The scuba diver needs some form of extra weight to go
underwater and stay there comfortably. The need for this is due to several
When the diver takes air in their lungs underwater, unlike the snorkeler,
it usually makes them float.
If the diver wears an air space, such as a face mask, it adds buoyancy.
Fat floats. Muscle, bone, blood, skin, and most organs do not. The more fat
on a diver the more weight that will be needed to keep them underwater.
As most scuba tanks get low on air they have a tendency to float. Toward
the end of a dive the amount of weight needed may be 5 or 6 pounds more than
at the beginning.
Wet suits float. How much they float is determined by the size of the suit,
the thickness, and the type. For example, a medium wet suit, that is 7 mm
in thickness, with a Farmer John bottom and step-in top floats with a buoyancy
of close to 20 lbs!
In salt water things float much better than in fresh so that compounds all
of the above.
There have been a variety of weight systems invented
to overcome the diver's buoyancy. The most common is the "weight belt." It
consists of nylon webbing about as wide as a car seat belt but much thicker.
Molded lead weights are threaded on the belt. Those weights have a hole in
each side for the belt to fit through, or, if they are "bullet weights,"
they have one hole in the center and the belt is pushed through. The weights
come in a variety of sizes: 1, 2, 3, 4, 5, 6, 8, and 10 pounds are the most
common. The smaller are more comfortable but sometimes so much weight is
needed they would not all fit on the belt. The larger ones tend to "roll"
and pull the belt out and down from the top. They are usually worn on the
side to minimize the problem. The belt has a buckle on the front that has
to have a type of quick-release for instant removal by the diver or buddy
in the case of an emergency.
There are more expensive belts available. Some belts
are similar to the one described above but may have cordura pockets
in which to insert the lead . Bags of lead shot could be used instead of
the molded weights. They are more flexible and conform to the contours of
the body. Wearing this belt is usually more comfortable.
Some buoyancy compensators (BC's) have the capability of allowing
some or all of the diver's weights to be placed in special pockets within
the BC. These are called, "Integrated BC's." In that way some or all of the
weights may be taken off the belt. There are usually quick-release methods
built into the BC. so the weights may be removed from the vest and fall away
from the diver.
Lead is a heavy metal. Most heavy metals are poisonous
to humans. In this case, lead poisoning causes serious brain damage and also
seriously affects other organs. If you handle lead weights it is important
to wash your hands thoroughly so the lead atoms do not enter your mouth.
Some weights are covered with vinyl so the lead does not come in contact
with the hands. If the weights are in pockets they are safe to handle but
the water dripping from the weight belt after being underwater may contain
large doses of lead. The majority of weight belts have the bare lead weights
threaded on because they are the least expensive.
Weight belts can aggravate a bad back condition especially
in cold water requiring buoyant wet suits and/or doing lots of dives in a
short period of time. Wet suits are buoyant. When a weight belt is placed
in the middle of the back it draws that part of the body down. The chest
and legs are each drawn up by the wet suit. This places a strain on the back.
Some divers remove a small amount of weight from the waist and put it on
the ankles. Ankle weights are usually made of lead shot in a bag that
wraps around the ankles. They weigh 1.5 to 3 lbs. each. This helps
to bring the legs down. Also, small amounts of weight can be added to integrated
BC's or to the shoulder straps of many BC's. In either case, the stress on
the back is lessened.
There is a right way and a wrong way to put on a weight
belt. If it is put on wrong it may present a problem when someone has to
take it off. Hold the FREE END (not the buckle end) of the belt in the RIGHT
HAND, swing it around the back, and lean over so the belt hangs by itself
on the back. Reach under and connect the buckle after pulling it as tight
as possible. On land with a wet suit the belt rarely will be made as tight
as it should be. The final adjustment should be done when the diver is about
15 feet underwater. At that point the wet suit is compressed, things are
lubricated due to the water, and the diver is "weightless." These conditions
allow the belt to be drawn tighter. While maintaining a horizontal diving
position, the diver reaches for the belt and pulls it up to the smallest
part of the waist. Then the diver should grab the strap sticking out
of the buckle and pull it out from the body. This will open the buckle. Pull
the buckle one way and the belt the other. After closing the buckle the belt
is there to stay. Failure to do this simple procedure has resulted in weight
belts slipping down the legs and off the diver as the wet suit compresses
with depth. You will NOT be able to get a weight belt
tight enough on the surface if wearing a wet suit. It is critically important
to make the above adjustment ON EVERY DIVE!
This brings us to another serious problem: What happens
if the weight belt is lost. The diver will go into an uncontrolled ascent.
Uncontrolled ascents may result in decompression sickness, lung damage, and
crashing into things at the surface. If the weight belt drops, flair back
face up and assume a spread eagle position with the legs and arms out. Dump
all the air out of the BC as you rise to the surface. Keep breathing normally.
You will be surprised as to how much this flare will slow the ascent, especially
in deeper water. Of course, if the diver has been down deep enough and long
enough to get decompression sickness because an uncontrolled ascent, serious
consequences may still result.
It has been shown that in most emergencies divers do
not remove their weight belts. Divers have been found dead, on the bottom
with their weights still on. Whether this is due to the lack of ditching
practice, not thinking about weight removal during an emergency, or the fear
of losing a piece of equipment that costs money is unknown. Ditching a weight
belt is part of most scuba courses and it teaches the diver just how easy
it is to surface without one.
It is important for your buddy to know where your weights
are located and how to remove them in an emergency. If you have integrated
weights built into the BC and the buddy is looking for a waist belt the delay
could result in far greater problems. When a buddy check is done one of the
things said is, "Put your hand on your weight belt buckle." If this were
done by every buddy prior to entering the water, not only would each be better
qualified to handle an emergency, but far fewer divers would plunge into
the water only to realize they have to get back out because they forgot to
put their weight belt on. It is also a good idea to make sure the weight
belt has not been placed on top of other equipment such as the alternate
air hose, and that nothing has been put on the top of the weight belt that
would prevent it from being removed easily!
Weight belts (and tanks) should never be packed in a
gear bag. They might do damage to equipment in that bag, or equipment in
a bag that might be under it. Weights and weight belts are packed separately,
possibly in a weight box. When the belts are placed in the weight box they
should be carefully lowered into it to avoid damage to someone else's buckle.
Buckles must be protected from damage so they don't allow the belt to slip
off underwater. Also, when the belt is not on the diver it should be buckled.
This keeps the belt from hitting the divers legs when carried and, more
importantly, while it is carried the diver is also vicariously testing the
buckle to be sure it will not open.
Dive shops and dive boats usually supply weight belts
and tanks. That eliminates the need for the traveler to take these bulky
and heavy items when traveling.
One last thought: Never dive under a dive boat when divers
are entering or leaving the water. When divers are leaving the water they
are sometimes asked by the Divemaster to remove their weight belts and hand
them up prior to the exit. This author has observed at least one diver
accidentally drop his weight belt during removal and have it crash into the
coral at the bottom under the dive boat! Another time a 5 lb. weight landed
on the bottom about 6' away from me. That is scary! Having a weight or weight
belt hit a diver on the head could prove fatal.