航海学3期末考试简答题答案

1,Gnomonic chart can be used to design a passage plan of ocean route. Please describe the steps which should be followed when use a gnomonic chart to design a passage plan of ocean route.

①Easy method but is not very exact

②Any great circle appears as a straight line.

③Consulting NP 131, choose corresponding Gnomonic charts.

④Draw a straight line connecting the point of departure and the destination on the chart.

⑤Inspect it to see that it passes clear of all dangers to navigation.

⑥If this requirement is met, the courses are then transferred to a Mercator chart by selecting a number of points along the great circle, determining their latitude and longitude and plotting these points on the Mercator chart.

⑦These points are then connected by straight lines to represent the rhumb line courses to be steered.

2，Gnomonic chart can be used to design a passage plan of ocean route. Please describe the steps which should be followed when use a gnomonic chart to design a passage plan of ocean composite route.

①Refer to relative navigation publications, determine the reasonable limiting latitude φL.

②From the departure A and destination B make the straight lines AM and BN tangent to the limiting latitude, and they are two great circle routes, the line between the two points of tangency M, N is limiting parallel track.

③Determine every rhumb line’s course and distance in the two great circle tracks.

④The course of parallel route course is 090°or 270 °, the distance could be measured in navigational chart.

⑤Make a table using the every rhumb line course and distance for next voyage.

3，The factors to be considered for ocean route choice.

①Meteorological conditions②State of the sea③Obstructions④Fixing and navigable water area conditions⑤Own ship conditions⑥Navigation regulations

4，The notes should be covered during ocean navigation.

①Do not ignore Dead reckoning②Use any resource to fix position③Note the safety problem when approaching shore④Receive and analyze forecast and weather facsimile⑤Receive navigational warning on time ⑥Adjust ship’s mean time (SMT) in time⑦Apply the position plotting charts⑧Select a suitable speed

5，There are four routes are usually chosen while in ocean navigation, please describe them.

①Great circle route②Rhumb line route③Parallel route④Composite route

6，List these factors to determine the safe distance off dangers during coastal navigating.

①The distance and time to a danger calculated from the final precise ship position

②Mapping accuracy near the dangers (high or low)

③Whether there are obvious objects or marks for fixing position or avoiding dangers

④Visibility conditions when transiting the dangers ( day or night)

⑤Winds and currents ( onshore or offshore )

7，The minimum safe depth of water required for passing through shoals may be related to some factors, please describe them.

①draft of departure②reduced draft because of consumption of oil and water (cm) ③changes of mean draft due to the specific gravity of seawater ④Increased draft due to transverse inclination or heel

⑤Squat and trimming effect⑥Height of semiwave ⑦Reserved depth of water

8，List the necessary notes for passing through shallow waters.

①Adjust draft ②Wait the high tide③Control the vessel speed ④Grasp the new information⑤Avoid overtaking and meeting in shallow waters (ship suction)

9，Please list five kinds of piloting methods during navigating in narrow waters.

①Observing buoys 观测浮标导航

②Observing ranges/transits 观测方位叠标导航

③Observing two landmarks at the same ranges 观测距离叠标导航

④Observing the bearing of a leading mark 观测导标位置线导航

⑤Parallel Indexing 平行线导航

10，Please list five kinds of methods of clearing dangers during navigating in narrow waters.

①Danger Bearings (方位避险)

②Danger Ranges （距离避险）

③Horizontal angles （水平角避险）

④Vertical angles （垂直角避险）

⑤Parallel indexing (the same to using Parallel indexing to navigation ) （平行线避险）

11，Some preparations should be made by OOW as soon as possible, prior to navigation in fog. Please describe them.

①acquire precise position (GPS and Paper Charts prior to entering situation), know the dynamic information of surrounding ships.

②Prepare to give appropriate sound signals and reduce speed to safe speed according to COLREG and local regulations;

③Radar/ARPA are in operational condition;

④VHF listening watch is maintained on Ch16 and a proper channel stipulated by local rules;

⑤Assign lookouts properly to look and listen, keep quiet, open bridge doors and intensify watch of surrounding conditions;

⑥Check and change over to manual steering operation;

⑦Report to the master, give engineers notice for stand-by engines;

⑧Switch on navigation lights;

⑨Use the instruments such as ECDIS, AIS, DGPS, etc. prudently.

⑩Consider anchoring if out of shipping lanes;

⑾Any additional instructions from the Master.

12，Some preparations should be made by OOW prior to entry into ice regions. Please describe them.

①Before attempting any passage through ice it is essential to determine the type, thickness, hardness, floe size and concentration of ice

②Ships navigating in ice-covered waters may experience delays and, therefore, should be stored with sufficient fresh-water supplies and manoeuvring fuel.

③Navigation in pack ice after dark should equip high-power searchlights in bow and stern which can be controlled easily from the bridge.

④Prepare enough leak stoppers and protections against the cold, close watertight doors and portholes.

⑤Adopting any effective method to fix precise ship position.

⑥Ships intending to operate in ice should be ballasted and trimmed by the stern slightly

⑦The navigational and communications equipment must be equally reliable

13 Describe main functions of VTS.

14 List 8 kinds of ships reports which are divided and provided by the resolution A.598 (15) of IMO.

15，List four types of topmark used in the IALA Maritime Buoyage System.

can,conical, spherical, and X-shaped.

16，List five types of marks in the IALA Maritime Buoyage System.

①Lateral marks②Cardinal marks③Isolated danger marks④Special marks⑤Safe water marks⑤New danger marks

17，List four colors of lights used in the IALA Maritime Buoyage System.

Red Yellow Green Blue

18, List functions of Catalogue of Admiralty Charts and other Hydrographic Publications(NP 131)

①Select navigational charts

②Select nautical publications

③Check the validity of navigational charts on board

④Get the Admiralty Authorised Chart Agents/ Distributors and ANM supplies

19，List seven publications which published by UKHO.

①Admiralty Notices to Mariners②Admiralty Lists of Lights and Fog Signals③Admiralty Lists of Radio Signals④Admiralty Sailing Directions⑤Admiralty Tide tables⑥Guide to Port Entry⑦Ocean Passage for the World

20，Describe the contents of Admiralty Notices to Mariners.

I Explanatory Notes. Publications List

II Admiralty Notices to Mariners. Updates to Standard Navigational Charts

III Reprints of Radio Navigational Warnings

IV Corrections to Admiralty Sailing Directions

V Corrections to Admiralty Lists of Lights and Fog Signals

VI Corrections to Admiralty Lists of Radio Signals