Checking index error of sextants prior to conducting launch hydrography.

The tools of the trade for navigating during launch hydrography. Metallic and plastic three-arm protractors for plotting three-point fixes. Sextant in background. 1931 Hydrographic Manual

Checking boatsheet during wiredrag survey of Mitchell Jordan Reservoir. Plastic three-arm protractor for plotting fixes barely visible under hand. Surveying reservoir for seaplane landing site during WWII ferrying operations. Wiredrag party of Max G. Ricketts

Plotting three-point sextant fix with metallic three-arm protractor. On the FATHOMER

Manual plotting of three-point sextant fix. Using plastic three-arm protractor

Geometry of the three-point sextant fix. Diagram shows shoreline, stations, and angles measured. 1931 Hydrographic Manual

Graphic of various combinations of strong and weak three-point fixes. Hydrographic Manual

Graphic demonstrating Radio Acoustic Ranging (RAR). Developed in 1923, RAR was the first non-visual navigation system. Combined velocity of sound in water with radio to obtain fix.

Planting a hydrophone anchor with the cable attached. On the GUIDE. Hydrophone would pick up sound from RAR TNT explosion.

Cable drum being pulled by horses across dunes. Cable lead to offshore hydrophone for Radio Acoustic Ranging. On the GUIDE

Electronics setup for Radio Acoustic Ranging shore station. Navigation station for the GUIDE

Planting anchor for Radio Acoustic Ranging hydrophone. Must have been warm - note bare foot helping push anchor away from ship

A new type of hydrophone block for Radio Acoustic Ranging. On the GUIDE

Transferring the hydrophone block and cable to launch for planting. Radio acoustic ranging operations on the GUIDE

Launch laying the cable from hydrophone to the shore station. Radio acoustic ranging operations on the GUIDE

Shore Radio Acoustic Ranging Station on San Clemente Island. Radio acoustic ranging operations on the GUIDE

Radio operator at work at Radio Acoustic Ranging shore station KGHS. Radio acoustic ranging operations on the SURVEYOR

The first Odessey Protractor. This instrument was used to plot intersecting ranges from two RAR stations. Invented while Herman Odessey attached to DISCOVERER. Variations of this instrument were used for plotting positions for over 60 years

Radio Acoustic Ranging bomb making. TNT bombs were sound source for RAR. RAR work on OCEANOGRAPHER

Radio Acoustic Ranging bomb making. TNT bombs were sound source for RAR. RAR work on OCEANOGRAPHER

Radio Acoustic Ranging - igniting the bomb and timing fuse. TNT bombs were sound source for RAR. RAR work on OCEANOGRAPHER

Timing the fuse on a quart bomb during RAR operations. TNT bombs were sound source for RAR. RAR work on OCEANOGRAPHER

Quart bombs exploding during RAR operations. TNT bombs were sound source for RAR. RAR work on OCEANOGRAPHER

A schematic view of RAR and echo-sounding. Diagram in public information brochure

The Launch PRATT - an RAR hydrophone boat. Worked as station boat while HYDROGRAPHER conducted sounding operations

A sono-radio-buoy developed to eliminate need for station boats. RAR operations in the Gulf of Mexico. Forerunner of Anti-submarine warfare sonobuoys

Electronics package of sono-radio-buoy for RAR. This instrument was developed by Almon Vincent on the GUIDE. Forerunner of Anti-submarine warfare sonobuoys

Sono-radio-buoy for RAR work on pier --- Almon Vincent design. Forerunner of anti-submarine warfare sonobuoys

Almon Vincent tuning the antenna circuit on sono-radio-buoy. RAR work on the GUIDE

Railroad car couplers used to anchor RAR hydrophone. On the OCEANOGRAPHER

Vincent type sono-radio-buoy being deployed from the GUIDE. RAR operations on north coast of Unimak Island

Sono-radio-buoy developed by Almon Vincent for RAR work. Buoy deployed from the GUIDE

Sono-radio-buoy deployed in the Aleutians for RAR work. Buoy deployed from the PIONEER

Inspecting the electronics package of a sono-radio-buoy. RAR work on the OCEANOGRAPHER

Holding RAR bomb. In 1944 issue of the magazine "The Military Engineer"

RAR bomb being exploded astern of EXPLORER. In vicinity of Islands of the Four Mountains

RAR bomb being exploded astern of GUIDE. North shore of Unimak Island

"Gee" or Shoran hyperbolic navigation lattice over France. Allies installed electronic navigation systems to guide bombers. Adapted to hydrographic survey needs at end of war

Front page of first report detailing tests of Shoran by C&GS. Clarence Burmister spearheaded efforts to adapt Shoran to survey use. Tests run in vicinity of Attu Island

Shoran was high frequency line-of-sight system

Shipboard Shoran antenna from below. On EXPLORER

Shipboard Shoran antenna as viewed from bow. On EXPLORER

Shore station Shoran antenna being raised. First electronic navigation antenna ever raised by C&GS. Party off of EXPLORER. Photo No. 1 of sequence

Shore station Shoran antenna being raised. First electronic navigation antenna ever raised by C&GS. Party off of EXPLORER. Photo No. 2 of sequence

Range-range navigation lattice generated by Attu-Semichi stations. First purely electronic navigation lattice used by C&GS. Electronic navigation lattice developed by party off of EXPLORER

Closeup of Shoran antenna mounted on radar antenna. Shoran array installed by party off of LYDONIA

Shoran antenna installed on radar tower. Shoran array installed by party off of LYDONIA

Shoran antenna installed on radar tower. Shoran array installed by party off of LYDONIA

Plotting range-range Shoran position with Odessey protractor. On LYDONIA

A conceptual Shoran station layout. Circular lines of position with Shoran in range-range mode