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#283718 - 02/12/17 06:46 AM Improvisation - sextant from signal mirror
rafowell Offline
Member

Registered: 11/29/09
Posts: 195
Loc: Southern California
I've seen instructions on using a sextant mirror as a signal mirror, but this is the first account I've seen of a signal mirror used as a sextant!

After their ship was torpedoed in 1944, 3rd officer F.L. Newal cobbled up a sextant from a protractor, a biscuit tin, chewing gum, and a metal signal mirror, and headed for Diego Suarez, Madagascar, more than 1200 miles away.

After 42 days, a ship picked them up just 60 miles short of their goal.

Story and side view of homemade sextant

Story and top view of homemade sextant
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A signal mirror should be backup for a 24 hr, all-weather radio distress signal, such as a 406 MHz PLB (ACR PLB)

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#283719 - 02/12/17 02:32 PM Re: Improvisation - sextant from signal mirror [Re: rafowell]
hikermor Offline
Geezer in Chief
Geezer

Registered: 08/26/06
Posts: 5656
Loc: southern Cal
Wow! Knowledge and skills are what count, more so than gadgets and gear....
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#283720 - 02/12/17 02:53 PM Re: Improvisation - sextant from signal mirror [Re: rafowell]
Russ Offline
Carpal Tunnel

Registered: 06/02/06
Posts: 4414
Loc: SOCAL
Interesting indeed. The two photo's at the links show the protractor in one but not the other. I wonder how the protractor is measuring elevation since it's stuck to the side at the top with gum. Something simple that points to "down" seems to missing in the images. That something would cross the protractor and yield elevation.

How could this be improved with a modern glass/plexiglass signal mirror with a fireball. I may need to breakout my mirror and a protractor, and play around.

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#283721 - 02/12/17 04:14 PM Re: Improvisation - sextant from signal mirror [Re: Russ]
M_a_x Offline
Old Hand

Registered: 08/16/02
Posts: 848
Loc: Germany
Originally Posted By: Russ
Something simple that points to "down" seems to missing in the images. That something would cross the protractor and yield elevation.

You may notice the piece of wire that suspiciously looks like an indicator next to protractor.
The biscuit box has a hinge on the open side and the protractor has a hole at the intersection point of the radials for the angle. The mirror is fixed to some sort of wire so it pivot around the hinge. You aim at the horizon through the hole in the signal mirror and the front sight (stuck to the bottom of the box). Now you pivot the mirror to put the reflection of the sun on the front sight. The indicator shows the angle of the mirror.
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#283722 - 02/12/17 06:53 PM Re: Improvisation - sextant from signal mirror [Re: M_a_x]
Russ Offline
Carpal Tunnel

Registered: 06/02/06
Posts: 4414
Loc: SOCAL
Thanks, good explanation, that makes much more sense.

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#283723 - 02/12/17 07:45 PM Re: Improvisation - sextant from signal mirror [Re: rafowell]
chaosmagnet Offline
Sheriff
Carpal Tunnel

Registered: 12/03/09
Posts: 2643
That's pretty epic. Great share.

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#283724 - 02/12/17 08:10 PM Re: Improvisation - sextant from signal mirror [Re: rafowell]
Montanero Offline
Old Hand

Registered: 10/14/08
Posts: 994
Loc: North Carolina
Impressive!

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#283725 - 02/12/17 10:07 PM Re: Improvisation - sextant from signal mirror [Re: rafowell]
rafowell Offline
Member

Registered: 11/29/09
Posts: 195
Loc: Southern California
Originally Posted By: rafowell
F.L. Newal cobbled up a sextant from a protractor, a biscuit tin, chewing gum, and a metal signal mirror

Chewing gum ... why was chewing gum in the lifeboat?

I expected biscuit tins in a British WW2 lifeboat (food) and a signal mirror (signaling). Less so the protractor, but the there were charts in the lifeboat - maybe the protractor was with the charts for computing navigation compass bearings.

Chewing gum isn't on any modern "ten essentials" lists I remember.

As a check, I electronically searched the ~500 page, 4 volume 1985 USAF AFR 64-4 Survival Manual for "gum", and the only reference to chewing gum was that scented chewing gum could reveal your presence to hostiles.

However, my "go-to" quick reference for military survival kits[1], lists chewing gum in many WW2 survival kits: USAAF E3 kit: 1 stick, USAAF E3A kit: 4 sticks, Navy E3A: 4 sticks, E17: 4 sticks.

The Emergency Parachute Ration tin had gum, and 2 such tins were in the C-1 Emergency Sustenance Vest. Pulling out my manual for that vest[2], it says (p. 10):

"Four Pieces Chewing Gum – Chewing a piece of gum occasionally will help to relieve thirst. The gum also can be used to patch small holes in rubber rafts, in plastic containers, and for other patching purposes."

... and also to make a sextant!!! wink


[1] Breuninger, Michael S., "United States Combat Aircrew Survival Equipment: World War II to the Present, A Reference Guide for Collectors", Schiffer Military History
[2] Instructions for the use of Emergency Sustenance Vest, Type C-1, Prepared by the Artic-Desert_Tropic Branch HQ, AF Tactical Center.
_________________________
A signal mirror should be backup for a 24 hr, all-weather radio distress signal, such as a 406 MHz PLB (ACR PLB)

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#283726 - 02/12/17 11:27 PM Re: Improvisation - sextant from signal mirror [Re: rafowell]
hikermor Offline
Geezer in Chief
Geezer

Registered: 08/26/06
Posts: 5656
Loc: southern Cal
There's always the chance that someone brought chewing gum aboard...

Could one use duct tape today?


Edited by hikermor (02/12/17 11:29 PM)
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#283727 - 02/13/17 12:28 AM Re: Improvisation - sextant from signal mirror [Re: hikermor]
rafowell Offline
Member

Registered: 11/29/09
Posts: 195
Loc: Southern California
Originally Posted By: hikermor
Wow! Knowledge and skills are what count, more so than gadgets and gear....

Yes, the best survival gear is the gear between your ears. wink

However, you can still lose that gear when under stress eek

That's why the Boy Scouts are taught to STOP[1] when things go wrong, so they don't lose that stowed gear.
  • Stop : and calm yourself down, so you don't lose that precious gear
  • Think : rummage around in that survival gear to see what may be useful
  • Observe
  • Plan

While I'm on this metaphor, mnemonics like STOP and catchphrases like "the gear between your ears" are handy containers for the gear between your ears.

I wonder - do we already have a thread on survival mnemonics and catch phrases? Should we start one?

Here are a few: Scout mnemonics that could save a life

On the thread topic of improvised sun navigation devices, there's Finding North with a Shadow Stick and Using an analog watch as a compass.

You are usually far better off with a compass and the knowledge to use it, though.
_________________________
A signal mirror should be backup for a 24 hr, all-weather radio distress signal, such as a 406 MHz PLB (ACR PLB)

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