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    Silicon Sea II: Leg 49
    From: Dan Hogan
    Date: 1999 Mar 15, 7:19 AM

    Chart(s): Plotting Sheets
    Dead-Reckoning problem     Leg 49  031599   Test your knowledge!
    ----------------------     ------  ------   --------------------
    Our last position FIX was at (35d 00.2'S  156d 59.7'E) at 09:05:22 {at}
    18/02/1999GMT.Speed 8.7Kts, TC 86.8d Var 13dE, Dev 2.0dE. Current Drift
    17 mi/day, set 185 according to the Pilot Chart. We continue on course
    through the night. The weather is deteriorating and it begins to rain.
    At 19:45:00GMT the wind heads us and we are forced to change our
    Course(CC) 45d to port to stay close-hauled.
    1)  What is the DR position at the time of the course change?
    --  ---------------------------------------------------------
    2)  Taking all factors in consideration, what is the TC we are
        making good?
    --  ----------------------------------------------------------
    A storm has come up and we battle Wind and Sea. The boat is bouncing
    hard and the knotmeter is oscillating wildly. We use the distance log
    on the knotmeter. The storm has caused us to sail the following legs:
        TC      Speed   Dist    Time/in/Hrs
       072d     8.7     91.3    10:30:00
       027d     8.7     52.2    18:30:00
       122d     7.5    198.1    26:25:00
       095d     9.5    311.1    32:40:00
    3)  What is the DR position at the end of the storm?
    --  ------------------------------------------------
    4)  What is the GMT Time and Date of the DR position?
        What is the Zone Time(ZT) and Date of the DR position?
    --  ------------------------------------------------------
    5)  What is the TC and distance to our destination at(40d 50.0'S
         174d 20.0'E)?
    --  ------------------------------------------------------------
    A look at our charts shows that we are off of New Zealand's North
    Island. The chart shows that Mt. Egmont, 2518 mtrs high, sits on the
    headland at the bight between North and South Islands and is our best
    land mark.
    6)  At what distance should we be able to see the mountain on the
    With a speed of 9.7 Kts.
    7)  About what what Zone Time(ZT) and date should we expect to have
        Mt.Ebmont on the horizon?
    --  ---------------------------------------------------------------
    Lat & Lo = XXd XX.X', Date=DD/MM/YY, HE 9 Feet, Index correction
    -2.5', Time hh:mm:ss in UTC/GMT,unless otherwise stated. Silicon Sea II
    is a 34,000 lb(15.40t) displacement sailing vessel, 48' 3"(14.70m) LOA.
    39' (12.00m) LWL; Cutter rigged. Can tack to 45d. Water Tanks = 220
    gal(1000 ltrs). Fuel Tanks = 155 gal(700 ltrs). Fuel consumption .675
    gal/Hr at 8.5 Kts. DR(Ded-Reckoning)=position by sailings, EP(Estimated
    Position)=DR+current affect. Dist to Horizon: Nmi = SQRT HE{at}mtrs x
    2.07; Nmi = SQRT HE{at}ft x 1.17.
    PLEASE respond with your results and thinking on these exercises to the
    NAVIGATION list at large. If you have questions or problems, A lot of
    folks on the list are knowledgeable and willing to help. Any questions
    or doubtful areas will be responded to promptly. Let us hear from you
    Good Navigating!
       -=The Navigation List Working Group=-
            Peter Smith  - psmith{at}wellspring.us.dg.com
            John Simmonds- mobi{at}netconnect.com.au
            Jim Manzari  - manzari{at}bluewin.ch
            Dan Hogan    - dhhogan{at}concentric.net
    Dan Hogan WA6PBY
    Catalina 27 "GACHA"
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