Navigation Using an Artificial Horizon

[@JohnSwain-n2x]

I'm a retired Master Mariner and navigated before GPS, in the 70's, but I didn't know about the pan of water method of finding double the suns angle from the actual horizon. This is the method of finding the suns true angle above the horizon from an inland location surrounded by hills. I'm Impressed. Otherwise my navigational knowledge using a Sextant is almost complete after using one daily for years.

[@mikefochtman7164]

Fun bit of trivia I'd mention. I tried doing this last summer during the solstice and came across a 'gotcha'. I live about 45 degrees north, so on the summer solstice, the sun is about 68.5 degrees above the horizon at noon. That meant my sextant would be reading (using the artificial horizon) about 137 degrees. OOPS!!! Mine (a Davis model 25) doesn't go that high. lol So I waited a couple months and tried again, got fairly good results (well, good for an amateur like myself).

[@1616katerst]

Excellent. Thank you. No doubt I’ll watch more of your videos. The Ancient Greek info sounds intriguing to learn. I’m sharing celestial navigation with my 88 yo mom cause it interests her as much as me. Old school rocks !

[@josephlai9759]

Thank you, Bob. I like your unique way of explaining the fix by stars. It is refreshing.

[@williamkuhns2387]

Very black coffee or used motor oil in a flask with funnel makes (non mercury) fluid. In the old days mercury was used in artificial horizons that had heavy cast iron or lead base pans to keep them sliding on a heaving deck. The Davis Co. makes a good plastic artificial horizon.

[@tkolkebeck]

I was wondering if you could explain how Amundsen used a sextant to determine how to get to the south pole and also to know that he was at the correct location?

[@sliderulesandmathematics9232]

pretty much the same way I found my house in Michigan. Lewis and Clark also used an artificial horizon on their sextant readings.

[@jima4656]

Good information was given. Thank you for that. The title was misleading. People looking for information on 3 point fixes would not find this video by searching titles.

[@jima4656]

I tried using an artificial horizon to take a noon site in south Florida the other day. I wasn’t able to do it because the sun was at roughly 70⁰ above the horizon. Twice that would be 140⁰, but my sextant only reads up to 120⁰. I was able to take a reading a few hours later when the sun was lower in the sky. I'm curious which sextant you are using.

[@sliderulesandmathematics9232]

I use a Davis Mark 25 (remember I am up by the 45th parallel) and a Link Bubble sextant.

[@danielhulme5577]

Thanks for posting this is a very good instructional video.

[@marcg1686]

Hi Bob. I have used the roof of my car as an horizon. My intercept was less than 20 minutes. 😃

[@hmalbet]

Thanks Bob...I've been waiting for this

[@tomwhent8073]

Great video! You lost me at "phone pole" though 😂

[@sliderulesandmathematics9232]

What do you mean?

[@tomwhent8073]

@sliderulesandmathematics9232 a poor attempt at humor! No one seems to use wires for telephone communications these days. My kids didn't know what to make of a rotary dial phone! I enjoyed your video very much. Thanks!

[@omanamanikkan9701]

Is that very expensive

[@sliderulesandmathematics9232]

No about $250 for a good one brand new. Davis mark 25 is what I have.

[@adumont]

Where is the previous video?

[@adumont]

Nevermind, found it. Great videos BTW!

[@ReinoGoo]

I know a better way to illustrate what we measure with a sextant and why we use a horizon (and it is more difficult to abuse by flat earthers): You have three parallel rays from an object in the sky, to three angles on the same ray for zenith. The middle one is to a right angle, between tangent and zenith on the horizon. The upper one is a zenith angle on the sextant. The lower one is a zenith angle around the globe, from the ground point for the horizon to the ground point for the object in the sky. The dip correction is for the angle to the ground point for the sextant.

[@photosphotos]

The horizon is horizontal… not curved.

[@sliderulesandmathematics9232]

You sure about that?

[@photosphotos]

@@sliderulesandmathematics9232 large bodies of water cannot conform to the exterior of large shapes.. I’m not sure what else you require. The the horizon is horizontal, it’s a fact and you can take it to the bank.

[@sliderulesandmathematics9232]

so you keep saying without proof. so what?

[@williamwood709]

Can't normally see around corners without a mirror

[@marcg1686]

@@photosphotos The horizon around you is a circle of equal altitude. That's why it's flat. You're living on a globe with a mean radius of 3440.1 NM.

[@tonywhitcombe8357]

we only have 1 horizon and its not geometric , you cant get an elevation angle from a curved surface , the black swan proved that the earth is flat , its beyond the limitations of the globe math

[@sliderulesandmathematics9232]

yet, there it is

[@karhukivi]

The angle is measured from the tangent to the curved surface, not the curved surface as such. A builders level measures this tangent also. You don't know what you are talking about!

[@sliderulesandmathematics9232]

No he is just parroting Nathan and qe

[@marcg1686]

It's been about two years since flerfers discovered the sextant. Two years and you still don't understand how celestial navigation using a sextant actually works.

[@sliderulesandmathematics9232]

I love to screw with them and ask them how to use the Nautical Almanac to calculate the GP of a star. When they find out they need to account for the rotation of the earth (time) they melt down.