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MIDDLE LATITUDE SAILING BY INSPECTION

Lat. ship 35° 55'05" N.
Lat. Dia. S. - 35 05 08 N.
Dif. 49'.95 = 49 57 S.

Long. ship — 75° 05' 45" W.
Long. Dia. S. 75 19 38 W.
Dif. 13.9= 13 53 W. ·

Lat. ship
Lat. Dia. S.

35 55 05 N. ·
+ 35 05 08 N.
2)71 00 13

35 30 06 =35° 72 dif. long. 13'.9 dep. 11'.3

Middle lat.

Dif. lat. 49'.95 S; } =Co. S. 13° W. dist. 51'.2
Dep. II.3 W.

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PRACTICAL DEAD RECKONING The traverse table is not used in the practice of navigation, but its use must be learned that more practical means may be used to keep account of a ship’s track.

Usually the following method is not wanted at an examination, but should be used in practice. The former is quite satisfactory so far as the final result is concerned, which is not known until the end of the day. By this the ship's position may be known at any moment. In other words, by one the ship takes the man and by the other the man takes the ship.

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Lat. Cape H.
Dif.
Lat. noon
Dif.
Lat. 4 P.M.
Dif.
Lat. 8 P.M.
Dif.
Lat. Mdt.
Dif.
Lat. 4 A.M.
Dif.
Lat. 8 A.M.
Dif.
Lat. noon
Dif. (current)
Lat. noon

36° 55'.6 N.

Long. Cape H.
_ 4.8 S. = 37° dep. 7'.6 = dif.
36 50.8 N.

Long. noon
_41.05. = 36 dep. 29.3= dif.
36 09.8 N.

Long. 4 P.M.
- 36.5 S. = 36 dep. 30.1 = dif.
35 33.3 N.

Long. 8 P.M.
.8 N. = 36 dep. 9.8= dif.
35 34.1 N.

Long. Mdt.
6.8 S. = 36 dep. 19.0= dif.
35 27.3 N.

Long. 4 A.M.
+ 5.4 N. = 36 dep. 9.2= dif.
35 32 .7 N.

Long. 8 A.M.
-_ 3.5 S. = 36 dep. 11.9= dif.
35 29.2 N.

Long. noon
+ 25.9 N. = 36 dep. 7.7= dif. (current)
35 55.1 N.

Long. noon

76° oo'.4 W.

_ 9.5 E.
75 50.9 W.
-_36.2 E.

75 14.7 W.
- 37.2 E.
74 37.5 W.

12.1 E.
74 25.4 W.
+ 23.5 W.

74 48.9 W.
+_11.4 W.

75 00.3 W.
+_14.7 W.

75 15.0 W.
- 9.5 E.

75 05.5 W.

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The result is two noon positions, the first without considering the current which in the other is taken into account.

The current could be considered on each course, but such a degree of precision is seldom necessary.

The ship's position differs slightly from that found by the preceding method; but is quite near enough to meet the demands of practice.

Lat. Cape H. 36° 55'.6 N. Long. Cape H.
Lat. ship

– 35 55.1 N. Long. ship
Dif. 60'.5= I 00.5 S. Dif.
Mid. lat. 36° dif. long. 54.9 = dep. 44.4

76° 00'.4 W. –75 05.5 W.

54.9 E.

Dif. lat. 60°.5 S.?
Dep. 44 4 E. )

e{

= Co. S. 36° E. dist. 75'.

- 75°05'.5 W. 75 19.6 W.

14.1 W.

Lat. ship

35° 55'.1 N. Long. ship Lat. Dia. S. — 35 05.1 N. Long. Dia. S. Dif.

50.0 S. Dif. Mid. lat. 35° 72 dif. long. 14'.I = dep. II'.5 Dif. lat 50'. S. L.

50. W} = Co. S. 13° W. dist. 51'.3 Dep. 11.5 W. S

The distance being small, middle latitude sailing is used in the last part of this example.

DAY'S WORK Example 2.-A ship had Fire Island light bearing N. N. E. distant 105/10 miles, ship's head S. 12 W. Variation 10° 00' W. Deviations as per table on page 16. Throughout the 24 hours a current set N. E. magnetic and its drift 78 mile per hour. The ship was sailed as follows:

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Find the course and distance made good and the ship's position. From that point find the course and distance to Cape Henry light.

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S.S. W.
E. bv S. 4, s. s. by E. K
S.by W.4 W. S. E.
S. E. & S. S. S. W.

S. 42. W
S. E. by S. w.Ñ. w.

RWBWHww

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76 45
2 30

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32.5

8.7 39.4 36.6 27.9

ly

37.5

1.7 42.5 57.2 12.0

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N. E.

35 00

17.2

32.3 155.0

32.3

188.5
20.5

20.5

I 22.7

168.0

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