Unless you are a maritime scholar, the average person probably has not thought much about the array of lights needed for a ship. The most common of these lights are the masthead, navigational, signal and deck lights. Depending on the size of the ship, the numbers of lights could easily be in the hundreds. Over the centuries vessels navigated the seas at night with little more than oil lanterns, candles, and hope. Oil lamps were not only smelly, they provided only limited illumination for night travel, and, more importantly, posed a tremendous fire risk. On wooden ships, with their seams caulked with tar and ropes greased with fat, there was little that would not burn. Swinging oil lanterns could easily be knocked over by strong winds or waves, not to mention simple onboard accidents that could quickly create an inferno that left no escape for anyone.
By the 1850’s most merchant ships were using small pieces of glass, known as deck prisms, as a way of illuminating the holds below. Affixed on the deck the glass prisms diffused light below. This increased the safety for the merchants’ ships, but passenger ships still needed stronger illumination. As late as the 1870’s, companies like the White Star Line were still building huge cruising ships, some nearly 500 feet in length, fully furnished throughout with oil lanterns.
With the advent of electricity, maritime engineers quickly began planning its use for ship lights. In 1880 the British warship Inflexible was the first ship to have electric cable installed. Although its initial power was weak, less than 100 kilowatts, the ships general illumination was considerably better than the old oil lanterns. There existed from the beginning serious doubts about electricity’s reliability. Some claimed that a ship’s compass could become corrupted by the magnetic field of electric current and, of course, a ship off course meant certain disaster. How could the electric cables be bound with strong enough rubber to keep bystanders safe from electrocution? Confidence was so weak that early twentieth century standards for ship lights were still based on using oil lanterns. Most ships continued to have on board a supply of oil lanterns, in case the electric lights failed.
Despite the long history of ship fires at sea, the public was still slow to give up their malodorous and dangerous oil lanterns. Progress continued in developing and safely containing electric ship cables. The power of electricity on ships improved. By 1930, electric ship lights, and more importantly, electric power on ships, were being fully embraced by the public and oil lanterns became a thing of the past