Mark 25 Sextant Navigation Tool - SKU 25

$499.99 USD

A sextant is an excellent tool to have on board any size craft as a backup in case there is a failure of the navigational systems. Used to measure the angular distance between two visible objects, the most common sextant navigation points are an astronomical object and the horizon. Sextants have many uses, ranging from measuring the distance of a landmark to determining Greenwich Mean Time.

The top-of-the-line Davis plastic sextant, the Mark 25 features our Beam Converger™ mirror, sometimes referred to as a “full horizon mirror." A special coating is applied to high quality optical glass to allow the user to see through this mirror, yet still pick up images as faint as low-light stars.

Highlights Click here to learn more about the product.


  • The top-of-the-line Davis plastic sextant, the Mark 25 features our Beam Converger™ mirror, sometimes referred to as a “full horizon mirror." A special coating is applied to high quality optical glass to allow the user to see through this mirror, yet still pick up images as faint as low-light stars.
  • The Mark 25 is illuminated by a long-life LED and made of an upgraded plastic that is very stable.
  • Comes with instruction booklet.
FAQsClick here to view popular questions and answers about the product.

Are Sextants Still Used Today?

The sextant was first used in 1731. In recent times, they have been used to backup electronic navigational systems. In 2016, the Chief of Naval Operations and U.S. Navy ordered that crewmen should be trained to use the sextant as a backup navigational device in case of power failure. It is always considered a good idea to have a sextant and know how to use one in case of navigational instrument failure. When you are ready to buy sextant instruments for your craft, Davis Instruments is known for its quality.

How Does a Sextant Work?

The sextant uses two mirrors to measure the distance between objects. One of the mirrors only has silver on half of it to allow some light to pass through. This half-silver mirror is used to look at the horizon. Meanwhile, the second mirror is attached to an arm that moves. This mirror is moved to a position where the sun’s reflection also reflects onto the first mirror. When you view this through the eyepiece, you see the sun superimposed on the horizon. The angle can then be read using the scale at the bottom of the sextant. You can use any two objects to do this.

What is a Sextant Used to Measure?

When a sextant is used to estimate the angle of a celestial object and the horizon, it is called sighting the object or taking a sight. The angle and the time when the measurement was taken are used to determine the position on a nautical chart. For instance, you can shoot the sun at noon or Polaris at night to estimate your latitude.

A sextant can also be used to measure the distance of an object using its height, and it can be used to measure the angles between two objects to obtain the position on a chart. Another use of the sextant is to shoot the moon and another object to determine Greenwich Mean Time and longitude.

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We can ship to virtually any address in the world. Note that there are restrictions on some products, and some products cannot be shipped to international destinations.

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Making A Purchase

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 When you place your order with us, your credit card number is encrypted for transmission to us using 128 bit encryption. Your credit card details are never by us since they are transmitted directly to the processing company.  As such, all refunds must be made to the same card used for the purchase.

Contacting Us
If you need to reach us, please email us using the link on the store page, alternatively, you can reach us at:

Tech Instrumentation Inc.
750 E Kiowa Ave.
PO Box 2029
Elizabeth, CO 80107-2029
USA

Phone: [800) 390-0004 Toll free
Phone: (303) 841-7567
Fax: (303) 840-8568

NOTE: We do not accept unsolicited advertisements at the facsimile number.


Email: info@techinstrument.com

Shipping And Handling
Shipping and handling charges are shown on a page just prior to your placing the order. We can ship to many parts of the world that are not allowed on the site. Please e-mail us for a shipping quote. Please call if you have any questions. PLEASE NOTE: If you return an item that you ordered with free shipping, we may, at our option deduct our shipping cost from your refund.

Delivery Schedule
We will normally ship your order to you within 1 to 3 business days. We will notify you via e-mail or telephone if we will be unable to ship within 3 business days. If your order is urgent, please let us know. We'll do our best to expedite urgent orders.
Back Orders
If your item is not in stock and we will not be able to ship within 10 business days, we will back order for you. You will always be emailed with the option to cancel your order if you would rather not wait.
Tax Charges
Orders made from within Colorado - sales tax will be applied. We do not currently charge taxes outside of Colorado, but some of our payment processors may charge sales tax and remit it directly to your state.
Guarantee
Most of our products come with a one year warranty. Most of the Cooper-Atkins thermometers which carry a five-year warranty. Most probes come with a one year warranty. Buyer assumes full responsibility in determining the suitability of these items for buyers intended use.
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Tech Instrumentation will not disclose buyers' information to third parties other than when order details are processed as part of the order fulfillment.  Cookies are used on this shopping site to keep track of the contents of your shopping cart, to store delivery addresses if the address book is used and to store your details if you select the 'Remember Me' Option. They are also used after you have logged on as part of that process. You can turn off cookies within your browser by going to 'Tools | Internet Options | Privacy' and selecting to block cookies. If you turn off cookies, you will be unable to place orders or benefit from the other features that use cookies.

Returns Policy
Buyer assumes full responsibility in determining the suitability of these items for buyers intended use.  Most items come with a minimum one year warranty against defects in manufacturing.

CLAIMS FOR SHORTAGES OR ITEMS DAMAGED IN TRANSIT MUST BE SUBMITTED TO US WITHIN 3 DAYS OF RECEIPT OF THE PRODUCT. IF DAMAGE IS NOTED UPON DELIVERY, PLEASE NOTIFY CARRIER IMMEDIATELY AND BE SURE TO KEEP THE SHIPPING CONTAINER AND ALL PACKING MATERIAL. NO CLAIMS FOR SHORTAGES OR CARRIER DAMAGE WILL BE HONORED BEYOND 3 DAYS AFTER DELIVERY.

New and unopened items sold by Tech Instrumentation.com may be returned within 30 days of delivery. All items require prior authorization from Tech Instrumentation before they can be returned. We will also pay the return shipping costs if the return is a result of our error (e.g. you received an incorrect or defective item). New and unopened items being returned due to a customer error in ordering or handling will be subject to a restocking fee of 30% and must be returned freight prepaid.

All returns require a RGA number from Tech Instrumentation prior to being returned. Items must be returned postage paid to our facility in order to be considered for refund. Please call 303 841-7567 to obtain a RGA number if you need to return an item. Non defective returns must be in the original unopened packaging with all accessories to be eligible for a refund. Unopened items are subject to a 20% inspection and restocking charge. Non defective items that have been opened or are missing any parts including instructions are not eligible for return. Defective items will be repaired or replaced per mfg. policy. Shipping & Handling charges are not refundable. Service charges (repairs, certifications etc.) and special order items are never refundable. Non defective items must be returned within 30 days of the date we shipped to you in order to be eligible for refund. We pay shipping back you your location for all warranty returns. Items that have been damaged due to misuse or abuse, as judged by Tech Instrumentation are never eligible for a refund.

Refused/Undeliverable shipments: We will refund a minimum 75% of the cost of the product less shipping costs (both ways) for shipments that are returned to us as refused or undeliverable. Service charges (repairs, certifications etc.) are warranted but never refundable. Purchaser agrees to pay all charge-back and related costs incurred by us in the event a credit card charge-back is initiated by the purchaser for refused shipments. Please contact us directly and we will refund per our policies.  Shipping and handling charges are not refundable except in the event of an error on our part.

by Davis Instruments
Type: Marine

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A sextant is an excellent tool to have on board any size craft as a backup in case there is a failure of the navigational systems. Used to measure the angular distance between two visible objects, the most common sextant navigation points are an astronomical object and the horizon. Sextants have many uses, ranging from measuring the distance of a landmark to determining Greenwich Mean Time.

The top-of-the-line Davis plastic sextant, the Mark 25 features our Beam Converger™ mirror, sometimes referred to as a “full horizon mirror." A special coating is applied to high quality optical glass to allow the user to see through this mirror, yet still pick up images as faint as low-light stars.

Highlights Click here to learn more about the product.


  • The top-of-the-line Davis plastic sextant, the Mark 25 features our Beam Converger™ mirror, sometimes referred to as a “full horizon mirror." A special coating is applied to high quality optical glass to allow the user to see through this mirror, yet still pick up images as faint as low-light stars.
  • The Mark 25 is illuminated by a long-life LED and made of an upgraded plastic that is very stable.
  • Comes with instruction booklet.
FAQsClick here to view popular questions and answers about the product.

The sextant was first used in 1731. In recent times, they have been used to backup electronic navigational systems. In 2016, the Chief of Naval Operations and U.S. Navy ordered that crewmen should be trained to use the sextant as a backup navigational device in case of power failure. It is always considered a good idea to have a sextant and know how to use one in case of navigational instrument failure. When you are ready to buy sextant instruments for your craft, Davis Instruments is known for its quality.

The sextant uses two mirrors to measure the distance between objects. One of the mirrors only has silver on half of it to allow some light to pass through. This half-silver mirror is used to look at the horizon. Meanwhile, the second mirror is attached to an arm that moves. This mirror is moved to a position where the sun’s reflection also reflects onto the first mirror. When you view this through the eyepiece, you see the sun superimposed on the horizon. The angle can then be read using the scale at the bottom of the sextant. You can use any two objects to do this.

When a sextant is used to estimate the angle of a celestial object and the horizon, it is called sighting the object or taking a sight. The angle and the time when the measurement was taken are used to determine the position on a nautical chart. For instance, you can shoot the sun at noon or Polaris at night to estimate your latitude.

A sextant can also be used to measure the distance of an object using its height, and it can be used to measure the angles between two objects to obtain the position on a chart. Another use of the sextant is to shoot the moon and another object to determine Greenwich Mean Time and longitude.