How did people on army boats communicate at night without using radios in the 1900s?

Answer 1

Spot Lights and Morse Code. Morse Code was invented along with the Telegraph. Samuel Morse invented the telegraph. There was a predetermined set of codes for each letter of the alphabet and numbers represented by dots and dashes. Dots would be signaled by quick flashes of light, and dashes slightly longer flashes of light. These spotlights were covered by horizontal rows of metal panels that when not in use, covered the light totally. When the message signaler would start to communicate the dots and dashes, he would flip the horizontal metal panels up and drop them (rapidly in succession) to convey letters > words >sentences. This form of communication was effective, because the distance of sight to horizon on a ships "bridge" (control room) was about 5 miles. At night, ships could communicate in this way over 4 - 5 miles away from each other if necessary. Otherwise it was a message in a bottle (just kidding). The Germans actually utilized the first electronic communication (via radio waves) with a device that was much similar to a steno graph machine that is used in court rooms today. The movie U-571 is an excellent movie that depicted this.