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Chart(s): Plotting Sheets
   1998 Nautical Almanac

Sight Reduction and
Ded-Reckoning problem      Leg 41  052298   Test your knowledge!
----------------------     ------  ------   --------------------

We have rounded Cape Leeuwin by following the 100 fathom line. Then
taken departure bearings on the Australian coast which gave us a
Departure FIX of(34d 50.2'S  116d 03.5'E) on 20/07/1998 at 04:08:29ZT.

Our next waypoint is at Bass Strait(39d 18.0'S  144d 00.0'E). Speed
10Kts, Var 3dW, Dev 2Dw, Current Set 105d Drift 6 miles per day.
Clouds are solid overcast stratocumulus. The wind has veered to the
SW. Large waves are beginning to form; white crests are more
extensive.

1)  Based on the waves we're seeing, what is the Beaufort
    wind force?

    What is the Beaufort wind speed range in knots?
--  -------------------------------------------------------------

2)  What Beaufort wave heights can be expected if the wind
    continues at this force?

    What is the Beaufort wave height in meters?
--  -------------------------------------------

We maintain our TC for 59Hrs 15Min 20Sec. But due to the sea
conditions our speed has been 9Kts. The wind has increased to Force
10. The storm sails have been set. There are very high waves with long
overhanging crests. The surface of the sea is white with great patches
of foam and visibility is affected. We Heave-to on a |TC of 245d.

3)  What is the DR position at the time of Heaving-to?
--  --------------------------------------------------

4)  What is the Zone Time(ZT) at Heaving-to?
    What is the GMT at Heaving-to?
--  ----------------------------------------

We are hove-to for 68Hrs 21min 11sec before we decide to set sail.
The wind has decreased and is now blowing at Force 7.

5)  What is the DR position based on TC and Speed when
    we decide to set sail?

    What is the Zone Time(ZT) and Date?
--  ---------------------------------------------------

6)  Based on Q5 Ded-Reckoning what is the TC & Dist to
    Base Strait?
--  --------------------------------------------------

A look at our Indian Ocean Pilot Chart for July shows that we are in
an area of NO VARIATION. Dev 2dW. Current Set 95d Drift 6 miles per
day. Speed 9Kts. The cloud ceiling is beginning to raise.

7)  What is the Compass Course(CC) to Bass Strait?
--  ----------------------------------------------

While we are setting sail the navigator takes a LAN sight of
the Sun Lower Limb, Hs 32d 48.1'.

8)  What is the Noon latitude?
    Which direction is the navigator facing during his sight?
--  ---------------------------------------------------------

Note:
Lat & Lo = XXd XX.X', Date=DD/MM/YY, HE 8 Feet, Index correction
-.2', Time hh:mm:ss in UTC/GMT. Silicon Sea is a medium displacement
sailing vessel, 40 Feet LOA. 38 Feet LWL; Cutter rigged. Looks a lot
like a Mason. Can tack to 45d. Dist to Horizon: Nmi = SQRT HE@mtrs x
2.07; Nmi = SQRT HE@ft x 1.17. Water Tank = 60 gal(Imp.). Fuel Tanks =
90 gal (Imp.). Fuel consumption .450 gal/Hr at 8.3 Kts.

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 soon!

Good Navigating!

   -=The Navigation List Working Group=-

        Peter Smith  - psmith@wellspring.us.dg.com
        Ron Legere   - ronald.legere@yale.edu
        Tony Severdia- anthonys@pacbell.net
        Wes Murfin   - wmurfin@onslowonline.net (Cartographer)
        John Simmonds- mobi@netconnect.com.au
        Jim Manzari  - manzari@bluewin.ch
        Buck Godwin  - bgodwin@newsguy.com (Archive Files)
        Dan Hogan    - dhhogan@lightside.com

Dan Hogan WA6PBY
"Gacha" Catalina 27
San Pedro, CA
dhhogan@concentric.net
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