NAV SOLVING PROBLEM 4 (1-10).ppt

8/13/2019 NAV SOLVING PROBLEM 4 (1-10).ppt

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2/26

1. You are steering 287T, and a ligh t is

picked up dead ahead at a distance of

19.4 miles at 0419. You change course topass the l ight 4 m iles o ff abeam to

starboard . If you are making 13 kno ts,

what is your ETA at the pos i tion 4 m i les

of f the l igh t?

A. 0541

B. 0544

C. 0547

D. 0550


3/26

1. Solu t ion:

Co. 287 Spd. 13 K

0419 Hrs.

b = c - a

b = 19.4 - 4

b = 376.36 - 16

b = 360.36b = 18.98 nm

Dist = Speed x Time

Time = Dist / Speed

Time = 18.98 / 13Time = 1.46 Hrs

Time 1= 0419 Hrs.

Time 2= 0128 Hrs +

ETA = 0547 Hrs .

A

C

B


4/26

2. You are steering 115T, and a ligh t is

picked up dead ahead at a distance of

16.7 miles at 0522. You change course topass the l igh t 3.5 m iles o ff abeam to por t .

If you are making 12 knots , what is you r

ETA at the posi t ion 3.5 miles o ff the l igh t?

A. 0644

B. 0647

C. 0650

D. 0653


5/26

2. Solu t ion:

3.5 nm

Co. 115 Spd. 12 K

0522 Hrs.

Find: ETA 3.5 nm

Abeam of LTHO

b = c - b

b = 16.7 - 3.5

b = 278.89 12.25b = 266.64

b = 16.33 nm

Dist = Speed x Time

Time = Dist / Speed

Time = 16.33 / 12

Time = 1.36 Hrs.Time 1 = 0522 Hrs.

Time 2 = 0122 Hrs +

ETA = 0644 Hrs.

A

C

B


6/26

3. You are underway on course 163T at

a speed of 15.8 kno ts. You sight a buoy

bearing 161T at a radar range o f 5.5m iles at 1319. If you change course at

1325, What is the course to s teer to leave

the buoy abeam to starboard at 1.0 mi le?

A. 145 T

B. 148 T

C. 151 T

D. 171 T


7/26

3. Solu t ion :

1319 Hrs.

1325 Hrs.

Find: Course to Steer


8/26

3. Solu t ion :

Time 1 = 1319

Time 2 = 1325

St. Time = 6 minutes

Dist = Speed x Time

= 15.8 x 0.1

Dis t. = 1.58 nm

New Dist = Old Dist

1.58 nm

New Dist = 5.5 nm1.58 nm

New Dist = 3.92 nm

Sin = Opp / Hyp.

= 1.0 / 3.92

= 0.25510 inv Sin= 14.77

Brg. = 161

= 15 ( - )CTS = 146


9/26

4. You are steaming on a course o f 025T

at 15.5 kno ts . A t 0645H, you observe a

ligh thouse bearin g 059T. At 0655H, thesame ligh thouse bears 075T. What is

your d is tance of f at the second bear ing?

A. 1.5 miles

B. 2.6 miles

C. 4.0 miles

D. 5.3 miles


10/26

4. Solu t ion :

0645 Hrs.

LIGHTHOUSE

0655 Hrs.

A

B

C

D

Find: Dist at 2nd

Bearing


11/26

Co. = 025

1stBrg. = 059 ( - )

< a = 034

< b = 050

< a = 034

( b a ) = 016

AB = Spd x Time /60

AB = 15.5 x 10/60

AB = 2.58 nm

Co. =025

2ndBrg. = 075 ( - )

< b = 050

Time of 1stBrg. = 0645

Time of 2ndBrg.= 0655

Steaming Time = 10 m

BC = AB x Sin


12/26

5. You are s team ing on course 168T at a

speed of 18 knots . A t 1426H, you s igh t a

buoy bearing 144T. A t 1435H you s igh tth e same buoy bearing 116T. What is

your d istance off at the 2nd bear ing and

predicted distance when abeam?

A. 2.3 miles 2nd bearing, 1.8 miles abeam

B. 2.5 miles 2nd bearing, 2.8 miles abeam

C. 2.8 miles 2nd bearing, 1.8 miles abeam

D. 3.3 miles 2nd bearing, 2.8 miles abeam


13/26

5. Solut ion:

1426 Hrs

1435 Hrs.

A

CB

DFind: Dist. At 2nd

Bearing and Predicted

Dist. when Abeam


14/26

Co. = 168

1stBrg. = 144 ( - )

< a = 24

Time of 1stBrg. = 1426

Time of 2ndBrg.= 1435

Steam ing Time = 9 m ins .

AB = Spd x Time / 60

AB = 18 x 9/60

AB = 2.7 nm

Co. = 168

2ndBrg. = 116 ( - )

< b = 52< a = 24

( b a ) = 28

BC = AB x Sin a

Sin (ba )

= 2.7 x Sin 24

Sin 28

BC = 2.33 nmCD = BC x Sin < b

= 2.33 x Sin 52

CD = 1.83 (Dis t Abeam )


15/26

6. Your vessel is s teer in g 143T at 16

kno ts . A t 2147H a lig h t bears 106T and

at 2206H the same ligh t bears 078T.What w i l l be your d istance off abeam?

A. 5.1 miles

B. 5.4 miles C. 5.9 miles

D. 6.5 miles


16/26

6. Solu t ion :

2147 Hrs.

2206 Hrs.

Find: Dist. Abeam

A

B

C

D


17/26

Co. = 143

1stBrg. = 106 ( - )

< a = 37

Time of 1stBrg = 2147

Time of 2ndBrg.=2206

Steam ing Time = 19 min s.

AB = Speed x Time /60

= 16 x 19/60

AB = 5.07 nm

Co. = 143

2ndBrg. = 078 ( - )

< b = 65< a = 37

( b a ) = 28


18/26

BC = AB x Sin < a

Sin ( ba )

BC = 5.07 x Sin 37 Sin 28

BC = 6.50 nm

CD = BC x Sin < b

= 6.50 x Sin 65

CD = 5.89 nm ( Distance Abeam )


19/26

7. A vessel is on a course o f 079T at a

speed o f 18 kno ts. A t 0218H, a l igh thouse

is observed bearing 111T. On what 2ndbear ing must the lighthouse again be

observed so that the distance run

between bear ings is equal to the distance

of f when abeam of the lighthouse?

A. 059 T

B. 064 T

C. 138 T

D. 143 T


20/26

7. Solu t ion :

A

C

D

B

AB = CD

Course = 079 T

1st

Brg. = 111 T ( - )< a = 32

Cot b = Cot a1.0

= Cot 32 -1.0= 1.601.0

= 0.60

b = 59 TT/Co. = 79 T ( + )

2nd = 138 T


21/26

8. Your vessel is on a course 223T at 17

kno ts . A t 1323H, a ligh t bears 318

relat ive. A t 1341H, the same ligh t bears287relativ e. What is your d is tance off the

l igh t at 1341H?

A. 4.3 miles

B. 5.1 miles

C. 6.6 miles

D. 7.8 miles


22/26

8. Solu t ion :1323 Hrs.

Ltho Brg 181

1341 Hrs.

Ltho Brg. 150

Find: Dist of the

Ltho at 1341

AB = Speed x Time

= 17 x 18m / 60

AB = 5.1 nmA

B

C

Co. = 223

1st= 181( - )


23/26

9. Your vessel is on course 312PGC and

you s igh t a l ighthouse dead ahead at a

range of 10 m iles . The gyro erro r is 3E.What course wou ld you s teer to leave the

l ighthouse 1.5 m iles abeam to s tarboard?

A. 309 PGC

B. 304 PGC

C. 309 T

D. 304 T


24/26

9. Solu t ion :

Find: Course to Steer

Sin = Opp / Hyp

= 1.5 / 10

= 0.15 inv Sin

= 8.62

G/Co = 312

= 9 ( - )CTS = 303 PGC


25/26

10. You s igh t a ligh t 9on your starboard

bow at a distance of 21 m i les. Assum ing

you make good you r cou rse, what w i ll beyour d is tance of f the light when abeam?

A. 3.3 miles

B. 3.7 miles

C. 4.0 miles

D. 4.3 miles


26/26

10. Solu t ion :

Light Brg. 009

Dist 21 nm

Find: Dist Abeamof Light

Dist Abeam = Sin Brg. x Dist

= Sin 9 x 21 nm

Dist Abeam = 3.28 nm

NAV SOLVING PROBLEM 4 (1-10).ppt

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