Sextant

[lustyd]

Hi all, I've just been wandering around in the National Maritime Museum and looking at all the sextants from throughout history as well as the various other instruments from before sextants.
It occurred to me that although they are quite intricate they can't be that hard to make. Has anyone ever tried making a home made one? If so, how did you get on?
Cheers
Dave

 

[FergusM]

Fred Rebell, who sailed an open 18' boat from Australia to the US in the 1930s on a Great Depression budget of just about nothing, made his own sextant, bending a hacksaw blade to give a toothed arc, with a screwnail engaging in it, so that turn of the screwhead (which he calibrated) noved the arm and so the mirror.

His book 'Escape to the Sea' is well worth a read.

An engineer I worked with 30 years ago was planning to replicate a plastic Ebbco sextant in metal, as he had access to full machine shop. I left the job and went abroad, so I never found out whether he ever got round to it.

I have a plastic Ebbco and a very nice metal Astra sextant, and I reckon a competent engineer should certainly be able to make a working instrument.

Tony Crowley's excellent book 'The Lo-Tech Navigator', is, however, the answer to your prayers, as he gives clear instructions for making a number of instruments, including a Backstaff, quadrant (just about as effective as a sextant), sun compass, tidal abacus and more. I thoroughly recommend it.

Another cracking book is Alastair Buchan's (he writes in PBO, and took a small Hurley across the Atlantic) 'Pencil, Paper and Stars' shows how to make the old Arab Kamal, to measure all sorts of arngles, including stars (take a ruler and a length of cord - I kid you not), a latitude hook from a wire coathanger, and a crossstaff from bits of wood you have lying around.

I would suggest you get these last two books, as they will let you make good, accurate, effective instruments, without investing a load of time or money. Then you can make a sextant in metal if you feel like it, but with a lot of useful experience under your belt.

Best of luck.

 

[lustyd]

Thanks very much, that's one of the most useful posts I've seen in a long time

 

[electrosys]

http://books.google.co.uk/books?id=_CcDAAAAMBAJ
September 1933

Full plans to make your own.

 

[DanTribe]

Also worth Googling Bris sextant.
I think it was invented by Sven Yrvind, a bit of an eccentric maybe, but a fascinating character.

 

[FergusM]

Glad to help. By the way, I accidently deleted 'octant' from my comments on Tony Crowley's book after quadrant. The octant is an accurate reflecting instrument very like a sextant, but measures up to 90 deg angles, rather than the sextant's 120.

 

[Gadget257]

Depending how accurate you want to be this link may be a started for ten.

http://www.tecepe.com.br/nav/CDSextantProject.htm

 

[DownWest]

http://books.google.co.uk/books?id=_CcDAAAAMBAJ
September 1933

Full plans to make your own.

I used to read PS at school in the early '60s. But your link has WAY more wild ideas than I used to see.
DW