Original Item: Only One Available. This is an exceptionally appealing German WWII Kriegsmarine marked marine sextant by C. Plath of Hamburg, one of Germany’s most respected manufacturers of precision nautical instruments. Unlike an ordinary civilian navigation sextant, this example carries the distinctive Kriegsmarine Eagle / M naval property marking directly above serial number 6493, providing an unmistakable connection to German naval service during WWII. It remains remarkably complete with its original frame, mirrors, micrometer assembly, monocular, telescope, Bakelite handle, and correct fitted wooden carrying case. Adding considerably to its history are two later Japanese examination sheets retained inside the case, including one dated March 6th, 1973 from Sasebo, Japan, documenting that the instrument was still being examined for serviceability nearly three decades after WWII.

The center of the index arm is clearly marked:

(EAGLE)
M
6493

C. Plath
Hamburg

The Eagle over M marking is the most important military feature of the instrument and identifies it as Kriegsmarine property. Combined with the C. Plath Hamburg manufacturer marking and individual serial number, it gives the sextant excellent appeal to collectors of German naval navigation equipment.

C. Plath was established in Hamburg in 1862 by Carl Plath and became internationally known for high quality sextants and other precision marine navigation instruments. Hamburg’s position as one of Europe’s major ports created a natural market for such equipment, and Plath instruments became well regarded among both merchant and naval mariners.

During WWII, accurate celestial navigation remained essential aboard warships and submarines despite enormous advances in radio navigation and other technologies. Naval vessels operating far from recognizable landmarks still depended upon traditional navigation instruments to independently establish their position at sea.

The sextant was among the navigator’s most important precision instruments.

The word “sextant” derives from the Latin concept of a sixth, referring to the instrument’s graduated arc, which traditionally represents approximately one sixth of a complete circle. Through its system of mirrors, however, a sextant can measure angles considerably larger than the physical arc itself.

This example uses the classic ladder pattern frame associated with high quality marine sextants.

The graduated arc runs from approximately:

0 to 120 degrees

The principal function of the sextant was to measure the angular altitude of a celestial object, such as the sun, moon, planet, or navigational star, above the visible horizon. When combined with an accurate timepiece, nautical almanac, charts, and the necessary calculations, those observations could be used to determine a vessel’s position.

The sextant is a double reflection instrument. Light from the celestial object is reflected through the index and horizon mirrors until the image can be brought into apparent contact with the horizon. The navigator then reads the resulting angle from the graduated arc and micrometer.

This system allowed skilled navigators to establish their position with remarkable accuracy using no external electronic signal. For a naval vessel operating under wartime conditions, that independence was particularly valuable.

The instrument would have been especially important during long range operations when radio silence was required or when electronic navigation aids were unavailable, unreliable, or undesirable.

Kriegsmarine navigation officers and trained personnel aboard surface vessels required accurate position fixing for route planning, convoy operations, rendezvous, minefield avoidance, coastal approaches, and general open ocean navigation.

Celestial navigation also had particular importance to U-Boat operations. A submarine operating far into the Atlantic could surface when conditions permitted and use observations of the sun or stars to help establish its position. There is no provenance identifying this specific sextant with a particular U-Boat or vessel, however, so it should be regarded more broadly as an original Kriegsmarine naval navigation instrument.

The sextant retains its major components, including the:

frame
index arm
micrometer assembly
index mirror
split horizon mirror
four index shades
three horizon shades
monocular
telescope
Bakelite handle

The optical components are somewhat dusty but remain in fine condition.

The index mirror and circular split horizon mirror are still present. The four index shades and three horizon shades also survive.

These colored shades were essential when taking observations of particularly bright objects, most notably the sun. By positioning one or more shades into the optical path, the navigator could safely reduce glare while maintaining a clearly defined image for measurement.

The index arm retains its micrometer assembly and remains functional. There is some normal light surface and edge flaking to this portion of the instrument.

The main metal frame retains its satin black enamel finish and is in very good condition, showing almost no significant wear or chipping.

The graduated 120 degree arc is an alloy component with the graduations highlighted in white for visibility. Other markings are similarly factory highlighted, allowing the navigator to read the instrument more easily under working conditions.

The lower Bakelite handle remains in excellent condition and is properly maker marked.

The sextant comes in its correct wooden carrying case measuring approximately:

12 ½ x 12 ½ x 6 ¾”

The fitted case was important not simply for transportation but for protecting the instrument’s delicate optical and mechanical alignment. A precision sextant could only provide reliable measurements if its mirrors, index arm, and other components remained correctly aligned.

The case retains both original latches but shows very heavy exterior wear, consistent with substantial handling and long term storage.

No additional accessories are currently present inside the case.

Of particular interest are two later “Sextant Exam” sheets retained inside.

Both are Japanese, documenting a fascinating postwar chapter in the instrument’s history. The front examination sheet is dated:

March 6th, 1973

and bears the name:

Sasebo Kokai Sokkisha Co.
Sasebo-City, Japan

These papers indicate that the sextant was being examined decades after its wartime manufacture and suggest that it remained regarded as a functional precision navigation instrument long after WWII.

Sasebo itself adds an interesting maritime context. The city has long been an important Japanese naval port, making the presence there of a former Kriegsmarine C. Plath sextant particularly intriguing. The documents do not establish exactly how or when the instrument reached Japan, but they provide genuine evidence of its postwar history and offer an excellent avenue for additional research.

The story of this sextant therefore spans two distinct periods of maritime history. It began as a precision C. Plath instrument bearing German Kriegsmarine property markings during WWII and was still being professionally examined in Japan in 1973.

That continued life is a testament to both the durability of traditional celestial navigation and the quality of instruments produced by firms such as C. Plath. Even as radar, radio direction finding, and increasingly sophisticated electronic systems transformed navigation, a properly adjusted sextant remained a completely independent means of determining position.

For collectors, original navigation instruments have a particularly strong connection to the daily operation of a warship. A sextant was not decorative equipment. It was a precision tool upon which a vessel’s position, course, and ultimately its safe operation could depend.

This example combines nearly all of the features one hopes to find: the prominent Kriegsmarine Eagle / M property marking, C. Plath Hamburg manufacturer identification, serial number 6493, excellent surviving satin black finish, intact optical and mechanical components, original Bakelite handle, correct wooden case, and unusually interesting 1973 Japanese examination papers. The dusty optics, minor edge flaking, heavy wear to the case, and absence of additional case accessories are fully disclosed. It would make an outstanding centerpiece for a Kriegsmarine, German naval navigation, U-Boat equipment, C. Plath, celestial navigation, or advanced WWII maritime collection.