Hello again out there scuba world. I, your humble webmaster, am taking this
opportunity to discuss Drift Diving.
Allegedly, it's so great and so easy and relaxing. I, however, have
failed to master this type of dive, despite repeated attempts. I understand the concepts and theories and
all that. My issues come from control.
In a current, in my experience, it's hard to stop and look at things,
and maneuver around other divers. I
prefer to be control of my speed, direction and start/stop at all times. I
recognize that i just need practice. Currently, I tend to flail around with my
arms in an embarrassing yet humerus manner. But the closest body of water to me
is the Mighty Mississippi, and there is no way I'm learning on that
current. :) So for now, enjoy an article about drift
diving.
Drift Diving
Current is not an issue when diving quarries and most lakes,
but elsewhere, rivers, oceans and large lakes, like the Great Lakes, divers can
expect water movement to range anywhere from mild to wild. Unless carefully
calculated, monitored and accounted for, current, even in its mildest form, can
cause difficulties for unsuspecting divers. It sweeps them away from the boat,
causes shore divers to miss the planned exit location and when strong, it
physically taxes divers as they labor to swim against it.
When to Go With the Flow — and When Not To
In most cases, divers are taught to “begin the dive into the
current.” This is done for two reasons. First, swimming into the current can be
tiring, so divers are told to spend the first part of the dive, when they are
fresh, swimming against it. Then they complete the dive by drifting with the
current back to the exit location. Theoretically this is a sound concept,
however, divers occasionally still miss the boat on the way back or overshoot
the exit location. The stronger the current, the greater the chance of slipping
up.
Second, unless the dive is a planned drift dive, a diver who
begins the dive swimming with the current is asking for trouble. Aided by the
current, he will cover a lot of seascape in less time than he thinks. When he
reverses course to return to the exit location, he will find the going much
slower because he now is battling the current. Unless the current is very mild
and the diver reverses course well before the halfway point of the dive, it is
unlikely that he will make it back to the planned exit location before
depleting his air supply or exceeding the planned bottom time. This will
require him to ascend sooner than planned, resulting in a long surface swim. In
some cases it could result in a rescue situation.
When circumstances permit, experienced divers often prefer
to drift dive. They go with the flow for the entire dive, intentionally
allowing the current to carry them along. Their dive plan is built around
entering the water at one location and exiting at another.
Drift diving offers many advantages over diving from an
anchored boat or entering and exiting at the same location on shore. First,
drifting with the water movement is less physically demanding than struggling
against current for half the dive. Drift diving generally results in less air
being consumed, which could allow many divers to stay down longer.
For those who have experienced the ease of drift diving,
especially from a boat, it often quickly becomes their favorite style of
diving. Drift diving, when done correctly, eliminates any concern about finding
the boat at the end of the dive. When the planned bottom time is up or the air
supply runs low the diver simply performs a drifting safety stop and surfaces.
The boat comes to the diver as opposed to the diver having to find and swim to
the boat.
Drift diving from shore requires additional planning and is
a bit more complicated, but it still eliminates the need to fight the current.
Divers enter at an upcurrent location and exit at a predetermined spot farther
downcurrent.
The drift diving technique can be used anywhere that has
consistent water movement, even in areas with slight to moderate current.
However, it is used more often in areas that are known for having mild to brisk,
or even ripping, currents.
On the extreme end of the spectrum, some places offer drift
diving that resembles a water park adventure. In areas like Deception Pass on
Washington’s Northwest coast, the Current Cut in the Bahamas and the Komodo
Islands in Indonesia, drift diving is as much a thrill ride as a diving
technique. At these and a handful of other similar spots around the world
divers drop into the water purposely overweighted by a few pounds, descend
quickly and ride currents of six or more knots. Generally such novelty dives
are shorter in bottom time than a normal recreational dive since these types of
currents are associated with tidal change in places where the incoming or
outgoing tide funnels through a narrow passage. This type of drift diving
experience is a thrill one does not soon forget.
The majority of drift diving is performed in areas that
experience moderate longshore current on a consistent basis. In some cases the
direction of a diver’s drift changes depending on the time of day or the tidal
flow. Deciding when, where and how to conduct a drift dive is a decision not to
be taken lightly. Drift divers should be trained in the technique and be
familiar with the area and water conditions of the site they plan to drift.
Drift Diving From a Boat
Drift diving can be done from a boat or from shore; although
the techniques and planning required for each vary greatly. Drift diving from a
boat, especially a dive charter boat, is less involved than drift diving from
shore. On a dive charter boat the captain and crew have done most of the work
for you in advance. In addition to having already addressed the planning and
safety considerations, they are familiar with the area and possess the
necessary boating knowledge and skills. Simply follow their directions and
employ a few basic diving skills and you’ll have a fun, enjoyable and safe
drift diving experience.
Boat drift diving is commonly done using one of two
techniques: float line drifting or live boating. Float line drift diving
involves the use of a surface marker. One of the divers tows a line and float,
which often includes a dive flag that trails along on the surface above the
dive group. The captain and crew keep track of the divers’ whereabouts by
watching and following the marker.
Live boat drift diving is conducted in the same fashion as
float drifting but without the line and float. The captain and crew keep track
of the group by observing their bubbles breaking the surface. The boat stands
off a safe distance but near enough that the divers’ bubbles are clearly
visible. This works fine in calm water, but is not as reliable in rough seas.
The choppier the water the more difficult the bubbles are to see.
Using a float line is the easiest and safest method of drift
diving. It is the surest way for the boat captain to know the location of the
divers. Underwater the line serves as a reference for the group and during the
safety stop it is helpful in maintaining a consistent depth. On the surface the
float provides a staging area for divers waiting to exit the water.
On the downside, float diving is more restrictive than live
boating since one of the divers in the group has to be responsible for tending
the line and towing the float. On a guided dive this is usually the guide’s
job, but not always.
If you happen to be the diver responsible for the float, as
the group descends you must pay out the line. During the dive you must adjust
the line scope (the length of line from you to the float) to account for
significant changes in depth and to keep it from becoming snagged. Upon ascent
the line must be retracted to prevent anyone from becoming tangled in the
excess.
Some float line divers carry the excess line coiled in their
hand; however, most use a reel. For safety’s sake, when towing a float the coil
of line or reel should be held in the diver’s hand and never secured to his
equipment or body. As unlikely as it might sound, if a passing boat were to run
over the float and snag the line a diver with the reel secured to his buoyancy
compensator (BC) or the line wrapped around his arm could be dragged to the
surface, resulting in a decompression injury.
When drift diving, whether the technique used is float line
or live boating, it is important that all divers stay together as a group. This
requires that everyone be geared up and ready to enter the water before the
first diver enters; the others follow close behind.
If using a float, divers can remain on the surface near the
float until everyone is in, and then descend together. When live boating,
depending on the type and velocity of the current, it often is important that
divers enter in rapid succession, descend immediately and regroup at the
bottom. When diving from a charter boat the technique to be followed will be
included in the predive briefing.
Once at depth the group must not stray too far from the
diver towing the float or the designated leader, if live boating. This is
important because the boat captain and crew are concentrating on following the
float or the group’s bubbles.
Generally, as individual members of the group run low on air
they notify the guide that they are ascending, proceed to safety-stop depth,
complete the stop while drifting above the group, and then surface. They will
quickly be spotted since this technique places them either adjacent to the
float or near where the group’s bubbles are breaking the surface. If they
surface elsewhere they run the chance of not being seen and may end up waiting
at the surface until the remainder of the group has reboarded the boat.
Depending on the charter operation, water conditions and the
destination, when participating in a guided drift dive the entire group may be
required to surface when the first diver begins to run low on air. Generally,
however, individual divers or buddy teams who run low on air before reaching
the planned maximum bottom time are permitted to proceed to safety-stop depth
and complete the dive as described above.
The technique used for reboarding the boat varies from
vessel to vessel and will be addressed during the predive briefing. When drift
diving from a boat, exiting the water always involves the boat coming to the
diver rather than the diver having to surface, find and swim to the boat. When
diving from a large vessel, entering and exiting the water often is done from a
smaller tender boat that is used to shuttle divers to and from the drift dive
location.
Reboarding the boat is the most critical part of drift
diving. First, keep in mind that both the boat and any divers on the surface
waiting to reboard are drifting with the current, but not necessarily at the
same speed. If the boat is drifting faster than the divers, divers positioned
on the downcurrent side of the boat face the risk of being overrun by the
vessel.
Second, most dive boats are driven by one or more
propellers, which are underwater at the stern of the vessel. When engaged,
these propellers turn at a dangerously high speed. Divers waiting to reboard
are near the propeller, creating a potentially dangerous situation.
Whenever in the water near the stern of a boat, especially
when the engine is running, be aware of your position in relation to the
propeller. If the engine suddenly starts or an idling boat’s propeller begins
turning, immediately move away from the boat.
When drift diving it is important that each diver closely
follow the instructions of the crew, exit quickly and efficiently, and
immediately clear the exit area so other divers can reboard.
It is recommended that any boat involved in drift diving
leave two people on board; one to operate the boat and the other to act as a
spotter, helping follow the divers’ movement and controlling the entry and exit
processes.
The easiest and safest way to experience drift diving,
especially for the first time, is on a guided dive from a dive charter boat;
the planning and safety considerations have been addressed by the charter crew.
All the diver has to do is enter the water when instructed, stay with the
group, keep the guide informed of remaining air supply and surface when
directed to do so. In between, the diver simply floats along at depth, enjoying
the sights.
Read the rest of the article here. http://www.dtmag.com/Stories/Dive%20Equipment/02-05-2feature.htm