#11 Search and Recovery

how to tye a sheet bend know

1. Form a bight (open end bend) in the thicker of the two lines. Pass the bitter end of the second line up through the bight formed by the first line. 2. Wrap the end of line around the bight. 3. Pass the end over the bight, putting it under its own standing part. 4. Pull taut on both standing parts to set the knot.

Tying a bowline

1. Make an overhand loop in the line the size of "eye" desired. 2. Pass the bitter (free) end up through the overhand loop. 3. Bring the bitter end around the standing part (main line) and back down through the overhand loop. 4. Pull the knot tight by holding the bitter end and the loop with one hand, and pulling the standing part with the other.

how to tye two half-hitches

1. Take a turn around the object. This knot may be combined with a round turn, which is simply passing the rope all the way around the object twice before tying the knot. 2. Bring the bitter end under and over the standing part and back under itself. 3. Continue by passing the bitter end under and over the standing part, then back under itself. 4. Draw tight.

5 general steps to search and recovery dives

1. define the search objective 2. Collect and analyze all available information 3. Diving or snorkeling? 4. dive team 5. briefing

What is the procedure for lifting an object to the surface with a lift bag? 7 steps

1. mark the object with a bouy line which stays attached until the object is safely out of the water 2. attach the lift bag securely to the object 3. use alternate air source to fill it 4. Pull up on the rigging to be sure it is secure. 5. add gas in small amounts, pulling up periodically to check the buoyancy 6. When ready, start upward, pulling up on the bag and object 7. At the surface, you may add air to the bag to give it ample buoyancy, or attach a second bag. You may also want to secure it to a boat or float while you exit the water.

3 benefits to learning search and recovery

1. saves you money 2. makes you a better rounded diver 3. can be rewarding and challenging 4. foundation for a professional career in salvaging

Potential Search and Recovery Hazards

1. sharp objects and debris 2. entanglement 3. low visibility 4. current 5. falling objects 6. boat traffic

wo main reasons for specifically planning the search and recovery portions of a dive, in addition to your general dive plan

1. success 2. safety

What three advantages does using a commercially made lift bag to recover an object have over using a homemade lift bag?

1. they have built-in dump valve systems so you can release expanding air and control the ascent. 2. they have rigging to which you attach the object, made to withstand the stress of lifting 3. they're made of rugged materials designed for the job to withstand the diving environment

line based search pattern procedue

As with the expanding square, start at the search area center. One buddy anchors the line while the other swims a circle, holding the line taut. After each circle, the team lets out a little more line so that the search continues in widening, overlapping circles. The anchor diver may control the reel, letting out line on each pass, but the search diver may do so to accommodate topography and visibility.

expanding square procedure

Begin the expanding square at the search area center - the best guess where the object is, or was seen last. Swim a short, straight length - for example, three kick cycles. Turn 90 degrees, either right or left, and swim a slightly longer length - for example, six kick cycles. Turn 90 degrees again, always maintaining the same left or right turn as your first, and the next length increased same amount - for our example, nine kick cycles.

My buddy and I come across two BCD weight pouches on the bottom. After trying to pick them up, we realize they are heavy and probably weigh more than eight kilograms/20 pounds each. My buddy signals for me to take one pouch and he'll carry the other to the surface. What should I do?

Disagree, mark the location and leave the weights until we can return with a lift bag.

rope signals

One pull = Attention or Stop; when starting a search, Begin Pattern Two pulls = Okay? or Okay Three pulls = I've finished the leg (circle orlength of pattern) Four pulls = Come toward me or Let's unite Continuous pulls = Emergency - come to me immediately

when a U search is effective

The U search is particularly effective for searching a larger area. It works well when searching for small to large objects over flat bottom, though with care, it can also be effective over uneven bottom or in current.

On shore after a dive, I realize that my fish identification slates are missing. I last saw them when I surfaced by our float before swimming to shore on the surface. The float is still deployed about 20 metres/yards offshore in 9 metres/30 feet of water on a gently sloping sandy bottom. My buddy and I decide to look for the slates on the next dive and choose to use a/an _________ search pattern.

The U search pattern is the best choice because you know the slates are within a relatively large but defined area - on a path between shore and the float - and the bottom is relatively flat and unobstructed.

A diver drops a weight belt off the end of a long pier. My buddy and I know the bottom off the pier is about 12 metres/40 feet deep and is covered with large, irregular protruding rocks. I decide to use a/an __________ search pattern.

The expanding square pattern is the best choice, because you have a good starting point and the bottom has relatively rough terrain.

My buddy and I are searching for a lost snorkel that was dropped onto flat, open bottom. Compared to irregular bottom, with obstructions and all else being the same, which of the following are likely true?

The search will be easier. We have more choice of search techniques.

when to use a bowline

This forms a loop with a very secure, but easily untied knot. You usually use it to attach line to an object.

What is wrong with using my BCD as a lifting device to recover an object?

This is important, because doing so risks a rapid, uncontrolled ascent if you were to accidentally lose hold of the recovered object. This creates an unacceptable DCI risk.

U search procedure

To complete the U pattern, search teams swim along the bottom in a straight line, turn 90 degrees for a short length, and then 90 degrees for a long length. At the end of the long length, they make a right turn, swim a short length, then make another right turn and repeat a long length.

My buddy and I need to search for a lost deck chair in a 60-metre by 30-metre/200-foot by 100-foot search area. Of those listed, probably the best choice would be the ____________ pattern.

U search

2 types of compass patterns

U search expanding square

when to use a sheet bend know

You use this knot to attach two lines together; it works well with two different diameters.

If I have a line available and am looking for a small object in a relatively small area, over a flat bottom, a circular search pattern may be a good choice. t/f

a circular search pattern is good for finding a small object in a small area on a flat and unobstructed bottom. The line keeps your position well marked, even in a current.

While raising a small outboard motor with a lift bag, my buddy and I should be ______________ the motor and bag as we ascend with it.

alongside

what does my search area include

an area you can be sure the object is within, but no larger than necessary

I'm inflating a lift bag to raise a bicycle to the surface. I should add air until the bag and bicycle

are neutral or just slightly negatively buoyant.

While gearing up on a dive boat, I accidentally dropped my favorite mask overboard, but fortunately I have a spare. The wind is making the boat swing, so to establish our search area when my buddy and I look for it, we should use _________________ as our starting point.

as best we can estimate, where I dropped it

what to do If you find an artifact that may have historical significance on a wreck or other site

best way to preserve it is to leave it undisturbed, note the location and report it to appropriate local historical authorities for proper documentation and study

when a line based search pattern is effective

better choices for obstructed bottoms, and tend to work better in currents, because the line is anchored and helps control navigation more closely. This pattern is usually a good choice when looking for something small in limited visibility.

Of the knots listed, I will normally use a ____________ to form a loop to tie a line to something, and a __________ to tie two lines together.

bowline/sheet bend

The first step in planning a search and recovery dive is generally to

define the objective

Why do I choose a lift bag based on the weight of the object being lifted?

expanding gas escapes from it during ascent, which makes it easier to control the ascent

A crime weapon is thought to have been thrown into a lake in my neighborhood. My buddy and I should see if we can locate it for the local authorities. t/f

false

Although it's best to use a line and reel for the circular search pattern, with practice I can navigate an accurate circle using my compass. t/f

false

I should use my primary second stage to inflate a lift bag, and position myself below the bag and object as I control it on the way to the surface. t/f

false

Ideally, I should use a lift bag with significantly more lift than the weight of the object I'm bringing up. t/f

false

While searching for a lost wallet, my buddy and I stumble upon a pile of pottery likely made hundreds of years ago. We should recover the pottery and give it to local historical authorities. t/f

false

My buddy and I plan to raise an object that weighs 10 kilograms/22 pounds. My buddy doesn't think we need a lift bag, but based on accepted recommendations, I do. Who is right?

i am

how water movement affects search and recovery

includes currents, tide and surge, which may sweep an object away from where it enters the water Water movement tends to bury lost objects over time, but changes in speed and direction can uncover them, too. surge takes items deeper

Searching for specific objects means

looking for something someone lost or threw in the water. When you do this, you can be generally sure it is in the search area. The dive ends when you find and recover the object, or you reach a dive limit (no stop time, gas supply, cold, etc.).

two types of search

looking for specific objects looking for nonspecific objects

Searching for nonspecific objects (bottom combing) means

looking for whatever may turn up. It can be a cleanup dive; you don't have to use search patterns (though doing so can help, because you're more thorough) and finding something doesn't necessarily end the dive

Based on the weight of an object, when should I use a lift bag for recovery?

more than 15 lbs

Which air source should I use to fill a lift bag?

my alternate air source or an accessory inflator

A friend tells me that he lost his 48-kilogram/105-pound anchor near the harbor entrance in 35-45 metres/115-150 feet of water. He's looking for divers to recover his anchor. Is this a task for a recreational search and recovery diver?

no The object is too large and the depth range goes beyond recreational diving limits, plus a harbor entrance is a potentially hazardous area. Recreational search-and-recovery divers learn to recover small- to medium-sized objects within recreational depths and environments

Where should I position myself when a lift bag is ascending?

not under it

While conducting a search for a lost fishing rod, my buddy and I hear a boat that sounds like it's coming very close to us. Generally, the best action would be

stay deep enough to be safe from its propellers.

Ideally, I should be able to tie a bowline, sheet bend and two half-hitches in low visibility by feel while wearing gloves. t/f

true

My buddy and I are looking for a fin a friend lost on the previous dive. If we don't hit a dive limit like depth, gas supply or no stop time, normally the dive would end when we find it. t/f

true

My buddy and I want to specifically plan the search and recovery portion of our dive to increase our chance of success, and to prepare for and avoid hazards that may be present in the search area. t/f

true

The most serious problem with using my BCD to lift more weight than I can comfortably swim with is that I could drop the object I'm lifting and have a rapid, uncontrollable ascent. t/f

true

My buddy and I are conducting a search that uses a line. We should

use a reel or line caddy for the line.

where do you start

use the most precise estimate available of where the object was lost

when a two half-hitches tie is beneficial

used to attach line to an object

My buddy and I are raising a small outboard motor using a commercially made lift bag. The advantages of using this instead of a homemade one include that commercially made ones

usually have exhaust valves. have rigging suited to lifting an object. are made of rugged material.

when an expanding square search i effective

well suited for medium-sized objects in rough topography, and is a good choice when there is only a single buddy team. It's a popular pattern when you discover you need to look for something while already diving.

My buddy and I plan to search for a lost mask at a local dive site that has excellent visibility (18 metres/60 feet). I talk to the diver who lost the mask and determine that much of the search area is no deeper than 10 metres/30 feet over sand bottom. Would it be appropriate to search from the surface snorkeling?

yes

What features of a commercially made lift bag make it desirable for recovering underwater objects?

Is constructed from heavy-duty materials Has exhaust valves to vent air on ascent Has loops or slings for easy rigging

useful information includes:

Expected location, as close as possible where the object was lost Size, shape, material and weight of the object Any special equipment needed (more about this later) Where to attach a lift bag (if needed) Bottom topography, visibility, composition, temperature Surface conditions Possible hazards

My neighbor wants my help finding some expensive golf clubs that "got lost" in a lake after something called a "three putt on a par three." After getting permission to make the dive from the course owners, based on the general steps of planning a search and recovery dive, what should i do first?

Find out how many clubs were lost, what the lake is like and how big the search area is.

Bottom topography effect on search

Flat, open bottoms are easiest to search, but allow water movement to more easily move an object. Irregular bottoms limit your search techniques. Crevices and obstacles may hide objects, but may also prevent water movement from carrying those objects away.