Nautical Charts

7DOCUBENT RESUME

,Ar ED 125 934 ,_ SONI 160

AUTBOR tcCallum, W. F.; Botly, D. B. TITLE Eautical.Charts: Another Dimension in Developing Map Skills. Instructional Activities Series IA/S-11. INSTITUTION National Council for Geographic Education. PUB DATE (75) NOTE, 2Cp.; For related documents, see ED 096 235 and SO 1 009 140-167 AVAILABLE ?RCM NCGE Central Office, 115 North Marion Street, Oak Park, Illinois 60301 ($1.00, secondary set $15.25)

EDRS PRICE 8F-$0.83 Plus Postage. BC Not Available from EDRS. DESCRIPTORS *Classroom Techniques; earth SIence; *Geography Instruction; Illustrations; Knowledge Level; Learning Lctivities; saps; *tap Skills; *Navigation; Oceanokogy; Physical Environment; Physical Geography; Seconda ry Education; *Simulation; Skill Development; Social Studies; Teaching Methods;-, Visual Aids

ABSTPACT These activities are part of a series of 17 teacher- developed instructional activities for geography at the secondary-grade level described in SO 009 140. In theactivities

students develop map skills by learning about and using nautical . charts. The first activity involves stUdents in using parallelrulers and a compass rose to find their hearings. Their ship, Prince Edward, . lies in an anchorage. They must take a bearing of eight otherships and record these bearings in the deck log. In the second activity students use dividers and the latitucle scale to peasure distance. During the class project they lay out courses to.steer and distances to run to bring their ship from one designated position itoanother. In the third activity students learn to interprettle common symbols found on a nautical chart by responding to discussion question g. Activity four is a simulation exercise in which students apply'the skills learned and the knowledge gained'in the first three exerises %by using z-namtical c4a-st- to move their ship from Passage Island to Thunder Bay. Brief explanations, .diagrams; maps, symboldefinitions, and a glossary of terms are provided. (Author/DB) fi 110

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v*" ,I1MtyT5 NAL."' AUIVITIES SERIES IA/S-11

NAUTICAL CHARTS:

ANOTHER DIMENSION IN. DEVELOPING MAP SKILLS 1

W.F. McCallum and D.H. Botly. Associate Professors, Faculty of Education,Lake,head Diversity

Thunder Bay, Ontario ,

Anew and added dimension to the development of map skills can be provided by the use of nautical charts in the geography classroom. The authors provide a sample of activities that might be used to help stu-' dents understand the use of nautical charts and to further the develqp- ment'of selected map skills. Each of the following activities will aid students in achieving competency in a skill or concept identified in the performance objectives that accompany'each activity.

Activity 41 , Using the parallel rulers and compass rose to find bearings.

Activity 42 - Using dividers and the latitude Scale tomeasure distance.

Activity #3 - Interpreting Jhe common symbolsfound on a nautical chart.

Activity'44 Chartwork activities.

The fourth session will have the students apply the skills and knowledge in a simulation ,actiVity using an actual nautical chart.

6Activity 41 USING PARALLEL RULERS- TO LAY OFF BEARINGS Objectives:

, Upon completion of this activity the. student will be able to:

1. express as a true bearing the direction froM one point to

0 another on a nautical chart using parallel rulers and the

compass rose.

s 2

2.Atte parallel rulers With enough dexterity to measure within

2° the actual bearing between two locations identified on a nap.

3. explain each of the following terms and their significance in 1 taking bearings on a nap;

bearing, compass rose, parallel rulers.

BEARINGS'

A bearing is nothing more Wan a direction frdm one point to another and is indicated by a number of degrees from000° (due North) to

359° (1° West of North).

If one is using a magnetic compass rater than a gyro compass, then bearings are usually indicated by readings such N 30° E, S 50° E,

S 15° W,,N 600 V. (See Diag.1): TRUE N MAGNETIC VARIATION NORTH

This diagram is called a "compass rose" 270 90°

7`;'

14°0, "P" Bears 130° (T) or III' \ s:6e E (MY , 4W from "K` , 1 0 ,-, :,. . \v DIAGRAM 1 P . '''' ,

, 4 3

To obtain a true bearing from a magnetic compass onemust make a correction in accordance with the 'variation", which ISthe difference between

. magnetic north and tru north. The amount of variation and the direction of variation east or west of true north depend upon theobserver's gosition on

the face of the earth but the compass rise usually indicates whatthe -traria:.

tion is in that particular region.6 (See diagrah 01) It might be advisatle

to limit thi work of pupils to-the Truetirectiorrs.,

DIAGRAM 2

"B" bears "A" bears I. A o 270from "B" 0900 from "A"

o" It,is obvious'that, if` an observer at' A says rhat "B bears 090 then'an

observer at B would sa4y, "A bears 270°", 090° and270° are called

reciprocal bearings. Pupils must be careful to read the bearing fro

observer to the point of which he is "taking a bearing." (See Diag. 0,2)

The following wall indicate the procedure thAc would be followed

on the bridge of a ship.

(a) The officer on duty tells his assistant to "Take a bearing

of the Trowbridge:Tsland light."

(b) The assistant sights across the top of the ship's compass

through a pairsof sights like those on a rifle and reads

the direction or bearing of the light from the ship.

1 saying, "Trowbridge Island light bears145°".

4 4

,d) The officer lays his parallel rulers acrossthe compass rose oi

on the chart sothat one edge of the ruler'cuts through the

center of the rose and throughthe point on the circumference 4 which ;narks 145°. f (e) The rulers are then moved step-by-step Acrossthe chart until

. , the edge passes through the point onthe.chart which marks.the

f posit ion of Trowbridge Island Liggft

(f) If a line is then drawn along theruler's edge, the officer .

knows that his ship is somewhere onthat line.

To know that one's ship is "somewh4-re'on that line" is rather f 4 3 unsatisfactory as that line may well traverse dan gerous rocks and shoals.

Therefore it is necessary to take beatings of two or more landmarks

(lighthouses,buoys, points of land, etc.) in order to "fix" the ship's ' --.. 1 , position at the point where the lines of bearing intertect.'(See Diagram 03)

Fl R 5 sec. , BLEAK

PT. 315°

"Ship's" position

DIAGRAM 3

5 -4

Activity #1 PRACTICE WITH PARkLLEL RULERS *

nce Eth ard-isyour ship lying in an anchorage. Eig\

other ships are also at anchor. The duty officeron your

1 ship "takes' a bearing"of each of the other shipsand

cords these bearings in his deck-log. Completethe deck-

ldg entries for each s14 (as shown here for the Acton and

4^7,,,;,: bearing 315°

1.7p-1.-cton bearing 020°

:Ziffhal: bearing J Dar: bearing

Exeter bearing

Forester bearing

.3!ranada bearing

Hydra bearing

4 Po

* Students.will need to use the chart on the following page in order to complete this activity.

6S. Vs 4 .1 6 N A ACT/VIT

xB rixto n

Actor,

XDaft

A"1.4 yd r

05.,;-nce Ed e

IWO

''Granada .1 X F °rester

4' xetRr

. (This Chart should be used for a transparency and for reproduction for studerml use.) 7 7

Aciivity #2' 17SINC DIVIDERS b LATITUDE SCALE TO MEASURE DISTANCE

Objectives:

Upon completion of this exercise the studeftt will be able to:

1. measure with95XAccuracy the distance in nautical miles

between two locations on a chart using dividers and the

latitude scale along the sides of the 41trt.

2. expressin degrees and minutes the latitude and longitude

of given points on a nautical cha.rt accurate to the nearest

minute.

3. explain each of the following terms:

anchorage, nautical mile, minute of latitude, knot.

4. express as a true bearing within 20 of accuracy the direction

from one point to another on a ship's course usingparallel

rulers andothe coiopass rose.

DISTANCE EiSPEEDOti A NAUTICAL CHART

Pupils should /he made `aware thatoneIegree oflatitude is equal to 60 nautical miles andthane minute of latitude is, therefore, equal to one nautical mile. (approximately 2,000 yardl)

Since the mariner measures the speed of his ship in nauticalmiles per hour, it is convenient. to use thelatitude scale at the sides of the chart for the measurement of distance.

(Note:, The expressionAnotspet hour" is incorrect as a unit

of speed because the word "knotoP means "nautical miles

per hOur". We therefore bay that "a ship's speed is

10 knots. ") . . To find the distance between "A" and "B" on a chart, place "") one point of a pair of dividers kin "A" andtheother point on "B".

Transfer the dividers to the latitude scale at either side of the chart andread-the number of minutes separating-the points. This / will be the number of miles between "A" and "B".

If "A" and "B" are too far.apart to be spanned by the'dividers, then with the dividers set at.4,converbeent distance (say 3 or 5 miles) /.? mark off this diftance as often aq possible along the line joining

"A" and "B", then measure the remaining segment of "AB" and by addition find the tdtal distance ft= "A" to "B".

(Note: Pupils must not use the scale of longitudea'tthe

top or bottom of the chart'to measure distance for

i, only, at the equator will one minute of longitude be

equivalent to one nautical mile.)

41%

9 ItY 9 .

Activity 02 DIRECTION AND. DISTANCE ON NAUTICAL CHARTS * i 1. Lay out courses to steer and distances to Tun tobring

your ship from her present position"P" to an anchorage,at

"Pii", passing through "Pi", rP2", and "P3". ,

(Disregard tidal stream and currents).

True course Distance

P to P 1

to P 2

P to P 2 3

P to P 3 4

, TOTAL DISTAN6E=

* Studen ts will need to use the chart on thefollowing page in order to complete this activity. ,

r-,

10 '10 . . ACTivir5e46 2

7e co' w #o' 7o 34'

3o' Et.leaatTH rSL. ..

v, ,1,, iti" to \ ) P V! 04 X P, SOuat,IOCKer PT.

A 3Vo olo Po 37c 30NE N 310 36 NO MAU'S 2.1. LAND 280

AV 24o

2+4 (This chart should be used 23, for a transparency and for S 2.0 ceproduction far students' use.) 11 1,0 1/4 I ACTIVITY #3

Oblectives

Upon completion of this activity the student wrlbe able to:

identify with 100% accuracy on nautical chart the symbol& 4ven in the legend bel

SYMBOLS CO NLY FOUND ON NA ICAL 'CHARTS 4-

4 Sythbols Showing Depths of W

...... 1 fathm line (* On haibdur charts the soundings are shown IA feet rather than . 2 fa' hOm line 'fathoms.)

,. ..3 fathom line

fathom line

SymbolsShowing°Subsurface Characterittics: _ shoal with a rqck belotf the surface

a . - +. rock ( sometimes the height of the rock.above,wateris recorded)

robk ) All of those cl or/cy.clay ) describe the type s or S sand ) of bottom g or G gravel )

m or'M mud )

Symtola Showing the CharacteristIcs'of Lights:

R - red ), ) W -white ) Combinations of these will

G - green ) indicate the nacure.of

) the light observed F1.- flashing )

F - fixed )

,) Int.- interrupted ) U - unwatched or unmanned light )

) 20 sec.- flashing intervals , )

12 12

Other Significant Symbols: _ I-., can buoy

n.conical buoy - I 1 spar buoy

common shipping tracks

rock

anchorage

13 of \ Activity '3 CHART SYMBOLS *

1.- Whats the greatest depth of water that a vessel will

encounter on the "track usually followed" from Middlebrun

Channel to the NE corner of Edward Island?

2. Haw deep is the water over Copp Rock which lies It mi. West

Pof Cranberry Is.?

3. If your ship has a draft of 12 feet,'would you consider sailing

between Porphyry Is. and Edward Is.? Give a reason f r your -1 '7 answer.

4. Why is the bay West of Copp Rock marked as an anchorage while

Squaw Bay is not so marked?

5. Compare the underwater slope along the West side of Edward Is.

with the underwater slope off Kidd Pt.

- .

6. At what distance would Point Porphyry Light be visibleona 7

clear night? What is the characteristic of that light?

7. Locate three places whererocks, reefs or shoals would make

navigation hazardous.

Identify one location where the rock shows above water.

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$Activity 114 CHARTWORK

Objectives:

Upon the completion of this simulation exercise the student

will be able to:

1. use parallel rulers and the compass rose on anautical

chart to lay out a course between two points on the chart

with a measurement error of less than three degrees.

2. use parallel rulers and the compass rose tostate within

2° of accuracy the true bearing between two points

4 on a nautical chart.

3. use dividers and the latitudescale to measure the distance

between two points on a nautical chart with 95% accuracy.

4. use the terms nautical mile,minute of latitude, bearing,

anchorage, knot, compass rose, starboard, port correctlyw a. when plotting a course on a nautical chart.

5. identify the following symbols on a nautical chart in

order to make a logiAl decision as to the selectionof

a safe anchorage for a ship:

cl, s, m, --$

-1 6 4 16

CRARWORK - PASSAGE ISLAND TO THMER BAY *

I Your ship; on the regular shipping track, is bound for

)-4, 0 Thunder Say from Sault Ste. Marie. When Passage I

light bears 0316;1/2 mi. to starboard, you alter course

to3106. 1-

(a) What will be the bearing of Passage I light and

Blake Point light when you must alter course to

277°. J 1 (b) What is the distance in nautical miles to

Pt. Porphyry light when it bears0076 1.

A severe SE gale causes you tode4de to run for

shelter in Sawyer Bay (48622!N, 88652'W.) ti

. Lay off acourse to reach Sawyer Bai, as follows:

(a) When Thunder Cape lightsears 020 °, alter

4 course to 3556.

(b) When the south edge of.the entrance to Sawyer 3, Bay bears b74 °, alter course to60

Indicate with an X oil the chart where jou would

anchor your ship. Expliin why you chose this

particular location in the bay.

III (a) When thegale abates, what course would you

steer to reach the North entrance of

Ttrnder By harbour?

*In order to complete this activity students will need to use the chart Passage Island to Thunder Bay which is available from the Canadian HydrogTaphic Survey. If the teacher wishes, another chart can be substituted and a similarworksheet can'be formulated. .. 17 17

III contsd. (b) how fat (in nautical miles) is it

ficp Sawyer Say' to the North entrance?

'(c) If your speed is 6,Lf. knots, when will

you reach the Nerth entrance if you

/ leave Sawyer Bey at 6:00 a.m.?

rule p

18 18

f GLOSSARY

Anchorage - a placei/otected from winds or storms where

ships may lie at anchor in safety.

- a direction from one point to another indicated

by a compass reading.

Fathom , a measure of 6 feet in'depth

Fathom lines - a series of dots or dots and short lines on a chart

connecting pointis of common depth:

Fixed light - alight that shines without fAitshing.

Interrupted Light - a light that is visible only within aparticular

sector of the circle.

hour. . Knot - a measure of speed equal to one nautical mile per

Nautical Mile - a distance equal6) one degree of latitude (approximatey

2000 yards.

Port - the left side when facing forward in aship - (indicated

by a red light)

Shoal - a ridge of rock or sandbelow or close to thesurface

of the water.

Soundings - recorded- depths .of water, usually infathoms but 'often

in feet on harbour charts

Starboird' - the right sidelihen facing forward in aship (indicated z by a green light). Variation - the angular difference betweenmagnetic north and

true north. 19

SOME SUGGESTIONS FROM THE AUTHORS

1. Thause of parallel rulers and dividers in laying off bearings

and in measurin distance can be effectively demonstrated by the

teacher utlliiing transpareties 'of regions of charts and the

appropriate instrument. Stbdents could carry out the activity

on their own copies of the same chart:.region.

2. When using the actual charts all woOk should be done lightly in

pencil so that the markings may be erased.

'3. The activities may be individualized by providing work-cards for

s'S students with accompanying self-correcting materials such as

answer-cards anacetate overlays.

4.' Have students draw cross-section diagrams of the bottom of achannel

or bay as a means of illustrating the significance offathom lines. 11111 ...... --

5. Charts'of the Great Lakes may be obtained from the following sources, .. 1 4 . or from bookstores it part cities:

Canadian charts: Canadian Hydrographic Service Marine Sciences Btanch (approx.$1 - 1.50) 'Dept. of Energy Mines & Resources, 615 Booth Street,'Ottawa, Ont.

U.S. charts: Dept. Of Commerce, National Ocean Survey, Lake SurveyCentre (approx.$1.75 each) 630 Federal Building, U.S. Courthouse DVroit, Michigan 48226

**********