zoidberg
Well-known member
Would you buy a sextant these days? Would you acquire the necessary skills, or just carry an aged copy of 'Blewitt' on board and hope to muddle through....?
Sextant skills
- Thread starter zoidberg
- Start date
Sandy
Well-known member
Got mine years ago. As for the Blewitt book that was thrown in the bin for something more understandable.
Blueboatman
Well-known member
Gosh I still have my ‘ kit’, tables and Blewitt
Retro can be very fashionable .. in time ?
Retro can be very fashionable .. in time ?
Praxinoscope
Well-known member
I still practice using my sextant even though I don’t do any ‘blue water’ sailing any more, so instead of being stowed on board it lives on a shelf at home.
If. I was planning a major deep water cruise then I would certainly have it on board, satnav is great but I still feel that electronics and salt water aren’t happy bedfellows and the extant is independent of the ‘vagaries‘ of electronics.
If. I was planning a major deep water cruise then I would certainly have it on board, satnav is great but I still feel that electronics and salt water aren’t happy bedfellows and the extant is independent of the ‘vagaries‘ of electronics.
Minerva
Well-known member
I won a Sextant on eBay after a few wines years ago. Pulled it out during lockdown for the first time and played with it. Using a celestial calculator app on my phone and the sextant I ended up getting a pretty accurate result at around 5miles adrift of my actual position. I managed to replicate this several times during this summers' cruise.
As a combo together I'd say they are well with having stashed away. Phone doesn't need internet to do the sums and whilst it derives its estimated position from GPS, you can manually put in estimated lat/long to start the sums off. App was free fwiw
As a combo together I'd say they are well with having stashed away. Phone doesn't need internet to do the sums and whilst it derives its estimated position from GPS, you can manually put in estimated lat/long to start the sums off. App was free fwiw
Buck Turgidson
Well-known member
I use the same. Saves messing with tables and proforma but I can do it either way. The hard part is taking the sight in anything but flat sea so that’s what I practice. It can be a bit hit and miss on my rolly little yacht.
davidaprice
Active member
GPS is also an excellent precise time source when taking sextant sights 
capnsensible
Well-known member
So is my ten quid Casio watch....?GPS is also an excellent precise time source when taking sextant sights
capnsensible
Well-known member
Agree. Both Mr. Cunliffe and Mr. Bartlett have made the whole thing much easier to grasp. ?
zoidberg
Well-known member
Yeah! None o' that 'obliquity of the ecliptic' nor 'precession and nutation' to wrestle with.....
lustyd
Well-known member
Both of them failed me entirely*, their approach just seemed backwards and overcomplicated. In the end it was a YouTube video that explained it nicely and started with the how it works before then going into what things are called. Much better content.
* edit to add, failed me for celestial, both authors did a fine job with other topics
bedouin
Well-known member
It is very difficult to use a sextant accurately without an up-to-date Nautical Almanac. which costs a number of beer tokens a year.
Presumably there are apps etc that can calculate that data on a PC or smartphone but it rather misses the point of the sextant if you need your (GPS equipped) smartphone to use it.
But if I were planning to cross any oceans I would certainly pack the sextant and buy the Almanac "just in case".
Presumably there are apps etc that can calculate that data on a PC or smartphone but it rather misses the point of the sextant if you need your (GPS equipped) smartphone to use it.
But if I were planning to cross any oceans I would certainly pack the sextant and buy the Almanac "just in case".
TiggerToo
Well-known member
what app did you use?
Neeves
Well-known member
Mr Zoidberg,
You have asked more than one question, I think.
How many value the use of a Sextant and the necessary calculations (though this latter part can be more easily completed now with some for of electronic support)
and
How many feel the need for the expertise in case of the ultimate collapse of all systems.
there may be other reasons - that I miss.
I wonder how many GPS have actually failed on a blue water crossing, the owners did not have a back up and did not maintain a DR such that when they 'found' somewhere - they had no idea at all what they had found.
Is this not a bit like asking - how many carry a spare fan belt (and know how to replace) - or grill a tuna having rubbed 2 sticks together.
Jonathan
I carry a sextant, historically I could use it and if push came to shove - I could still use it - but if ever........?
You have asked more than one question, I think.
How many value the use of a Sextant and the necessary calculations (though this latter part can be more easily completed now with some for of electronic support)
and
How many feel the need for the expertise in case of the ultimate collapse of all systems.
there may be other reasons - that I miss.
I wonder how many GPS have actually failed on a blue water crossing, the owners did not have a back up and did not maintain a DR such that when they 'found' somewhere - they had no idea at all what they had found.
Is this not a bit like asking - how many carry a spare fan belt (and know how to replace) - or grill a tuna having rubbed 2 sticks together.
Jonathan
I carry a sextant, historically I could use it and if push came to shove - I could still use it - but if ever........?
Minerva
Well-known member
An app called "astro Calculator" on android - does the sums for you, shows you the working and plots your position. Really quite good
RobbieW
Well-known member
Thanks, I'll watch that later. My experience was that most books, and the RYA course around 2004, wanted to teach me spherical trigonometry to start. What I wanted was a set of steps that would get the required result, writing my own pro-forma helped with that. Understanding that the technique is a fancy transferred position line fix helped too
capnsensible
Well-known member
When we ran our sailing school, nearly all our ocean students required the qualification to advance I their chosen commercial career path. Mrs S still mentors the course for an online training centre.
Others are just curious or want to keep something to do on an ocean crossing. That's how it started for me. Its not difficult and to be honest much more satisfying than staring g at a screen that anyone an do.
But it's not compulsory.....
capnsensible
Well-known member
Cunliffe and Bartlett for that for most people. Pro formas.Thanks, I'll watch that later. My experience was that most books, and the RYA course around 2004, wanted to teach me spherical trigonometry to start. What I wanted was a set of steps that would get the required result, writing my own pro-forma helped with that. Understanding that the technique is a fancy transferred position line fix helped
Buck Turgidson
Well-known member
Also for iPhone and iPad. It’s what I use on my none gps iPad ?
lustyd
Well-known member
The nice thing about this video is that it does neither of those things first. He shows how and why it works without trigonometry or really any technical information and then works back from there to how the calculation works to get you the result. All of the others get too bogged down in detail too early on and so I found it too disconnected to really follow. The video solves that really well, albeit with a lot of rambling!