NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Time on a small boat CN
From: Dick Savage
Date: 2004 Jan 7, 22:14 -0800
From: Dick Savage
Date: 2004 Jan 7, 22:14 -0800
Jim,here is a list of equipment and some techniques
you may find interesting.
Every vessel I work on has a chrono,S.S.B.
radio,multiple gps units and G.M.D.D.S.
I carry my own chrono onboard with me though I
rairly take it out and use it.It is a Hamilton Mod. 21 analog
chrono.
I do use my Hamilton Mod. 23 stop/lap analog watch
all the time.It's time keeping accuracy is greater than any of us will ever need
for practical purposes.
You can use any of the main time keepers to get the
base GMT and the stop watch to record the actual time of the sight.
This is what I'm most comfortable with
:
I use the W.W.V. 2.5 - 15 MHz S.S.B. radio signal
from Ft. Collens which is slaved to an atomic clock to get my tome
stamp.Your copy of Duttons should explain its' use.
Before the round is to begin have all forms
ready,the sextant ready,a red penlight if at night,and the stop watch secured
to the wrist and in the hand you will turn the micrometer with.You don't
need the light because you can take 1 cut and move back into
the bridge to read everything.
Take the GMT time stamp off WWV and start the watch
when the signal sounds.Move to where you will take the cut and take the
sight.Remember,the stop watch is in the hand that turns the knob so it must
be positioned so as your thumb can hit the stop crown.When the body is on the
horizon hit the stop crown of the watch.Read the time off and add it to the
GMT time stamp from WWV.Read hs off the sextant.Your sight is done and your time
is really exact.I really don't even play around with the chronos,as this I
believe,takes out any chrono error in the ensueing calculations.If you don't
have a SSB radio on board use the gps time function and a stop watch.I wouldn't
rely on a wristwatch for takeing any sights unless it is emergency navigation
such as shipwreck or being adrift.
Here is another technique I use.This is not to be
used with a timed shot!
As above have everything as stated.Place the
body(this is great for sights useing the sun or moon,upper or lower
limb) a little above or below the horizon depending if the body
is climbing or falling.Keep the sextant up and don't touch the
micrometer drum.When the body or limb just touches the horizon as seen through
your sextant hit the stop crown of the stop watch.The cut is now
finished.Read the time and the hs and go make your calculations at your leisure
to find the LOP.
Try to eliminate as many steps that can result in a
math error in your sight takeing.Chrono and watch error are good ones to
eliminate in you paperwork.
The only real reason commercial vessels have a
sextant and chrono on board is because the Coast Guard requires the vessels
to carry them.Someone must keep track of the rates and errors and log them in
case the 2nd officer or nav watch must rely on them as the primary navigation
tool in the event all other systems go down.
