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129 Cards in this Set
- Front
- Back
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Who controls the use of the 1MC
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OOD
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In a free net, is the NCS relieved of responsibility of maintaining circuit disicipline
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NO
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AR
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out
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proword to cancel a transmission
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Negat
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HF
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High Frequency
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High Frequency
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Long-range circuits
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Dead Reckoning
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the process of estimating your ships future position without taking current and wind into effect
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What does Dead Reckoning help determine (6)
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-when to adjust speed
-when to make a course change -identify landmarks -the effects of wind and current -the validity of the fix -which nav aids to use |
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The 6 rules of Dead Reckoning
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1- at least every hour while in open ocean
2- after every speed change 3- after every course change 4- after plotting a single LOP 5- after every fix or running fix 6- DR out twice after every fix |
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what to use for time-distance-speed calculations (4)
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slide ruler
calculator pre computed tables speed nomogram |
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3 minute rule
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D=Speed * 100
yards |
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6 minute rule
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Distance= Speed/10
nautical miles |
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When do you plot a running fix
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when only one nav aid is available
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the intended direction of travel with respect to the Earth
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Track
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the intended speed to be made good when planning a voyage
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Speed of Advance
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the direction from which the current is flowing
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set
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the speed of the current (knots)
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drift
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the direction of the net movement from one point to another
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Course made good
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the net speed based on the distance and time of passage from one point to another
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Speed made good
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Current Triangle
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takes into account set and drift
-1 vector represents ordered course/speed -other vector represent course and speed made good |
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To calculate SMG
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Speed= Distance/Time
distance between 2 fixes |
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To calculate CMG
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-slide ruler between 1st and 2nd fix and see when direction on compass rose
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to calculate set
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DR to 2nd fix
slide ruler to compass rose |
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to calculate drift
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distance between DR and 2nd fix
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Purpose of estimated position
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to estimate a fix when there are no nav aids available
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the distance gained in the ORIGINAL direction the ship was traveling from the point that the rudder was put over to the point when the ship is steady on the new course
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Advance
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the distance gained PERPINDICULAR TO THE ORIGINAL course from the point where the rudder was put over to the point where the ship is steady on the new course
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Transfer
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Advance and Transfer Table
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different for every ship
measured in degrees True |
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transfer during a 180 degree turn
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Tactical Diameter
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the diameter of the approximate circular path that a ship describes if the rudder is kept over indefinatly
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Final Diameter
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green on chart
parallel to new course |
Slide Bar
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Purpose of the Slide bar
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assists in quickley revising a turn bearing if the vessel is off track just prior to turn
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Steps to plotting Advance and transfer
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1- transfer
2- steadying point 3- advance 4 turn point 5- slide bar 6- turn bearing |
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based upon a visual aid
identifys when the ship needs to turn dotted line |
Turn Bearing
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final leg that the ship must follow to arrive at the center of an anchorage
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approach track
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the bearing to a prominent nav aid which is on the same bearing as the approach track (T/M)
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Head Bearing
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Letting Go Circle
radius |
Distance from the hawsepipe to the pelorus
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Swing Circle
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Length of ship + amount of chain veered out
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Drag Circle
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Amount of chain veered out + distance from hawspipe to the pelorus
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A bearing that marks anchor drop point
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Letting go bearing
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If a ships fix is outside the drag circle, the ship is...
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dragging anchor
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arcs drawn around the anchorage designating distance to the anchorage
100-1000 (100 yd increments) 1200,1500,2000 |
Range Arcs
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PIVA
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Part Integrated Vulnerability Assignment
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Sources of information for an anchorage
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-chart
-experience -passed down files |
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Pre-Anchorage Considerations (6)
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-water depth
-characteristics of the bottom -sufficent nav aids -underwater obstructions -proximity to boat landings -anticipated direction of seas and wind |
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Accurate method for designating anchorages
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bearing and range to a nav aid
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Less accurate method for designating anchorages
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latitude and longitude
GPS |
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Post-Anchorage Considerations (4)
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-enough anchor chain (5-7 times water depth)
-cover chart with acetate over swing and drag circle -selecting nav aids -setting the "Anchor Watch" |
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Is it ideal to head into the wind and current while going to anchor
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YES
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Plotting the anchorage
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1- predict wind/current
2- identify nav aid for head bearing 3- lay approach track 4- plot LGC and center of anchorage 5- plot range arcs 6-nav aid for LGB 7- plot LGB |
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Plotting at anchor
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1- take a fix
2- plot swing and drag circles |
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RADAR
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Radio Detecting and Ranging
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Advantages of Radar (5)
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day,night, poor visibility use
-fixes can be determined at farther distances -calculation of position can be obtained from a single object -can be used to detect heavy precipitation -determine range of object at sea |
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Disadvantages of radar (7)
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electronic and mechanical failure
range and resolution limitations display may be difficult to interpret -less accurate -may not be tactically desirable -small objects may not be detected requires power |
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How is direction calculated using radar
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direction the antenna is pointing
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high frequency + low pulse length =
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high resolution but short range
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Limitations of radar (3)
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blind spots
waves rain |
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transmits outgoing pulses
recieves returning echoes |
Antenna
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produces electromagnetic waves of energy
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Transmitter
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isolates the reciever from the transmitter while permitting them to share the same antenna
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Duplexer
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amplifies the very weak returning echos and demodulates them for display
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reciever
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displays information and provides access to functions
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display
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Uses of Radar (3)
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anti-collision-detects surface contacts
DivTacs-moniter ships position in relation to the guide Navigation |
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transmitter mounted on a nav aid which produces distinctive indications on the radar display within range
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Beacon
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2 types of Beacons
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Racon
Ramark |
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a radar beacon that provides the bearing and range of the nav aid on the radar display of the ship
extended flash or morse code flash |
Racon
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a radar beacon that provides the bearing of the nav aid
appears as a single line from the center of the display to its circumference |
Ramark
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What is minimum range determined by (1)
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pulse length
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What is maximum range determined by (4)
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pulse length
pulse repetition rate peak power frequency |
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Why is max range limited to line of sight
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curvature of the earth
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the minimum difference in bearing between 2 objects at the same range that can be seperated by the radar
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Resolution in bearing
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the minimum difference in range between 2 objects on the same bearing that can be seperated by the radar
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Resolution in range
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Resolution in range is directly related to...
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pulse length
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Resoution in bearing is related to...
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beam width
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3 setting of radar
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gain
rain sea |
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Radar efficiency is extremely affected by...
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rain, gain, sea
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adjustable filter which blocks unwanted radar return from rain
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Rain setting
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adjustable filter which blocks wanted radar return caused by sea clutter
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Sea setting
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adjustable radar input which determines the amplication of signal or video
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Gain setting
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a preplanned bearing line
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EBL (electronic bearing line)
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distance point on an EBL
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VRM (Variable Range marker)
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Purpose of EBL and VRM
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allows radar operator to determine is contact is staying on course
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2 types of Orientations
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Heads/Course Up
North Up |
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North Up orientation
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top is 000
the ship will travel through fixed radar picture |
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Which orientation is preferred for navigation
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North Up
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Heads/ Course up orientation
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top is ships heading
radar picture will rotate around the ship |
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Parts of a Transmission
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Call up
Text Ending Response CTER |
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Hull number/ Ships name
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used in US waters and ports
used on encrypted circuits NOT ON TACTICAL CIRCUIT |
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combination of letters and numbers that identiy a communications facility, organization or individuation on radio net
used in tactical communications change daily |
Call signs
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What is used in foreign ports
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flags
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AS
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wait
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DE
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this is
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R
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roger
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K
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over
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AR
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out
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IMI
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I say again
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IX
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Immediate Execute
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X
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Execute
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XTF
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execute to follow
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BT
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Break
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repeating a transmission
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Say again
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cancel a messgae after being sent
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NEGAT
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Major error
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disregard the transmision
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Minor error
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correction
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Radio checks
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signal strength
readability |
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Signal Strength
LGWVF |
Loud
Good Weak Very Weak Fading |
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Readability
CRUDWI |
Clear
Readable Unreadable Distorted With interference Intermittent |
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stations may transmit without obtaining permission from NCS
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free net
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stations must contact NCS for permission to send a transmission over the net
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directed net
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EMCON
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emission control
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COMSEC
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Communications security
-measures to protect comms to deny info to enemy |
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Defense against interception
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radio silence
electronic silence avoid unnecesary transmission and length of transmission changing frequency use alternative means of communication |
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Circuit discipline
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-prowards
speak slowly and clearly strong voice write down long messages |
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method of speech
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RSVP
rhythm speed volume pitch |
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Circuit logs- continuous receiver watch
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Guard-transmitter ready
Cover-transmitter available Copy-complete log Listen-log optional |
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spell out uncommon words
say each number digit individually use phonitic alphabet |
common practices
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deal with ship itself and provide the means for informing and directing the ship's crew
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internal communications
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External Communications
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Voice Radio Telephone
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Who controls R/T
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-operators on bridge
operators in CIC |
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Purpose of R/T
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pass tactical signals
report sensor information coordinates operation between units |
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Vessels restricted in ability to manuever
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towing
dredging surveying unrep personnel transfer mine clearance launching recoving aircraft |
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Factors of Safe Speed (8)
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Traffic density
background lights visibility # of radar contacts radar performance maneuverability of ship draft wind/sea/current |
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Actions to avoid collision
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positive
ample time course change |
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Right of Way
1) vessels have wind to different sides 2) both vessels have wind on same side 3) vessel with wind to port and vessel with no determination |
vessel with wind to starboard
leeward vessel unknown vesel |
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Head on situation
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alter to starboard
pass port to port vessel traveling with current has right of way |
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Crossing Situation
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vessel with the other vessel on her starboard side shall keep away
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ACtion of the giveway vessel
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early and substanial
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action of the stand on vessel
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maintain course and speed
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Hierachy of Responsibilities
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Not under command
restricted in ability to manuever constrained by draft fishing sailing power driven vessel seaplane |
