Systems and Equipment

AN/BRN-3 Satellite Navigation System

Receiver manufacturer: Westinghouse.
Computer manufacturer: Bunker-Ramo.

The first operational satellite navigation system, known as Transit, developed for the US Navy's Fleet Ballistic Missle program.

(Photo from National Electronics Museum in Wikimedia Commons.)

The AN/BRN-3 aboard USNS Michelson, 1970-1971.

Bunker Ramo CP-677A/BRN-3 computer  (1st cabinet on the left).
CV-1296/BRN-3 Data Processor  (2nd cabinet).
Westinghouse R-1132/BRN-3 Receiver  (3rd and 4th cabinets).

(Photo courtesy of Earl Adams)

From the Sea to the Stars, Chap 2: Satellites for Strategic Defense

AN/SQN-6 (XN-1) Stabilized Narrow-Beam Sonar Sounding Set

The SQN-6 (XN-1)  was a modified UQN-1 type sonar set connected to an external precision depth recorder (PDR), whch keyed the UQN transmitter and recorded the received returns. To compensate for the ship's roll and pitch the sonar transducer was stabilized vertically by an electro-mechanical apparatus.

Doc: NAVSHIPS 93143

AN/UQN-1B Sonar Sounding Set Technical Data (pdf file)

Timesfax Precision Depth Recorder (PDR)

In the 1960s Bowditch, Dutton and Michelson had two each of these PDRs, made by a company called Timesfax, somehow related to the New York Times newspaper. PDRs of that vintage were derivatives of facsimile (fax) machines, originally used to transmit photographs for news organizations.

These PDRs keyed the transmitter in the SQN-6 sonar and recorded the returns on rolls of special electrically charged paper.

Trackline Survey Sonar Bathymetry

(Article by John Hansen.)

Raytheon PTR-105 Sonar and Associated PDR

This photo taken in the mid-1970s Bowditch Survey Control Center shows what appears to be Raytheon PTR-105 sonar and a pair of Raytheon precision depth recorders (PDR) for trackline surveys.

Some PTR-105 advertising from Raytheon can be found here.

(Photo courtesy of Roger Gilfert)

AN/SSQ-27 (XN-1) Time and Frequency Standard

Manufacturer: Borg.

Installed in NIC, "Borg Time" distributed date and time information to the NAVDAC computer, PDRs  and perhaps other devices. It also furnished precise 120 volt 60 hertz AC to electric clocks in the Navy spaces and in the pilot house.


AN/WPN-3 Loran-C Receiver

Manufacturer: Sperry.

R-1014/ WPN-3 Receiver:

Hyperbolic Radionavigation Systems:

AN/SPN-7 Lorac Receiving Set

Manufacturer: Seismograph Service Company (Seiscor).

Michelson used Lorac "B" extensively for survey control during the spring and summer of 1964 while conducting sea trials in the Bahamas.

ASPS-III Acoustic Ships Positioning System

AT-092AR, AT-095 Deep Ocean Transponders

Installed only aboard USNS Bowditch. Photo shows Earl Adams preparing a transponder for launching.

Bendix G-15D Computer

Two Bendix G-15D general purpose digital computers were installed in Hydroplot. These computers were used in the onboard production of bathymetric contour charts.

In 1964 they were used aboard Michelson to compute the ship's position from Lorac receiver readings. 

These computers were used off line, not being electronically interfaced with SASS or any other shipboard systems.

At right, the front panel with the paper tape reader at top.

The right door open showing the right assembly bays.

The right side open and one of the tube modules. 

(Photos from the Australian Computer Museum.)

An extensive set of technical manuals, brochures and schematic diagrams for the Bendix G-15 computer can be found here:

AN/UYK-1 General Purpose Digital Computer / CP677

Manufacturer: Bunker-Ramo.

The Bunker-Ramo CP677 was the data processor for SASS, the AN/BRN-3 and, ca. 1969-1970, replaced the Sperry NAVDAC Mk I as NAVDAC.

(Left photo from Roger Gilfert, front panel from product brochure.)
A product brochure, dated May 1964, for a Bunker-Ramo 133 Computer System.The 133 looks almost identical to the CP677, and has very similar specifications.

The CP677 was installed on the TAGS ships during the 196-64 yard periods as part of SASS and the AN/BRN-3.

Front and back of the AN/UYK-1 Logand Card, listing the machine language programming commands for the computer. CP677 Techs carried these around in their shirt pockets.

((Images furnished by Phil Brooks & Gordon Powell).

Friden Flexowriter

Manufacturer: Friden Commercial Controls.

These were 80 pound electric typewriters equipped with paper punches and readers. They were used aboard the TAGS ships as computer terminals for the Sperry NAVDAC computer.

IBM Selectric Typewriter

Manufacturer: IBM.

These were initially used as input/output devices for the Bendic G-15 computer. Selectrics were located in Hydroplot and in the Survey Control Center. Later they were deployed as terminals for the CP-677 computer, which replaced NAVDAC.

Mk. 19 Gyrocompass

Manufacturer: Sperry.

When the ships were constructed in 1944-45 they were originally equipped with Sperry Mk. 14 gyrocompasses. These were located on the O2 level, amidships, across from the radio room. Parts for these became hard to find by the 1960s.

Sperry Mk. 19 gyrocompasses were installed in NIC during yard periods in 1964-65.

Sperry Mk. 19 Gyrocompass Technical Description (pdf file).


Manufacturer: Sperry..

NAVDAC was an acronym for Navigation Data Assimilation Computer, which describes concisely what the equipment was, and what it did.  It's unusual for an acronym to end up being so precisely correct!  It was a general purpose computer which ran a program that assimilated navigation data.

The original NAVDAC on the TAGS was a Sperry computer built to a UNIVAC design.  See the excellent commentaries by John Prough and Jack Keenan.  Photos of the computer, which unfortunately do not show the face of the control console (with nixie tubes!), are here and here. The computer consisted of the two three-cabinet stacks seen in the photo, one behind the Sid Mitman on the left, and the other behind LCDR Hammer on the right.

By 1969-1970 the Sperry NAVDAC had been replaced on the TAGS by the Bunker-Ramo CP677.

The Sperry NAVDAC Mk I is the two stacks of  horizontal cabinets to the left and right of the Tech Rep in the yellow shirt.

The preferred maintenance tool seems to be a spray bottle of 409.

(Photo courtesy of Earl Adams).

NAVDAC MARK I Technical Manual

(Comments and documents from Jack Keenan.)

This tech manual is the "final" version, published in 1962. There was a "preliminary" version which was all we had back in '62 when I was on Dutton. If memory serves me, the final version was just a reprint of the prelim!

There were two major modifications to the Mark I in later years. These were the addition of a stepping magnetic tape recorder and the modification to the input and output units to provide communication with the Sperry SINDAC computer (MK3 SINS) and possibly other navcenter systems. To my knowledge, there was never a formal "change" to the tech manual to incorporate either of these mods.

The only information I have for the first mod is an informal "installation manual" for the tape recorder, which includes instructions for the modification to the Mark I. I have this because I designed the mod and wrote the manual.

As for the second mod, I do not have anything more than some pictures of, and technical information for, the "Sugar-cube" components used for the new Input/Output Unit logic circuits. I was not involved in the design, development and installation of this mod.

MK3 Mod3 (Mod6) SINS (Ship's Inertial Navigation System)

Manufacturer: Sperry.

The Sperry Mk 3 Mod 3 SINS, (Later upgraded to Mod 6). SINDAC, The SINS Data Assimilation Computer, is the 3 cabinets on the left. The SINS binnacle is hanging from the overhead on the right.

(Photo coutesy of
Roger Gilfert)

The Sperry Mk 3 Mod 3 SINS binnacle, with its skirt raised. The binnacle houses the stable table, which isolates the gyroscopes and accelerometers from the local vertical.

(Photo courtesy of Earl Adams.)
TenderJobs: SINS Gang - Ship's Inertial Navigation System

Sonar Array Sounding System (SASS)

Manufacturer: General Instruments..

SASS was installed on Bowditch, Dutton and Michelson during the 1963-64 yard periods.The first multibeam phased array sonar sounding system was the ancestor of all side scans and fish finders in use today.

The SASS control console aboard USNS Michelson, 1972-1973.

(Photo courtesy of Steve Campbell.)

The SASS CP-677 computer, aboard USNS Bowditch, 1972-1973.  The cabinet on the left is the extended memory cabinet.

(Photo courtesy of Bob Lord.)

LAZARUS: FROM SEVEN TO SEVENTY SEVEN by Eugene Weisberger, with and introduction by Earl Adams. All about SASS from the general manager at General Instruments..

Introducing an Operational Multi-Beam Array Sonar by Morris F. Glenn, US Naval Oceanographic Office.(pdf file)

An advertisement for Sea Beam, the commercial version of SASS from the late 1970s.

Equipment Notebooks

Earl Adams' "wheelbook" containing equipment operating instructions from USNS Bowditch in 1967-68 (left).

At right, his wheelbook, expanded to a small loose leaf notebook, covered equipment aboard USNS Michelson in 1970-71.

Navigation Information Center (NIC)

The equipment floor plan of NIC c. 1963-71. Redrawn from the diagram in USNS Dutton Information Booklet, contributed by Henry Alubowicz.

Communications Equipment

At some time in the early 1970s the Navy took over responsibility for receiving and transmitting radio message traffic between the ships and Navy shore stations. A billet for an enlisted radioman was added. Prior to this, the ship's radio officer handled these duties for the Navy group using morse code over HF radio.

Messages were encrypted and decoded off line by Navy officers or their designees.Standard Navy communications equipment was installed in the Navigation Information Center (NIC) in the space previously occupied by the NAVDAC computer.

The photo at right identifies most of the comm hardware, typical for 1970s HF radioteletype installations. Note the curtain and track attached to the overhead, presumably for security reasons.

(Photo by Roger Gilfert, equipment identified by John Hansen.)