 | From Ocean Navigator #90 May/June 1998 |
Lightning protection plans are included in these drawings of an 19th-century frigate.
Harris began serious investigations into the nature of lightning phenomena by studying the writings of earlier natural philosophers, including Ben Franklin, who proposed the use of lightning arrestors on buildings to safely lead the “electric fluid” to the ground during storms. He also studied the effects of strikes on hundreds of vessels such as the American ship, Amphion, which sailed for Rio de Janeiro in 1822. Amphion received a lightning strike on her mizzenmast, destroying her compasses, bulkheads, and rudder trunk, as well as most of her cabin furniture, before passing out through the quarter into the sea. The Royal Navy’s HMS Duke, 90 guns, was similarly struck by a bolt at the island of Martinique in 1793, while engaging an enemy shore battery. Duke suffered heavy damage, including the disintegration of her main-topmast, and severe damage to the crew’s morale when they witnessed what appeared to be God’s intervention on behalf of the enemy.
Harris successfully enquired “how far it is possible to carry the violent operation of discharges on shipboard,” and proposed “to perfect (improve) the conducting power of the masts together with that of the rigging by efficient copper conductors,” which were connected by copper wires to copper sheets on the bottom of the vessel. He further proposed “to connect in a similar way, all the detached metal bodies of the ship, both with each other and the general (grounding) system. . .” to complete “the conducting power of the whole mass, and remove all resistance to the process of electrical diffusion.” Estimates for installing Harris’s lightning protection system on a first rate naval ship of 120 guns were £ 60 for labor and £ 306 for copper materials. While this was a small fortune in 1834, it seemed money well spent to protect a man-of-war, which, when fully equipped, could be worth as much as £110,000. Even today, the protection from a boat grounding system based on the ideas of Harris justifies the expenses involved.
