The size of ships has increased notably over recent decades. The size of harbours and ports has h... more The size of ships has increased notably over recent decades. The size of harbours and ports has however not grown in proportion. As a result ship manoeuvring in harbours and ports has become more problematic, and more of an art than a science. The ‘pivot point’ concept can be useful in analysing slow ship manoeuvring and has therefore been widely adopted by practitioners and training institutions. As a result many practitioners now routinely plan con-fined manoeuvring using the ‘pivot point’ concept. Traditionally the ‘pivot point’ concept has been defined in a number of contradictory and inaccurate ways leading to confusion and mystification. As a result many practitioners and trainers often rely on intuition to bridge the gap between reality and their flawed understanding of theory. In this presentation the theoretical aspect of the pivot point is reviewed and correct definitions put forward and applied to basic and ‘special’ ship’s manoeuvres.
Traditionally, the pivot point of a ship has been defined as the centre of the ship’s rotation. T... more Traditionally, the pivot point of a ship has been defined as the centre of the ship’s rotation. This reduces the ship’s motion to a simple question of surge and yaw. The simplicity of this concept has been very useful in helping to analyse the manoeuvring of a ship, and the term is used extensively in teaching the essential techniques of ship handling. However, as ships have become bigger in size and forced to operate in relatively smaller port or harbour areas, more precise and skilled manoeuvring is needed. The traditional concept of the pivot point is no longer accurate enough for these purposes. In this article the pivot point is regarded as an apparent centre of rotation, taking the centre point at mid-ship as the actual centre of the ship’s yaw motion. A few basic ship manoeuvres are described in the light of this new definition and some frequently encountered manoeuvres which were difficult to explain using the traditional pivot point definition are also discussed.
The concept of the pivot point of a turning ship has been in existence for more than two centurie... more The concept of the pivot point of a turning ship has been in existence for more than two centuries. It was not, how-ever, properly understood from the beginning, and thus some misconceptions developed. This in turn caused it to be viewed as something mystical, thus preventing ship handling from scientific approach. The concept is expound-ed in a fresh light, deriving an equation for the definition and others for the calculation of the pivot point location both in general and for specific examples in an idealized condition. The implications of the derived equations are discussed. The results of a verification experiment are presented, which proved centuries’ of teachings and learnings to have been incorrect. A number of exercises for both steady and unsteady cases have been suggested for the train-ing of the practitioners in the light of these new findings.
The size of ships has increased notably over recent decades. The size of harbours and ports has h... more The size of ships has increased notably over recent decades. The size of harbours and ports has however not grown in proportion. As a result ship manoeuvring in harbours and ports has become more problematic, and more of an art than a science. The ‘pivot point’ concept can be useful in analysing slow ship manoeuvring and has therefore been widely adopted by practitioners and training institutions. As a result many practitioners now routinely plan con-fined manoeuvring using the ‘pivot point’ concept. Traditionally the ‘pivot point’ concept has been defined in a number of contradictory and inaccurate ways leading to confusion and mystification. As a result many practitioners and trainers often rely on intuition to bridge the gap between reality and their flawed understanding of theory. In this presentation the theoretical aspect of the pivot point is reviewed and correct definitions put forward and applied to basic and ‘special’ ship’s manoeuvres.
Traditionally, the pivot point of a ship has been defined as the centre of the ship’s rotation. T... more Traditionally, the pivot point of a ship has been defined as the centre of the ship’s rotation. This reduces the ship’s motion to a simple question of surge and yaw. The simplicity of this concept has been very useful in helping to analyse the manoeuvring of a ship, and the term is used extensively in teaching the essential techniques of ship handling. However, as ships have become bigger in size and forced to operate in relatively smaller port or harbour areas, more precise and skilled manoeuvring is needed. The traditional concept of the pivot point is no longer accurate enough for these purposes. In this article the pivot point is regarded as an apparent centre of rotation, taking the centre point at mid-ship as the actual centre of the ship’s yaw motion. A few basic ship manoeuvres are described in the light of this new definition and some frequently encountered manoeuvres which were difficult to explain using the traditional pivot point definition are also discussed.
The concept of the pivot point of a turning ship has been in existence for more than two centurie... more The concept of the pivot point of a turning ship has been in existence for more than two centuries. It was not, how-ever, properly understood from the beginning, and thus some misconceptions developed. This in turn caused it to be viewed as something mystical, thus preventing ship handling from scientific approach. The concept is expound-ed in a fresh light, deriving an equation for the definition and others for the calculation of the pivot point location both in general and for specific examples in an idealized condition. The implications of the derived equations are discussed. The results of a verification experiment are presented, which proved centuries’ of teachings and learnings to have been incorrect. A number of exercises for both steady and unsteady cases have been suggested for the train-ing of the practitioners in the light of these new findings.
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Papers by Seong-Gi Seo