Here is an
article you should read. Steve describes differences between wreck and cave diving. The article is from his excellent presentation that he gave at the NACD conference last November.
interesting. do you agree with his summary of the differences between caves and wrecks:
"Gas Management: The Rule of Thirds is sacrosanct to cave divers and wreck divers but there are few wrecks offering several hundred metres of penetration; and so the rule’s application in wreck diving is far more like the Hub Plan used by CCR cave divers than the classic and simpler one third in, one third out used by OC cavers.
Propulsion Techniques: Wreck divers may have to employ a modified pull and glide to navigate narrow corridors inside a wreck where ANY fin movement is guaranteed to reduce visibility to zero in seconds. One other difference is that when a wreck diver kicks a wall by mistake is moves… it might even fall down. Anyhow, finning is NOT the default propulsion technique in “real” wrecks.
Guideline: Cave divers are warned about line traps. Cave divers can follow and usually do follow permanent lines for miles. Wrecks are one big line trap and a permanent line is the stuff of dreams. One might also consider that a continuous line to the surface covers a wreck diver’s need to be able to deploy a DSMB and decompress in blue water. In fact, that constitutes a required skill: hang off knotted line… keeping track of the knots to judge depth, with a blacked out mask, and counting breaths to track time.
Lost Line: Not a big issue when you carry the “permanent” line on a reel in your hand, but a required skill nevertheless for a wreck diver. However, more often than not, during their search for the lost line, students manage to get a manifold, spg, fin or something wrapped up in hanging cable… or their instructor’s simulation of hanging cable. Last time I audited a cave class, tying up the student was not part of the course work. It is in a wreck class. Another time for rodeo work is when students exit through a restriction with blacked out masks sharing air.
Communications, light failures and so on, are no different, but problem solving is. In a cave, the shortest route to fresh air is almost invariably back the way you came. In a wreck, the surface is closer but not necessarily easier to get to. And once there, getting out of the water may be a challenge.
Now if we stopped right now, some of you might leave here thinking, wow, wreck diving sure sounds tougher than cave diving. And in lots of ways, it is. But if things were that simple, how come we are not looking at a bunch of dead cave divers dying in wrecks instead of a bunch of wreck divers who are dying in caves. To be honest, I am able to turn up a constant and irreversible answer to that."