Greetings all, my first message here.
anyone have any tips other than the ones discussed here before on
making
a navigational sliderule replica?
as things stand I have the scales and am currently waiting for tubing to
mchine into a MHR1 replica (fairly simple task thanks to scales
published here).
will be interesting to see if it is as "easy" and accurate in my hands
as claimed, as I only have a 6m wooden tub any intercept better than 3'
is my usual limits afloat, as anyone tried to take a sight from such a
small vessel can testify not for a beginner to keep horizon in sight
with even moderate 1.5m waves never mind both star (preferably right
one) and horizon, on land using my mirror AH and my Astra IIIb I mostly
get around 1' intercepts (further quiestions as to that later).
as things stand now I use Henning Umlands larger Table and regular
Nautical almanac for regular afloat sightreduction and the old version
of Geoffrey Kolbe's Long Term almanac (the one with Ageton tables) in my
"grab bag" (I use the LTA
every now and then to keep in practise though).
if it was simpler for me I would use calculator and usual formulas
probably known by most here but my old sci-calculator require me to
convert everything to radians before using it, kind of takes the speed
advantage away and a computer in a 6m open boat... no great idea.
Any hints as to as to why my terrestrial cel-nav intercepts if I use the
symedian point more or less constantly show me to be 0.5-0.7' east of
GPS even with over 20 ?
My sextant is a reasonably accurate Astra IIIB,
My artificial horizon is accurate first surface mirror flat to less than
100nm according to maker.
For time I use radio time signal and a very good boxed gimbal
chronometer that is within fraction of a second/week (recertified after
last overhaul).
Even with assistant (wife) to read and note time I get a shift to the east.
never mind what celestial body, be it sun, moon, star or
planet,
whatever azimuth body has seems to make little difference my fix always
end up east of GPS.
First I thought it was me doing something wrong so I bought Omar Reis
Navigator Software, not much better still get that shift (actually seem
to get worce on sunsights with AH) .
my only explanation is either GPS and maps/charts are wrong (unlikely)
or I am doing something wrong, ideas?.
oh, might as well say that I reposition and re level my AH every time as
it is mounted on a tripod, the level I use is a 6 arc-second machine
level that I turn end for end until bubble is centred, everyone that has
used one of these know that at some point we have to say good enough as
only breeding on the mirror moves the bubble.
For sunsights I have to re level every now and then as sun moves and
make legs of tripod expand/contract in different configurations, stars
are easier as sun is mostly low on horizon or already
down but in winter
snow and ice moves enough to force me to re level every now and then.
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