Have Sextant, will travel!
Without a GPS chartplotter to guide us safely southward, I doubt Rebecca and I, or the majority of cruisers for that matter, would have made it this far. A GPS chartplotter, with reliable cartography (our Garmin GPSMAP 546 has been excellent for us) is indispensable on a modern cruising boat. In fact, many cruisers, ourselves included, carry at least one backup system, just in case. Paper charts? Of course we have those too, and guide books as well for each port that we hoped to enter. We always consulted them when planning passages or approaching tricky anchorages. Combined with the electronic navigation aides that we carried, I think we had the best of both worlds.
But what about the worst case navigation scenario? That being, a lightning strike which takes out all electronic gear on board, while you are out of sight of land, crossing an ocean. What can we rely upon then to point us safely to land? Of course those previously mentioned paper charts will come in handy but to tell us exactly where we are on the charts, we could reply upon a nautical sextant, the traditional tool for plotting fixes.
Is such a device necessary for those heading down the thorny path as we did? I would say definitely not. For those crossing oceans though, knowledge of how to use one, and of course carrying one on board, would certainly add points to the black box.
When I discussed this subject with our friend Pete, the Captain on Coral, he actually gave me one that he had on board as a gift! Isn’t that awesome? That’s right, we now have in our possession a Davis Master Sextant Mark 15. Do we know how to use it? Of course not, even though I downloaded the user’s guide written by Andrew Evans which promises that I’ll have the basics down in a matter of hours. Included with Pete’s gift was also Tom Cunliffe’s Ocean Sailing book. It was either that book or perhaps it was Cunliffe’s book Celestial Navigation that he told me I should read on the subject. Either way, this should keep me busy for a while.
Bonus: I found a bunch of celestial navigation links here.
You will get the hang of it. One trick I was taught is to use a stick or old broom handle to rest the hand holding the instrument. This will greatly increase your accuracy.
I would like to find someone here to give me a 10 minute intro lesson. I think I could figure it out after that.
Three thoughts for you.
1. Use dead-reckoning when you have problems. If you maintain your log, maybe just a deck log, it can become very important. It has done for me.
2. Sextants are good for establishing ‘distance off’ provided the object you are measuring from is big. eg a mountain. It is almost impossible just from a headland lighthouse sort of height.
3. You can use it horizontally to measure the angle between to objects identified on a chart. I have never done this but my father did as it was accurate and our handbearing compas was not.
(4. He used celestial too, I haven’t yet.)
Mike
Interesting. I have no idea how to do any of the things you’re describing (other than the DR), but I’m sure I’ll figure it out.
That’s a cool way to get LOP’s, rather than using a compass, you use the sextant. Nice idea!
Are you familiar with how to work a sextant Lynn? If so, perhaps I could beg a few minutes of your time for a quick intro lesson.
Great Post! Tate and I are going to get a sextant and learn how to use it before our big trip, to be prepared no matter what..Now, just have to make sure not to lose the sextant!
The one I have has a lanyard attached to it. Keep that around your wrist and it’s doubtful you’ll drop it overboard, unless of course you fall overboard with it. 🙂
keep us up to date on this… as an armchair sailor this is something that has always intrigued me… not enough to drop the cash required ( especially considering the lack of value on land, and the raw number of times I have actually seen an entire horizon filled with sea )
seems that since you have become certified and now have a sextant… should you consider a wooden boat with multiple masts and start using the word ‘yar’ more? are you really allowed to talk to land-lubbers anymore?
The last thing I want is a wooden boat. I actually like to do things OTHER THAN boat maintenance. Yar!
On a related note, the other day I was in Weems & Plath in Annapolis to pick up our ship’s clock which was in for repair (movement replaced – no charge, BTW 🙂 ) and there was apparently a company strategy meeting going on in the next room. I overheard them saying that today, pretty much every cruising boat has an electronic chart plotter and hardly anyone carries paper charts anymore. It sounded as if W&P was trying to figure out haw the direction of navigation was going to affect their business (NPI).
they are having their annual tent sale during the boat show next week. I wonder if there will be a lot of charts (and sextants?) on sale.
Be there with your cash, Kirk! And have some oyster shooters for us.
In the chunk of the world you travel in, (and I hope to be joining you soon) just kind of head NNW…kind of hard to miss North America, isn’t it?
Yes, the Pacific would be a different story.
I took a course through the US Power Squadron which taught how to use the sextant. There are tables and forms you use to ‘reduce the sight.’ It takes awhile to learn how to do it – or, there are computer programs (if your computer is still working) which will reduce the sight for you. You need a very, very accurate time piece. I don’t remember exactly, but for every second it is wrong, you can be off by something like a quarter of a mile.
I only ever tried it once, on a little boat on Lake Erie 15 years ago. (Moon shots, lower limb.) We were bouncing around causing me to be off by so much that it was almost useless. The timepiece was the GPS so it was spot on. I had others check my calculations and they were right, too. It was just the sight which was wrong.
On shore, however, I could come up with readings which were within a quarter of a mile. (A plastic Davis sextant though in the winter in NY State had to be recalibrated every sight – the warmth of the hand, I discovered, affected the reading, each one being further and further off.)
I would suggest keeping the sextant for a hobby. Get a spare GPS and lots of extra batteries. Put the spare GPS in a Faraday cage in a lightning storm. (A microwave – still plugged in so it’s grounded will probably work. Not sure if your oven will work – they’re stainless steel and usually will protect against the surge, but not, as I understand it, the EMF.
Good luck and have fun with the learning curve.
Yes, I did read that the time is VERY important. Perhaps I should have one of those $35,000.00 Rolex Yachtmaster watches? 😉
My first sextant fixes were off by 75 miles… which put us on the wrong side of the Cascade Mountains.
bob
s/v Eolian
Seattle
Ooops. Did you improve after that, or run into the mountains and sink?
Sorry to come back again on sextants, but there are simple ways to keep the instrument much steadier than merely relying on your balance. Someone above mentioned using a broom handle, this works well.
Another way is to tie a cord to the handle and drop the end on the floor. Put your foot on it and pull upwards so it is tight (at the right height of course). This is surprisingly effective, as well as simple. You can keep the horizon lined up while sighting the sun/moon/star. Reasonable readings and accuracy become feasible.
The cord method also works well with a camera, particularly for video. Tie onto something screwed into the tripod fixing, put your foot on the line and pan (more) smoothly.
The ‘distance off’ measurement I mentioned above should have been covered on your course. The tables for it are in your almanac.
Mike
Nice tips for keeping it steady. As for the distance off measurement being covered on our course, we had no instruction is using a sextant.
Google “Sextant_Users_GuideV6.pdf” for some help on the math and basic concepts… what an awesome gift!
The line in the post that says “Users Guide” actually goes to that very document.
Mike,
I’d like to go back to the first part of your post on the chartplotter issue and raise a topic of discussion. Do you see anyone out there using iPads for chartplotting with Navionics software? This seems to be a good option for us on our boat. We would buy 2 of them and pack one away safely as a spare in the event that one was damaged or failed. I’m pretty happy with the Navionics software so far on my PC and they do have an integration to iPad. The big issue for us is budget. We can get multiple iPads for less than the price of one chartplotter and this means we get out there sooner.
Comments??
Deb
S/V Kintala
http://www.theretirementproject.blogspot.com
Hi Deb
No, I have not seen anyone using an Ipad for their primary chartplotter. I not sure on the math of buying two ipads for the price of one chartplotter. A new ipad is comparable in price to the Garmin that I linked to. The Garmin is also meant to be mounted in the cockpit, exposed to the elements. It also outputs NMEA dats so that it can be tied to the autopilot. I’m not sure if the iPad can do that. I would love to have an iPad for a hundred reasons but I would definitely not replace my Garmin with one.
The problem is that they aren’t waterproof. There is a lot to be said for a fixed chartplotter that sits at the helm that has a big screen, is waterproof, AND can be hooked up to your DSC enabled radio (with the MMSI number plugged in, of course) so that the red panic button actually does something for you. If you have an AIS receiver, you can also plug that into it…
What she said (even though I know there are waterproof (water-resistant?) cases for them.
It looks like a medieval torture device! I’ve been designated ‘navigator’ and wanted to get into it and now a bit scared. Ugh! #sigh… albeit, pretty much everything about the idea of cruising scares the poop out of me.
On that note, when we meet up (note, I did not say if) I want lessons in martial arts so I can kick the ass out of whatever pirate I need to, okay? (The pirate in question might really by my BF, but he’ll deserve it, I promise. You’ve met him… Michael Brown in Baltimore on La Vie Dansante)
Oh, HE definitely deserves it. I’m sure of that! 😉
http://www.ehow.com/how_8055991_use-sextant-navigation.html
Mike I found this on the internet. Might be a little basic but hey, thats where we all start right. If you ever get this worked out let me know how to do it. While not very practical it could be useful.
Thanks Izzy. Basic is what I need!
If you are having a particular problem with my Sextant Users Guide, or if there is something that can be better explained, then I would certainly like to know. The beauty of publishing a book on the internet is the ability to make changes.
Andrew Evans
Hi Andrew
Thanks for the comment! As a matter of fact, I read the basic theory in your book and I think that I already have an understanding of the basics behind this. Being a hands on learner though, it would be nice if I could find someone here to give me a bit of a head start in terms of how to do the initial setup, etc. with my sextant. I think with that done, your book will be perfect to teach me how to use it.
Show me I see you, tell me I hear you, help me do it and I learn!
Exactly.
There are lots of videos on Youtube that show you how to use the sextant. Take a look.
I don’t know why I didn’t think of that. I use Youtube to learn just about everything else. Thanks.
Glad you found my site of some use. Best of luck with the astro, it gets easier with practice! FYI. I’ve just uploaded the 2012 almanac.