Coastal Navigation Course
Answers to Putting It All Together:
It is 0900 and you have been drift fishing, without much luck, since dawn. You decide to move but, being a conscientious navigator, you fix your position first. You consult your chart and find that you have a variation of 14° W. (Use this variation for all parts of this question.)
- Using your hand-bearing compass, you find the Fl 10sec 74ft 16M HORN at Cleveland East Edge bears 354M. At the same time you find the lookout tower at West Falmouth bears 094M. Your 0900 two bearing fix is 41° 35.5′ N Latitude and 070° 40.5′ W Longitude.
- You set out from this location at 0900 on a course of 345° PSC. Your deviation is 3° W and you are operating at a speed of 5.5 kts. At what time should you have marker R “14” Fl R 2.5 sec broad on your starboard beam? — 0926
What will be its relative bearing at that time? — 090° T
- You continue on this course and at approximately 0920 you notice that you have marker R “12” Fl R broad off your starboard bow. What might this mean? — You are being slowed and pushed south by current.
- At 0950 you get a GPS fix that puts you at 41° 38.0′ N and 070° 45.0′ W. What was the set and drift that you experienced that put you at this location? Set: 214° T Drift: 1.9 kts
- From this new position, and at the same speed, you want to make good a course of 056° T. Your deviation is 3° E. Not yet taking into consideration set and drift, what course PSC would you steer? — 067° C
- Applying the set and drift found above, what would be your estimated position at 1015?
Latitude 41° 38.7′ N Longitude 070° 43.0′ WSince this estimated position seems to be putting you back where you should have been at approximately 0940 this morning, it would appear that if you do nothing to correct your course you will be going in circles or perhaps worse “back in time!”
- What is the True course necessary to steer to make good your intended course of 067 psc. Deviation is still 3° E?
CTS — 048° T
What will be our SMG? — 3.8 kts SMG
What course psc will we steer? — 059° C
- You give instructions to the helmsperson to correct for set and drift and continue on your intended track. You want to keep out of Cleveland Ledge Channel because of heavy traffic, so you intend to change course when G “13” Bell (located at 41° 40.0′ N) bears 214° relative and the traffic light at Wings Neck bears 070 M. What is the latitude and longitude of this position?
Latitude 41° 40.0′ N Longitude 070° 41.3′ W
What time will you be at this position? — 1044
What is the True direction to G “13” Bell? 270° T*Remember when advancing using set and drift corrections, when asked for an ETA, you will use your speed made good as your speed of advance.
- From this position, you decide to make way for Swift Beach on a course of 340° T. Again ignoring set and drift, you proceed at 4.7 kts and figure you’ll just get a running fix at 1110 to check your progress. At 1110 the Traffic Lt at Wings Neck bears 134° M. Advance your 1044 bearing on the Traffic Lt to find your 1110 running fix. What is the location of your running fix?
Latitude 41° 42.1′ N Longitude 070° 42.7′ W
Should you continue on this course? — NO If not, why not? You are about to run into Grant Hill Point.
- Having narrowly escaped a grounding, you decide to call it a day and head back home to your mooring at West Falmouth Harbor. You want to enter the harbor, between markers G 13 C”1″ and Fl 4sec “2A” at the entrance to the harbor on a course of 110° T. In order to line up your approach, you program into your GPS a position on this approaches’ reciprocal which is 0.5 miles from the entrance markers. What is this position which you will enter as a waypoint? Latitude 41° 36.7′ N Longitude 070° 40.2′ W
- You decide once again to ignore set and drift on the way home and rely on your GPS’s cross track error and autopilot interface to monitor and correct your course. From your 1110 running fix position, at a speed of 6 kts, what direction will you steer PSC (your deviation is 2° W) to get to the waypoint you entered? — 176° C
What is the distance to the waypoint? — 5.7 nm
What is your estimated time enroute (ETE)? — 57 min.
What is your ETA if you left your 1110 running fix location at 1115? — 1212