ccga cox 303 navigation and chartwork

7/29/2019 CCGA Cox 303 Navigation and Chartwork

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CANADIAN COAST GUARD AUXILIARY - PACIFIC

NAVIGATION AND

CHARTWORK


February 2012


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Navigation and Chartwork

This powerpoint is not intended to cover this

whole subject.

While it covers the main pertinent points ofthe standard, the candidate is expected to be

already familiar with nautical charts, symbols,

and various methods of obtaining fixes using

visual means, radar and other electronicnavigational aids, as well as the nautical

publications.


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Standard


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Standard

Comprehensive knowledge of charts, chart

symbols and chartwork

Knowledge of bearings, ranges, fixes, runningfixes, set and drift

Compass use

Knowledge and use of nautical publications Navigate in all conditions with due regard for

good seamanship


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Chart Information


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Chart Information

Chart 1 is the publication containing

explanations of the symbols, terms

and abbreviations needed to interpretnautical charts published by the

Canadian Hydrographic Service.

Coxswains must be familiar with this

document.

It is available online.


7/39CANADIAN COAST GUARD AUXILIARY - PACIFIC

Chart Information



Chart Information


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Chart Information


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Standard Chartwork Symbols


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Standard Chartwork Symbols


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Descriptions


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Taking Visual Fixes

Visual fixes with bearing taken at the same

time.

Take bearings on the beam first, and thosedirectly ahead or astern last.

When measuring objects to determine a line

of position, measure first those which have

the greatest rate of change in the quantity

being measured; measure last those which

have the least rate of change in that quantity.


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Dead Reckoning

Fix

1010 DR1030

A method to forecast where the vessel will be,

knowing true course and speed alone

Course 100T @ 30 knots 20 minutes at 30 knots = 10nm


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Estimated Position

Fix

1010 EP1030

A method to forecast where the vessel will be,

knowing true course and speed, set and drift

Course 100T @ 30 knots 20 minutes at 30 knots = 10nm

Set 040T at 6 knots 20 minutes at 6 knots = 2nm


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Allowing for Set and Drift

Fix

1010

A method to maintain the desired track allowing

for set and drift

Set 040T Drift 6 knots

Course to make good 100 T

Speed made good 31.5 knots

Course to steer 115TSpeed 30 knots


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Running Fix

A method to find the vessel with two bearings

off the same object or two different objects


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Running Fix 1

A method to find the vessel with two bearings

off the same object or two different objects

1000 Bearing 1 010T

Course 300T @ 30 knots


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Running Fix 2

Lay off second bearing taken at 1015

1000 Bearing 1 010T


1015 Bearing 2 070T


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Running Fix 3

Lay off course and distance traveled to time of

second bearing

1000 Bearing 1 010T


(7.5nm)

1015 Bearing 2 070T


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Running Fix 4

Move bearing 1 to end of course line and distance

travelled - fix will be where two bearings cross

1000 Bearing 1 010T


1015 Bearing 2 070T

1015


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Running Fix 5

Set and drift can be added to the course and distance

vector, and the transferred bearing line run from that.

1000 Bearing 1 010T


1015 Bearing 2 070T

1015


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Fixes and Cocked Hats


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Compass Work


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Compass Work

Remember that the steering compass

deviation table will only be accurate if:

1. No major alterations of structure or wiringhave been made to the vessel;

2. No metallic objects (walkie talkies, knives,

etc.) have been placed close to the compass;

3. Time - a vessels deviation can change over

time.


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Compass Work

The variation on this

compass rose 021E

(1988 13W). What would the

variation be today?


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Compass Work

What would be the

deviation on a

compass course of315C and a

compass bearing of

000C?

15.75 E 2012


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Compass Work What would be the compass course to steer, if

the true course required was 200T in 2012?

6W


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Compass Work

Remember that the hand bearing compass

will have different deviation from the vessels

steering compass.

180C


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Radar Navigation


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Radar Navigation

The variable range marker (VRM) should be

moved out until it just touches the object to

be measured - that will be the range.


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Radar Navigation

When taking fixes using ranges taken at the

same time, measure objects directly ahead or

astern first, and measure objects closest tothe beam last.

This is different to visual bearings.


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Radar Navigation

Radar ranges off two objects should be as

close to 90 degrees apart as possible, and

with three objects about 60 degrees apart toobtain the greatest accuracy.

Identify points off the chart, before obtaining

radar ranges, NOT the other way around.

Use two or more objects (points of land or

small isolated islands) that can be positively

identified, both on the chart and by the radar.


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Radar Navigation

Racons are receiver/transmitter (R/T)

transponder devices that can be used as a

navigation aid that shows on the radarscreen.

Racons and their identifying Morse mark are

indicated on marine charts.

Measure the range to the racon from the first

dot or dash nearest your own vessel on the

screen.


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Radar Visibility

Sight relies on light waves.

Radar relies on electromagnetic waves.

On our rescue vessels, the horizon for both isnot far

Height of eye or

radar

Distance to

Visual Horizon

Distance to

Radar Horizon

2 metres 3.0 nm 3.1 nm




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Radar Visibility

As such, care needs to be taken when

measuring radar ranges over the radar

horizon, unless the range being measured isa charted vertical face.


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Detection Ranges


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Detection Ranges for Low

Antenna Heights Tankers, bulk carriers, cruise ships 912 nm

Freighters, cargo ships, medium warships 69 nm

Lightships 47 nm Trawlers, coasters, small warships 36 nm

Metal-hulled boats 34 nm

Wood, fiberglass boats with radar reflectors 24 nm

Large sized buoys with reflector 35 nm

Large sized buoys without reflector 23 nm

Medium sized fairway buoys 12 nm

ccga cox 303 navigation and chartwork

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