NAUI Advanced Scuba Diver
72 Search and Recovery
provides the buoyancy used to lift objects underwater.
Divers are often tempted to simply grasp the object and
inflate their buoyancy compensators and use themselves
as “human lift bags,” but this is a dangerous practice that
should be avoided. If the diver with the excess buoyancy
accidentally drops the object, a dangerous, uncontrolled
ascent can occur and result in injury. Even if the object is
retained during the ascent, holding onto it occupies the
diver’s hands and may prevent the diver from controlling
buoyancy as the air in the BC expands. Never risk being a
“human lift bag.”
To salvage an object that has been found and
marked, the first step is to “rig” the item securely.
Rigging is the term used to describe the attachment of
ropes, cords, and straps between the object to be salvaged
and the lifting device. You may be required to tie
a line to an object, so knowledge of and the ability to tie
several knots will be required. The main idea to be kept
in mind when rigging an item is that preventing the
item from coming loose during the lift is essential for
safety.
The next salvage fundamental is to match the lifting
force of a lift bag to the weight of the object being
recovered. A lift bag is a bag that can be filled with air to
provide a buoyant force for the lifting. More on lift bags
will be presented in the Equipment part of this chapter.
When a lift bag is used to raise an item, the lifting capacity
of the bag should not greatly exceed the weight of the
object. If it does, the air inside the bag will expand during
ascent, accelerate the lift, and the lift can get out of control.
By matching the capacity of the bag to the weight of
the object being recovered, the bag will be full or nearly
full at the start of the ascent, the excess air will simply
bubble out the bottom of the bag, and the ascent will take
place at a fairly constant, controlled rate. You will learn
how to estimate the size of the lift bag in the Techniques
and Precautions part of this chapter.
The next principle of recovery is to maintain control
during the lifting process. Even when the object is
properly rigged and when the appropriate size of lift bag
is being used, control is required. You must control the
entire situation, including yourself, your buddy, other
divers present, and the lift itself. The procedures for
doing this are also presented in the part on Techniques
and Precautions.
Become familiar with these basic principles, which
are now summarized for you. No matter how much you
learn about search and recovery, you will find that these
apply.
Basic Procedures of Search and Recovery:
1. Define the area to be searched and mark the starting
point.
2. Select the appropriate search pattern.
3. Keep track of the areas searched.
4. Mark the position of an object when it has been
found.
5. Securely rig the object to be lifted.
6. Match the lift bag capacity to the weight of the
object being recovered.
7. Control the lift.
Equipment
Many of the items of extra equipment used for
search and recovery have already been mentioned.
Continue reading to learn more about this equipment.
Marker buoys are available in various sizes and
configurations. They are small and compact so they can
be easily carried by divers. Well-designed marker buoys
obtained from a dive center are recommended over
homemade. Most buoys have nothing to stop their line
from completely unraveling (make sure you’ve checked
that the bitter end of the line is secured to the buoy or
you can lose the float in the current) when deployed
underwater resulting in the excess knotting at the surface
or drifting down current. This can be unavoidable
when used to mark an unexpected find. Once you have
regained the surface tie off the line, but allow a little slack
to accommodate waves and tide changes. You don’t want
your marker buoy to be hidden underwater because you
made the line taut and the tide has come in when you
return to begin the recovery phase.
Underwater slates are useful for communications as
well as for information recording. Time can be saved and
frustration avoided when coordinating with your buddy