Re: Escaping a large hydraulic?
Posted by:
rob (IP Logged)
Date: June 29, 2008 07:00PM
Such hydraulics are generally rare (fortunately), but could occur in even relatively lower flow situations. Even a few hundred cfs going over a low-head dam, or in a narrow slot-canyon pourover into a deep, steep-walled cauldron could create a nasty hydraulic.
The longest time it could hold a swimmer? Well beyond what you could hold your breath. I've seen logs, volleyballs, basketballs, and all manner of debris recirculated for days in the backwash of low-head dams.
Yes, there can be undercuts in the riverbed (or logs, large branches, or whole trees stuck underwater in the area below the drop) which could snag you and hold you under. These are certainly rare (especially at such locations as form keeper hydraulics) but nonetheless not impossible.
What you can do as a swimmer? Well, I think it is well covered in one of the old William Nealy books (and no doubt other places). I don't have any of those at hand, but my recollection is something as follows:
Your first choice is trying to stay in your boat, working to one edge of the hole or the other to try to work your way out. Failing that, sometimes you can find a spot where perhaps the backwash is weaker and you can paddle your way out. Or perhaps dig in an edge (of the boat) or get the flow to take the bow or stern under to 'ender out'. Or if you intentionally (or unintentionally) flip, the fact that your entire weight is no longer in the boat, but is now providing some additional buoyancy (you and your PFD), sometimes that is enough to cause the boat to flush out of the hole. If not, it may help if (instead of tucking as tightly to the boat as possible, as in setting up to roll) you 'hang out', extending your body, your arms, and your paddle as deeply as possible, to catch the downstream-flowing water deeper in the river. There may have been some additional options, but they don't come to me now. Other than a totally 'last chance' option. Before going for the full 'wet exit', I've heard some folks propose that you might intentionally pop your skirt off the rim of the boat and let the boat fill with water while you remain firmly in the saddle. Again, the lack of buoyancy can be enough to let you flush out of the hydraulic. The 'plus' side is that you are still in your boat, with your paddle (so no 'yard sale' -- yet!) and (by some theory) you can try to paddle toward shore and save yourself or someone else the problem of having to fetch your gear (or the possibility that you may lose it completely). The downside is that you are in a boat full of water . . . well, half-full, if you have equipped your boat with float bags . . . either way, it will paddle like a slug! If you can't get to shore immediately, you are trying to paddle a full boat through whatever is downstream. Your boat full of water is floating so much lower, and is so much heavier, the likelihood of it catching on a rock and pinning is waaayy increased. Your maneuverability will be almost nil, so you will mostly end up where the river wants to take you. (I have never really considered this whole option as being anything remotely 'viable'. I'm curious if anyone has ever used it successfully, and what the scenario was which made it feasible.)
Failing any of the above . . . once you are out of your boat . . . first, the river may flush you out as soon as you exit the boat (since you now lack it's bouyancy). If it doesn't, the first tendency and option may be to try to swim out (either downstream, or to one side or the other) if you can keep your head above water enough to do so. Depending upon the situation (the nature of the hole, the geology of the river, the flow, the size of the river, etc) an option which should not be ignored may be as simple as to try to find bottom. If the river is not too deep, it may be possible to just stand up and walk out! (YES, I've actually done that! More than once! On relatively low-flow rivers, at a bedrock ledge or boulder/pourover.) In larger rivers, or rivers with large rocks or with sieves and undercuts, this may not be a good strategy, as there may be significant risk of becoming entrapped, entangled, or pinned under or between rocks or other stuff in the drop or downstream. I've heard of (or seen) places where it may be possible (if there is a considerable 'hollow' behind the face of the falls) to get 'behind the curtain' and walk/crawl, swim/clamor your way to shore. Or to get to a spot where you could push off (as a swimmer in a swimming pool, pushing off the wall to accelerate away from it) or dive-through the falls. Failing any of those, caught in a hydraulic which keeps recirculating you, generally trying to 'go deep' is recommended, to try to catch the downstream flowing water. Another strategy is 'making shapes'. Try 'balling up'. Try extending your arms and legs (together) straight. Try extending them out to the sides. Arch your body into a "C". Stiffen up. Go limp. (Often holes flush the body after the victim has quit struggling.) Again, a last-ditch desperation measure I've heard proposed is taking off the PFD, hoping that the loss of that bouyancy may make the difference. I'm hard pressed to imagine that making enough of a difference, and having the presence of mind (and air supply remaining in my lungs) to try that (after trying everything else possible first!). And, the problem then is that (even if it does get you out of the hole) you are now completely exhausted and in the river without a PFD, and likely to drown anyway!
Well, again, these are RARE situations. If you boat high volume rivers, rivers in flood, class V-VI rivers, and so forth, maybe your odds of such a thing get a tad higher. But for most boaters, extremely few of these measures will ever have to be employed. There is never ONE RIGHT ANSWER. Rivers are almost infinitely different, as are water levels, rapids, falls, and hydraulics. What may be THE RIGHT thing to do one time and place may be completely WRONG another time (same place) or another place.
Good luck!
Rob Smage
AW member since 1992, volunteer since 2000, Midwest Regional StreamTeam Editor