistance. Residuary resistance is made up of many other components that will be discussed later. The primary discussion of this paper is on the various methods researchers have discovered and formulated to predict a ship’s resistance. These methods are categorized into three: experimental, numerical and empirical. After evaluating the various methods, we will discuss in detail the chosen methodology in finding ship resistance: which is Holtrop-Mennen method that falls under empirical. After analysing and experimenting with the formulae based on Holtrop-Mennen method, we are then able to develop an algorithm using a simple software - Microsoft Office Excel 2013. We are then able to obtain the total resistance of ship and effective power when the ship is in operation. From the results we obtain, it is easier to understand how the ship performs with resistance. When the ship is moving in a high speed, it encounters a higher degree of resistance. Therefore, to overcome this resistance, the ship engine needs to produce a sufficient amount of effective power.
Final Year Project (FYP)
Nanyang Technological University