RESEARCH METHODOLOGY
3.1 Introduction
Upon completion of this research, a proper and sequence steps are developed in determining its successfulness. Concerning the earlier objectives and scopes, the research is divided into two parts. The first part of the research is carried out in semester one and the second part of the research is performed in the second semester.
3.2 Research Methodology
As for the first part of the study, the research work began with the understanding and familiarization of the background and conducting literature review on the ship resistance fundamental and theory, methods for predicting ship resistance as well as effect of lateral drift in ship resistance. All those materials of literature review are obtained through several different sources such as books, journals also electronic resources such as e-journal, internet, websites and online materials.
Consequently, with familiarization of research topic, and understanding the related and useful literature, in the second part, the next step is to identify and investigate the suitable parameters or factors in ship resistance prediction that can be correlated with the effect of lateral drift. This approach, will be the main principle of this research. It was decided purposely to get the first insight in relating the ship resistance determination with the effect of lateral drift. At this stage, it mainly will bring to the mathematical modification/ derivation of ship resistance prediction with lateral drift effect. A number of methods for ship resistance prediction will be reviewed and modified to correlate with lateral drift effect. The modified mathematical ship resistance prediction will then be developed in calculation program for further analysis. For this initial investigation, Microsoft Excel and FORTRAN program can be seen capable to be applied for calculation program. From there, the computed results can be analyzed by comparing the resistance performance between with and without lateral drift effect. Also the comparison with lateral drift effect can be investigated between forward speed and lateral speed on ship performance. The flow of the research methodology as described above can be referred to the Figure 3.1.
Figure 3.1: Flowchart of the research methodology
Based on the sequence of flow of the research methodology, it can be summarized that several main activities will be carried out in ensuring objectives and outcomes of this study are successfully achieved. The main activities are:
i. Identifying the applicable and suitable ship resistance prediction method
ii. Familiarizing and specifying the lateral drift condition
iii. Derivation of ship resistance prediction formula with the effect of high speed current and/ or wind
Identifying of Problem Statement
Literature Review
Ship Resistance Theory/ Ship Resistance Prediction
Lateral Drift Effect (River Mouth Area)
Identifying Applicable Ship Resistance Prediction Method
Mathematical Derivation
Calculation Program
Data Gathering/ Data Analysis
iv. Computer Programming Development
All these summarized activities are explained in detail separately in the next Chapters.
In deriving the ship resistance prediction method by taking the lateral drift effects into account, there have two main methodologies that will be used, which are specified as Case 1 and Case 2. The methodologies applied are as follows;
i. Case 1; Effects of Ship Speed
• In this case, the assumption made is the drift effect due to drift angle considerably only has an effect on the ship velocity, VS.
• Due to that, the ship velocity, VS is broke down into two separate components which are longitudinal component, namely as longitudinal ship velocity, VS(L) and lateral component, known as lateral ship velocity, VS(T).
• The detail discussion about Case 1 is explained in the next Chapters, which in Chapter IV and Chapter V.
ii. Case 2; Effects of Ship Speed, Length and Breadth
• In this case, the assumption made is drift effect due to drift angle considerably only has the effect on ship velocity, VS, length, L and breadth, B of the ship.
• Similarly to the Case 1, the ship velocity, VS is broke down into separate components which are longitudinal component, namely as longitudinal ship velocity, VS(L) and lateral component, known as lateral ship velocity, VS(T).
• The ship length, L and breath, B values basically are inverted in lateral component. The explanation for the Case 2 can be referred to the Figure 3.2.
Figure 3.2: Definition of length, L and breadth, B in lateral direction for a laterally drifting ship
Referring to the Figure 3.2, in longitudinal direction, the value of ship length and breadth certainly similar to the original ship coordination. This is because the direction of longitudinal velocity is the same as ship direction without lateral drift effect. In lateral direction, if we consider the direction of lateral speed, then the ship length becomes a ship breadth while the ship breadth becomes a ship length. The different of speed direction cause the changing values between ship length and breadth.
In Case 2, the main problem is due to the unsymmetrical of ship form, which possibly will bring the assumption and results slightly difference.
However, for comparison purpose with the result in Case 1, the result for Case 2 will be analyzed as well. Both detail discussion about the results and analysis will be presented in the Chapter VI later.
Longitudinal velocity, VS (L)
L
B
B
L
Lateral velocity, VS(T)
CHAPTER IV
LATERAL DRIFT EFFECT
4.1 Introduction
In practical, when ship travels in real nature, there have several elements of nature which considerably cannot be neglected and will influence its operation.
These environment elements which acting on the operated ship could contribute to the drift effect, which certainly will influence the ship performance. Before discussing further about the definition of the lateral drift effect, as well as its detail, it is certainly to overview first about the possible causes of lateral drift effect. These causes are essential to be identified in comprehending entirely the lateral drift effect.
4.2 Lateral Drift Factors
When dealing with real nature operation, there are several major factors or sources which can possibly cause a drift effect, depending on the situation. In general, lateral drift effect can be caused by individually or combination of action of following factors;