Sextant restoration and/or calibration

[dofthesea]

Anyone have a resource for a Co that restores sextants or calibrates them? Im thinking about getting a used sextant and would like ot have it checked out? Or should I just get a modern day plastic one?

[Snowpetrel]

Any well looked after sextant of reasonable quality shouldnt have any major errors that can't be fixed easily by adjusting the mirrors. If the issue is bigger than that, prehaps a worn pivot or warped or bent frame its probably not worth rebuilding.

A great resource is the sextant book. Most of the metal sextants are a fair jump above the plastics in terms of accuracy and pleasure of use. But the plastics work well enough offshore to get you across an ocean.

Sent from my SM-G930F using Cruisers Sailing Forum mobile app

[UNCIVILIZED]

What Snowpetrel said. And to expound on the comment on plastic ones. Generally when you shoot fixes with them, the area of uncertainty will be larger than with a good metal one. Which is fine out on the ocean, but not when within sight of land.

[donradcliffe]

Even the best metal sextant which has been lovingly refurbished will not tell you where you are the 0.01% of the accuracy of the cheapest GPS. That's why they have gone the way of the dodo bird. If you want to pretend you are an old sea captain, you might as well use a plastic one. The Davis Mark 25 with the beam converger is easier to use.

[Snowpetrel]

Very true about the sextant accuracy vs GPS. I still like carrying one offshore, but I am happy enough not to these days as well, given enough backup GPS units. Ive got a davis 15, and a very nice metal frieburger. The 15 has let me down accuracy wise with a worn thread over the zero index region. I am not sure of its history. It was my grandfathers, and may have been used for training, hence the wear and slop in the micrometer, so is only accurate to about 15' or so.

A mark3 I used gave more honest results with a simple vernier, good to about 5-10' or so. I used a new mark 15 coming back from antarctica recently and my first sight was within a few miles of our real position and a new mark 25 I used on passage to Chile also gave excellant results, consistantly within 5' and often better, so the plastics can work. If I was buying a plastic one for myself I'd get a mark 3. And save the money towards a metal sextant in the future. But a mk 15 or 25 is much nicer to use than the mk 3 with its fine adjustment and micrometer.

[GordMay]

➥ Sextant - The Compass Adjuster
➥ Robert E. White Instruments Services - Barographs Service, Barometers Service, Sextants Service and all Weather Instruments service in Medfield and Eastern Mass, MA.
➥ Sextant refurbishment

[royalstar]

Originally Posted by donradcliffe

Even the best metal sextant which has been lovingly refurbished will not tell you where you are the 0.01% of the accuracy of the cheapest GPS. That's why they have gone the way of the dodo bird.

GPS...Yeah, poor people, they did not knew what they are missing

https://www.youtube.com/watch?v=q5m061JZNYQ

[double u]

second that! very satifying to have the palmtops creep over the horizon after taking starsights all through the early hours of the morning by the light of the full moon...very!

[wjhutchings]

Sextants and GPS

As a professional navigator who sailed umpteen thousand miles in the days before GPS and afterwards, All I can say is that I noticed no difference between the two eras, why do you need to know exactly where you are in the middle of an ocean, and when coasting you really should be looking out of the window or over the gunnel rather than at a bunch of electronics. Also though there are now various systems most receivers use the USA GNSS system, what are you going to do if it gets switched off or the code changes to fit a military application which of course is it prime reason for being, or god forbid some idiot sets of a 1 kiloton nuclear air burst which fries all the un -hardened electronics we now use.

[Smokeys Kitchen]

Originally Posted by dofthesea

Anyone have a resource for a Co that restores sextants or calibrates them? Im thinking about getting a used sextant and would like ot have it checked out? Or should I just get a modern day plastic one?

You can call and talk to the techs at Captain's Supplies (formerly Captain's Nautical). The repair and refurbish quite a variety of marine instruments including sextants. They are located in the Ballard area of Seattle.

https://www.captainsnautical.com/

[ArmyDaveNY]

Originally Posted by dofthesea

Anyone have a resource for a Co that restores sextants or calibrates them? Im thinking about getting a used sextant and would like ot have it checked out? Or should I just get a modern day plastic one?

Try New York Nautical
200 Church Street
New York, New York 10013
(212) 962-4522
www.NewYorkNautical.com

The last time I was in there several months ago they were repairing a number of sextants. Good luck with your repair.

[jmschmidt]

There is one in Seattle. Can't remember the name. It's on the street that runs north and south on the west side of Queen Ann Hill and over the Ballard bridge. Usually cheaper to buy new rather that overhaul unless you have a valuable museum piece.

[Seerauber]

The sextant is still one of the handiest, and safest,instruments when coastal cruising. As it records in degrees true, as do paper charts, it is a cinch taking sextant horizontal sightings combined with a three pointer plotter and - voila ! - where you mark, that is where you are.
AND there is no way you can have a power failure!!

[UNCIVILIZED]

People seem fixated on sextants for purely celestial nav, but they have a lot of other navigational uses, including coastally & piloting. Such as determining ranges to various known objects. And when you're navigating, the more ways you have to cross check your position the better. Relying on only one source of data for your position amounts to poor seamanship, period. Regardless of what that data source is. GPS, or other. Particularly as there are plenty of incorrect charts out there. Incorrect in that they were created based on surveys done a decade, or a century ago. And or, that things have changed in the area that you're currently navigating in. Such as that new channel that's being dredged, or underwater obstructions in an old but commonly used one, etc.

[IslandHopper]

Originally Posted by UNCIVILIZED

Particularly as there are plenty of incorrect charts out there. Incorrect in that they were created based on surveys done a decade, or a century ago. And or, that things have changed in the area that you're currently navigating in. Such as that new channel that's being dredged, or underwater obstructions in an old but commonly used one, etc.

1. If you have the current edition
2. If you know how to read them eg; error/zone of confidence, or “ZOC” notes.
3. If you know what Notices to Mariners are and how to get them (including T & P's)
4. And know how to apply them

Then most of the above shouldn't be to much of a problem, having said that, "bumps in the road" are still found today and will continue to be found for some time yet. Those newly found nearly always end up as a correction on a chart (literally thousands are every year worldwide) so if you luckily or unluckily find one, report it to the correct authority (and not just some crowd sourcing app distributor), ongoing official hydrographic surveys aside, that is how it's done............