https://www.commsmuseum.co.uk/signallamps.htm &
https://www.commsmuseum.co.uk/tactical/lights/aldis.jpg
"...These signal lights give a peak candle power of 150,000 with a divergence of 6 degrees. A range of 5 miles in bright sunlight in good weather may be expected in home waters...."
OUTTA DIS Worlde data transmission aslo: [somewhere there is a more intelligible explanation (compared to link below) of transmitting data via a powerful light source:
https://fabacademy.org/archives/2011...ons/index.html
Some more links - the one I have in mind cannot be found at the moment:
https://allhands.navy.mil/Stories/Di...n-the-us-navy/
&
https://www.usni.org/magazines/proce...h-another-look