6926476519

Scientific Journals    Zeszyty Naukowe

Maritime University of Szczecin    '-"(7'.    Akademia Morska w Szczecinie

2010, 20(92) pp. 45-51    2010, 20(92) s. 45-51

Navigational systems employed on gas carriers while approaching terminals

Systemy nawigacyjne stosowane na gazowcach LNG przy podejściach do terminali

Stanisław Gucma¹, Maciej Gucma

Maritime University of Szczecin, Faculty of Navigation, Institute of Marinę Traffic Engineering Akademia Morska w Szczecinie, Wydział Nawigacyjny, Instytut Inżynierii Ruchu Morskiego 70-500 Szczecin, ul. Wały Chrobrego 1-2, e-mail: '[e-mail]

Key words: navigation system. LNG transportation Abstract

Navigational systems employed al LNG terminals assist the navigation of gas carriers along approach chan-nels and in port waters leading to LNG terminals. i.e. in reslricted waters. Tlie na\ igation in restricted waters is often referrcd to as pilot navigation. Tlie term is derived from the fact. that a pilot assists in navigating through restricted areas. and the process of marinę navigation the pilot participates is called pilotage.

Słowa kluczowe: systemy nawigacyjne, transport LNG Abstrakt

Artykuł omawia systemy wspomagania nawigacji na akwenach ograniczonych dla statków LNG. Ten rodzaj nawigacji często jest odnoszony do nawigacji pilotow ej, w której doświadczony ekspert (pilot) znający lokalne warunki asystuje w prowadzeniu statków na akwenie ograniczonym.

Pilot navigation and its tasks

The navigation in restricted waters, due to fast changes in the ship’s position relative to land-based objects, its fix and DR position is not determined on a navigational chart, as is the case when pro-ceeding in open or offshore waters. The ship’s position is established in the mental process of the pilot handling / conducting, and pilot navigation is based on good local knowledge of navigational conditions and their effect on ship’s manoeuvres. At present several pilot navigation systems exist, featuring the ship position display on an electronic chart. This eąuipment enhances the accuracy of the determined position regarded as a point or the vessel’s water-plane [1],

The ship can safely manoeuvre in an area that satisfies the conditions of the reąuired depth. This area, called the available navigable area, and the isobath bounding it, called the safe isobath, is de-fined by this relationship:

h„ = T+A    (1)

where: h_b — safe depth, T — ship’s maximum draught, A - under keel clearance.

The determination of ship’s position in open or offshore areas is identified as the determination of its coordinates (ę>, A), which in fact describe the point of observation. Depending on the method of observation, this point can be the location point of the observer or the antenna of the navigational system in use.

This manner of determining the ship’s position is not sufficient in restricted waters navigation, as the information is not available on ship’s linear parameters: length, breadth and position relative to navigational dangers (safe isobath). Information on the linear parameters is included in ship’s water-plane, but instead of actual / real waterplane position, the pilot is interested in its position relative to a danger (safe isobath). Thus, the determination

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