I had a dream last night that my crew and I were sailing into dangerous waters.  My neighbor's chickens woke me up so I didnt find out what happened,  but it made me think of the great voyages of discovery during the sailing ship era.

If you had a chance to go back in time to witness one of those great voyages, which would it be?

What would you say to Cook, or Magellan,  or Darwin, Columbus,  Ericson,  or a hundred other voyagers?  Would you even want to be a sailor during those times.  If you do then what would you prefer; whalers, china tea cutters, general merchants, Navy ships, or something else like a British barge or a pirate ship.

I think I would have enjoyed the china tea runs or perhaps a coastal merchant.  If I was to witness some great adventure it might be Darwin on the beagle, or one of the polar expeditions.  

It almost goes without saying though that I wouldnt want to work as an ordinary seaman.  I'd have to be a mate or navigator or captain or better yet - owner.

Anyway, I'd be interested in your perspective.

Cheers

Ok, so this is kinda difficult to admit, but I've never taken a shot of Polaris.   I know, it's the most basic thing one can do with which to navigate, but I've sort of shied away from polars until recently.... I will soon give it a go. 

I do have, though, a preliminary question.

What ever happened to the A0, A1, A2 reduction?  All I see now is some Q method ive not yet grasped.  Please tell me what IS the current prevailing Polaris reduction and what tables are required.

Thanks in advance
Stupid me

Hello esteemed members of this forum.
I heil from Southern Coastal Florida and I'm dusting off my Celestial Nav abilities  to keep my brain going.
Merry XMass to all.
JP

The American Practical Navigator (Bowditch) 2019 version is on the site.

It's perfectly organized by Sections and Chapters allowing you to easily find and download the material you want.

You can download the entire work also.


Get it here- 2019 Bowditch- American Practical Navigator

Hello fellow CN freaks,

Its been 2 years since I logged in last.  I hope some of the old shipmates are still breathing.

I was wondering if any of you guys have become more active in celestial navigation since the covid hoax began. 

I started taking more shots with an artificial horizon and with no little difficulty.  For some reason my lops are always 4 or 5 nautical miles short of my gps fix.

I've gone over the math a hundred times, checked my time, checked the sextant, checked everything. 

Recently I began to wonder if my sun shots are wrong.  My habit is to bring the sun down to the AH then touch the two suns with the AH sun on the bottom.  Do I have this backwards?

I add index error, divide by 2, then add altitude correction.  Am I missing something?  should I be using SD, semi diameter,  instead of altc, or is there a step of which I'm unaware?  I dont add dip to AH shots.

Anyway,  I hope to hear from some of the old gang; including admin.

Merry Christmas

Does anyone have experience with bubble sextants?  I recently acquired one, but am finding it difficult to move the Slow Motion Knob.  When I first inspected it, the knob seemed to moved freely.  Then I mistakenly turned the winding crank only one click.  After it wound down, the knob was extremely hard to turn, almost as if it is locked so the user can get a reading?  Maybe there is a way to unlock it?  

Any help is greatly appreciated!

Mike

I found an Ebbco sextant online for a really great price and had to have it. Everything on it is in top shape except a couple of the shades were darkened to the point of uselessness or someone replaced them with opaque material. I have some theatrical gels so it was simple enough to fix. 

I could probably make some adjustments to the mirrors but the error has remained consistent over several days. Its probably best to just subtract from the sighting, rather than go messing around, loosening things ups that might not tighten again.

Yesterday was my first attempt at a sight reduction and I found it works quite well. I rather like it. Given the poor conditions, wind blowing the artificial horizon around and pushing tree limbs into the line of sight, the accuracy was well within expectations especially for a new piece of gear. I have a Davis Mk15 and the Ebbco (so far) seems a little more consistent and accurate. The error varies more with the Davis.

Hi All. I'm currently studying Celestial Nav, and have a problem I'm hoping to have someone provide a little help with if you wouldn't mind.  http://www.seasources.net/youtube%20vide...uction.mp4. If you jump about 5mins 20 secs into the video, there is a Problem 3.  I don't get the same answer, and just can't see where I'm going wrong.  Thanks

Gentlemen,  I found the following piece kind of interesting.

Earth's magnetic north pole, which has been wandering faster than expected in recent years, has now crossed the prime meridian. 

Magnetic north has been lurching away from its previous home in the Canadian Arctic toward Siberia at a rate of about 34 miles (55 kilometers) a year over the past two decades. The latest model of the Earth's magnetic field, released Dec. 10 by the National Centers for Environmental Information and the British Geological Survey, predicts that this movement will continue, though likely at a slower rate of 25 miles (40 km) each year. 
This model is used to calibrate GPS and other navigation measurements. 

Earth's magnetic field is produced by the churning of the planet's iron outer core, which produces a complex, but largely north-south magnetic field. For reasons not entirely understood but related to the planet's interior dynamics, the magnetic field is currently undergoing a period of weakening. That's why magnetic north is drifting. 

As of February 2019, magnetic north was located at 86.54 N 170.88 E, within the Arctic Ocean, according to the NCEI. (Magnetic south similarly does not line up with geographic south; it was at at 64.13 S 136.02 E off the coast of Antarctica as of February 2019.) 

Scientists release a new version of the World Magnetic Model every five years, so this 2020 update was expected. In February 2019, though, they had to release an update ahead of schedule due to the fast clip of magnetic north's movements. The 2020 model shows the "Blackout Zone" around magnetic north where compasses become unreliable and start to fail because of the proximity of true north. The new maps also show magnetic north east of the prime meridian, a boundary the pole crossed in September 2019, according to Newsweek. The prime, or Greenwich, meridian is the meridian that was set as the official marker of zero degrees, zero minutes and zero seconds in 1884;iIt runs through the Royal Observatory at Greenwich in England. 

Related: What If Earth's Magnetic Poles Flip?

It's currently unclear whether Earth's magnetic poles are headed for a flip-flop — switching north and south — or whether the magnetic field will soon strengthen again. Both events have happened in Earth's history without any notable effect on biology. However, modern navigation systems rely on magnetic north and will have to be recalibrated as the poles continue to wander. Already, for example, airports have had to rename some of their runways, which have names based on compass directions. 

Gentlemen,  found  an old 1940 book US Naval Academy,  Plane and Spherical Trigonometry , by Kells, Kern, and Bland.  Admittedly,  majority of the book is trig and exercises, but there are a few spherical trig items which will be helpful if the battery  is dead.  What I personally like about this book, it  does not consider its reader too knowledgable and therefore explains everything to the bone. Which is as a refresher I personally found helpful.  Just for information, of course. ;> ;>

Thank you