Sextant for sale

Sextant for sale


  • Sextants: Do We Really Have To?
  • Brass Sextant
  • The Sextant
  • BRIS-SEXTANT FOR SALE
  • Sextants: Do We Really Have To?

    We are, of course, not much different from most sailors. So we asked ourselves two questions: Is it worth learning or re-learning to use a sextant these days, and if it is, what sextant should we buy? To answer the first question, we did some soul searching. To answer the second we went out and got half a dozen models in our grips, and sought competent advice. It can be physically damaged; it can possibly be sabotaged by hackers.

    None of those things is likely to happen. More likely are on-the-water problems: GPS receivers can be fried by lightning, dropped overboard, crushed and damaged. Batteries do run out or get soaked. Well, as any offshore sailor knows, you just carry a back-up handheld. Or two, or three. Plus batteries and waterproof bags. With all that, the chances of being far offshore without the ability to find a way home have diminished to a point where the demand for sextants has decreased markedly over the past 10 years.

    Only 68 percent of cruisers responding to a recent Seven Seas Cruising Club poll now carry one aboard. Like chess, celestial navigation starts with easy openers, and like chess it can challenge you for a lifetime. Those skills, in turn, connect us in a practical way to the relationship of the earth to the sun, moon, and stars — a relationship that fewer and fewer sailors understand, to their detriment.

    The challenge of reading data on a GPS receiver pales next to the challenge of navigating by sextant, and for many people the resultant levels of satisfaction are proportional. From our point of view, prudence alone might no longer send us scurrying out to the nearest sextant store, but a bit of prudence combined with a simple urge to know how, to reacquaint, is enough for us.

    Selecting a Sextant The clearer you are about your intended uses for the sextant, the better your chance of finding a place along the price range where your standards of value can be met. The cheapest are made of cardboard a German-made kit available through Celestaire and plastic. The other side of the story is that the Davis sextants, when used and adjusted by those who understand them, can yield results that are very close to those received from metal sextants: While most metal sextants can be shown to yield accuracy within a nautical mile generally conceded to be about as close as a mortal can come to perfection on a regular basis the limitations built into plastic sextants give them a margin of error of five miles at best.

    We found it surprising, but when you enter the realm of precision metal sextants, instrument accuracy is really the least of your worries. Virtually all new sextants have negligible instrument or uncorrectable error. They also come with instructions for removing index correctable error. At that point you can bank on your new sextant as being virtually error free. Data reduction, refraction, and the oblateness of the earth are all more likely to be sources of inaccuracy than the sextant itself.

    Perhaps the biggest development in sextants over the past 20 years has been an across-the-board improvement of the optics involved. Mirrors have gotten bigger, coatings have been hardened, scopes made more versatile. Part of the new optical improvements wave is the full-horizon mirror. Fitting a sextant with a telescope is also part of the process. Most sextants come with 4 x 40 or 3. These standard scopes provide a modest amount of magnification that helps acquire and retain celestial targets.

    Larger 6 x 30 scopes with greater magnification are often used for sun sights; a larger image makes it easier to determine when the lower limb of the sun is tangent to the horizon. A clear sight tube suits the sextant for rough weather, horizontal angles, and star finding. Many navigators change scopes to suit conditions.

    Sextant cases vary a great deal, but whether the box is plywood, plastic, aluminum, or mahogany makes much less difference than how well the instrument is immobilized in the box.

    Celestaire Navigation Equipment, a good source for instruments and sextant information, sells an all-weather case that is designed to replace hard cases for onboard use. Modern sextants range from 2 to just over 4 pounds. Comfort in the grip of the handle is also important. This raises the topic of maintenance and the spectre of dissimilar metals. Even though you will obviously do your best to keep your sextant dry, smallboat use makes it likely that sooner or later it will get wet. Many factors have contributed to reducing the selection of sextants available today to a fraction of what it was 20 or even five years ago.

    Duties from Germany have priced previously affordable units like the Freiberger Drum sextants effectively out of the American market. Plath has announced an end to its sextant production.

    Currency fluctuations have hurt several Japanese sextants. Still, our survey found a solid half dozen that offer, we feel, representative choice in construction, precision, and price, as well as significant variation in size and features.

    Davis Mk 15 A black plastic sextant, the Mk 15 has a traditional split mirror. It is not illuminated. Mirror adjustment needs attention and index correction varies with temperature variations. It weighs 15 oz. The battery-powered handheld contains all of the tables necessary to do sight reductions. Davis Mk 25 The Mk 25 is made from gray temperature-resistant plastic. It has an illuminated arc and the horizon mirror is full-view.

    Like the Mk 15 it comes with instruction book, neck lanyard, sight tube, and 3x scope. Still, as with all plastic sextants, the coefficient of expansion of the material means that temperature variations will produce significant change, and therefore the need for significant correction, due to variations in temperature. This basic instability makes attention to index error a full-time concern, but many navigators say the problem is over-rated.

    One key to getting good results with a plastic sextant is mirror adjustment. Once the navigator accepts these realities and learns to tend to his mirrors on a regular basis as regular as every sight, we would suggest he can expect results that put him in close competition with a metal sextant.

    Astra III B One reason why the selection of traditional metal sextants has shrunk over the years is the extraordinary success of this Chinese-made unit. Fabricated by Changzou Celestaire Instrument Co. In the past 15 years over 13, have been sold in the U. This has a lot to do with its tidy overall weight of just 2 lbs.

    There are more lustrous finishes on German and Japanese competitors, but the Astra has much more than price to recommend it. Optics are excellent. Each mirror and shade glass, for instance, is tested for perfect flatness by the Fresnel pattern diffraction method. The sextant also offers interchangeable horizon mirrors allowing the navigator to make the shift quickly to suit his preference. While the Standard model has a round index mirror with the silvering applied behind the glass, the deluxe version has a rectangular index mirror with front-face silvering.

    Tamaya Jupiter The Jupiter combines an aluminum alloy frame with a brass arc. The sextant still tips the scales at a robust 4 pounds, but it achieves an excellent comfort level due to its balance and the ease of working the brass arc. The frame is painted in dull black while the other parts are semi-gloss black. Its mirrors are the largest available.

    It has seven large shades. The mirrors are held firmly in place by the same retainer clips used in the finest German instruments.

    The tangent screw assembly is exposed for ease of maintenance and cleaning. The arm is electrically lit. Tamayas have long been recognized for high quality at a competitive price. Unfortunately, while quality remains first-rate, currency fluctuations have made the Jupiter less of a bargain.

    The frame and arc are constructed of special brass alloy, and the entire instrument has been treated and enameled to prevent corrosion. The very traditional webbed frame with its distinctive large circle in the middle has a gleaming brass arc with black gradations. The mirrors are enormous. Both fixed and variable density polarized sunshades are provided for both the index and horizon mirrors. Lighting of the micrometer drum and arc is powered by 2 AA penlight batteries contained in the handle.

    The handle is angled to take the weight of the instrument equally on either side, which makes grip and heft very comfortable. The fit and finish of all the parts is smooth, tight, and solid. A distinctive feature is a drum index corrector. This is a separate smaller knob that extends forward from the micrometer drum and which can be turned to quickly reset the index error to 0.

    The Standard is offered with either a full-horizon viewer or a split mirror for viewing. A 4 x 40 scope is standard. Plath Navistars While the original C. Plath Classic. The real scenario, though, is that we want to start from scratch and learn the art. Celestaire , S. Davis Instruments , Diablo Ave. Tamaya Technics, Inc. Darrell Nicholson Practical Sailor has been independently testing and reporting on marine products for serious sailors for more than 45 years.

    Supported entirely by subscribers, Practical Sailor accepts no advertising or any form of compensation from manufacturers whose products we test. Testing is carried out by a team of experts from a wide range of fields including marine electronics, marine safety, marine surveying, sailboat rigging, sailmaking, engineering, ocean sailing, sailboat racing, and sailboat construction and design.

    This diversity of expertise allows us to carry out in-depth, objective evaluation of virtually every product available to serious sailors. Practical Sailor is edited by Darrell Nicholson, a long-time liveaboard sailor and trans-Pacific cruiser with more than three decades of experience as a marine writer, photographer, boat captain, and product tester.

    He holds a U.

    Jump to: Antique sextants for sale An antique sextant is a wonderful maritime collectible to behold. Its intricate beauty underscores the fact that, for all our modern technology, the simple ingenuity of tools invented centuries ago still works fine on the sea. Indeed, sextants still have advantages over modern devices that rely on electricity or other accoutrements to work properly.

    Antique sextant technology was perfected after the invention of the octant in the s. These proved the most popular of the various instruments that would eventually be devised. There were octants, quintants, and quadrants, each with a different arc. These days, anyone looking for a unique decorative element for a nautical-themed space can use a great sextant. Collectors of maritime antiques and those with the sea in their heart or in their lives will love browsing the one-of-a-kind antique sextant sales listings online.

    The pieces are undeniably beautiful, each and every one. How an Antique Sextant Works The purpose of the antique sextant was to measure the apparent distance of an object, often a celestial object like the sun or other star, above the horizon. This was done by pointing the instrument in the general direction of the horizon and sliding a moveable piece down.

    The user had to line up the object in question in the bifurcated-view scope. Then the sextant was tilted back and forth to make sure it was in the center. Finally it was just a matter of reading the number where the moveable piece had been stopped along the arc.

    Basic and practical, the sextant is still used as a backup tool for navigation on boats worldwide. A nice illustrated guide to using a sextant can be found on Wikihow. These divide the view in the telescope in half using two mirrors. The horizon shows on one side, the object being spotted on the other, similar to a split-screen TV broadcast.

    Whole-horizon sextants show the entire horizon but are usually thought of as less versatile. Antique Sextants Today A collector may buy an antique sextant for its value as a beautiful piece of rare vintage art rather than a tool for navigation. This is due to several factors, not the least of which is that a sextant is a very delicate instrument. Any slight bend in the arc can cause it to be unreliable.

    Modern mariners guard their sextants like possessive hawks, keeping them from harm and from children. Great care must be taken even when removing sextants from their cases.

    Still, our survey found a solid half dozen that offer, we feel, representative choice in construction, precision, and price, as well as significant variation in size and features. Davis Mk 15 A black plastic sextant, the Mk 15 has a traditional split mirror. It is not illuminated.

    Brass Sextant

    Mirror adjustment needs attention and index correction varies with temperature variations. It weighs 15 oz. The battery-powered handheld contains all of the tables necessary to do sight reductions. Davis Mk 25 The Mk 25 is made from gray temperature-resistant plastic. It has an illuminated arc and the horizon mirror is full-view. Like the Mk 15 it comes with instruction book, neck lanyard, sight tube, and 3x scope.

    Still, as with all plastic sextants, the coefficient of expansion of the material means that temperature variations will produce significant change, and therefore the need for significant correction, due to variations in temperature.

    This basic instability makes attention to index error a full-time concern, but many navigators say the problem is over-rated. One key to getting good results with a plastic sextant is mirror adjustment. Once the navigator accepts these realities and learns to tend to his mirrors on a regular basis as regular as every sight, we would suggest he can expect results that put him in close competition with a metal sextant.

    Astra III B One reason why the selection of traditional metal sextants has shrunk over the years is the extraordinary success of this Chinese-made unit. Fabricated by Changzou Celestaire Instrument Co. In the past 15 years over 13, have been sold in the U. This has a lot to do with its tidy overall weight of just 2 lbs.

    There are more lustrous finishes on German and Japanese competitors, but the Astra has much more than price to recommend it. Optics are excellent. Each mirror and shade glass, for instance, is tested for perfect flatness by the Fresnel pattern diffraction method. The sextant also offers interchangeable horizon mirrors allowing the navigator to make the shift quickly to suit his preference. While the Standard model has a round index mirror with the silvering applied behind the glass, the deluxe version has a rectangular index mirror with front-face silvering.

    Tamaya Jupiter The Jupiter combines an aluminum alloy frame with a brass arc.

    The Sextant

    The sextant still tips the scales at a robust 4 pounds, but it achieves an excellent comfort level due to its balance and the ease of working the brass arc. The frame is painted in dull black while the other parts are semi-gloss black. Its mirrors are the largest available. It has seven large shades. The mirrors are held firmly in place by the same retainer clips used in the finest German instruments. The tangent screw assembly is exposed for ease of maintenance and cleaning.

    The arm is electrically lit. Tamayas have long been recognized for high quality at a competitive price. Unfortunately, while quality remains first-rate, currency fluctuations have made the Jupiter less of a bargain.

    The frame and arc are constructed of special brass alloy, and the entire instrument has been treated and enameled to prevent corrosion. The very traditional webbed frame with its distinctive large circle in the middle has a gleaming brass arc with black gradations.

    The mirrors are enormous. Both fixed and variable density polarized sunshades are provided for both the index and horizon mirrors. Lighting of the micrometer drum and arc is powered by 2 AA penlight batteries contained in the handle.

    The handle is angled to take the weight of the instrument equally on either side, which makes grip and heft very comfortable. The fit and finish of all the parts is smooth, tight, and solid.

    A distinctive feature is a drum index corrector. This is a separate smaller knob that extends forward from the micrometer drum and which can be turned to quickly reset the index error to 0. The Standard is offered with either a full-horizon viewer or a split mirror for viewing.

    A 4 x 40 scope is standard. Plath Navistars While the original C. Plath Classic. The real scenario, though, is that we want to start from scratch and learn the art. CelestaireS. Davis InstrumentsDiablo Ave. Tamaya Technics, Inc. Darrell Nicholson Practical Sailor has been independently testing and reporting on marine products for serious sailors for more than 45 years.

    BRIS-SEXTANT FOR SALE

    The pieces are undeniably beautiful, each and every one. How an Antique Sextant Works The purpose of the antique sextant was to measure the apparent distance of an object, often a celestial object like the sun or other star, above the horizon. This was done by pointing the instrument in the general direction of the horizon and sliding a moveable piece down.

    The user had to line up the object in question in the bifurcated-view scope. Then the sextant was tilted back and forth to make sure it was in the center. Finally it was just a matter of reading the number where the moveable piece had been stopped along the arc. Basic and practical, the sextant is still used as a backup tool for navigation on boats worldwide. A nice illustrated guide to using a sextant can be found on Wikihow.

    These divide the view in the telescope in half using two mirrors. The horizon shows on one side, the object being spotted on the other, similar to a split-screen TV broadcast. Whole-horizon sextants show the entire horizon but are usually thought of as less versatile. Antique Sextants Today A collector may buy an antique sextant for its value as a beautiful piece of rare vintage art rather than a tool for navigation.


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