Chelsea Polished Brass Navy MK I Deck Clock

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Observatory Cartouche 1940



The WW II Chelsea MK I Deck Clock’s case was made differently
than the ubiquitous nickel plated Seth Thomas version. It is more refined and far better looking in this
pleasing rose colored polished brass.



DIMENSIONS: 5 1/2″ Diameter of face 3
Deep 8″ Full Diameter Weight 10 lbs 6 oz

is a superior example of a Chelsea, back winding, Navy MK I Deck Clock
a hinged front that is complete with two backing plates. One of these plates acts as a water tight cover and shock absorber
and the other mounts it to a bulkead or wall. It is rare to get these clocks with their back cover plate and finding one with
the original mounting plate is an even rarer exception. The Chelsea version of what was supposed to be a standardized mil-spec
design is more refined and has a different hinge arrangement than the thousands of nickel plated clocks that were made by
Seth Thomas.This clock is in polished brass with a lacquer coating to preserve its luster. The movement, serial number 276871
dates from 1940, and was recently serviced by a clock smith. It is keeping good time compared to a quartz comparison watch.
Navy MK I DECK clocks
of WW II were manufactured in accordance with military specifications 18C-11 and 18C -13. This Chelsea example has modifications
which are unique. The front section holds the movement and has an integral stud on the backing plate that acts as the hinge.
This compares to the more common Seth Thomas version which uses a removable pin, and has a chrome plated case. In both designs,
the back of the front section has all the controls on the rear.

Chelsea clock has an integral stud on the mounting plate as
a hinge
plus shock
absorbing damper. 3 pieces total


Typical Seth Thomas MK I casting uses a separate pin as a hinge


Both Andrew Demeter
in his definitive book, “Chelsea Clock Company, the first 100 years” and Marvin Whitney in his
encyclopedic work, “MILITARY TIMEPIECES” say that these clocks were chromium plated up to 1941
when cases were switched to Bakelite, a phenolic.


Markings on face
on back have a dust cover over




A Mark I Deck clock made by Chelsea is a rare find, as is a clock of this age and service
at sea to be found in this fine condition. It is perfect for a collector of military pieces or as an important gift.

Beneath the hand arbor is etched:


(NO) 3038



(NO) represents the Naval Observatory which means the clock not only met the military specifications,
but also met the stringent standards of this institution which maintains the Nation’s Time Standard. At the bottom of the
dial it is marked Chelsea.

following controls are accessed on the back:


  • Fast – Slow adjustment.
    To regulate turn towards S to Slow and vice versa
  • Stop – allows to precision
    setting with master clock
  • Set – moves hands
  • Wind – a key is included


It has a Chelsea Model 17K, 11 jewel 8 day movement that is wound, set and adjusted through a slotted
dust cover at its rear which closes. A separate start/stop mechanism allows it to be synchronized with a master time piece.


The removable vibration
dampener backing plate is attached to the bulkhead plate by six screws and holds the front case secure by a wing nut dog.


Opposing views of this special MK I Deck clock=”center”>





CONDITION: This example has seen about 73 years of service, much of it at sea, and gives the appearance
of being new. The face is in very good condition, but shows a little evidence of aging when viewed close-up. The dots over
the numbers once were painted with irradium for night viewing, but this has been removed because it was radio active.
The lens under most light conditions shows clear, and
has only one small scratch. The movement has been recently serviced and is keeping good time. A Chelsea key is included. The
case has been recently polished and lacquered.

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Celebrating 18 Years of Exellence in Nautical Antiques

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