NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Howard G
Date: 2022 Apr 2, 03:09 +0000
Hi Jim
I have zilch knowledge of marine navigation but as this was the origin of the aeronautical very keen to have experience in all aspects.
I have no experience of marine sextant and live 100 km inland Australia, 3000 ft up where a natural sea level horizon is missing –
somewhat. My wife bought me a marine sextant for Xmas after I decided I needed to regain celestial navigation skill.
It is a Davis Mk 25 plastic – probably not as robust as a ship’s brass ‘real one’ – but one of those was just a bit too expensive.
I then visited the coast – East coast after midday – to practice with ‘The Sun’ – my 1st mistake and only needed a little
thought – the sun was now West and obviously no natural horizon that way. So I just practiced and got use to the marine sextant horizon – and have since purchased a Davis false horizon – which works well but is messy and in the hot sun steams up or shimmers
if you leave a glass cover off to prevent steaming up.
So I decided to get an aeronautical sextant to enable day/night shots – I did see Kollsman’s for sale but none in pristine condition
– remembering they are sensitive instruments and dirty worn old lens and gadget prone to corrosion would render them useless.
Then Bob S contacted me as I saw he was selling the B & L A-8A & A-12A aeronautical – these are fully reconditioned and aligned – I
was going to buy the A-12A (historically the type used by “Dutch” Van Kirk on the Enola Gay) – though typically this was more of a training sextant and the general use one was the A-8A.
My first sextant was an astrodome RAF Mk IX or X – a robust and good sextant – however none were available – so I decided to get an
A-8A bubble sextant after talking with Bob S.
It duly arrived in pristine condition – no bubble – but a phone call from Bob S quickly had that working and the sextant is wonderful
and a joy.
And a plus plus with it I was not aware of when I bought it – and hence why I am now recommending you buy this model (notwithstanding
Bob is a fully qualified instrument maker) – but the A-8A is one of only a few aeronautical sextants that can be BOTH a Bubble sextant or a real horizon sextant - yep it is BOTH!!!
Unlike the Mk IX, X RAF and the Kollsman the average is manual – but it averages 8 shots – a bit more mechanical than the true wind
up average but perfectly workable.
I just haven’t had time to get up to speed but it sits lovingly on my desk.
Regards Howard
From: NavList@navlist.net <NavList@navlist.net>
On Behalf Of Jim Rives
Sent: Saturday, 2 April 2022 13:15
To: Howard George <HHG@raptorbusinessservices.com.au>
Subject: [NavList] Re: Kollsman Periscopic Sextant for sale
Hi Howard,
Thank you for your thoughts on the Kollsman. I was a surface Navy navigator so am not at all familiar with aviation sextants. I became intrigued after reading a thread on Navlist about using FS 2020 for celnav practice. Which
lead to a little investigation into the process of navigating a plane. A very different process indeed! I had better study up on the various aviation sextant designs out there and see if there is one that is suitable for practice only.
