NavList:

   

Reply

I have finally found a really simple** way to prove to kids that you
can locate yourself using the sun (in the surroundings of a campsite
without the sea for a horizon) ... and that is to use a theodolite.

It seems to work very well, I buy a cheap theodolite, spend a week
fixing it so that I can measure the position of the sun, another
realising I hadn't so much calibrated as bodged.

Then eventually the sun comes out, I point the theodolite at the sun
and focussing the sun on my hand, I align the sun so that it is
visually located within the shadow of the telescope and .... hey
presto, I confirm I am only 1 nautical mile away from real position.

... but ... how do I know whether this is just a lucky observation?

Obviously I can't simply look through the telescope and check the sun
is centrally located with the cross hairs ... or can I? I wouldn't
have thought I could just take my sextant filter and use them on the
back of the theodolite .... or could I ... and surely I would not see
the cross hairs.

What if I bought some solar filter and put that on the front of the
telescope? Would I (and children) be able to see the cross hairs then?

.... and is there any danger to the theodolite from solar heating if I
keep pointing at the sun?

==============

** SIMPLE WAY:- I tried using a false horizon with a few children and
quickly discovered that it was virtually impossible to use. The basic
problem is that whereas children can easily find one object in a
telescope and then you only need ask "can you see the sea, or the
sky", and adjust the angle appropriately, with a false horizon,
you are trying to bring two points into view when there are 14 ways
they can be hidden:

1/2 the object can be out of view because you are pointed too high/
low,
3/4  too far left/right,
5/6 the sextant is tilted toward the left/right
7/8 or that the angle is too great/small.
9-12 the sextant may be correctly angled to see the sun/reflection,
but the child has moved to left/right or forward/back and can no
longer see the reflection.

and without physically being able to look down the same eyepiece as
the children, it is impossible to work out in which way they are going
wrong and therefore impossible to help them find the "two suns".
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to NavList@fer3.com
To , send email to NavList-@fer3.com
-~----------~----~----~----~------~----~------~--~---

   

Reply