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By: odessa.escartin (42 month(s) ago)

PLease let me download your Lesson 6: lines of position, fixes and dead reckoning. Thank you vey much.

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Lesson 6: Lines of Position, Fixes, and Dead Reckoning: 

Lesson 6: Lines of Position, Fixes, and Dead Reckoning

Slide2: 

Understand Visual and Radar Lines of Position (LOPs) Correctly plot and label fixes Understand the use of radar in piloting Understand the use of danger bearings and correctly plot and label such bearings Know the difference between a fix and an estimated position (EP) and know proper labeling procedures for EPs. Learning Objectives

Lines of Position (LOP’s) : 

Lines of Position (LOP’s) LOP - A single observation that does not establish a fix but does mean that ship’s position is somewhere along that line. Label - After the LOP is drawn from a Navaid, a four digit time must be written above and parallel to the Line of Position.

Slide4: 

Sources of Lines of Position (LOP’s) A visual LOP can be taken, or “shot”, using fixed navigational aids such as tanks, water towers, church steeples, spires, radio and TV towers, daymarkers, fixed navigation lights, flagpoles, or tangents to points of land.

Slide5: 

1000 Light Visual LOP 9 9 9 9 9 9 9 9 9 9 9 5 5 5 5 11 11 11 11 11 11 11 11 6 pa FL 6s 58ft 9M Tank Long Point 20 20 20 20 20 20 21 20 20 20 21 21 21 21 21 23 23 23 23 23 15 15 15 15 17 17 17 17 19 19 19 19

Slide6: 

Light Radar Range LOP or Distance LOP 9 9 9 9 9 9 9 9 9 9 9 5 5 5 5 11 11 11 11 11 11 11 11 6 pa FL 6s 58ft 9M Tank Long Point 20 20 20 20 20 20 21 20 20 20 21 21 21 21 21 21 23 23 23 23 23 23 15 15 15 15 17 17 17 17 19 19 19 19 1500

Slide7: 

0635 070

Slide8: 

Visual Ranges The most accurate type of LOP, when two known objects line up. Some ranges are man made: “intentional” and others are natural: “coincidental.” Only useful at the exact moment the two objects are aligned

Slide9: 

COINCIDENTAL RANGE 1005

Slide10: 

INTENTIONAL RANGE

Slide11: 

0815 LOP 0835 0900 Range Tangent Bearing Distance Arcs 0915

Measurement of LOP’s: 

Measurement of LOP’s Visual Bearings can be measured in: - Degrees Relative ( # # # 0R ) - Degrees Magnetic ( # # # 0M ) - Degrees True ( # # # 0T) Degrees true is almost always used. The navigator must convert any of these types of bearings to True before they can be plotted on the chart.

Plotting and Labeling a Fix : 

Plotting and Labeling a Fix Fix - The point where two or more LOP’s cross. This indicates the ship’s position on the chart. Navy standard is a minimum of 3 LOPs for a fix. Label - Use the four digit time next to the fix, it should be parallel to the bottom of the chart. The times of the individual LOPs are not written on each LOP.

Slide14: 

Light Visual Fix 9 9 9 9 9 9 9 9 9 9 9 5 5 5 5 11 11 11 11 11 11 11 11 6 pa FL 6s 58ft 9M Tank Long Point 20 20 20 20 20 20 21 20 20 20 21 21 21 21 21 21 23 23 23 23 23 23 15 15 15 15 17 17 17 17 19 19 19 19 1000

Slide15: 

12 6 6 6 6 12 12 12 Tank Electronic Fix 1000

Fix Ambiguity: 

Fix Ambiguity Problem - If a large triangle is formed by a 3 LOP fix, mark the center of the triangle as the fix. Danger - If the large triangle is near a hazard then choose the part of the triangle closest to the hazard as your fix.

Slide17: 

SPIRE TWR TANK 1036 1145 wk Visual Fix

Determining the Sequence of Shooting LOP’s: 

Determining the Sequence of Shooting LOP’s Bearing LOP’s - “Shoot” visual bearings that are on the beam first because they change the fastest. Shoot Bearings: “Beam-Bow-Stern” Range LOP’s - “Shoot” radar ranges on the bow/stern first because their range changes fastest. Shoot Ranges: “Bow-Stern-Beam”

Navigational Aid Selection: 

Navigational Aid Selection Choose Nav Aids based on: - Provide the best bearing spread. - Lighted so that Nav Aids can be used in low visibility and day or night. - Easily distinguishable by bearing takers. Example: Which tower?

Dead Reckoning: 

Dead Reckoning - DR is the process of determining a ship’s approximate position by applying, from its last known position, a vector or a series of consecutive vectors representing the true courses steered and the distance run as determined by the ship’s speed and time, without considering the effects of wind and current.

Labeling DRs: 

Labeling DRs Current course is labeled above line Current speed is labeled below the line DR position is labeled with a half-circle. Time is written diagonally. DR is based on fix interval. For example, if you are taking fixes every 15 minutes, your DR will be for 15 minutes.

Six Rules of DR : 

Six Rules of DR

Slide23: 

1. Plot a DR Position Every Hour on the Hour 0900 1000 1100 C-090T S-10

2. Plot a DR Position at Every Course Change: 

2. Plot a DR Position at Every Course Change 1120 1124 1129 C-125 c-090 C-080 C-090T

3. Plot a DR Position at Every Speed Change: 

3. Plot a DR Position at Every Speed Change 0800 0830 0900 S-10 S-15 S-5 0930

4. Plot a DR Position for Every Line of Position (LOP): 

4. Plot a DR Position for Every Line of Position (LOP) Tank 0826 0826 C-020T

5. Plot a DR Position for Every Fix or Running Fix: 

5. Plot a DR Position for Every Fix or Running Fix 0846 37 0937 R-Fix S-10 C-120T 0900

6. Plot a new Course Line with Every Fix or Running Fix: 

6. Plot a new Course Line with Every Fix or Running Fix 0937 R-Fix C-075 S-15 0856 0906 Always DR out two fix intervals

Estimated Position: 

Estimated Position Sometimes impossible to obtain more than one LOP (fog, bad weather, night) Can determine an estimated position (EP) based on limited info available One method: draw a line from your DR perpendicular to your single LOP

Estimated Position: 

Estimated Position tower C-110 S-10 1805 1820 1830 1830 1830 C-070 S-10 Note: A new track is NOT drawn from an EP

The Track: 

The Track A pre-planned DR plot representing intended course and planned speed Laid down by navigator prior to getting underway Label intended course with “TR” Label planned speed with “SOA” Speed of Advance=avg speed which must be maintained during a transit to arrive at destination at the appointed time

Danger Bearings: 

Danger Bearings A pre-determined/pre-plotted bearing to a nav-aid indicating the direction of a hazard to navigation Represented by a “NMT XXX” or “NLT XXX” (no more than, no less than), along with hatch marks in the direction of the danger

Danger Bearings: 

Danger Bearings TR 075 SOA 15 TR 100 SOA 15 Tower Light NMT 082T Shoal NLT 115T Shoal

Slide34: 

Symbol Type Meaning Labeling Fixes Review Fix Fix DR EP Accurate Visual Fix Accurate Fix obtained by electronic means Dead reckon position, advanced from previous fix. Estimated position. Most probable position of ship.

Review Questions: 

Review Questions 1. What are the two types of LOP’s ? 2. How do you label a single LOP ? 3. The most accurate type of LOP is called? 4. Name two ways visual bearings can be measured? And what must they be converted to in order to plot them on the chart? 5. Name the Six rules of DR?

Homework: 

Homework Read pg 138-142 Chapter 8: Section 1: 1-7 Quiz Thursday Lessons 3-5