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Question From Readers #9: Solving For ETA (estimated time of arrival)

What Is Your ETA? 

AT 0800 zone time, on 15 april, your vessel is heading west in position LAT. 15?10? N, LONG. 165?15? W at a speed of 22 knots. The distance to your destination at LAT. 15?10?N, LONG. 135?15? E is 3600 nautical miles. What is your ETA???ANS: 2339, 22 APRIL

This is a question submitted from someone who is new to this blog. The answer according to his review material is 2339, 22 April. But when I tried to solve it, my answer is 0338H, 22 April. I'm going to show my solution.

Solution:

Step 1. Get the steaming time.

           Time =  Distance
                        Speed
                   =  3600 nm 
                        22 nm/hr
                   = 3600 nm   
                        22 nm /hr
                   = 163.63636 hrs is the steaming time

            163.63636 hr ÷ 24 = 6.81818 days

            0.81818 days x 24 = 19.63632 hrs

              0.63632 hrs x 60 = 38 mins 
                          
             6 days 19 hours 38 mins steaming time

Step 2. Add steaming time to the time of departure. Add because your ship is east-bound.

            15        0800               April
     +       6 day 19 hr  38 min             
            21 day  27hr  38 min   April
           + 1      - 24                              
            22 day  03 hr  38 min  April

Simply put 0338H, 22 April as your ETA

17 comments:

  1. Sir, may i ask why did u add 1 and subtract 24 thankz

    ReplyDelete
  2. I get it now the 24 , imen the add 1

    ReplyDelete
    Replies
    1. There's no such time in your clock as 2738H isn't it? Or shall I say it this way -- 2738H is more than 1 day, right? That's why I subtract 24 hours of it which is equivalent of 1 day. Therefore, I have to add one day to the steaming time.

      I hope this answer satisfies.

      Delete
    2. thankz a lot sir im fully undrstand now sir

      Delete
    3. sorry but you forgot to change you zone time to zulu u have to solve this problem in zulu then change it back to local time

      L to Z Let it be Z to L reverse the spell

      Delete
    4. Sir you forgot to add the arrival ZD which is -9
      And to get the right answer you should reverse the sign ZD to possitive

      Delete
  3. I have another question sir:


    A ship steers the following courses and distances:
    080 T for 42 miles; 201 T for 36 miles
    145 T for 27 miles; 045 T for 45 miles Calculate (using plane sailing) the course and distance made:

    ANSWER: 099 T, 81 miles

    THANKZ...

    ReplyDelete
  4. At 0600 zone time, on 22 october you depart Manila, LAT 14°46.0'N, LONG 118°11.0' W, with an estimated speed of advance at 20.2 knots. The distance is 6,385.9NM. What is the estimated zone time of arrival at Los Angeles? Ans 1008LT, 04 November

    ReplyDelete
    Replies
    1. manila in lies at long East not WEST

      Delete
    2. The answer should be; 3 Nov at 1808H
      There's a 16 hour gap between the two

      ZD= - 8W(LA) - (+8)E (Manila)
      = - 16 H

      Delete
    3. Wrong. Zone descript in west is (+) and east is (-). So the answer 1008LT, 04 NOV is correct.

      Delete
  5. Wrong computation sir. U forgot time local time to utc to local time ✓ right answer is 22 APR 2338

    ReplyDelete
    Replies
    1. this is the right anwer

      Delete
    2. this is correct, but the answer he gave on the question 2339 may be also right, it's just that he added the 1 minute on the zone description. kaya sya nagka ganun. 🤣🤣🤣

      Delete
    3. ni round off na lang

      Delete
  6. sir since the zone description is not given, you will get it by dividing the longitude to /15. Long 165*15*W/ 15 = (+11 W) then you will get the zone description of departure. LONG 135*15*E / 15 = (-9 E) zone description of arrival. after getting the given of both zone description, you will get the same answer with it.

    ReplyDelete
  7. Your answer is wrong. Doing shortcuts? Where are the zone descriptions? +11W -9E. ETA is April 22 @2338

    ReplyDelete