Session IV

Measuring

Latitude and Longitude

General Rules

On a chart, LAT/LON is read in: Degrees Minutes Seconds or Tenth’s of a Minute

Set your GPS to read DEGREES – MINTUES - SECONDS

Rules for reading LAT/LON

On a Nautical Chart: Read the Degrees from the

LAT/LON scales. Read the Minutes from the

LAT/LON scales.Measure the Seconds or

Tenth’s of a Minute.

Measuring the Seconds of Latitude.

Step TWO - Stretch the other point of the dividers to nearest Parallel of Latitude.

Step THREE - Without disturbing the opening, move the dividers to the Latitude scale in the left or right margins.

Step FOUR - Read the seconds or tenths of latitude.

1

2

3

4

Step ONE – Place one point of the dividers on the

object or target.

11.0 min.

10.5 min

041 10.7’ N

The LATITUDE SCALE on a Small Scale Chart usually depicts decimal minutes.

Degrees

Minutes

Seconds or Tenths

10.0 min.

041 10’ 42” N

One Minute of

Latitude

equals

One Nautical Mile

DISTANCE

SIXTYSECONDS

OFLATITUDE

ONENAUTICAL

MILE

6 seconds1/10 of a Mile

The Second Scale on a Small Scale Chart

Measuring the Seconds of LongitudeStep ONE - Place one divider point on the object or

target..

Step TWO - Stretch the other point of the dividers back to the nearest meridian of Longitude.

Step THREE - Without disturbing the opening, move the dividers to the Longitude Scale at the top or bottom margin. 1

2

3

4Step FOUR - Read the seconds or tenths of Longitude.

The Longitude Scale

The vertical line from the Bell.

DegreesMinutesSeconds or

Tenths

071 01.4’ W or 071 01’ 24” W

END OF Session IV