Cos AB = Cos P Sin PA Sin PB + Cos PA Cos PB

www.SeamanshipTutor.Com

Chief Mate Navigation – 28th March 2006

Q1

Distance to winter mark = = 1920

1st Leg A to B

A 30° 00.0’N 079° 40.0’ W PA = 60°

B 36° 00.0’N 050° 00.0’ W PB = 54°

D’Long = 29.666° E

Cos AB = Cos P Sin PA Sin PB + Cos PA Cos PB

Cos 29.666 Sin 60 Sin 54 + Cos 60 Cos 54

AB = 25.487°

= 1529.2 nm

2nd Leg B to C

B 36° 00.0’N 050° 00.0’ W PB = 54°

C 40° 00.0’N 040° 00.0’ W PC = 50°

D’Long = 10.0° E

Cos BC = Cos P Sin PB Sin PC + Cos PB Cos PC

Cos 10 Sin 54 Sin 50 + Cos 54 Cos 50

BC = 8.82977°

= 529.8 nm

3rd Leg C to D

C 40° 00.0’N 040° 00.0’ W PC = 50°

D 61° 14.0’N 006° 40.0’ W PD = 28.766°

D’Long = 10.0° E

Cos CD = Cos P Sin PC Sin PD + Cos PC Cos PD

Cos 10 Sin 54 Sin 50 + Cos 54 Cos 50

CD = 29.37°

= 1762.2 nm

AB 1529.2

BC 529.8

CD 1762.2

______

TOTAL 3821.2 nm

______

Q2

Q5

Time: 1022 Target A Target B Target C

Bearing / 174°T, opening slowly / 106°T, closing slowly / 305°T, constant
Range / 3.5 nm, decreasing / 3.5 nm, decreasing / 2.5 nm, decreasing
CPA / 0.35 / 0.45 / Collision
TCPA / 1040 hrs in 18 min / 1104 hrs in 52 min / 1052 hrs in 30 min
BCPA / 254°T / 189°T / Collision
Course / 35°T / 158°T / 125°T
Speed / 7.6 kts / 4.1kts / 12.5 kts
Aspect / R41° / G128° / 00
Action / b) A/C 61° to STBD, 186°T
New CPA / TCPA / d) Target ‘B’ = 0.5nm @1119 hrs/BCPA 010°T

www.SeamanshipTutor.Com