This Great Sextant Has Been Sold.
Thank you!

U.S. NAVY MK III SEXTANT
~ C. Plath Descendent ~  

 

Presented is only the fourth Navy MK III that we have offered for sale in fourteen years, the last was seven years ago. This one was made by M. Low, the original manufacturer of this design, and carries a low two digit serial number which marks it as one of the first batch of this design made. Engraved on the index arm are:

US Navy MK 3 Mod 0
Serial No. L-18
Low

The sextant comes complete with all its original accessories including a spare set of mirrors with a value of $350.00 today, a mirror adjustment wrench and a Mahogany wood case. The matching certificate is dated April 4, 1970.

SOME BACKGROUND: At the time this sextant was being issued to the fleet round 1975, I was a member of the Navy Department's Navigation Symposium, and remember discussing the criteria that was established for the new sextant. They coincided with those already being used in the commercial maritime community and the German Reichmarine as far back as WW II. Overall, the new design was far advanced from the ubiquitous Navy WW II standby, the Navy MK II, but 30 years late in being adopted by the US Navy. 

 

Vernier reads to 6 arc seconds                Official US Navy logo on the back of the index mirror frame               Markings stamped on index arm includes serial number

Other sextants of this era that met these criteria were the Tamaya MS 733 and the C. Plath Classic sextants as did a few others, but there was strong emphasis in government procurement to "Buy American" in contrast to today's World Economy. Consequently, an American company, M. Low of New York City was selected as the original contractor. M. Low was active in New York City at 69 Pearl St. and 110 Hudson Street as a seller of sextants and other nautical instruments. Their advertising shows they were active through 1975 after which they disappeared from the scene.

Franklin Instrument of Rosboro, Pennsylvania seems to have become the second contractor, but we've only seen one example of their MK III in 50 years in the sextant business. They were followed by Scientific Instruments of Milwaukee, WI. whose management insists they made the sextants from scratch using only their own design drawings and manufacturing tools and dies.

Scientific Instruments came into the picture as early as 1975 which was at the tail end of the Star Shooting Era. They made fewer and fewer sextants as Satellite Navigation (Sat Nav), the newly accepted electronic system, became more prevalent. The current system, GPS, succeeded SatNav in general use in 1983. "SIC" stayed in business until 2008, when they closed their doors. In one of our last conversations with the owners, they told us sextants were still being made in very small numbers for newly built U.S. Navy ships at a price of $4300.00.  Two were issued to each ship.

However, C. Plath contradicts Scientific Instruments statements as to the origin of the "SIC" MK III sextant. Plath says these sextants were made under license from C. Plath, Hamburg, Germany. 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.

Plath's claim is noted on page 119 of the book by Friedrich Jerchow, "From Sextant to Satellite Navigation, (1837-1987) 150 years C. Plath" and reads as follows: "As the US Navy insisted that the instruments be manufactured in the USA, C. Plath granted the firm of M. Low, Inc. in New York a manufacturing license for the C. Plath sextants. Up through 1987, all MK 3 sextants for the US Navy have been manufactured by this firm and a successor firm (presumably Scientific Instruments) under this license."

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, after a ten year hiatus, is now being taught again at the U.S. Naval Academy since 2015. Whether or not ships carry sextants today is meaningless since it is not practiced as part of the daily routine. In 2001, I was invited on a three day "DV" cruise on the Spruance Class destroyer, USS CARON DD 970. 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 sights. I appreciated its lighter than average weight, but not its grip.

PROVENANCE: Formerly owned by a US Navy captain who acquired it about 40 years ago through the University of Georgia. It had been transferred to the Marine Sciences Department years before for a Navy funded scientific study.

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

 

Closed MK III sextant case

CONDITION: Near new. There is no evidence of use. All its machinery works a little stiffly and will benefit from being used. Both fitted mirrors show as new.   There is a set of new replacement mirrors. We adjusted the sextant to minimum index error. The lighting doesn't work. Everything simple such as a new bulb, and batteries were tried without success. Use a pencil flashlight and you will be fine. The nicely refinished Mahogany case also shows as new with only a few scuffs. The original April 1970 certificate of accuracy is included and matches the sextant L-18 serial number. No locks are fitted to this Navy style case. 

 

MK III Housed in oversize case with hi impact cushioning

 

The cavities hold a set of mirrors, screw driver, spare bulb, wrench and a brush