It’s a great day for diving. You’re excited to see the reef you’ve read so much about in your dive magazines and finally, you’re on the dive boat and on your way. The warm tropical sun is shining down on you, you’re well rested, well hydrated and you’ve got the echo of Bob Marley in your head from last night. You descend with the group, and enjoy the superb visibility on the reef along with the 11 other divers in your group. The divemaster signals for everyone to start your ascent so you pick up your inflator hose, look at your gauges and start up. Up the anchor line you go, watching your accent rate indicator as you rise. As you arrive at 15 feet to do you safety stop, because you’re a safe diver, you run into something that unfortunately reminds you of home; a HUGE TRAFFIC JAM! There’s just not enough room for you at 15 feet with all the other divers trying to do the same thing. You notice that there is a bit of a current so you don’t want to let go and drift away, nor do you want to do your stop too shallow or deep negating the purpose. What do you do now?
This is probably something that you have experienced at least once, and possibly many times depending on where you dive and what operation you use. The good news is that, like most things in diving, there’s a solution to this predicament. Given excellent buoyancy control and low current, it’s possible to do your stop without hanging onto the accent line. I’ve done a free-floating safety stop many times, however at certain times conditions don’t allow it. Even divers with immaculate buoyancy skills encounter current and surge on the accent that makes a free-floating safety stop both difficult and unadvisable. That’s where a Jon line comes in handy.
No, a Jon line is not where you wait to relieve yourself. A Jon line is nothing more than a 6-12′ lead you use to give yourself a little room at that very important 15′ mark. Instead of bumping and crowding the group at the proper depth, you take out your Jon line, attach it to the accent line, attach the other end to your BC, and fly like a kite in the breeze, safely away from the crowd.
Although commercially available Jon lines are available, in reality it’s nothing more than a lightweight dog leash. I use a 10′ leash designed for a poodle or other small dog. I keep it tucked in my cummerbund pocket, pre-attached to a small key loop on the inside. And on the loose end, is the small brass snap. I pull it out, loop it around the anchor line and snap it to itself and I’m all set. I fly in the current like a kite on the beach, comfortably away from the crowd. When your safety stop is over, you can pull yourself in, unsnap, stow your line and head to the boat.
Crowds aren’t the only reason to use a Jon line. Often times, surge from wave action on the surface can get so severe that holding onto a bucking anchor line is all but impossible. However your Jon line acts like a shock absorber, allowing you to comfortably stay at your desired depth, without being beaten up by what’s happening to the boat.
It’s important to note that you must still concentrate on good buoyancy control. Although “attached” to the anchor line, the length of the line can potentially allow you do drift up or down outside of your desired depth, so one must still monitor their buoyancy and pay attention. Another important note of safety is to not choose a line that’s too large for the job. Not only will an oversized line make it hard to stow in your BC, but also it becomes more difficult to cut in an emergency. All that is required is the smallest gauge leash in the pet store, something suitable for a small dog or even a cat (I’m still not sure why those exist). Which brings us to our final point of safety; have a knife. When allowed by local regulation, you should always carry a knife on every dive, and especially when diving with a Jon line, should unsnapping your Jon line become difficult or impossible.
The Jon line was developed by technical wreck divers who encounter both heavy surge on distant offshore wrecks that make the anchor line buck wildly. But more importantly, technical wreck divers often perform lengthy decompression stops, and having to hold onto a line for hours can be rather daunting, thus the Jon line was developed making these technical dives that much safer and enjoyable. Although this type of diving is well out of the realm most of want to achieve, we can still adapt their great ingenuity and make our recreational dives just a little bit easier.
*As an added bonus, I have taken many great shots of jellyfish, schooling jacks, and bait balls while enjoying my hands free safety stop!
Scott Shenton
