1. Piloting and Navigation
ABL-10
Piloting and
Navigation
Instructor: George Crowl
This and other plans are for Sea Scout and leaders to teach maritime and leadership skills. They are based on the 2016 Sea Scout Manual and requirements. Some lessons have an accompanying PowerPoint presentation. I consider PowerPoint an introduction the topic, to be followed by hands-on practice. Several lessons will not have PowerPoint, usually because it is my judgement that PowerPoint is not an appropriate aid to teaching that lesson. Lesson plans and presentations will be added and modified when ready.
Each plan and presentation has the rank, requirement number and short name. LP means lesson plan, PPT means PowerPoint. APP means Apprentice, the number is the number of the requirement. ORD = Ordinary. ABL = Able. QM = Quartermaster. There are a few miscellaneous items as well.
I created these lesson plans primarily for the Houston area Sea Scout Academy. However, I hope that they are also useful for other Sea Scout situations and venues. So, I expect everyone using the lesson plans to modify them to fit their audience and their style. There are also other resources in the DVD with the Sea Scout Manual, and on seascout.org.
I invite comments from those that use these lesson plans, so we can have continuous improvement. If you are aware of a better example, or a great illustration that is not in them, please send them to me for inclusion. Especially, if I miss applying a change from the Sea Scout Manual, Guide to Safe Scouting, or a Coast Guard publication, please contact me so we can keep these current and accurate.
You may contact me at or
George Crowl; Skipper, Ship 1996; Sam Houston Area Council

2. Requirements (1)
a. Supervise the proper keeping of a complete deck log for three days of cruising (one cruise or a combination of day cruises). Submit the cruise logs to your Skipper. Or, keep a journal of paddling trips that includes names of participants, access points, waterway description and notable events. Record at least three trips in the journal and submit to your Skipper.

3. Requirements (2)
b. Lay a course of at least three legs and execute it using dead reckoning.
c. Demonstrate your ability to fix your position by the following methods: taking bearings from two known objects, running fix, and estimated position.
d. Establish distance from a known object using “double the angle on the bow” and explain how to set a danger bearing.

4. Requirements (3)
e. Enter three waypoints into an electronic navigation device (i.e. GPS, chartplotter) and navigate your vessel to each point. Demonstrate the use of the MOB function of your electronic navigation device.
f. Discuss how radar is used in situational awareness and the method of taking a radar fix.
g. Explain the use of tide tables, current tables, and light lists, and how to update a chart using the Notice to Mariners

5. Deck Logs
a. Supervise the proper keeping of a complete deck log for three days of cruising (one cruise or a combination of day cruises). Submit the cruise logs to your Skipper. Or, keep a journal of paddling trips that includes names of participants, access points, waterway description and notable events. Record at least three trips in the journal and submit to your Skipper.

6. 10a. Deck Log
The current Sea Scout deck log is excellent. Go over the column headings so the Scouts can relate to their earlier training and apply it. See SSM p. 182 or the SHAC deck log.
Headers Fill out as needed
Crowl recommends that the first few lines be a mission plan. The first line is the departure point, and nothing else is on it. The next line is the first waypoint, and the information is how to get there. You may choose to not put times or ETAs in your mission plan, but you should have ETEs. After the mission plan is made, skip a line, then start logging the observations as they occur as you sail.
Time No navigation occurs without writing down the time of the observation. Observations may include a fix, DR position, hand-bearing LOPs, estimated position, etc.
Position Normally the name of something you take a fix at, such as a marker or buoy. May use a fix or DR or other symbol, or LOP.
Latitude/longitude Not needed if the position above is at an identifiable point, such as a marker. Lat/long is used in open water. N and W may be assumed if appropriate. Normally use DD- MM.M, but if your chart and GPS are in DD-MM-SS, use that.
True Course (or heading, or track).
Var. Variation for this leg only. Whole degrees. Crowl recommends annotate -3E so Scouts remember to subtract east variation (or +15W on Bowditch Bay).
Mag. Magnetic course (or heading, or track), applying variation above as indicated.
Dev. Ship's compass deviation on the magnetic course above. Annotate like variation, i.e. -3E or +15W. Remember, it is different on every heading, you need a deviation table. Leave it blank if unknown, or using a hand-bearing compass.
Comp. Compass course (or heading, or track), applying deviation above as indicated.
Speed Intended speed for mission planning, calculated speed for DR positions, fixes and ETAs.
Distance Measured distance, either to go, or traveled.
ETA Estimated Time of Arrival. May be used in both mission planning and execution. Sometimes it is useful to calculate an ETE (Estimated Time Enroute), note it in Remarks, and use it later during the mission.
Remarks Anything that will help you explain or reconstruct the mission.

7. Paddling Journal Names Access points (in, out, spare) Descriptions
Events
Who, what, why, where, when, and how

8. Paddling Journal Mechanics
3x5 or 4x6 lined notebook
Packed in waterproof container (baggie?)
Accessible so you can write in it easily
Use a pencil (it will get wet, ink will run)
Do as much as you can the day before, or on the way there. Write during each stop. Write after the end.

9. Execute Course Using DR
b. Lay a course of at least three legs and execute it using dead reckoning.

10. 10b. Execute Course Using DR
Plot three legs, totaling about an hour's cruise.
Start and end at identifiable points.
Use a motor-driven boat. Sailboats under sail make this much harder.
A closed course, such as 120°M, 360°M, 240°M is convenient.
Pay attention to speed and heading.
Determine your error at the end.
This is done best under motor. We have often done it at night, because there are fewer distractions. A convenient location is to depart from Clear Creek Channel Marker 2 at a constant speed (4 K) on a course of 120M, proceed for 20 minutes, turn course 360M for 20 minutes, turn course 240M for 20 minutes. Helm is directed to steer the heading, not to turn to likely looking objects. Experience has shown that the average error after the hour is about yards out of 8000 traveled. Sails up, or strong winds, or a current, of course, will affect the results. Where such a triangular course is not available in your location, pick a generally clear area where you can sail for about an hour with three changes of direction, toward a terminal fix to show the youth the accuracy and limitations of DR.

11. Fixing Methods
c. Demonstrate your ability to fix your position by the following methods: taking bearings from two known objects, running fix, and estimated position.

12. 10c(1). Two-Bearing Fix Take bearings using a hand-bearing compass.
Two-bearing fix – This should be practiced on land before doing it on the water. First, show the students how to take hand-bearing compass readings. Have students use available hand-bearing compasses. Hockey pucks are best. This is best done outdoors, where there are objects far enough away that different individuals in the group may sight on the same object and get approximately the same bearing while standing slightly apart. Insure that everyone is getting about the same bearing on several different distant objects. Insure they understand that these are magnetic bearings, uncorrected for deviation (we can’t determine deviation of a hand-bearing compass on a boat).

13. Plan a Fix DR ahead to a good time and place for a fix.
Select someplace with good bearing cuts (90° is ideal, should not be less than 30°).
Select identifiable landmarks (towers, points of land, hill tops, etc.)
Orient yourself so you have the right points.
Second, give the students a short dead reckoning problem, departure time and fix time, planned speed, determine the DR position for fix time. Insure the DR position is correct before proceeding. Have them use their logs to help solve the problem. Announce two magnetic bearings on specific objects that resolve to a fix near the DR position. Have them write the bearings in their log. Solve for the true bearings. Plot the true bearings. Determine the fix. Recalculate position, speed, and new ETA to destination.

14. Execute the Fix Two bearings within a minute
Write the time and bearings down!
Convert to true OR use parallel rules with compass circle
Plot lines
Crossing point is fix
Write the bearings down! Time also. If within about a minute, plot without moving the LOP. Lay a line from the sighting point along the reciprocal of your bearing (you use the bearing, you just plot it backwards). If using a plotter, you must convert to true, if using parallel rules, you may use the mag compass rose. Where the two lines cross is your fix. Compare it with your DR for the same time to insure you did not make a gross error.
Third, do it all again. They will need practice to grasp this. Expect them to plot reciprocal bearings, have trouble lining things up, getting lots of things wrong. Most just don’t do it enough to maintain proficiency.
Finally, take them out on the water to take their bearings.

15. 2-LOP Fix (Line of Position)
Take two bearings
Plot mag bearings backwards OR
Apply variation backwards and plot true bearing backwards
EXERCISE – What do we plot?
SSPR
p. 27

16. 3-Bearing Fix Take 3 mag bearings w/handheld compass
Convert to true using deck log
Plot RECIPROCAL from the actual point
Triangle is your position

17. 10c(2). Running Fix
Often used to establish distance from an object or a shore.
May take a long time.
Take a bearing. Take a second bearing. Advance the 1st bearing to the 2nd bearing.
Running fix – A running fix along a coast establishes your distance from the coast, and can take several hours to execute. However, the principles can be taught in less time in smaller waters such as Galveston Bay. Establish the vessel on a stable heading you can maintain for 10 minutes or so. Take a bearing on an object ahead and off to the side. Record the time and bearing. Plot it. Determine the vessel speed to the best of your ability, maintain that speed. At the end of the 10 minutes, take a second bearing on the object. Plot the bearing and time. You should have more than a 30° bearing change to have a valid running fix. Calculate the distance over ground the vessel has traveled in the time (10 minutes in this case), and move the first bearing along track that distance. Maintain the same angle. Where the adjusted (moved) bearing intersects the second bearing is the fix. The accuracy of this fix is very dependent on a good groundspeed.
GSxT

18. Running Fix Take an initial bearing and time, hold course and speed.
Plot initial bearing. Move it along course for amount of time run.
Plot second bearing. Where they cross is fix.

19. 10c(3). Estimated Position
Normal DR position to start
Add various vectors
Current (set / drift)
Heading / speed error
Single line of position (LOP)
Estimated position – An estimated position is determined by plotting a normal DR position, then correcting it for known errors or a single line of position. If you know your actual speed or heading is different than planned, correct for that. If you know of set/drift corrections, apply them. If you have a single LOP, you can move your position to or close to the LOP. All of these yield an estimated position.
The lesson plan has an extended discussion of the Estimated Position at the end.

20. Set and Drift Set = direction Inbound or outbound tidal flow
Ocean current movement
Drift = speed
Set – SE, drift 3 K Set ENE, drift 5 K

21. Estimated Position (EP)
DR + Set (135°) and Drift (5K)
1445
10K 5K
1345
Track over ground
13K
1445 EP

22. Special Techniques
d. Establish distance from a known object using “double the angle on the bow” and explain how to set a danger bearing.

23. 10d(1). Double the Angle on the Bow
Pick any angle, 15°- 45°. Take first bearing, time.
Double it. Take time of 2nd bearing.
Figure distance traveled from GS.
2nd bearing angle & time is fix. Distance is distance traveled from 1st to 2nd bearing.
(Isosceles triangle)
1) Double the Angle On the Bow (pp )
Double the angle on the bow is a specialized fix. It makes use of the special properties of isosceles triangles, and it also establishes your vessel’s position off a coast.
1. Take a bearing and a time on an object 20 degrees off the bow.
2. Take a second bearing and time on the same object when it is 40 degrees off the bow. (You can use 15/30, 25/50, 30/60, etc. The operation is the same, but the angle must be doubled.)
Plot the bearings, and you will have an isosceles triangle with the leg between the first and second bearing the same length as the leg from the second bearing on the object.
(This method is valuable because it predicts in advance the distance off when abeam.)
GSxT

24. Double the Angle
Take an angle off the bow (22.5°, 30°, 45°), start a time, hold your course and speed.
When you DOUBLE it, stop your time. Calculate distance run.
That is the distance to the object, and the angle from your heading.

25. 10d(2). Danger Bearing Determine the area to avoid.
Plot a line (bearing) that keeps you clear.
If you need to stay on the LEFT of the line, keep your bearing Not Less Than (NLT) the bearing.
If you need to stay on the RIGHT of the line, keep your bearing Not More Than (NMT).
2) Danger Bearing (p. 188)
When planning a sail, you choose a path that will keep your boat in safe waters. Often there are hazards to be avoided. Establishing a danger bearing is a technique used to avoid going into treacherous waters.
When plotting your course, determine the area you need to avoid. Find a landmark or aid to navigation on the chart, and draw a line of position on an angle from the object that avoids the danger area. This establishes a safe area and an unsafe area. If you stay on the correct side of the line while underway, you will be safe.
Measure the bearing of the line and convert it to a compass bearing. If you need to stay to the left of the line, the line should be labeled with NLT (no less than) and the compass bearing. The line is labeled with NMT (no more than) and the compass bearing if you must stay to the right of the line.
When your vessel approaches the danger area, take frequent sightings on the landmark or object you selected earlier. If the hazard lies to port, then any bearing greater than the danger bearing indicates trouble. If the hazard lies to starboard, the opposite applies.
NLT 252M

26. Set a Danger Bearing Determine how close you can go to the danger
Read the bearing, then set the “danger bearing”
Steer between or beyond the bearing
SSPR
p. 23

27. ABL-10e
e. Enter three waypoints into an electronic navigation device (i.e. GPS, chartplotter) and navigate your vessel to each point. Demonstrate the use of the MOB function of your electronic navigation device.

28. Waypoints Waypoints – places you are going along the way!
Marker 2 to Redfish to HSC 69 …
Coordinates, elevation, description (from list?)
GPS provides steering and calculates time to arrival at your current speed
Waypoints are places you want to go, or just to locate yourself in relation to. A waypoint may be Marker 2 on the Clear Lake Channel. If you set in the coordinates of a waypoint, the GPS can calculate the bearing, distance, and ETA to the point. It can tell you if you are off the course between two waypoints.
Students will enter three waypoints in a hand-held or boat-mounted GPS, and direct the boat via the homing function to each of the waypoints. Since each GPS is somewhat different, the instructor will have to teach to the equipment.
069 HSC 69
002 Mkr 2
018 Redfish

29. Entering Waypoints
Enter waypoints from measuring on the chart or from Light List or other references
Light List & inland are DD-MM-SS.SS
Coastal navigation is done is DD-MM.MMM
GPS will accept input in any system, then output in the system you want. Just change the parameters.
This is done best under motor. We have often done it at night, because there are fewer distractions. A convenient location is to depart from Clear Creek Channel Marker 2 at a constant speed (4 K) on a course of 120M, proceed for 20 minutes, turn course 360M for 20 minutes, turn course 240M for 20 minutes. Helm is directed to steer the heading, not to turn to likely looking objects. Experience has shown that the average error after the hour is about yards out of 8000 traveled. Sails up, or strong winds, or a current, of course, will affect the results. Where such a triangular course is not available in your location, pick a generally clear area where you can sail for about an hour with three changes of direction, toward a terminal fix to show the youth the accuracy and limitations of DR.

30. Cross-Checking Entries
You need to have a pre-cleared line on the chart with course, distance and planned speed
Check your GPS has similar course and distance
GPS time (ETE, ETA) is much less reliable, better to figure it manually
Set up your highway screen if you have it
Keep your head out of the cockpit

31. Monitoring the Path Monitor distance off course, correct as needed
Compute manual ETAs to every turn point
Take GPS fixes every minutes, plot them

32. MOB Function
Most newer GPSs and chartplotters have a MOB (man overboard) button.
Push the button and it takes your present position, and gives you steering to go back to it. Don’t try to follow it until you have made the appropriate turn for your situation.
Then look for the steering, steer to stop at the MOB.
Every GPS and chartplotter is different. Even those without MOB have a function to take a position, use it.
Don’t rely on the MOB function, people should have their head out of the cockpit and searching.

33. Exercise! Handout Compass GPS Packet (GPS, Quick Start, Instructions)
We do ded reckoning on land, with a compass and timing our walks
If you are conducting this class without immediate access to a boat and water, we have found it effective to issue a compass and GPS to the students.
In one exercise, they can do ded reckoning on land with a compass and watch (3 MPH walk).
In the second exercise, have them set up their GPS for three or more waypoints, then follow the GPS indications to reach the waypoints.
You will have to invent your own course, it should take less than 30 minutes.

34. ABL-10f
f. Discuss how radar is used in situational awareness and the method of taking a radar fix.

35. Radar Use
FIRST – the primary purpose of sea-borne radar is collision avoidance!
If a bright spot is getting closer to you and not changing bearing, take avoiding action!
Since we don’t have radar sets on most Sea Scout boats, you may have to simulate this by drawing diagrams. Some radar images are available from George Crowl. USPS has a radar seminar that may be useful. Radar fixes may be determined many ways.
First, the primary purpose of sea-borne radar is collision avoidance! If a bright spot is getting closer and not changing bearing, there is a risk of collision! Take avoiding action. It can also be used to help with weather issues.
Radar returns. Radar provides a series of bright spots on the scope that must be interpreted. Water does not reflect, and is generally black. Generally, if you are not moving, ships will be moving spots. Various buoys, towers, platforms, etc., will be stationary blips of varying intensity. Shoreline will normally be a continuous line of undefined objects generally following the mapped shoreline. Some objects, such as power plants, refineries, bridges, etc., will be strong, bright returns. These may be identified by turning down the gain. If you are moving, everything on the scope moves in the opposite direction from your heading.

36. Possible Collisions?
The two on the right between the first and second rings could be collision problems. Neither are classic “unchanging bearing.”

37. Radar Bearings
Radar bearings. Most inexpensive radars are heading oriented, i.e. the radar set displays the bow at the top of the scope (0°). All bearings are relative, measured in degrees. (This illustrates that larger boats may have a radar set stabilized to true north by compass or GPS.) Use the compass heading to determine true heading, then add the relative bearing to derive true bearing to one or more points. You may quickly take a 2-, 3-, or 4-bearing fix using the movable cursor on the radar set. The bearings are then plotted conventionally.
Note that this is actually displaced center, but you may use the circle in the center as the presumed location.

38. Range and Bearing Range and bearing 005°T/2.5NM point of land
Dashed lines
Range and bearing fix. If you are sure you have accurately identified one point, you can take the range and bearing of one point. Plot the reciprocal bearing from the point to your location, and measure the range for an accurate fix.

39. Multiple Ranges Ranges on nearby land shapes
Plot using drawing compass arcs
Radar ranges. Radar sets normally have electronically generated range marks that allow measurement of range, either exactly or by estimating approximately. For instance, the set above is set to 3NM total range and has range marks at ½, 1, 1½, 2, 2½, and 3 NM. You must determine the range mark interval for each range setting, and whether it is in NM, SM, or km. Ranges to an object must be estimated unless it is exactly under a range mark. If your heading stabilization is poor or inaccurate, you make take a multiple-range fix. Take 2, 3 or 4 ranges, then using a drawing compass, draw the range arcs from the points. Where the range arcs cross (these are a kind of LOP), there is your fix. (p. 190, for what it is worth!

40. ABL-10g
Explain the use of tide tables, current tables, light lists, and how to update a chart using the Notice to Mariners. T

41. Tide Tables Apply to coastal areas only, not to inland waters
Tide tables give the time and height of high and low tides at specific locations
Based on astronomical data (the Sun and Moon)
Tides also vary according to the weather, strong northerly winds will push water out of a bay that has a southern entrance. Weather effect is not predicted in tide tables.
s.html
Use the URL to bring up tide tables for your area.
Point out that local weather has a significant effect on many tides.
is the on-line source for tides and currents.
Have the Scouts pull up the site, and select a local tide station. Show how it is related to a specific datum (normally MLLW). Show the regular cycle for your locations, normally driven by the Sun and Moon, but affected by your location (seacoast or bay head, etc.). If possible, select a different location to show how the time and height of high and low tides will be different because water has to travel to those locations, and back out to sea. Note that some stations are “subordinate” stations, they are predicted based on a time difference and tide difference from a master station nearby.

42. Two Tables
Unfortunately, there is no room for labeling. Discuss these points.
The reference, as in most tide tables, is MLLW.
The top tide table is from Morgans Point, Galveston Bay, TX. This point is at the north end of the Bay from Galveston, on the Houston Ship Channel. The tide is predicted to flood to 1.40 feet above MLLW, and ebb to 0.40 feet below MLLW. First low water is at about The next day is very similar, slightly lower high tide, low tide near 0300.
The bottom tide table is the same day, for Clear Lake, a tidal lake off of Galveston Bay, about 7-8 miles southwest. The tide is predicted to flood only 1.00 foot above MLLW, and ebb to 0.40 feet below MLLW. Note the time is one hour later because the water must go through a narrow channel so it is slower rising, slower falling, and less water goes through.
Gulf of Mexico tides are generally of limited range and often “diurnal,” i.e. once a day. East Coast tides have greater range, are “semi- diurnal” (twice a day, about the same height). West Coast tides also have greater range, and are often “mixed semi-diurnal” meaning two highs and two lows, but of significantly different heights.

43. Current Tables
Tides cause currents, especially in restricted waterways
Think: Under the Golden Gate Bridge
Out Bolivar Roads next to Galveston
Minimum flow: near high and low tide times
Maximum flow: midway between high / low times
Not always true, but a good start
Varying depths, varying speeds. Sea Scouts use 6 feet or so, shallower draft.
Tidal currents are not very accurate for two reasons. First is that the position of the sensor is often not directly in the channel because it interferes with channel traffic. Second is that the reading is extremely localized. For instance, in the 40 ft deep Houston Ship Channel there is a current up and down channel with each ebb and flow. However, 100 yards to the side, Galveston Bay is only 10 feet deep for several miles to shore, and the direction and velocity of that water is markedly different than in the HSC.
There are fewer current stations. For instance, in Galveston Bay there are only two current tables, and 14 tide stations. Some current stations will show both the predicted current from astronomical tables, and the actual current being experienced. Currents are shown in knots of ebb (flow out to sea) and flood (flow in from the sea). Each station shows the direction of the current, remember ebb and flow will be opposite. It is possible to have somewhat different ebb and flood directions if not measured in a channel. Have the students examine the tables and charts carefully so they can explain and interpret them.

44. Two Different Currents
6 foot depth, Red Fish Island, Morgans Point, both on Houston Ship Channel, 40' deep channel
Current will not apply in 7' water depth 100 yards west of HSC
Redfish Flood 0.7K 341° Ebb 0.7K 154°
Morgan Pt Flood 0.5K 336° Ebb 0.7K 163° A

45. Calculating Speed Maximum speed is displayed in table
Determine time for maximum speed
Determine time for slack water
At 1/3 of the time from max to slack, speed will be 90% of maximum
At 2/3 of the time from max to slack, speed will be 50% of maximum
Interpolate as needed
Power Squadron Advanced Piloting (AP) teaches the 1/3 rule, flow will be at 90% after 1/3 of the time from maximum current to slack water, then 50% at 2/3 the time, and 0% at slack water.
Both tides and currents are affected by both local weather and offshore weather. In south Texas, a “norther” will push the water out of Galveston Bay, and local tides will be as much as a foot lower than those predicted by astronomical tables. Similarly, both the actual tide and the wind direction and strength will affect the currents in the Bay, especially the Houston Ship Channel, which serves as a funnel to take the Bay's water out into the Gulf.

46. Light Lists
USCG publishes electronically. Google “Light List,” click on your local area
Lists each navigational aid (ATON) that the USCG and private parties maintain.
Unique identifier, lat / long, full description
Coordinates in DDD-MM-SS.SSS
You can put them into your GPS in MM-SS, then switch your base to MM.MMM, the GPS will do the conversion automatically for you
Recommend you get the light list for your cruising area and set up your GPS to include ATONs you use, such as the first ATON in your channel, major ATONs along routes you travel, etc.
is the on-line source for light lists. Have the Scouts pull up the light list for your local area, which is shown on the map by Coast Guard District. Go to the Table of Contents (about p. 9±), find your general location, and go to that page number in the document (not on the scroll bar). Have the Scouts note what information is provided. Have them look up the abbreviations in the front.

47. Sample Light List L
Describe the contents of the light list as you point them out. Reference information, location names, chart numbers, etc.
(1) The light list number – Most have only one reference number.
(2) Name and location – These are typical, and more complex than many lists.
(3) Coordinates – in DDD-MM-SS.SSS N or W. These coordinates are excellent for copying for waypoints.
(4) (Light) Characteristic – note the light characteristics, such as quick green, or flashing green 4 seconds.
(5) Height – in feet, helps determine how far it can be seen.
(6) Range – distance, in nautical miles, it can be seen on a clear night.
(7) Structure – what kind is it? (SG is square green, TR is triangular red, many other abbreviations). Look up in front of light list.
(8) Remarks – Whatever is needed to make it more clear. “Ra ref.” means radar reflector. Notice that how well the light can be seen is identified, some all around, some only 2° along the range line.
The light list number. Unique in the US. Allows instant identification.
Name and location. Usually identified as a light, daybeacon or buoy, with a number where appropriate. A description if it is not exactly on a channel edge.
Position. In degrees, minutes, and seconds (DDD-MM-SS.SSS). Note that you can set up GPSs to accept these coordinates, then change the coordinate system in the GPS to DDD-MM.MMMM and those coordinates will be automatically converted.
Lights will show their characteristics, including red and green.
Height. In feet.
Range. Visible range of the light, in nautical miles.
Structure. How it is built. SG means square green, TR means triangular red.
Remarks. The most common is Ra ref. Means radar reflector. Other comments that may be useful to a mariner.
The light list is particularly useful for entering waypoints into a GPS. If it is a Federal aid, it is very likely spot-on and accurate. Private aids are less likely to be accurately located and maintained. If you see a problem with a navaid, you can report it to your local Coast Guard or your local US Power Squadron, who cooperates with NOAA to keep the Light List current.

48. Local Notice to Mariners
Downloadable from USCG A

49. Notice to Mariners Published weekly by USCG
Identifies changes to Light List, charts, other nautical publications.
Publishes coming changes and activities that affect the water, such as dredging, etc.
Available online, Google “Notice to Mariners” A
is the site for the Local Notice to Mariners. Select your Coast Guard District again. The LNM is updated every week, and is downloadable as a PDF. Section I is introductory information, including the abbreviations. Section II is Discrepancies. Using some of the light numbers in your local area, go to those light numbers, and see which in your area have a discrepancy. For instance, a LNM for the Houston Ship Channel had the following information in bold (indicating this was the first time it was published):

50. Typical Discrepancy Page
Lt # Description Discrepancy Chart St Dt
Go over each column with the Scouts.
Be aware that there a re separate lists for government aids and for private aids, so to check Clear Lake, you need to check two discrepancy lists, then the list of cleared discrepancies.
(1) Light List number
(2) Description
(3) Discrepancy – see page 1 for abbreviations
(4) Chart – such as or 11327
(5) The funny number is the Broadcast Notice to Mariners number, I suggest this is not really important
(6) This is the start date of the discrepancy
(7) There could be an end date, most of these pages do not have one.
For instance, a LNM for the Houston Ship Channel had the following information in bold (indicating this was the first time it was published):
LLNR – Light List Number 24095
Aid Name – Houston Ship Channel Light 44
Status – TRLB/STRUCT DEST (meaning that the structure was destroyed, and has been temporarily replaced by a lighted buoy)
Chart No (is the number of the largest scale chart on which it is shown)
BNM Ref (the Broadcast Notice to Mariners number)
LNM St – (the Local Notice to Mariners in which it is first published)
LNM End – blank (they don't know when they will de-list it)
Other sections in the LNM are:
Temporary Changes
Chart Corrections
Advance Notices
Proposed Changes
General
Light List Corrections

51. To Make Corrections Look at the chart number in each list
Annotate your chart if needed
For instance, if a light has been destroyed, mark it DEST or some way you understand
If a light is back in service, mark OK on chart
Charts are numbered in increasing value.

52. Questions?

53. Bonus Information
The information below is not required for advancement, but is useful for practical point-to- point navigation.

54. Practical Sea Scout Navigation
Memorize mental speed calculations
4 K, 15 min = 1 NM
5 K, 12 min = 1 NM
6 K, 10 min = 1 NM
30 min = 1/2 your speed
20 min = 1/3 your speed
15 min = 1/4 your speed
12 min = 1/5 your speed
10 min = 1/6 your speed
6 min = 1/10 your speed
Experience has shown that the practice missions similar to those taught in the USPS Piloting course and implied in the Sea Scout Ordinary and Able piloting requirements (and SEAL navigation exam) are a necessary basis for practical navigation, but additional coaching underway helps the youthful navigator transition to the practical arena.
Memorize some basic ideas for mental speed calculations:
At 4 knots, 15 minutes speed equals 1 NM traveled.
At 5 knots, 12 minutes speed equals 1 NM traveled.
At 6 knots, 10 minutes speed equals 1 NM traveled.
30 minutes travel equals 1/2 your speed.
20 minutes travel equals 1/3 your speed.
15 minutes travel equals 1/4 your speed.
12 minutes travel equals 1/5 your speed.
10 minutes travel equals 1/6 your speed.
6 minutes travel equals 1/10 your speed.

55. Normal Navigation Monitor average heading and speed
Calculate ETA to turning point
Plan fix about minutes short of TP
Plot DR for that time for orientation
Take fix, plot fix and time
Sailing is a dynamic environment. Groundspeed and heading are changing constantly as the wind, tide and sail trim are changed. Motoring is more stable, but still variable. Navigators must monitor heading and speed to determine an average of each. Navigators can often round speed to the nearest knot or half knot. Sometimes, heading can be rounded to 5°.
After reaching the leg departure point, calculate an estimated time of arrival (ETA) to the leg destination. Pass it to the boatswain. Next calculate and plot the 30-minute dead reckoning (DR) positions for this leg. Next, plan on taking a fix (visual two-bearing) about minutes prior to the destination. This gives time to plot the fix and alter heading to the destination. Mark a rough DR at that point for orienting yourself for fixing.
Take the fix at or near the planned time. Plot it.

56. DR Ahead Measure distance, calculate speed
Extend track line from departure through fix, add 1/10 your speed (speed 4.5K, extend line 0.45NM). This is your DR for 6 minutes later.
This will take some time. Now “DR ahead” by six minutes. Extend your track (per the illustration below) for a distance 1/10 of your groundspeed (see paragraph above). Mark the DR.

57. Alter Heading
Measure course to destination, calculate compass heading, tell bosun / skipper to turn at DR time.
Measure distance, apply speed, calculate ETA, announce it.
From your new DR position, measure true course, calculate mag and compass course. Tell bosun / skipper the new course and the time to turn. Proficient navigators can do this in less than six minutes.
Now, go back, measure the distance, apply the speed on the new course, calculate the ETA, and announce it to the bosun / skipper. This process is surprisingly simple and effective.

58. Remember “The perfect is the enemy of the good.”
A timely approximate solution is better than a late perfect solution.
You can continue to modify a timely approximation.
Remember: “The perfect is the enemy of the good.” A timely approximation is much better than a late perfect solution. If needed, you can improve an approximate answer later. Adjust your timing to your capabilities.
NOTE: For legs longer than about an hour, it is appropriate to take fixes an hour or so apart, correcting to course at each fix.
Instructor note: These will be new concepts to Sea Scouts. Good paper chart exercises (USPS style) are important as a foundation. Sea Scouts will need direct coaching in these procedures for a few legs before they become competent. Suggest the instructor take a GPS fix to compare with the two-bearing fix to analyze errors.

59. Questions?