Cave and Tech
SAC Rates and Cave Diving Bailout
At least 99 out of every 100 divers who read this article won’t be able to use the information it provides. Even among certified cave divers, what we cover here applies only to those who use Diver Propulsion Vehicles (DPVs) or rebreathers. Nevertheless, if you have gotten this far, it’s likely you have at least a general interest in cave and tech diving. If so, you just might find the subject matter interesting and — who knows? — it might just apply in some way to the kind of diving you do.
Planning Deep Dives Like a Tech Diver
Among the first things beginning divers learn is that gas consumption increases at depth. For example, a cylinder that would last a diver 50 minutes at the surface may only last ten minutes at 40 m/130 ft. That’s not a lot of time when there is so much water over your head. Because of this significant increase in gas consumption, deep divers need to be able to determine, ahead od time, whether or not they will have suficient breathing gas. One way to do so is to employ many of the same dive planning techniques technical divers use, including determining SAC rates and projecting gas consumption on each segment of a multilevel deep dive.
Getting Started In Cavern and Cave Diving
Each of us may have different goals when it comes to cavern and cave diving (not the least of which is just staying out of them altogether). Assuming you are somewhat interested in overhead environment diving, the question is really what do you want to do? Your answer will help determine which of the many available avenues is best for you. Just be aware that, if you decide you want to become a fully certified cave diver, you are looking at a fairly substantial commitment.
Sidemount: The New Revolution in Tech Diving Equipment
If you wanted to stand out at the recent NSS-CDS social at Jackson Blue spring, all you had to do was wear back-mounted doubles. If you did, you would be among the half dozen or so divers wearing this rig. The remaining 70+ divers were sidemounting. Cave divers in the USA began adopting sidemount in the early 1980s, as a means of passing through bedding planes — cave passages that can be several feet wide, but only a few inches high. Now sidemounting has gone mainstream, and is used by cave, technical and recreational divers alike.
Evolution in Action at Bathtub Spring
In 1990, five college students were staying at a laid-back, rural resort on the banks of north-central Florida’s Suwannee River. One afternoon they decided to take canoes up river to scout out potential dive sites. They soon discovered an outflowing of water on the opposite bank, known locally as Bathtub Spring. Excited by their find, the group beached the canoes and hiked inland to see what else might be in the immediate area. They soon came across a deep sinkhole, which they assumed connected with the spring, less than 200 feet away. Blinded by their eagerness to explore, little did two of these divers know they had just hours to live.
