Mercator Sailing Example 1
Home
Flashing Light
Watch Training Workbook
Campus Life
The Joe Show
Deck Skills
Cruise
Navigation
Celestial Nav.
Radar
Meteorology
Ship Structure
Stability
GMDSS
Rules of the Road
Marlinespike
Ship and Cargo Ops.
Shipping Info
FAQs
Shanties and Sea Lore
Terms/Acronyms
World Port/Drink Guide
Forum

L1: 3406'N
L2: 4406'N

λ1: 13045'E

λ2: 13515'E

If you know both the starting and ending positions and are attempting to find the course and distance from one location to the next, as described above, begin by finding the meridional parts (M) for between each of the positions and the equator.
Notice that M for P1 is written as M1, and M for P2 is written as M2.
 
Then find the difference between L1 and L2, l,  in degrees and tenths, and the difference between M1 and M2, m, in minutes of longitude at the equator.
 
The letters in the parenthesis after l and DLo indicate the direction of travel. If moving in a northerly direction, (N) follows l. If moving in a westerly direction, (W) follows the DLo.

L2: 4406'N
M2: 2938.2'

λ2: 13515'E

L1: 3406'N
M1: 2165.8'

λ1: 13045'E

l: 10(N)
m: 772.4'

DLo: 430'(W)

Next, enter the known m value and the known DLo value into the sine and cosine equations to find your course and distance. (See tables at right)

Back To Mercator Sailings

mercator_triangle.jpg

tan C = DLo/m
tan C = 270 / 772.4
C = N 19.3 E
Cn = 019.3 T

cos C = l/D
Cos 19.3 = 600/D
(10 of lat=600nm)
D = 635.72nm