Celestial Navigation for Dummies

[H3LlIoN]

I'm trying to learn this...can someone recommend good books/websites/workshops/etc that are helpful?

What other books has any one read that are MUSTS for sailing and particularly for blue water cruising?

Thanks


P.S. - moyer manual. There. Already got it. What's next?

[Mo]

Dead Reckoning...I'll stress it.

I'd bet I know 10 Master Mariner Captains. None of them (one is 73) have used it after passing that chapter in Marine College. Just to give you an idea:

-One ocean going tanker captain MM.
-One Container Ship Captain MM
-Four Harbor Pilots that were MM ocean going
-One Oil Rig OIM that was MM ocean going
-Two Coast Guard Skippers MM
-I can't remember how many Frigate Skippers I know and Exec officers....and MARS officers.

No one wants to hear it but this is it. If the Sats / or your gear go down and you can't use GPS...go for dead reckoning. As long as you know your general position you should be able to keep yourself out of trouble.

Story Time: My friend Fred was a Search and Rescue Pilot for about 20 odd years. After retiring, he and his wife were doing a passage from Halifax to Caribbean Sea...ocean run. Got caught in Tropical Storm on their Alberg 36. (or 37). The boat turtled and water came in through the vents and took out all the electronics, radio and nav gear. Fred dead reckoned to Bermuda and made repairs...he told me the biggest fear was believing in himself that his time, distance, speed would get him bang onto the little island. He nailed it first shot. I asked him if he had a sextant...his answer: "all I needed was to have an idea of where I was when everything went for ****...and where I was going. All Dead Reckon from there. If you want to learn something...learn to Dead Reckon" .... so I did.

I talked to my skipper friends about that and they said the same. The waters are charted, always know where you are as you travel...most plot a position every hour, then find an spot to go, and dead reckon for it.

I think if you learn how to dead reckon confidently, you will have a much better chance ... Imagine if you had 2 broken arms, a broken ankle, 3 teeth knocked out and the wife p'd right off at you (she broke up too) ...dead reckoning...nothing ever goes wrong on our terms my friends.

To be honest....I could have used a sextant a few mornings waking up after a good "rum run" wondering "Where TF am I"...all jokes aside. Dead Reckoning will save you.

Edit: We can all practice this even on short runs to stay sharp. If all goes well it will never be needed...but if you need it don't let experience be the teacher...take the lesson first and gain the experience on your own time.

[H3LlIoN]

good info

Thanks for the info, Maurice. Knowing celestial is not so much for a backup as it's just been something I'm curious to know and understand. Based on your advice, it sounds like I should learn dead reckoning too, so I will further my understanding. I'm already halfway decent from flying/diving experience. How do you dead reckon currents/drift though? With planes, you have the advantage of landmarks.

-JM

[Mo]

Hi H3LlIoN

Most dead reckoning depends where you are. Typically, something goes wrong in bad weather. The important thing is to know where you are when things go wrong. In bad weather the body takes a beating, crew may be incapacitated etc.

There is a course you can take for dead reckoning...Your version of the America Yachting Association (we have Canadian Yachting Assoc) can provide the course. I think it's call "cruisers course" or something along those lines.....you may even find it here on the internet. It takes practice and then you can almost do it mentally while you are travelling. The trick is the practice.

If you are reasonably close to land and cannot decipher landmarks due to weather, dead reckon for a clear, easily entered, safe harbor. If you can't do that. the best bet is to head out to sea and ask for local help if able. Charts will give a reasonable idea of currents, but if you cannot see...out to sea.

The main thing to remember is that if the weather is bad and you cannot visualize landmarks, sea room is your safety zone. Need to stay away from shoals as rough weather will rise up the sea there. Here it is all rock...few ever survive the rocks in a storm even trying to swim for it.

http://www.sailnet.com/forums/learning-sail-articles/18830-dead-reckoning-calculations.html

Currents are just part of the calculation if you see them noted on the chart.
-their direction, speed, length, width....all in relation to the direction of travel and speed the boat is making.

(I am talking offshore currents when I speak of currents. Local currents are best described by local knowledge, especially inshore....the local fishermen can tell you in minutes what it would take 2 hours to read and decipher)

[sastanley]

H3 - Some DR competence comes from experience when NOT in trouble.

I've cruised the Chesapeake my entire life. My Dad taught me (and he survived by) half-assed navigation when I was a kid. His finger sliding across the chart to the compass rose was the parallel rule. I've learned a few new tricks since then (LORAN was not around when he & I were cruising together..and if it was we did not have a receiver on board), but his seat-of-the-pants navigation, and ability to look at a chart and then translate that into the land contours we saw was a great help to me in DR navigation. This also helped a lot when cruising the Caribbean. The primary adjustment has been adding a GPS for actual pinpoint positioning on a chart and then compare the unfamiliar surroundings to the chart..I've seen most of the Cheseapeake at least twice, & much of it as a kid with my Dad, so things become familiar quickly...however, the skills that were acquired in the Chesapeake carry over into unfamiliar territory like the Caribbean as mentioned above. The currents & tide stuff comes from listening to the reports prior to heading out/during calm cruising time or at least high/low tide & vicinity station weather reports, or asking the locals if in unfamiliar land, or remembering the last personal observation before you are guessing like a crabpot or daymarker where you could observe the current. All this info stacked back in the short term memory banks over coffee in the AM becomes invaluable when the stuff hits the fan in an afternoon squall or multi-day bad weather event.

Laptops & associated SW is great..I use them for fun, but coming into ANY port, my main reference is a paper chart. I am very glad I was taught to read a chart and look ahead (on the chart) 10 miles at a time (like above, when weather goes bad, you must rely on your last visuals off the boat to compare to your chart)

Actually, when things are quiet and under control it is great to use the electronic aids to look ahead 20 or 30 miles.

I know I am not helping your initial question much. I'd love to learn celestial nav, but I simply have other things higher on the priority list.

[tenders]

Dead reckoning (actually ded reckoning, for DEDuctive) is an integral part of celestial navigation. In fact it's an important part of any piloting course, too, and isn't all that complicated either. I'd definitely agree, start with that.

Taking and reducing star shots on a small boat at sea is incredibly frustrating. There are only a few minutes at dusk and dawn to do it, and if you're really going old-school, it takes a ton of preparation...unless you're going to use your friendly iPad or iPhone to identify the stars as they rise; and if you're going to do that, then why not just use GPS?

My suggestion would be to first learn to do sun lines, especially one taken at local apparent noon, and run a few from a dock with a southern exposure so you can get a decent view of the horizon. You'll then have some appreciation for how inaccurate and frustrating a sun shot, never mind a star shot, to say nothing of a moon shot, will be on a pitching, yawing, heeling sailboat.

[TomG]

I remember trying to learn celestial navigation as a young Coast Guard officer candidate. We had wonderful equipment and superb instructors along with a grand classroom (the tall ship "Eagle"). What I took away from that course was how incredibly frustrating reducing sun lines were... these were noon sun shots on pretty days, with fantastic equipment and instruction and that was all I had to do. I learned that it could be done, but that it takes a lot of practice and patience to get reliably competent to trust your own solutions. I got pretty good at ded reckoning, but celestial remains in the realm of "dark arts" for me.

Tenders' advice is good: start shooting local noon and dusk/dawn sun shots with a clear southerly exposure from the dock then work your numbers down given those advantages. Then imagine doing it on a small boat...

[Al Schober]

Celestial is just spherical trig using 3 spots on the surface of the earth. These are your position (a guess), the point directly under the body you're looking at, and the pole in your hemisphere. The measured altitude of the body serves to refine your guess.
To solve the triangle, tradition uses the 'Tables' but I find it easier just to use a pocket calculator with trig functions.
Biggest problem I had was in figuring out what star I was looking at so I could calculate it's position using the Ephemeris.
Last time I used my sextant was to figure out the height of some trim work on the church so we could order a big enough lift to do the painting!

[msmith10]

I don't remember his name, but one of the "experts" in celestial navigation, an author and teacher, died a year or so ago. Prior to his death, even he joked about how he had stopped using the techniques, admitting that celestial navigation was essentially just an academic exercise now.
Maybe the same controversy happened 500 years ago with the introduction of the compass.

[Dave Neptune]

Time

JM, I went through the "hassle" of learning the "work a site" and for my life I could not do it today. I keep a sextant on my boat just to take up space. If you are serious about it I suggest you master the noon shot to get close on your latitude and DR for the rest. If all things fail on your time of need without accurate time the sextant is of little value for longitude.
Years ago I read a story about some "kids" taking a trailerable boat from Marina del Ray to Hawaii and all they had was a compass, water, beer, canned stew, bagged snacks, pot and a set of flight schedules from LAX to Hawaii. They made it in just over four weeks by looking up at the contrails. The story was in Pacific Skipper magazine.
I have thought of dragging the sextant out but only when really bored.

Dave Neptune

[sailhog]

Years ago I read a story about some "kids" taking a trailerable boat from Marina del Ray to Hawaii and all they had was a compass, water, beer, canned stew, bagged snacks, pot and a set of flight schedules from LAX to Hawaii. They made it in just over four weeks by looking up at the contrails. The story was in Pacific Skipper magazine.


Dave Neptune

That boat must have been stuffed to the headliner with pot....

[joe_db]

I found celestial to be quite inaccurate in rough weather. When you're in heavy seas, you just can't brace yourself and have both hands free for a good shot. I figured +/- 20 miles was about as good as I was getting. Going to Bermuda we mainly just DR'ed our way into RDF range.

The LORAN installation coincided with the last time the sextant was ever used. I believe now you can get software like this http://www.landfallnavigation.com/celestial.html that makes it much much easier. Of course now you need a computer. Don't forget a WWV receiver - you'll need the time in case the GPS dies and you can no longer get perfectly accurate time from it.

[Bigeye]

Bowditch is the Answer

The American Practical Navigator: Bowditch

The Classic used to train average seamen.

[Administrator]

I'm sorta like Dave. I bought a cheap sextant, studied, used it successfully once (on land), and never touched it again.

I do think I recall seeing ship's officers using them aboard cruise ships while at sea. A form of maritime hazing?

Anyone with even a passing interest in celestial navigation should read Longitude by Dava Sobel. Forewarned. Don't start it if you don't have time to read it cover-to-cover without putting it down.

Bill

[Mo]

Maritime Hazing...LOL...

I could see how that would go;
"right over the side".