With the jackline in place, you simply clip onto to it with the shackle on the end of the tether hooked to your harness. As you move along the deck in either direction, the tether simply slides along the jackline.
With a well-positioned jackline, you can clip on for safety before leaving the harness and attend to any business on deck without having to unclip.
Safety Issue vs Personal Preference?
Since most tethers are 6 feet long, a sailor who is thrown overboard while tethered to a jackline will likely go into the water but not with head immersed. Sailors who have had this happen while the boat is moving very fast in a high wind have described the plight of being bashed around in the water and against the hull until the crew can stop the boat and hoist them back aboard. Some sailors, therefore, prefer to use the 3-foot length of a double tether to clip on and crawl forward along the deck—the shorter tether should prevent you from hitting the water at all. With a double tether, you can always switch to the 6-foot tether when necessary to stand up at the bow.
Read more about other Sailing Safety topics.
