Welcome to the new FlexRadio Community! Please review the new Community Rules and other important new Community information on the Message Board.
If you are having a problem, please check the Help Center for known solutions.
Need technical support from FlexRadio? It's as simple as Creating a HelpDesk ticket.

A tugboat leaves Capetown...

Logan KE7AZLogan KE7AZ Member ✭✭
It was reported on Thursday that a tugboat is on its way from Capetown to assist the Bouvet DX team's return.  So while you are waiting for your invoice, shipping notice, or delivery of your new FlexRadio, here is a classic brainteaser to pass the time.

A tugboat leaves Capetown to meet a ship that is 1000 miles away when the tugboat leaves.  The tugboat averages 11 knots at sea.  The Bouvet DX team's ship is travelling at 5mph.  The two ships are headed directly toward each other.

1.  How long after leaving Capetown will the tugboat meet the Bouvet DX team's ship?
2.  How far from Capetown will the two ships be when they meet?

Extra Credit
Given that the tugboat can tow the Bouvet DX team's ship at 10 knots, how long after the two ships meet will the Bouvet DX team be able to stand on dry land?

Do you think your new radio will arrive before or after the Bouvet DX Team makes landfall?

Have fun.

Logan, KZ6O


  • Jerry - NG6RJerry - NG6R Member
    edited April 2018
    Assuming 1000 statute miles (not nautical miles),
    1. 2 days, 8 hours, 38 minutes
    2. ~717 miles
    EC: 2 days, 14 hours, 17 minutes
    B: Long time after; I ordered in September!!
  • Bill-N6RVBill-N6RV Member
    edited April 2018
    Assuming distance is in nautical miles and speeds are nm/hr. ( I am not going to convert mi to nm)

    Distance 1000 nm.
    Ship: 5 knots
    Tug: 11 knots
    Closure 16 knots

    Time of Intersection: 62.5 hours, 2.6 Days
    Distance to Intersection 687.5 miles    

    After Two Ships Meet
    Speed: 10 knots
    Arrival: 68.8 hours 2.9 days

    Time Saved
    Ship alone: 200.0 hours, 8.3 days (1000 nm)
    Towed Ship: 131.3 hours, 5.5 days (2.6 days to intersect + 2.9 days back)
    Time Saved 68.8   2.9 days
  • Bill-N6RVBill-N6RV Member
    edited February 2018
    OK ... We are both EX Hughes engineers!
  • Dave - W6OVPDave - W6OVP Member ✭✭
    edited February 2018
    Make that 3.
    HAC Div 96 1962-1968.

  • Bill-N6RVBill-N6RV Member
    edited February 2018
    Checking Jerry's numbers
     (No, we are not related but live really close to one another).

    Converting 11 knots to 12.7 mph

    Distance 1000 mi
    Ship 5 mph
    Tug 12.7 mph (11 knots) (1.1508 nm to mi )
    Closure 17.7 mph

    Time of Intersection 56.6 hours, 2.4 Days (2 days  8 hours  17 minutes 46.902 sec)
    Distance to Intersection 716.9 miles      Check

    Extra Credit
    Speed 10 knots (11.508 mph)
    Arrival 71.7 hours (2.596 days - 2 days  14 hours 17 minutes 33.59 sec)

    Of course we forgot to add the 6 hours they have to wait to disembark.

    Extra Extra Credit
    Ship alone: 200.0 hours, 8.3 days
    Towed Ship: 128.3 hours, 5.3 days
    Time Saved: 71.7   3.0 days

  • Bill-N6RVBill-N6RV Member
    edited February 2018
    Correction: 2 days 8 hours 37 min 46.9 seconds
  • Mark WS7MMark WS7M Member ✭✭
    edited April 2018
    You guys are failing to take into account both wind and ocean currents... in other words "chaos" which means at best your computations are a close estimate.

    Just sayin...   

    As a pilot wind is something we fight with regularly.  Tugboats and failed DX expedition boats must also consider ocean currents.

    Anyway I was sad to see that so much effort and time went into them getting so close.  But most important they are safe.

  • David SalomonDavid Salomon Member ✭✭
    edited April 3
    I think the tugboat should tow them back to Bouvet. :)
  • Bill-N6RVBill-N6RV Member
    edited February 2018
    I assumed the return speed in the discussion accounted for the wind and currents :-)!
  • MackMack Member ✭✭
    edited March 2019
    The radios are shipping in quantity!
  • KY6LA_HowardKY6LA_Howard La Jolla, CA. Paris and Sablet FranceMember ✭✭✭
    edited February 2018


    You are likely the most realistic..  One can never **** U ME that the real world will give you exact numbers...

  • Rich McCabeRich McCabe Member ✭✭
    edited February 2018
    I just hope if my radio ships it isn't coming from Texas at 9 mph.

  • Mark_WS7MMark_WS7M Member ✭✭
    edited February 2018
    I think this way because when in engineering school my instructor had us write a small controller program to control two electric trains around a figure 8 track.  We could sense the trains in several positions and send them a speed commands and that was it.

    The goal was to have them run the track as fast as possible with:

    a) not falling off
    b) not crashing into each other

    ALL of us, except for one girl got the problem wrong.  Sure we wrote our software and had perfect results on all of our test runs until the day of the test when the instructor oiled up one of the trains.

    It was hilarious to watch student after student including myself see our work go up in crashed or flung away trains.  Until the one girl got up and hers ran.

    She did the one thing the rest of us did not.  She measured each trains performance repeatedly between a set of sensors and her algorithm adjusted for the trains response to the velocity command.

    It was an eye opener that taught me that nothing is fixed and you had better plan on things being way different as your test runs.

    Anyway it was a fun problem and I just had to jump in here.  

    I am sorry the DXpedition could not continue... And yes hopefully Flex Radios do not ship at 9 mph!
  • Bill-N6RVBill-N6RV Member
    edited February 2018
    Since the distance, speed, and times were stipulated the problem was well defined. Had the question been "When will they reach dry land" without any other data the answer would have been different.

    I was going to add +/- 3 dB to all the results.... :-) !
  • Rich McCabeRich McCabe Member ✭✭
    edited February 2018
    Since they are down one engine I would think it would me -3db !

  • Mark WS7MMark WS7M Member ✭✭
    edited February 2018
    But Bill,

    Since this is flex I think you had better make it 6 db!
  • Bill-N6RVBill-N6RV Member
    edited February 2018
    Yes... the distribution is not Gaussian ... probably a Taylor distribution would be appropriate. Then maybe Mr. Peabody could show up with his Wayback Machine and they arrive tomorrow!

Leave a Comment

Rich Text Editor. To edit a paragraph's style, hit tab to get to the paragraph menu. From there you will be able to pick one style. Nothing defaults to paragraph. An inline formatting menu will show up when you select text. Hit tab to get into that menu. Some elements, such as rich link embeds, images, loading indicators, and error messages may get inserted into the editor. You may navigate to these using the arrow keys inside of the editor and delete them with the delete or backspace key.