Oct 2023 AM TCN
Q.1) At 0800 a vessel is in position with Bill of Portland bearing 330°(T) distance 4 miles by radar. Find course to steer from 0800 hrs at 12 knots to pass Start point (50° 13.3’N, 003° 38.3’W) 6 miles off when closed. The current in the area is setting 300° at 2 knots and wind is E’ly causing leeway of 2°. Later at 1130 hrs it was found that Start point was abeam of vessel at distance of 5 miles. If leeway was correctly estimated find the actual current experienced by the vessel.
Answer:
CTS – 237°T
Actual Current – 291°T x 2.8 Kts
Q.2) While steering course 270°(T) at 12 knots. Bill of Portland light bore 329°, 000° and 042° at 2250 hrs, 2315 hrs and 2345 hrs respectively. If the current was setting at 3.5 knots, find:
i) SMG
ii) Position at 2250 hrs
iii) Position at 2345 hrs
iv) SET of current.
Answer:
This Question has Two answers – With Favoring Current & With against the Current
Current Against Favoring Current
- SMG – 8.8 Kts SMG – 14.7 Kts
- 2250 Posn – 50°25’N; 002°21.9’W 2250 Posn – 50°20.9’N; 002°18.1’W
- 2345 Posn – 50°26.3’N; 002°34.2’W 2345 Posn – 50°23.1’N; 002°38.8’W
- Set of Current – 067°T Set of Current – 311°T
Q.3) At 2000 hrs in DR position 50° 00’N, 002° 00’W a star sight gave an intercept of 2’ (towards) with an azimuth of 321°(T) on a course of 266°(T). The visibility reduced to 5 miles thereafter. Later on Eastern Channel Light Buoy (49° 59’N, 002° 29’W) was first sighted at 2100 hrs. Current is estimated to set at 151° (T) x 1.5 knots. Find vessel’s position at 2100 hrs. Current is estimated to set at 151° (T) x 1.5 knots. Find Vessel’s position at 2100 hrs and also find CMG and SMG.
Answer:
Eastern Channel Light Buoy:
Geographical Range – 2.095√12+2.095√15 = 15.4M
Nominal Range – 12M
Luminous range – 7.8M
2100 Position: 50°00.6’N; 002°17.1’W
CMG – 259°T / SMG – 11.3 Kts