第1章船舶结构和驾驶台设备.doc

Chapter 1 the Ships Structure and Bridge EquipmentsShips StructureThe foremost part is called the bow and the rearmost part is called stern. When standing in a ship and facing the bow，the left-hand side is called port side and the right-hand side is called the starboard side. All permanent housing above the main deck is known as superstructure. At the fore end is the forecastle. At the after end is the poop.The main part of a ship is the hull. This is the area between the main decks，the sides and the bottom. It is made up of frames covered with plating. The hull is divided up into a number of watertight compartments by decks and bulkheads. Bulkheads are vertical steel walls going across the ship and along. Decks divide the hull horizontally. Those dividing up cargo spaces are known as tween-decks. The hull contains the engine room，cargo space and a number of tanks. In dry cargo ships the cargo space is divided into holds，in liquid cargo ships it is divided into tanks. At the fore end of the hull are the fore-peak tanks and at the after end the after peak tanks. They are used for fresh water and water ballast. The space between the holds and the bottom of the hull contains double bottom tanks. These are used for ballast water and fuel. 第1章 船舶结构和驾驶台设备船舶结构船舶最前部分称为船首，最后部分称为船尾。面向船首站在船上，左手一侧称为左舷，右手一侧称为右舷。主甲板以上的所有永久性结构称为上层建筑。在前端是艏楼。在后部是艉楼。船舶的主要部分是船体。这是主甲板、翼板和船底围成的区域。它是由覆盖有船壳板的肋骨构成的。船体由甲板和舱壁分成许多水密分舱。舱壁是纵横竖直钢质围壁。甲板水平分隔船体。划分货物空间的甲板称为二层甲板。船体包括机舱、货物舱位和一些液体舱。在干货船上，货物舱位被分成货舱，在液货船上货物舱位被分成液货舱。在船体的首端是艏尖舱，尾端是艉尖舱。它们是用于装淡水和压载水的。船体的货舱和船体之间的空间是双层底。它们是用于装压载水和燃料的。(be made up of由构成)(watertight compartment 水密分舱)(the fore-peak tank 艏尖舱)(the after peak tank 艉尖舱)(double bottom tank 双层底舱)The main deck covers the cargo spaces or holds. There are openings cut in the deck，and these openings are the hatches，one to each hold. Ships use either cranes or derricks to lift the cargo into the hold and discharge it. A derrick is simply a strong boom，made of steel or wood，that can swing from side to side. A wire from a powerful winch runs over a block at the head of the derrick. Its quite a simple arrangement. A crane is usually a much more complicated and expensive piece of lifting machinery. But a lot of ships are fitted with cranes. The forecastle on a ship is a small extra deck above the main deck，forward of number one hold，right up in the bows. It carries the anchors and their cables. The windlass is for raising and lowering the anchors. There are the port and starboard cable stoppers on the forecastle. The cable comes up from the cable locker through the spurling pipe，over the gypsy on the windlass，through the stopper and down through the hawse-pipe. Right forward of the forecastle is the jackstaff.The forecastle head is where the chief officer is stationed when the vessel is coming to a berth or a mooring. The second officer is on the poop，ready to look after the stern mooring lines or hawsers. In this way，the two ends of the ship can be secured as precisely and quickly as possible. There is an ensign staff right aft of the poop.There are two open wings of the bridge. They project out to the full width of the ship on each side，port and starboard. In between is the wheelhouse； thats enclosed for protection from the weather. And above the wheelhouse is the standard compass platform， one good magnetic compass is put there as far as possible from the ships magnetic field. And thats the compass they call the “standard”.The standard compass is supposed to have quite a lot less deviation error than the main steering compass. But actually we use a gyrocompass nearly all the time. There are several pairs of mooring bitts and fairlead fitted with rollers along the deck for wires and warps. The roller fairleads can cut down chafe and friction，so the owners are glad to reduce wear and tear，by using roller fairleads all over the place.A traditional general cargo ship has her engine room and bridge superstructure amidships. She may have three holds forward of the bridge and two holds aft of the bridge. Derricks are supported by masts and samson posts. They are sowed fore and aft when the ship is at sea. There are enough lifeboats，on the port and starboard side amidships. A ship is made fast to the quayside by mooring lines. The standard mooring lines consist of headline，forward breast line and forward spring line and stern line，aft breast line and aft spring line. Any of these lines may be doubled. Each line has a large eye spliced in the end. The eye is placed over a bollard on the quayside. If there is another line already on the bollard，the eye of the second line should be taken up through the eye of the first line before placing it over the bollard. This makes it possible for either line to be let go first.Bridge EquipmentAs soon as possible after joining a ship and before taking over the first watch，a watch officer must become familiar with all bridge and associated chart room equipment，its use，operation，capacity，and limitations. Instructions and manuals issued with the equipment must be studied and closely followed. Since models of bridge equipment vary with the manufacture，there are a variety of different operational procedures.The bridge equipment includes：radar；magnetic compass；gyro compass；the radio direction finder；echo sounder；GPS and DGPS；steering gear and the automatic pilot； GMDSS equipments；VHF etc.1. RadarRadar (Radio Direction And Ranging) is a method to determine distance and direction of objects by sending out a beam of microwave radio energy and detecting the returned reflections. The OOW must keep in mind that radar is more accurate as a ranging device than as a bearing device. Radar is a tremendous advantage both as a navigation aid and as an anticollision device. It can be used in all conditions of visibility，but is particularly useful in poor visibility and at night. Fixes can be obtained rapidly and anticollision solutions can provide tremendous peace of mind to the OOW. Radar can also be used to locate and track squall lines and other heavy weather. In avoiding collisions the importance of visual bearings cannot be overstressed. Visual bearings and radar ranges provide the best early assessment of the possibility of a threat to a vessel. One radar must be on for early detection. A second radar should be on at a close range scale. Range scales must be appropriate for the circumstances. When a pilot is embarked it is important for the OOW to ensure that one radar is available for the pilot and the other is available for the master/OOW. The OOW must be aware of the possibility of shadow sectors due to the ships superstructure. A change of course can unveil these areas for radar detection. No matter how good a radar is，its value as an aid will be entirely dependent upon the person who operate it. The OOW must be fully conversant with the radars capabilities and limitations in order to understand and interpret the radar picture correctly. It is important to carry out radar practice in clear weather whenever possible in order to obtain the confidence and routine that is necessary for proper use of radar in restricted visibility. Information obtained from the radar must be used so that early steps can be taken to prevent any risk of collision from arising. The use of radar does not under any circumstance relieve the navigator of the obligation to maneuver in a seamanlike manner according to the provisions of Rules. As radar become more automated，it will be even more important for watch officers to keep abreast by continuing education and experience in professional practice. 2. GPS and DGPSA global navigation satellite system is a satellite system that provides ships fitted with suitable receivers with a means of obtaining continuous worldwide position，time and speed information. The Global Positioning System (GPS) or Navstar operated by the United States and the Global Navigation Satellite System (GLONASS) operated by the Russian Federation are currently available for civilian use on ships. GPS offers commercial users a global positioning capability with accuracy of the order of 100 metres. Differential GPS (DGPS) receivers apply corrections to raw GPS signals determined and transmitted by terrestrial monitoring stations. Differential signals can be transmitted to ships via satellites or using HF radio links. Within DGPS coverage，positional accuracy of the order of 10 metres at the receiver antenna is possible.3. Echo Sounder (Fathometer)This instrument produces an underwater sound pulse and measures the elapsed time until return of an echo which is received by a microphone. The depth，in feet，meters，or fathoms，is interpreted according to an equation( depth = speed 1/2 time interval between sound pulse and echo) and then displayed on an indicator. Displays include rotary flashing light，electrical meter，digital readout，or bottom profile. Whatever the display，it is essential that the OOW be certain what unit of measure and range is being used. This instrument should be used whenever the ship navigate in waters where the depths make it serviceable and where the safe navigation of the ship requires it.Where the ship carries a depth recorder with an alarm，the echo sounder should be used when navigating in narrow waters and in all other circumstances where the depth of water makes it a useful aid that may increase the safe navigation of the ship.The echo sounder is not used to its maximum capability aboard the bridges of most merchant vessels. It can be very useful in an approach to port or when making a landfall where there are distinct depth contours，such as the 100-fathom curve，that can give an OOW an excellent line of position (LOP). This LOP can be utilized with a celestial LOP，visual bearing，and/or radar range to provide an excellent fix. In addition，a line of soundings may be used as a aid in determining a vessels position.A precaution in taking soundings：these depths on charts are uncorrected for any variation in salinity，density，or temperature. In addition，the quality of the bottom may indicate a different depth than on the chart. When comparing soundings from the chart with the fathometer，allowance for the height of the tide and the draft of the ship. A similar device is the sonar system，which uses high frequency sound signals. In sonar the sound signal can be sent ahead or sideways. The time for the echo to be sent back from an object，such as an underwater rock，is a measure of the objects distance from the ship. The sonar system can also be used to measure the speed of the ship over the seabed.4. Radio Direction Finding (RDF)Radio direction finding (RDF) systems operate in the upper part of medium frequency(MF) band and the lower part of the high-frequency (HF) band. Shoreside non-directional transmitters and shipboard receivers with direction-sensitive antennas allow radio bearings to be plotted directly on a chart. Since radio waves travel great circles，a correction to the bearing is not necessary if the range is less than 50 miles. A correction，if necessary on a Mercator chart，can be found in formula or graphs.Manual RDF receivers are rotated by hand until the minimum signal (null) of a desired frequency is obtained. A “sense” antenna is used to resolve the ambiguity of a possible 180error. Automatic receivers correct for this 180ambiguity as these direction finders rotate a loop either electronically or mechanically. The OOW must ensure the station is matched with the correct frequency. 5. VHFVHF operate in very high frequency (VHF) band(30 300 MHz). The two most used frequencies can be found on channel 16(156.8 MHz)，international distress，and on channel 13(156.65 MHz)，ship-to-ship or bridge-to-bridge. They are basically line-of-sight frequencies that are limited by the curvature of the earth and the heights of the respective antennae. Officers of the watch must be familiar with VHF procedures and get used to talking on the radio with brevity and clarity. It is a tremendous anticollision device which can give peace of mind to the officers of the watch on vessels that are approaching each other. Masters should encourage OOWs，and even cadets，to use VHF in contacting pilot services and arranging for pilot embarkation. In communicating by voice with other vessels uncertainties can arise over the identification of vessels and the interpretation of messages received. At night，in restricted visibility，or when there are more than two vessels in the vicinity the need for positive identification of the two vessels is essential but this can rarely be guaranteed. Even where positive identification has been achieved there is still the possibility of a misunderstanding between the parties concerned due to language difficulties-however fluent they are in the language being used. An imprecise，or ambiguously expressed，message can have serious consequences. 6. CompassesMagnetic compasses：The magnetic compass is generally fitted above the bridge on the centerline with a periscope so that the compass is readable from the helmsmans position. The deviation of the compasses should be determined after each alteration of course and when a steady course is being steered，at least once on every watch. The result of the determination should be entered in the ships log book as well as the deviation book. A compass deviation card should be maintained and posted on the bridge.Gyro compass： It is recommended that the gyro compass should be run continuously. Should a gyro compass stop for any reason，it should be restarted and subsequently checked before use to ensure it has settled and is reading correctly. Speed and latitude corrections need to be applied to the gyro compass. The gyro will support a number of repeaters，including a repeater at the emergency steering position. Gyro repeaters on the bridge should be checked against the main gyro at least once a watch，and after excessive manoeuvring. Other repeaters should be checked frequently. Magnetic and gyro compass errors should be checked and recorded each watch，where possible，using either azimuth or transit bearings. 7. Steering Gear and AutopilotThe officer on watch (OOW) should ensure that the SOLAS requirements for the operation and testing of the steering gear are observed. Steering control of the ship will comprise manual steering，probably supplemented by an automatic pilot. If an autopilot is fitted，a steering mode selector switch for changing between automatic and manual steering，and a manual override control to allow the OOW to gain instant manual control of the steering，will be required. Whenever the nature of the surrounding waters and weather conditions allows automatic pilot to be done，the automatic pilot should be used. The OOW should bear in mind the necessity to comply at all time with the requirements of SOLAS. The OOW must supervise changes of steering mode from hand to auto and vice versa. Adjustment settings of weather and rudder should be made by the OOW prior to engaging the auto mode. Once in the auto mode the performance of the steering must be monitored closely to see if the settings are having the desired effect，and then fine-tuned as necessary. During this period the helmsman must stand by the helm and assist in the monitoring. When changing from auto to hand steering，the OOW must take into account the need to station the helmsman and to put the steering in manual control in good time to allow any potential situation to be dealt with in a safe manner. Hand steering mode should be used during the first 30 minutes of each watch； in confined waters； in restricted visibility； within 5 miles of other closing vessels，navigation aids，obstructions，etc.；and when other circumstances deem it prudent. Helm orders must be loud and clear and leave the helmsman in no doubt as to what he is required to do. These orders must be repeated in a similar manner by the helmsman. The steering is to be closely monitored at all times to ensure that helm orders are correctly repeated and executed by the helmsman，and the course being steered is the correct one. Close monitoring of the steering is particularly necessary in pilotage waters，and it is the responsibility of the OOW to ensure that the course is being maintained and helm orders are being executed correctly. When operating an autopilot，the course to steer will need to be manually set on the autopilot and the autopilot will steer that course until a new course is entered.8. Course RecorderThe course recorder should show GMT，and when the ship is at sea the position，wind，and weather at noon shall be entered on the recording paper.9. Revolution Per Minute (RPM) IndicatorThe RPM indicator must be monitored by the OOW，particularly in pilotage waters，to ensure that the RPMs desired are answered when maneuvering and maintained when at sea.10. Rate of Turn (R.O.T.) IndicatorThe OOW，in addition to listening to the clicks of a gyrocompass (two clicks for each degree)，should observe the rate of turn indicator during course changes and any time when applying rudder. Knowing how fast a vessel turns with various angles of rudder is a tremendous aid to a shiphandler especially when entering a channel. Most indicators show in tenths of a degree to a maximum 2per second the rate of turn to port and starboard. The rate of increasing or decreasing can be used to advantage by both the OOW and the helmsman. There should be a rate of turn indicator on the bridge in addition to one on the helm. It is important for the OOW to know whether the R.O.T. is calibrated in degrees per minute or degrees per second.11. Doppler Speed LogThis indicator will provide information on lateral motion of the bow and stern and the forward and aft movement in knots，meters，or feet per second. An arrow should also indicate the direction o