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Deep drift diving can be extremely risky business. In WPB, drift diving is the only type of diving that anyone does and when you suggest anchor diving to these folks they just laugh at you. 99% of the deep socalled "technical" diving is performed tethered to either an anchor line or a drift float which is set free from the dive site (usually a wreck) at the end of a dive. The type of Charlie Foxtrot which took the lives of the three divers in WPB is generally a recoverable error then this occurs on a suspended floatation system. This is why we have never really heard of such a thing happening, although we have observed untold instances of equipment and procedural horrors over the years. WPB, where the Gulfstream cuts over the kneecap in South Florida's Gold Coast, has some of the best drift diving in the Continental US. Ask anyone who has been there and dived such sites as the Jupiter Ledge, Twin Double Ledges, Spanish Anchor, Lobster Country Safari or the Breakers Reef to name a few. As you go North and deeper there are some sites which blow everything away, the most famous of which is the Hole in the Wall cave in 150 fsw. In deeper water still, on the 40 fathom drop off (an old shoreline), there are seaward facing sheer rock walls as high as 40 - 50 ft. The big fish, lobsters and hungries which inhabit these sites defy description. Many of these sites have never been dived and all sorts of stories abound of shipwrecks, submarines, offshore springs and caves, not to mention big game hunting, the likes of which is encountered no where else. In theory "technical diving" makes all of this stuff fair game .In theory . This is the type of stuff that Andre and his associates were beginning to dive, applying, unfortunately it seems, the same forgiving methods which are routinely used for most wreck diving. Drift diving with a towed float works well when the water column is 100fsw or less. Under these circumstances the parabolic velocity profile yields a rate differential between surface and bottom which is insufficient to create a serious upward net force from the drift float line reel. In other words the float drifts out ahead of you and exerts an upward force which is counteracted by your displacement and drag. At 200fsw plus, the net upward force encountered, when there is a surface current of greater than 1 knot, makes it almost impossible to remain submerged close to the bottom. Certainly, Andre was aware of this problem and this is why he chose to dive without a float and "shoot" lift bags at the end of the dive to demarcate his position to the dive boat. Three dead people are testament to the downside risks associated with this practice. Obviously, in a perfect world you might be able to get away with this procedure often enough. Diving two miles offshore without a surface marker places a gigantic amount of stress on the dive chase boat, especially in the rainy reason where a sudden squall can reduce the visibility to zero making it impossible to see the lift bags when they break the surface. The large orange floats, which are typically used, are great decompression hanging buoy systems.and can support hundreds of pounds of dead weight. The bottom line is that the only way to do these extremely deep drift dives is with deep ranging scooters. The scooter can pull the float line at a velocity which is closer to that of the surface current. This permits the divers to remain close to the bottom, use minimal gas and effortlessly cruise over a long distance during the short duration bottom time. The bottom time should be kept as short as possible so that an abort to the surface will not be fatal. In most circumstances, twin 80cf cylinders are used with conventional, single bladder, flat profile wings (dive rite, Halcyon.or SeaTec). Aluminum 40cf bottles of deco gas are used (eanx 50/50 and o2) and these bottles are always positioned on the left side. Depending on the lighting conditions and depth, cave lights are used for signaling purposes. The team is tight and visual contact is always continuous. The methods here are those of the WKPP and "Doing it Right". These apply equally in the ocean as well as caves. -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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