FULLY RECONDITIONED – 5 STARS!

Presented is only the fourth Navy MK III that we have offered for sale in eight years. This one was made by M. Low, the original manufacturer of this design. It differs from those made by Scientific Instruments by having the M. Low name engraved on the index arm. Scientific Instruments of Milwaukee, WI riveted a tag on the index arm which lead us to believe SI may have acquired parts from M. Low and used that method to cover the Low name. The sextant comes complete, and fully functional with a working internal light, adjustment wrench, brush and the original inspection certificate dated March/25/70. A copy of the Navy ten page instructons are also included. The low number and the early date may indicate this instrument was made for the Navy’s evaluation.

SOME BACKGROUND: At the time the design of this sextant was formally adopted around 1975, I was a member of the Navy Department’s Navigation Symposium, and remember the criteria that was established for a new sextant. They coincided with already existing technology in the civilian maritime community. In total, the new design was far advanced from the ubiquitous Navy WW II standby, the Navy MK II which was long out-of-date.

Vernier reads to 6 arc seconds	Engraved maker’s name

The Tamaya MS 733 and the C. Plath Classic sextants met the Navy’s design criteria as did a few others, but there was strong emphasis in government procurement to “Buy American” in contrast to today’s World Economy. This I found out when the sextant we submitted was praised by the ship it was used on, but our proposal was rejected. Consequently, the little known instrument maker, M. Low of New York City was originally selected, and after they went out of business, Scientific Instruments of Milwaukee, Wisconsin became the sole manufacturer until they ceased operations in 2008 as a result of the economic recession.

The fact is that all MK III sextants were made under license from C. Plath, Hamburg, Germany. C. Plath aficionados take note, the design is clearly the same as the C. Plath Classic sextant down to the last detail other than its ergonomic handle and large size high impact resistant case, and this pedigree is noted on page 119 of the book by Friedrich Jerchow, “From Sextant to Satellite Navigation, (1837-1987) 150 years C. Plath”.

NAVY CELNAV TODAY: The Navy has moved away from traditional celestial navigation and even the use of paper charts. Their reliance is totally electronic position fixing. CelNav is no longer taught at the U.S. Naval Academy. Whether or not ships carry sextants today is meaningless since it is not practiced as part of the daily routine. Ten years ago I was invited to go on a brief cruise on the Spruance Class destroyer, USS CARON DD 970 as a Distinguished Visitor (DV). I used the one they had with good results (i.e. within one nautical mile of the ship’s GPS position), but no one in the wardroom or the lead quartermaster was interested in taking any sights. I appreciated its lighter than average weight, and comfortable handle.

In January 2008, Scientific Instruments ceased operations. Up to then they furnished two MK III sextants to newly commissioned ships at a price of $4300.00 each.

MK III DESIGN CRITERIA: Listed are what were “state of the art” design features, that are still the standard today:

• Light weight
• Large size index mirror
• Large size horizon mirror
• Lighting system
• Vernier reading to 6 seconds
• Handle for ergonomic fit
• Wide angle telescope
• Non adjustable instrument error of less
  than 20 arc seconds
• Military high impact absorbent case

 

CONDITION:
The sextant shows minor evidence of use which is to be expected after 42 years, but we fitted two new mirrors, replaced the missing adjustment wrench, touched-up the paint, and repaired the lighting so it works. The rest of the paint is in very good condition with no imperfections. The chromed screws and springs are all bright and shiny. All the machinery works smoothly. The original horizon mirror is still usable and acts as a spare. The old index mirror was disposed of. We refinished the Mahogany case which has some abrasions and scratches form its service at sea. The original March, 1970 certificate is included and matches the sextant’s serial number. No locks are fitted to this Navy style case. After adjustment, the index error is negligible, and there is a touch of side error which is a good thing.

STAR RANKING: This sextant and case as reconditioned rates 5 STARS

New index mirror	New horizon mirror

Refinished Mahogany case with hi-impact cushion interior

 

This is only the fourth Navy MK III sextant we have offered in the last eight years. It will be equally at home at sea or in a collection of fine instruments. They are becoming scarce since the Navy no longer uses them.

 

PLATH COMPANY HISTORY: In brief, Carl Plath started manufacturing sextants, in addition to other nautical products, in Hamburg Germany in 1862 by th purchase of David Filby Company, a Hamburg instrument maker of repute, which started making sextants in 1837. As a result WW II, C.Plath was dismantled completely by the occupation forces. Around 1950, various prohibitions were lifted, and C. Plath was allowed to begin production again of sextants and other nautical instruments. Also in 1949,C.Plath was offered a gyrocompass patent and in 1951 the first gyrocompass designed to this patent was presented to the public. C.Plath progressed from the role of instrument maker to that of a modern marine navigation equipment manufacturer. In the following years the product range was expanded by many more modern designs such as autopilots, speed logs, radio direction finders, etc.