John Hensel (1916–1999) was born in New York City and is of Danish descent. He spent a number of years at sea, beginning at the age of seventeen when he signed on as an ordinary seaman aboard a Canadian freighter out of Baltimore. Considered one of the world’s foremost authorities on knotting, he learned knot work aboard ship and in the hundreds of foreign ports to which his ships carried him. He is the coauthor of the Encyclopedia of Knots and Fancy Rope Work, Fourth Edition, and Splicing Wire and Fiber Rope.