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Old 30-12-2011, 20:28   #61
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Re: Any Suggestions for a Perfect Sextant ?

So much for my idea of overhauling my Davis Mark 3 with their 7 dollar kit. I opened the box today and discovered that the mirrors they sent me are too big. You cant just sand down glass like you can wood, so I will call Davis next week and see what they say. Because the shipping was as much as the cost of the kit, I will probably keep it for the nice new screws and brass nuts, and re-silver my old mirrors. Just goes to show you that in boats, when you think you have a problem solved, you better have a Plan B just in case._____Grant.
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Old 30-12-2011, 21:17   #62
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Re: Any Suggestions for a Perfect Sextant ?

Ouch, my MK15 kit worked fine. Too thick or too large? The MKIII is a good useful instrument when all else fails. Or in your liferaft. Ditch kit.
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Old 10-05-2014, 14:17   #63
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Re: Any Suggestions for a Perfect Sextant ?

be care full abouth electrical equipments!!! all doing cancer!
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Old 10-05-2014, 18:39   #64
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be care full abouth electrical equipments!!! all doing cancer!
Be careful of boats! All doing drowning people!
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Old 10-05-2014, 21:34   #65
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Re: Any Suggestions for a Perfect Sextant ?

I know nothing about sextants.

What's wrong with plastic?

Back In The Day, everyone said the same thing about "plastic" (fiberglass) handles on hammers. They turned out to be really wrong, but that's opinion.

I can see learning sextants, for the same reason I learned paper charts-- because when things go to hell in a hand basket, I want others to be highly motivated to pull me into the life raft. I want them to want me there.

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Old 11-05-2014, 06:01   #66
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Re: Any Suggestions for a Perfect Sextant ?

I use a 1976 Tamaya, and I have 2 of the Davis plastic ones for training and guests. I met an Englishman who had sailed from the UK to Hawaii using a Davis, I figured "that's good enough for me". If for no other reason, to keep up the skills that I learned as a young man, and in the back of my head it is a safety net in case all else fails. You forgot about the meteor storm that takes out all of the GPS satellites simultaneously. Plus you pay more attention to your surrounds, and I like looking at the stars as well.
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Old 11-05-2014, 07:56   #67
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Re: Any Suggestions for a Perfect Sextant ?

I have an old Freiberger yacht sextant and a plastic Davis Mark 15. The Freiberger is a beautiful instrument and is a joy to use. I find the Freiberger heavy and I'm afraid of knocking it about on the deck of a moving boat. Since celestial navigation is not something I practice regularly, I try to refresh my skills a couple times each year. Recently, I took a set of sights using the Davis plastic sextant and made a fix within 7 miles of my actual position. I was pleased with that.

I find when I take the sextant out, my wife and other crew want to try taking sights. I'm more comfortable handing over the plastic sextant than the heavier, expensive Freiberger.

The Freiberger is more precise, has a better "feel" and is heavier. Both help take sights with acceptable accuracy, and keeps the art of celestial navigation alive!

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Old 11-05-2014, 10:53   #68
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Re: Any Suggestions for a Perfect Sextant ?

One thing to take note of! the Davis lifeboat sextant will only be of use for sun shots. At least that was my experience. Without a scope, the horizon would disappear before you could pick out a star. I used an English made Ebbco plastic sextant for my first 12 or 13K miles, that had a 4 power scope and picking up stars was easy. My eyesight was very good back in those days, but I now am considering doing a long post on Celestial for the aging eye. It would be about sun, moon and planet sights, and forgetting about stars. The moon is available in the day time, for much of the month, and the Evening Star (Venus) is actually a planet , and enough brighter than than any star, that you can often pick it up before the horizon gets too vague for a decent shot. At risk of sounding like a broken record, I will repeat what I have said many times on this forum. For those learning celestial "DONT LEARN TO DO A NOON SIGHT", at least not at first. So many cruisers I met learned to do a noon sight, and felt accomplished, and never learned to do anything else. A proper sight reduction is not too much more complicated than a noon sight, and then the stars, planets and even the moon need only a little more knowledge. Enough of my opinions. ______Grant.
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Old 11-05-2014, 11:40   #69
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Re: Any Suggestions for a Perfect Sextant ?

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I will repeat what I have said many times on this forum. For those learning celestial "DONT LEARN TO DO A NOON SIGHT", at least not at first. So many cruisers I met learned to do a noon sight, and felt accomplished, and never learned to do anything else. A proper sight reduction is not too much more complicated than a noon sight, and then the stars, planets and even the moon need only a little more knowledge.
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Old 11-05-2014, 11:50   #70
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Re: Any Suggestions for a Perfect Sextant ?

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use whenever I can

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Old 11-05-2014, 12:38   #71
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Re: Any Suggestions for a Perfect Sextant ?

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In ALL of them?
  1. 2 pucks
  2. 1 handheld
  3. 1 old 126 at the nav station
  4. 2 GPS chipped cell phones
  5. The chartplotter
  6. An iPad

That's 8! Eight individual units that would all have to fail at one time! A lot better chance of it being cloudy and knocking the sextant offline! CRAP! I forgot the 2 SPOT locators! That's 10 individual, isolated GPS receivers in ONE boat!
Very unlikely, but the civilian signal can be turned off (I assume still so). Had it happen once, many years ago, while half way between Mass. and Bermuda. No device aboard had signal. We used celestial all the way into Bermuda and then learned that operation Desert Storm had launched.
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Old 11-05-2014, 13:53   #72
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Re: Any Suggestions for a Perfect Sextant ?

BECAREFULL about Turkish sailor !!! all Might be more of dutch populations
for JazzyO and İF the USA nsa want to cut gps power its probably possible in A minute.Where you are? how long distances : and how dangereous night and shallow waters rocks and all dangers whit out GpS.....
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Old 11-05-2014, 14:31   #73
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Re: Any Suggestions for a Perfect Sextant ?

Another reason I will learn sextant and celestial work is calculators.

That is, Back In The Day, when calculators were new, folks like me actually had to learn arithmetic and basic math. As a result, if you tell me that the building is 40 feet long and 30 feet wide, I can come up with a general idea of how many sheets of plywood you need for subfloor without really thinking about it.

Fast forward to the late nineties, when everyone had as many calculators available as there are GPS units now, and you end up with apprentices who had never done the arithmetic by hand, and have no real grounding in the relationship between math and reality.

I had an apprentice look up from the calculator on his phone, and tell me that we needed one thousand two hundred sheets of plywood for the subfloor I mentioned above. He said it without blinking, and the fact that he forgot a step and was off by a factor of 32 never occurred to him, and was not apparent to him by the size of his answer.

In the same way, I had another apprentice figure concrete on his calculator, and he told me that for a footing one foot high, eighteen feet long and two feet wide, we needed twelve yards of concrete, because he thought there are three cubic feet in a cubic yard. Again, the size of his answer didn't jump off the screen, grab him by the throat and scream that he was wrong. He'd never done it by hand, and that's the answer his calculator told him.

After that, I used one inch cubes of wood, paper and pencil to teach how to calculate cubic yards of concrete.

My point is this: if you do something step by step, by hand a few times, and gain a basic understanding of the relationships, the process and the basics, you will (very quickly) be able to tell when your electronics are lying to you, probably because you made a mistake in the use of those electronics. It will also help you track down that mistake.

Not knowing how to use a sextant or stars and planets to navigate, I have no idea if that principle of error recognition applies to navigation, but I know which way I'm betting. I've never seen a GPS lie, but I have seen plotters lie.

No, Martha, we are not in the southern hemisphere, and we're in the Pacific, not the Atlantic. I would have noticed the Panama Canal.
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Old 11-05-2014, 15:22   #74
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Re: Any Suggestions for a Perfect Sextant ?

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On the other hand, I've had more than several occasions where just a simple surge busted all the electronics that're hooked up to the system.
What! Offshore i.e. where you need a sextant? Not near lightening and not hooked up to shore power?

You should never disconnect your battery whilst the alternator is running

I like to practice too and prefer a morning star sight over a noon site. If buying an old sextant make sure it has a drum micrometer style scale and not a linear vernier like the one I inherited from my Grandfather. It has a built in magnifying glass but still a nightmare to read.

The ones from East Germany were nice, used a few but don't remember names sorry. I'm sure they are on Ebay.. must go and look!
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Old 11-05-2014, 18:38   #75
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Re: Any Suggestions for a Perfect Sextant ?

Jammer!, I have had my GPS lie to me, in my airplane. It was a clear day so it didnt do any harm, other than shake my faith in them. I was going out to an airport near the California coast and my recently purchased hand held moving map GPS was doing just fine. When I got within 4 or 5 miles of the airport, I started paying much more attention to the airport, and potential traffic, than the GPS. On downwind, alongside the airport, I glanced down at the GPS, and it had me about 15 miles out over the ocean. I was surprised, but since the airport was in full sight (and had been for miles) I continued my landing. When I stopped, the GPS showed me exactly where I was on the taxi way. I have no idea what went wrong, but it didnt build my trust in electronics. This was not a $99 unit from Walmart, it was an $800 Bendix aviation unit, and it still lied to me. It was one of those GO FIGURE? moments. _____Grant.
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