[Rhodes22-list] Sextants

Bob Dilk Bob.Dilk at TRW.COM
Tue Oct 12 16:08:17 EDT 2004


Using a Sextant to get within 6 feet????

Please Bill, share your secret.

As a practical navigator I try to use every tool in my book, including
magnetic bearings and "dipping the light" on a light house for range.

I also use a sextant. Please share your secret for accuracy.

Bob Dilk
S/V Knot Necessary

>>> bill at effros.com 10/12/04 01:32PM >>>
Bob,

Compasses are wildly inaccurate, including fluxgates.  Nobody corrects
them anymore.  Most of them can't even be corrected.  Roger's toy may be
interesting for other reasons, but not as a navigational tool.  The boat
is moving, you are moving, and the compass bearing is a guess at best.

A sextant is a much better tool.  Start on land.  I can put myself
within 6 feet of my actual location on land.  Sextant bearings on a boat
are harder, but the people who know how to do it, and practice all the
time will give you better bearings than laser range finder binoculars
every time.  Sextant bearings are more reliable than GPS bearings.  Last
time I checked their was still a guy on all our big military ships
taking sextant bearings.

You can use a sextant horizontally to get compass bearings far more
accurately than fooling around with those oil filled things with a
magnet inside.

You can get a high quality plastic sextant for $250 that will test the
accuracy of a traditional fix far more accurately than a laser range
finder binocular.  There are numerous programs available so you just
plug your readings into the program to calculate the full sight
reduction.

Compass bearings used as Roger proposes also require computers to
calculate the compass deviation for the exact spot you think you're at,
unless you know how to use a pelorus--another dying art--another
forgotten tool.

Bill Effros
                                     


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----- Original Message ----- 
From: Bob Weber 
To: rhodes22-list at rhodes22.org 
Sent: Tuesday, October 12, 2004 11:53 AM
Subject: RE: [Rhodes22-list] Radio - FM Recption - GPS Map


Brad, right now I am pushing for Rogers laser range finder, binoculars,

compass, thing.  I would propably have a heart attack at the price. 
But if 
it had a bottle opener and tweezers that might sway the deal. 
Seriously I 
am looking toward getting certified to teach navigation and that could

really help with fixes or at least test the accuracy of a traditional
fix.  
Bob

>From: brad haslett <flybrad at yahoo.com>
>Reply-To: The Rhodes 22 mail list <rhodes22-list at rhodes22.org>
>To: The Rhodes 22 mail list <rhodes22-list at rhodes22.org>
>Subject: RE: [Rhodes22-list] Radio - FM Recption - GPS Map
>Date: Tue, 12 Oct 2004 08:18:34 -0700 (PDT)
>
>Bob,
>
>About half the DC-10 fleet has Inertial Nav and half
>has two VOR's, same as a Cessna 150.  Often times
>center will give us direct to somewhere and I have to
>reply, "we're navigationally challenged" or "we're
>heading equipped". Some guys were carrying handhelds
>but the FAA and the company put the squash on it.  The
>non jurrasic jet equipment, Airbus and MD-11's have
>GPS moving map displays.
>
>Frankly, my handheld is more than enough for the boat.
>  Christmas is coming though and I don't know what to
>buy for myself.
>
>Brad
>
>
>--- Bob Weber <ruba1811 at hotmail.com> wrote:
>
> > Brad, I have found the GPS to be great on the boat.
> > I have brought it in
> > the car before but never found a use for it.  If I
> > were to be travelling to
> > parts unknowen it would be helpful.   It doesnt have
> > verbal comands "turn
> > right in 50 feet" but you should be able to get that
> > from the display.  I
> > cant believe you dont already have a handheld GPS
> > for backup while flying.
> > I guess it is more helpful in the egg beaters than
> > in commercial jets.  As
> > far as XM.  I am not in a rush to pay for radio.  We
> > all were in a hurry to
> > pay for tv.  Remember the promise.  Pay monthly and
> > get commercial free tv.
> > That didn't last too long.  I am due for a new car I
> > will keep that in mind
> > when ordering the stereo equipment on the car.  If
> > it is removable, it will
> > be a no brainer.  Bob
> >
> > >From: brad haslett <flybrad at yahoo.com>
> > >Reply-To: The Rhodes 22 mail list
> > <rhodes22-list at rhodes22.org>
> > >To: rhodes22-list at rhodes22.org 
> > >Subject: [Rhodes22-list] Radio - FM Recption - GPS
> > Map
> > >Date: Tue, 12 Oct 2004 05:27:36 -0700 (PDT)
> > >
> > >Am I the only one on a lake with almost no FM radio
> > >available? Last Christmas I purchased an XM
> > satellite
> > >radio for CoraShen and it has turned out to be a
> > >wonderfull investment.  Now I don't have to drag
> > CD's
> > >to the boat or listen to "swap shop" and the
> > >obituaries on the local stations.  Both Sirrius and
> > XM
> > >get about 160+ stations and the reception is
> > >outstanding.  The equipment is about $125 and the
> > >service $10 per month.  I move the equipment to my
> > car
> > >when not on the boat.
> > >
> > >This experiment with dual use equipment has gotten
> > me
> > >started looking at portable GPS moving map
> > displays.
> > >The Garmin 176 looks interesting.  You can use it
> > on
> > >the boat and then in the car as well.  Anyone on
> > the
> > >list have experience with one?
> > >
> > >Brad Haslett
> > >"CoraShen"
> > >
> > >
> > >
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