Jon Line Page

From Dan Bergs Website

The term Jon Line was first used after a diver named Jon Hulburt, who, while doing a dive on the Andrea Doria discovered that decompression hangs in rough water or in a current were made much easier with the use of a short line. This Jon Line is usually about seven to 15 feet long with a spliced loop at each end. One end attaches to the anchor line by simply passing an end through the loop and pulling it snug on the anchor line. The diver or divers (up to three can use the same line) doing a decompression stop can now hang onto the loose end behind the anchor line. In rough water, when the anchor line moves violently up and down, divers using a Jon Line will not find themselves being lifted from their stop depths, but able to maintain their depth relatively easily. Also a much desired benefit of the line is getting the diver out of the crowd. After completing a stop, the hang depth can be easily moved by making a fist around the anchor line just below the snug end and sliding the snug end up. While stage decompression diving is not recommended by any recreational diving agency, this line will also benefit those doing safety decompression stops.

I was first shown the Jon Line while diving the Coimbra wreck. We had about 14 foot seas on the surface, but with the use of this easy to make tool, our decompression stops were made more tolerable. One slight modification to the original design is to install a stainless steel locking carabineer to one end. For long stops in a strong current situation, this carabineer can be snapped onto a secure D-Ring on a harness. This reduces arm fatigue greatly.