Hill 640 Military Reservation


Hill 640 fire control stations

Hill 640 fire control stations with Stinson Beach in the distance.

As coastal artillery guns became larger, and their range increased, growing demands were placed on the fire control systems that targeted potential naval targets. By World War II the 16” guns of Battery Townsley and Battery Davis could fire a projectile 25 miles to sea. And there is a lot of sea out there at that range. To be effective the projectile would have to strike its target and that is where the artillery fire control system came into play.

Fire control station, Battery Smith Guthrie

Fire control station, Battery Smith Guthrie (courtesy GGNRA photo archive).

Fire control systems basically sighted targets from multiple vantage points along the shore. The vantage points were connected by baselines of known relationship. The sighting direction from each fire control station was transmitted to a central fire control plotting room where the readings were fed into an analog computer, essentially adjustable arms on a large plotting table (see video). The coordinates of a target ship were updated at 20 second intervals to establish a ship trajectory, A projectile fired by the 16” guns was in the air for about 90 seconds so several intervals of plotting would occur while the load was in flight.

Hill 640 fire control stations

Fire control stations for Battery Construction 243 (foreground) and Battery Construction 129.

Coastal batteries with smaller weapons could use fire control stations that were relatively close to each other. However, the range of the 16” guns required fire control stations that were quite far apart. In the Bay Area these began down past Pacifica to the south and ranged all the way up to Wildcat in Pt. Reyes. The Hill 640 Military Reservation, located on coastal bluffs just south of Stinson Beach near the intersection of Panoramic Highway and Highway 1, had five fire control stations with each station associated with a different 16” gun installation. The site has fire control stations for completed batteries (Townsley and Davis) and unfinished batteries (129 and 243) plus a fifth fire control station of unknown association. It is interesting that while the fire control stations all belonged to the same era they have different designs. There must be a story behind this circumstance. It is also interesting that targeting information was not shared between the batteries.

Our visit found the fire control stations all grouped together above Highway 1. They seem to be in pretty good shape for structures built 70 years ago.

Here is a set of images from the session that I have posted to Flickr:


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