Davis Mark 15 026 User's Guide

Davis Mark 15 026 Marine Sextant manual cover

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Davis Mark 15 026 Marine Sextant Specification

The Davis Mark 15 026 Marine Sextant is a precision navigational instrument designed for celestial navigation at sea. It features a high-impact, weather-resistant frame made from a durable plastic composite, ensuring longevity and reliability even in harsh marine environments. The sextant is equipped with a 3x magnification optical telescope, providing a clear and magnified view of celestial bodies, facilitating accurate measurements. The instrument includes a large, easy-to-read, 7-inch arc with a scale graduated to 2/10 of a degree, allowing for precise angular measurements. Additionally, the sextant is fitted with a micrometer drum gauge that enhances accuracy by enabling fine adjustments to be made, with a vernier scale that reads to 2 minutes of arc.

The Davis Mark 15 026 comes with a full-field beam converger mirror, which improves the visibility of the horizon and celestial objects. This feature is critical for accurate sighting and reliable navigation. The sextant also incorporates index and horizon mirrors that are adjustable, ensuring consistent precision and the ability to maintain calibration over time. The mirrors are silver-coated to enhance reflection quality and durability.

Furthermore, the sextant is equipped with a set of six sunshades, providing protection and versatility by allowing users to adjust the light level for optimal viewing under various lighting conditions. The lightweight design, combined with the ergonomic handle, ensures comfortable and stable handling during use. The Davis Mark 15 026 Marine Sextant is a dependable tool for both novice and experienced navigators, offering a balance of accuracy, durability, and ease of use, making it an essential instrument for marine navigation.

Davis Mark 15 026 Marine Sextant F.A.Q.

How do I calibrate the Davis Mark 15 026 Marine Sextant?

To calibrate the Davis Mark 15 026 Marine Sextant, align the sextant's index mirror with the horizon mirror by adjusting the micrometer drum until both images overlap perfectly. Check for index error and adjust the index arm if needed.

What are the steps for performing a horizon test on this sextant?

To perform a horizon test, direct the sextant at the horizon and adjust the micrometer drum until the images align. If the horizon line is continuous, the sextant is correctly adjusted. If not, note the discrepancy and adjust accordingly.

How should I clean and maintain the Davis Mark 15 026 Marine Sextant?

Clean the sextant with a soft, lint-free cloth to remove salt and grime. Avoid harsh chemicals. Regularly check and lubricate moving parts with a light oil to ensure smooth operation. Store in a dry, protective case when not in use.

What should I do if the sextant readings are inconsistent?

If readings are inconsistent, check if the mirrors and lenses are clean and properly aligned. Recalibrate the sextant and ensure there is no play in the index arm. Verify that the micrometer drum is functioning correctly.

Can the Davis Mark 15 026 be used at night?

Yes, the Davis Mark 15 026 can be used at night with the aid of a light source for reading the vernier and scale. Ensure that the horizon is visible by using celestial bodies like stars or the moon.

How do I perform a sun sight with this sextant?

To perform a sun sight, use the sextant's sun filters and bring the sun's image to the horizon line. Adjust the micrometer drum until the lower limb of the sun just touches the horizon. Record the sextant reading.

What is the purpose of the micrometer drum on the sextant?

The micrometer drum on the sextant allows for precise measurement of angles by enabling fine adjustments to the index arm, which are necessary for accurate celestial navigation.

How can I check for index error on the Davis Mark 15 026?

To check for index error, set the sextant to 0° and look at the horizon through both mirrors. If the horizon appears continuous, there is no index error. If misaligned, adjust the horizon mirror until the line is continuous and record the error.

Is it necessary to adjust the horizon mirror frequently?

Adjusting the horizon mirror is only necessary if you detect misalignment during routine checks, such as the horizon test or when diagnosing inconsistent readings. Regular maintenance will minimize frequent adjustments.

What safety precautions should I take while using the sextant?

Always use sun filters when observing the sun to protect your eyes. Handle the sextant carefully to avoid dropping it. Store it securely when not in use to prevent damage.