CASSENS & PLATH HORIZON ULTRA Sextant / full-view mirror / white

The HORIZON ULTRA is a top of the line sextant and perfect for celestial navigation at sea and, thanks to the full-view mirror, Schüler double prism and polarisation shade lenses, it is extremely advantageous when it comes to sun observations. Colour: white. Supplied in a robust case including accessories.

Sextant frame and engineering design
This sextant requires sophisitcated machining to build. The frame is made from a brass plate that weighs 5.5 kg. Once the milling work is complete, the frame weighs approx. 0.6 kg. After milling, the frame is heated, straightened, sanded and engraved. The individual components are then fitted. The sextant consists of over 100 individual parts, most of which are manufactured in-house. All components are fitted and adjusted by hand. Each sextant is tested after production and a quality certificate is issued.

Full view mirror
The sextant features a full-view mirror. The central vertical part is half-silvered and therefore semi-transparent,
which means that you see the horizon and the star in the same picture at the same time. This has the advantage that the star/sun can easily be kept in the field of view in turbulent seas. This simplifies observation.
The semi-transparent mirror can reduce the brightness of the horizon image somewhat, which can make twilight observations more difficult.

Schüler Double Prism
The Schüler double prism is fitted as standard only on the HORIZON ULTRA. It is mounted in front of the shade lenses in the direction of the horizon. Can only be used in combination with a full-view mirror. The lens is specially shaped and therefore blocks out a vertical area in the middle of the horizon viewing beam. This has 2 advantages for sun observations: The sun reflections on the water surface are faded out there are no measurement errors caused by glare. An inclination of the sextant can be clearly recognised as a step in the horizon.



Polarisation Shade Lenses:
Polarisation shade lenses are also fitted on the HORIZON ULTRA only. One shade is located in front of the horizon mirror and one in front of the index mirror. The polarised shade lenses allow the brightness of the star to be adjusted continuously by turning the filter. This means you don't have to add or remove any extra shade lenses during observation and you can keep the star in the field of view more easily.



Combined index error and dip error adjustment
The HORIZON ULTRA sextant has a combined dip and index error adjustment directly on the drum. There is an extra scale on the drum screw on which the index error can be corrected, so you do not have to take the error into account in further calculations. You can also correct the index error on the horizon mirror.
Note: Dip correction must be carried out before index correction. Since the height of the eye can be pre-set independently of the index error, it does not have to be taken into account in the calculations. In practice, the height of eye (dip) is rarely adjusted. The left-hand scale is for adjusting the dip and the right-hand scale is for adjusting the index error.

Technical specifications

• Measuring range: -5° to 125°
• Measuring accuracy: +/- 10"
• Telescope: 4x40
• Horizontal mirror: Full view
• Horizon mirror Ø: 56 mm
• Index mirror: 56 x 42 mm
• Light: Yes
• Frame material: brass
• Colour: white
• Sextant weight: 1.8 kg
• Weight incl. case: 5.5 kg
• Case dimensions: 380 x 310 x 190 mm