Since 1839, ships entering and leaving Yarmouth Harbour on a passage across the Gulf of Maine, a fishing trip, or, in earlier times, a voyage to distant lands aboard a square rigger, have passed the light tower at Cape Forchu. For decades, the day mark has been a red lantern and alternating red and white faces on the octagonal tower. The original timber tower was lit on 15th January, 1840. The lens was a classic Fresnel, a circular central lens surrounded by concentric rings of glass which concentrated the light of the lamp into one powerful beam which shot out into the night. The Cape Forchu example had eight faces, each of which produced a white flash. It was turned by a clockwork mechanism which had to be wound every three hours. (This original lens, which was manufactured in France, can now be viewed in the Yarmouth County Museum, Yarmouth.) The first lighting apparatus was a kerosene lamp. This was later replaced by a pressurized vapour lamp, and finally by electricity generated on the station. The early lamps had to be watched carefully, for they could easily go out. One keeper estimated that during his 31 years on duty he climbed the tower at least 47,000 times!

The old timber tower was much photographed, so when the Coast Guard decided in 1961 that it must be replaced, town and tourist officials requested that the new light tower be built along the lines of the old. In October, they were assured by their MP that the new tower would be an outward replica of the old and "there will be no change in the splendid harbour vista." The additional height of the 22.9 metre octagonal concrete tower and the added power of the new dioptric lens added 10 miles to visibility, so that the light can be seen for 22 miles to seaward. Electricity is provided by a cable run from the town of Yarmouth