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On Tue, 21 Jun 1994, Tracey Baker wrote: > These answers are fairly arbitrary... Use them, or pick a "typical" > setup if YOU were going to do this dive (or do you suffer from > nitrogen withdrawl at such shallow depths? :-). Thanks. I've included the answers below, in case anyone else had similar questions. I'll try to explain why I asked each question... > >1. Is the ascent line the anchor line to the boat? Yes > >2. If not, where is the boat, and is it anchored? n/a > >3. Are there any people in the boat, and do they know how to drive it? Yes, and yes > >4. Are there any/how many people in the water (i.e., buddies) with me with > > similar decompression obligations? Could be... I'd like to hear the possibilities either way! > >5. Do I have a "jon-line" or penetration line reel, or any other line with me? Yes, a jon line, and probably also an upline and/or penetration line of some sort > >6. What kind of backpack/B.C am I wearing? I'd assume a wings-type (back-buoyancy) > >7. Do I have any other independant cylinders, and if so, what gas is in them? You're wearing doubles with air in 'em, and have a 45ft^3 each of air and O2 (this is just a guesstimate of gas requirements). > >8. Do I have anything which might serve as an inflatable buoy (lift bag? > > non-mesh goodie bag? plastic bag?) Lift bag. > >9. What depth am I at half-way through this 40-minute decompression? (if > >the first stop is at 30', I suspect that at 20min I'm at or near my 10' stop) Say 20' (my O2 tables don't have 10' stops). > >10. Do I have a knife? > Yes, a small-ish one (no leg-mounted machetes :-). Before I begin, I want to briefly describe my philosophy of problem-solving during diving. One perspective is to try to anticipate problems before they occur, and develop standard, set responses to the most likely events during the pre-dive planning. When such problems do arise, divers react immediatly on a pre-planned contingency (i.e., a "no-brainer" response to a general problem). Another perspective is to understand the risks of each dive prior to conducting it, attain a level of experience such that consequences of various situations are very familiar (this all falls under the "dive within your own limits" maxim), and deal with problems as they arise by intelligently formulating a solution in "real time". I like to incorporate an element of both, but I tend torwards the latter philosophy. Critics of this philosophy (and there are many) often cite the hazards of trying to think your way through a problem while "under pressure" (i.e. task loading/narcosis/etc.). Obviously, the ideal solution depends on the individual. The reason I went into all of the above is to point out that, although these thought-games are certainly stimulating and perhaps often educational, there are many of us who simply cannot really say how we would respond to a situation unless we know every minute detail. So, here's my response: If the ascent line was simply a buoy (not a boat anchor), and since I have a knife, I probably would cut the ascent line and finish decompression drifting underneath the buoy - but I would do this only if I knew the boat crew were paying attention to the ascent-line and would be smart enough to follow it if it started drifting away (not unrealistic on a drift dive; but since it was a wreck, it probably isn't a drift-dive) But anyway, it was the boat anchor line; so..... If things seemed otherwise under control, and if I were wearing my usual "Hawaiian-style" backpack (shoulder-hooks instead of shoulder straps), I would pass the anchorline under one of the shoulder hooks to hold me and the rig in place while I set up my "jon-line" (hence, why I asked what kind of backpack). But since most folks don't use a Hawaiian-style backpack, let's assume that's not an option. I probably wouldn't try the leg thing (wrapping legs around line), 'cause if the current is as strong as you describe, it would probably rip my mask off if I turned sideways (I've been in such currents - they do exist). If it were a truely life-threatening situation, and there were no other people in the water below (on the bottom still or below on the decompression line), I would simply cut the anchor line and decompress drifting under the boat. The most likely response for me, given your answers to my questions, would be to coordinate with other members of the dive team, then let go of the anchorline and send up the lift-bag attached to my reel-line, doing a drift-decompression. If I didn't have a lift bag, but had a detachable pony bottle from which I could finsh my decompression on, I'd probably inflate my B.C. and send my rig up as a buoy. If the sea was very rough, or if it was getting dark, or if no-one was in the boat (or if they weren't savvy enough to figure out what was going on), or if I was relying on surface-supplied O2, then I might have to consider a different option. Although I would never recommend this to anyone else, and would probably publicly discourage it, if it were me I'd slowly ascend to the surface, ask the boat tenders to cut loose the anchor line (tie it off to a buoy and recover it later), and have them drop another decompression line. In any case, my underlying point is that I would have to take many details into consideration before I could tell you how I'd respond. As for preparation for such problems: I would have to assume that the divers knew in advance that the wreck gets hit by strong currents from time to time. When we dive in such areas, we have certain understandings and equipment: Equipment: -Divers ALWAYS carry ALL the gas they need to complete the ENTIRE dive with them THROUGHOUT the dive (no stage bottles) -Divers ALWAYS carry a line and an inflatable buoy (a long orange thing, sometimes called a "whale condom"). -Boat has a large buoy which can be tied to the anchor line incase the boat has to pick up a drifting diver. Understandings: -Boat crew knows when the diver(s) should be on the decompression line, and if they do not show up, they know to look down current. -Boat crew is keeping an eye down-current to look for decompression buoys. -Buddies are aware of the risks, and have an understanding of what to do if they become separated. IMHO, currents are probably the single most hazardous aspect of open-water diving. Because we encounter them often, we try to use them to our advantage (i.e. planned drift dives, etc.). Currents are also one of the biggest reasons why I feel safer doing deep dives alone. I think I've rambled on enough.... Aloha, Rich
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