Alcatraz — San Francisco Bay · OpenHelm light study

A decorative chart and light study. NOT FOR NAVIGATION. The chart is an original,
simplified portrayal; it omits features and is not an official NOAA product. NOAA's logos
are not used and NOAA does not endorse this work.

DATA

Office of Coast Survey. (2001). NOAA Electronic Navigational Charts (ENC) [Dataset].
National Oceanic and Atmospheric Administration. Accessed 2026-09-24.
https://doi.org/10.25923/jyyk-j845
Cells US5OAKEF, US5OAKEG, US5OAKEH, US5OAKFF, US5OAKFG and US5OAKFH: coastlines, land,
depth contours, soundings, bridges and navigation marks. Depths in metres.

Use of this data-derived work is subject to the NOAA ENC User Agreement, included with this
screen saver as NOAA-ENC-USER-AGREEMENT.html:
https://charts.noaa.gov/ENCs/ENC_Agreement.shtml
Data licensing: https://nauticalcharts.noaa.gov/data/data-licensing.html

THE LIGHT

Alcatraz Light: Fl W 5s, nominal range 20 M (US5OAKFG LIGHTS, LNAM 0226014E0B1B0032;
USCG Light List vol. VI no. 4315). NOAA gives no sector limits; the sweep uses a full white
circle clipped at the first charted land. It is an artistic interpretation of the light's
period, not its physical optic, brightness or flash.

SOFTWARE

OpenHelm Chart Saver — MIT licence. https://github.com/helmahoy/openhelm
