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Rope search patterns.
Rope search patterns sometimes require a bit more planning than ropeless patterns, but they are more accurate, especially when dealing with water movement and when searching for small objects. One aspect of using ropes is that in low visibility, divers may have to communicate with rope signals. Signals might be:
One pull = Attention, or Begin search.Two pulls = OK? Or OK!Three pulls = I’ve finished the sweep/ length.Four pulls = Come here or Let’s meet.Continuous = I need your assistance immediately.
You may develop your own signals, depending upon your dive plan and search technique. Rope pull signals aren’t standard like common hand signals, so be sure to review them with your buddy before diving.
Circular Search Pattern. Use this pattern for finding a small object in a small area. Although it requires a relatively flat and unobstructed bottom, it is a good pattern for currents, since the line keeps your position well-marked.
To execute a circular search, one buddy stays in the center of the search pattern acting as a pivot for one end of the rope. The searcher takes the other end on a reel, and swims a circle around the pivot using the line to maintain an even circle. Not found? The searcher plays out some line (length depending upon object size and visibility, allowing some overlap to assure no search gaps) and circles again, repeating this until finding the object or reaching a dive limit (time, air, temperature). You can accomplish the same pattern by attaching the pivot end to an anchor, post or other solid object that you won’t pull free, and in some instances, the pivot diver may control the reel.
Jackstay search pattern. Use the jackstay search to cover a large area with a relatively flat bottom and no more than a moderate current. There are actually several “jackstay patterns,” but the following is one of the most useful.
Start by establishing one edge of the search area as the baseline, along which the search will progress. Stretch a rope out perpendicular to the baseline with you at one end and your buddy at the other. Anchor the rope ends (weights work well), and then on signal (line pull or tank rap), swim down opposite sides of the rope (determined before hand) searching. You pass each other and continue until reaching the rope ends. If no luck, on signal, you both pick up the ends and move it along the baseline a short distance (determined by the visibility and object size), re-anchor the ends and swim the length searching. Do this until you find the object or reach a dive limit.
Once you locate your search object, you need to bring it up. For a small item, like a wallet, fin, mask or something, you just grab it and bring it along. But when an object weights more than you can swim up comfortably – about 4 kg/10 lbs as a rule of thump – it’s too heavy to raise that way. Yes, your BCD probably has enough buoyancy to raise objects weighing more than that, but you never use your BCD for lifting. If you were doing so and the object broke free, or you dropped it, you’d be overly buoyant and facing a hazardous runaway ascent, with a high risk of decompression illness. Since you don’t want that, when an object weighs more than 4 kgs/10 lbs, consider a lift bag (or other appropriate lifting device) mandatory for the job. Lift BagsLift bags are the most common recovery tool, and you can find a wide selection. Generally speaking, use a commercially-made lift bag rather than an improvised one for three reasons. First, you can rely on commercial bags, which are typically constructed from heavy-duty materials, to withstand the stress of raising a heavy object. Second, most lift bags have exhaust valves that allow you to control ascents. Third, commercial lift bags have loops, slings and other convenient locations for rigging and securing the recovery object.
On occasion, you may be forced to improvise. This might happen at a remote location where you weren’t planning a recovery, but the need came up. Oops. You can build a homemade lift bag out of almost any strong, heavy duty bag capable of holding air. A mesh goodie bag or duffel bag lined with a plastic trash bag or an inner tube with a side cut out and a line through it are just two examples. Note, however, that a plastic bag can tear and that homemade lift bags don’t have vents for releasing expanding air. Don’t use homemade bags unless you really need to, and then with caution. You can avoid this need, by the way, by keeping a moderate-sized commercial bag in your gear bag at all times. Then when you need one, you have it.
Whether commercial or homemade, try to pick one just large enough to handle the object’s weight. Air in a lift bag expands during ascent, so if the bag is nearly full before you start, the expanding air simply spills out. But if the bag is large and you only partially fill it to start ascending, it retains expanding air as you go, gaining buoyancy and speed. You need to control a lift bag when ascending, and matching a lift bag size to object weight minimises the likelihood of a runaway lift bag. Rigging the lift bagBefore you can raise an object, you have to tie it to the lift bag. Pre-stretched nylon rope makes an ideal rigging rope; avoid polypropylene, which tends to slip loose more easily. To tie the line, you’ll find three knots most useful for rigging and tying. The first is the bowline, which you normally use to tie line directly to an object. It is a strong dependable knot that unties easily. You use the sheet bend to tie two lines of different diameter together (it works for same diameter lines, too), and two half-hitches for a quick way to attach line to an object.
With low visibility a common situation in search and recovery, learn to tie all three knots wearing gloves and with both eyes closed. Practice the knots above water until you can tie them easily. Then put on your gloves and close your eyes. Not so easy huh? Keep going until you can. Lifting ProceduresOnce you’ve rigged the object and you’re ready to raise it, attach a marker line if you haven’t already so that if it sinks again while raising, you can relocate it without another search. Then use your alternate air source – not your primary second stage – to just put enough air in the bag to make it stand off the bottom. You’ll always use your alternate for putting air in the bag, taking care not to tangle it in the rigging.
Check the rigging. If it looks secure, add a little more air to put strain on the knots. Check them for slippage. Still okay? All systems go.
Use the bag to make the object neutrally buoyant – not positively buoyant. Add a small amount of air, pause, and then pull up on the rigging to see if you can raise the object. If not, repeat the process, a small burst each time, until you can. You may have to overcome suction from mud on some bottoms, so go slowly and pull firmly after each air burst.
At this point, if you need to move the object horizontally (to a dock, for example), you may wish to swim it along the bottom, which is easier than towing it at the surface of you don’t have a boat or something to do it. But, this usually depends on having a fairly level, unobstructed bottom.
When ready to take the object up, simply pull upward – don’t add air. The expanding air will increase its buoyancy naturally as you start up. Depending upon the situation, you may either accompany the bag to the surface, or you may allow it to rise independently. In either case, position yourself so that you are not under the lift bag and object. This way you avoid being hit if the object slips loose or the lift bag spills.
If you ascend with the bag, control its ascent by exhausting air periodically through the exhaust valve. Be cautious not to exceed 18 meters / 60 feet per minute or whatever your computer dictates. If you have difficulties and the lift bag begins to take off on you, don’t fight it – it’ll just drag you along. Let it go and pour on steam, getting out from under it in case it topples at the surface and sinks. Remember, your safety is more important than anything you may be recovering – even a chest full of rubies. PADI Search and Recovery Specialty Course Your Search and Recovery Adventure Dive may credit (at the instructor’s discretion) toward the Search and Recovery Specialty certification. In addition to what you’ve learned in this section and will practice on the Search and Recovery Adventure Dive,the Search and Recovery course covers: • Pinpointing lost objects from the surface• Boat and surface controlled searches• Semicircular and alternative jackstay searches• Practicing four different search patterns• Practice raising larger objects PADI 5 Star National Geographic Instructor Development Center. 198/12 Rat-U-Thit Road, Patong, Phuket, Thailand. Phone: (+66) 076292052 Fax: (+66) 076293034
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