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Step
By Step guide to learning Chart work
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How
to do a Set and Drift (Chart work)
(1)
Plot your starting position, call this "A"
(2) Find the true course you are steering.
(3) Draw a line from "A" and lay off your true course.
(4) Call the end of your course "D"
(5) Find the amount of time you have steamed for.
(6) Find your speed.
(7) On the line (A,D) measure the distance you will go in the time
your given. (E.g.) if your going at 10 knots for 3 hours then the
distance is 30 miles so you would measure 30 miles on the (A,D)
line.
(8) At the end of the line you steamed for call this "B"
(9) Find out the course and speed of the tide, make sure the hours
your are steaming for and the tide are the same. (E.g.) you steamed
for 3 hours and the tide is set at 0400 2 knots, you would have
to multiply 2 knots by 3 hours which is 6 miles of tide.
(10) At "B" measure off your tide for its course and distance.
(11) At the end of the tide call this "C"
(12) Give the line (B,C) 3 arrows.
(13) From "A" draw a line to "C" this is the
course you will be streaming.
(14) Give the line (A,C) 2 arrows.
(15) The rate of the tide = (B,C) speed of tide
The amount of hours steamed |
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Track
Made good,
the course the tide will take you.
(1)
Plot your start position "A"
(2) Find the true course you are steering.
(3) From "A" draw a line for the true course.
(4) At the end of this line call this "D"
(5) On the (A,D) line measure the distance you will go in 1 hour.
(6) Call this "B"
(7) Find the course and speed of the tide.
(8) From "B" lay of your course of the tide for 1 hour.
(9) Call this "C"
(10) From (A - C) this is the course and speed you will go in
1 hour (Ground track) |
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1
arrow = true course.
2 arrows = the course and speed made good.
3 arrows = speed and course of tide. |
Authors
tip;
Make sure all distances are for 1 hour, some questions gives you
the tide for 1 hour but you're steaming for 6 hours.
Measure the distance covered as well as the course from (A to C) |
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Running
fix (Without tide or wind)
(1)
You are given 2 bearings of a point of land and the times when
they where taken.
(2) Measure these courses off on your chart.
(3) Anywhere on the 1st bearing of the point of land, draw a line
for your true course.
(4) Call the starting position "A" and the end "D"
(5) The time given between the 2 bearings, work out the distance
you will go in that time.
(6) From "A" measure this distance on the (A,D) line.
(7) Call this "B"
(8) Using a parallel rules, lay them on the line from "A"
to the point of land, move the parallel rules onto "B"
(9) Draw a line from "B" along the parallel rules onto
the 2nd bearing of the point of land.
(10) This is your ships position. |
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Running
fix (With tide and/or wind)
(1)
You are given 2 bearings of a point of land and the times when
they where taken.
(2) Measure these courses off on your chart.
(3) Anywhere on the 1st bearing of the point of land, draw a line
for your true course.
(4) Call the starting position "A" and the end "D"
(5) The time given between the 2 bearings, work out the distance
you will go in that time.
(6) From "A" measure this distance on the (A,D) line.
(7) Call this "B"
(8) From "B" lay off the tide for 1 hour.
(9) At the end of the tide call this "C"
(10) Using a parallel rules, lay them on the line from "A"
to the point of land, move the parallel rules onto "C"
(11) Draw a line from "C" along the parallel rules onto
the 2nd bearing of the point of land.
(12) This is your ships position. |
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Counteraction
course
(countering against tide/wind)
(1)
Plot your start position and call this "A"
(2) Plot your finished position and call this "D"
(3) Draw a line from "A" to "D" (This is the
course you want to steer on)
(4) Find the speed and course of the tide.
(5) From "A" lay off the tide for 1 hour.
(6) At the end of the tide, call this "B"
(7) With a set of compasses, measure the distance your vessel
will go in 1 hour.
(8) From "B" cut an arc on the "A" - "D"
line, call this "C"
(9) Draw a line from "A" to "C"
(10) This is your course to steer and speed you make good (speed
you will do)
(11) Measure the line "A" - "D" and the line
"A" - "C"
(12) The time is takes from "A" - "D" = distance
AD
Distance AC |
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Horizontal
and/or vertical Sextant angles.
(1)
Find the positions of the land bearings on a chart.
(2) Draw a line from the 1st to the 2nd to the 3rd positions,
call them "A", "B" and "C"
(3) If the angle is less than 0900 then subtract it from 0900
(4) If the angle is more than 0900 then take the angle and subtract
0900 from it.
(5) If the angle is less than 0900 draw the angle towards the
sea.
(6) If the angle is more than 0900 draw the angle towards the
land.
(7) Using a protractor and the 00 is facing point "B"
is on the line at point "A" mark the degrees.
(8) From point "B" facing "A" mark the degrees.
(9) From point "B" facing "C" mark the degrees.
(10) From point "C" facing "B" mark the degrees.
(11) Where "A" and "B" intersect, using a
set of compasses, measure the distance from the intersection to
"A" and "B" they should both be the same,
draw a circle
(12) Where "B" and "C" intersect, do the same
again.
(13) Where both circles cut this is your ships position. |
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