By: John Boyer,
Diving Unlimited International, Inc.
In the drysuit business just as in scuba diving in general we are constantly
plagued by false impressions and stories that have been handed down from one
person to another, most of which have been embellished upon by the storytellers
whose only error is the desire to make a story more interesting.
This article will attempt to address the most common myths regarding diving in
drysuits and allow you, the potential purchaser, to make your decision with
more correct information than the "hearsay" attitudes that plague most things
in which there are few experts.
Drysuit keep you WARM!
For the most part this is an incorrect statement. The drysuit itself, with the
exception of the "foam neoprene" suits whose thermal protection is quickly lost
due to compression during descent, provide little or no thermal protection. The
purpose of the drysuit is simply to keep the diver dry.
The garment we wear under the suit, commonly referred to as "divewear
insulation," is what is responsible for keeping the diver warm. The warmth
accomplished as a result of wearing divewear insulation is a function of the
ability of the material to trap and hold air between the fibers. No garment,
including a heavy ski parka, has the ability to insulate as a result of the
material. Its ability to insulate is in its relative ability to trap air
between the fibers. Some fibers are much more efficient at trapping air than
others. Some fibers, such as Type "B" Thinsulate™ Insulation (100%
polypropylene micro fiber*) have the ability to resist absorption of water and,
therefore, are more efficient as a divewear insulation fabric.
The ability to change the configuration of the divewear insulation on each
dive, taking the water temperature, the diver’s personal metabolism, and the
anticipated activity (more activity generally requires less insulation) of the
dive is one of the most basic advantages of diving in a drysuit. In a 7mm
wetsuit the diver has 7mm of neoprene on each dive, regardless of the
conditions. On most occasions 7mm is either too much or too little. Also, foam
neoprene provides more insulation in shallow water and less in deeper water.
You will have an uncontrolled, feet first ascent to the surface
This is probably the most common fear expressed by non-drysuit divers. Nearly
every diver who has expressed this fear claims to have had or has seen someone
have this problem. When questioned in more detail about the actual sequence of
events, most of these stories are actually in the "a friend had it happen to
them" or "I heard it from a diver I know" category. On only one or two
occasions have I actually talked to someone who claims they have had this
happen to them. On those rare occasions the person frankly admitted they were
at fault since they improperly operated the equipment or didn’t take the time
to be trained in the proper procedures.
First, if properly operated, the amount of air required to obtain the "loft" of
the undergarment (loft is the term used to describe the process of making air
available so that the fabric can "trap the air" between the fibers) is very
minimal. Proper weighting in a drysuit is achieved by the diver entering water
too deep to stand up in, holding a normal breath, with no air in the BCD and
minimal residual air in the drysuit. Remaining motionless, the diver would
float at eyebrow level. A diver weighted in this manner would float at about
mouth level if a lung full of air was taken in and would slowly descend if the
"normal" breath were exhaled. This is neutral buoyancy (In a normal
recreational equipment configuration an additional five pounds of weight should
be added to compensate for the air that will be cast off during the dive. If an
80 cu. ft. aluminum tank were totally drained the weight difference would
actually be closer to six pounds.)
If the diver simply adds air to the drysuit during descent in the amount
necessary to maintain a constant volume, the ancillary benefit is the
maintenance of neutrality with just the air added to the suit. When dealing
with a large volume, double tanks or other heavy equipment a different
technique is required. The size of the bubble of air necessary to achieve the
state described in the paragraph above would, if the diver were to raise their
right arm toward the surface in a head up position, begin at the wrist seal and
continue down the raised arm about four to nine inches toward the elbow.
The "roving" bubble is always found at the high point in the suit. This bubble
needs to be kept to a minimum. The phrase "a pint (of air) is a pound (of
buoyancy) the world around" means that every extra pint of air in the suit
requires a pound on the weight system. Excess air in the suit does not increase
the insulation value of the divewear. Proper weighting is important to keep the
bubble small.
The bubble described above could not, under most circumstances, cause the diver
any concern. Also, since the diver is neutrally buoyant it doesn’t matter what
attitude (head up, butt up, feet up or belly up) they are in. Neutrality is
neutrality and nothing during the dive changes the laws of physics and allows
the attitude to change the buoyancy of the diver. Only in extremely shallow
water (15 feet or less) would there be a significant change of volume due to a
diver changing from horizontal to vertical.
A properly trained diver is taught to respond to an "over inflation" emergency
in the very unlikely event it should happen. First, most modern drysuits are
equipped with adjustable dump valves that will expel air as quickly as the
inflator will put air into the suit when the exhaust valve is positioned at the
highest point in the suit. Second, it is a simple procedure to disconnect the
power inflator should it get stuck in the open position. Third, and by no means
less important, is the fact that a diver trained properly in a drysuit is
taught to recover from a (falsely induced) feet up, positively buoyant
situation.
Recovery is accomplished within a minimum of vertical movement. One suit
manufacturer has installed exhaust valves in the ankles of the suit to combat
this "mythical" problem. All this does is perpetuate and give credence to a
problem that really doesn’t exist. Additionally, the diver with these valves
loses the air in the suit (which, as an ancillary benefit, provides neutral
buoyancy) each time their feet get above the level position. This requires
constant replacement of the air in the suit to maintain constant volume, avoid
squeeze and achieve neutral buoyancy. The important point is that by installing
these valves, that manufacturer lends credence (by putting equipment on the
suit designed to combat the problem) to the myth of an uncontrolled feet first
ascent. Also worthy of note is that the valve is positioned high enough on the
ankle that a large bubble would still form in the boots.
Drysuits are cumbersome and difficult to remove
This is probably the easiest myth to dispel. All a diver has to do is try on a
drysuit and the myth is dispelled. At the entry level, if a student is allowed
to don a modern drysuit immediately after struggling in and out of a typical
wetsuit, the dive student will probably ask to be allowed to take their course
in the drysuit. Almost everyone who has taken his or her entry-level course in
a wetsuit can remember the difficulty in donning and removing the wetsuit. At
consumer shows, when putting people in drysuits, the most common expression
heard is "I didn’t know it would be so easy and comfortable to get in and out
of this thing."
Foam neoprene neck and wrist seals are much better
In some special cases this statement may be true. As a rule, however, foam
neoprene is not the best choice. Many pieces of diving equipment are designed
to fulfill the same objective. In each case, the determining factors are the
pros and cons of each when applied to a specific situation.
The major advantage of foam neoprene seals is that they are somewhat more
durable in regard to abrasion. The negative aspects of foam neoprene seals, in
all applications, make them the poorer choice overall. Foam neoprene is much
more difficult to don and remove due to the thickness of the rubber and the
fact that foam neoprene has a nylon covering on at least one surface. Foam
neoprene is purported to be warmer than latex.
This is only slightly true. If the diver does not descend then the inherent
insulation in foam neoprene is a factor. Since divers do descend, the
compression of foam neoprene negates the insulation. Only because the material,
even when compressed at depth, is thicker is there any insulation value. Since
foam neoprene compresses at depth, the seal that is water tight on the surface
may leak when compressed. The continuous compression and expansion (descending
and ascending) of foam neoprene are the primary reasons foam neoprene drysuits
or wetsuits do not last as long as Trilaminate or Crushed Neoprene.
The same is true with foam neoprene seals. Foam neoprene has a memory. This
fact is evident even in the instructions furnished with the seals. If the foam
neoprene seal is too tight we suggest the customers "stretch" the seal (neck)
over a scuba cylinder overnight. This actually destroys some of the closed
cells thus permanently rendering the seal larger. If left to compression and
expansion the same thing would happen naturally.
High quality latex has very little memory. It will, after stretching, go back
to the original shape more readily. Since latex is considerably thinner it is
more comfortable simply from a standpoint of bulkiness. If properly maintained,
latex will last longer than foam neoprene that is dived frequently.
Proper maintenance includes proper trimming, (so there are no "saw tooth" edges
that lead to tearing) rinsing, dusting with unscented talcum powder when
storing for long periods and storing in "low ozone" areas.
Since latex seals are made in a cone shape, they are "trimmable" to fit the
individual. Care must be exercised to not trim too much off at one time. The
seals have "guide lines" to help in the trimming process. Only one line should
be removed at a time and the seal should be tried on after each line is
trimmed.
Drysuits are too expensive!
The initial up-front cost of the modern drysuit is somewhat more that the
typical wetsuit. Just as in any investment the price of the item is only one
part of the equation. Modern drysuits, with the exception of foam neoprene
suits, will last so much longer that the effective cost of the suit is much
less.
Just as with any item that depreciates, the cost should be divided by the
number of uses the item returns. Dividing the cost of the drysuit by the number
of dives a diver will get from the suit will yield a "cost per dive" figure. In
most all cases the "cost per dive" will be considerably lower in a modern
drysuit than a wetsuit (except for foam neoprene).
Even with the above information the fact remains that the customer has to take
a relatively large sum of money out of their pocket and put it on the counter.
Most dealers selling drysuits have innovative plans available that allow the
diver to get into a drysuit without causing a financial burden. Economics and
"just the facts" don’t take into consideration the increased degree of comfort
achieved by the drysuit diver.
Imagine all of the different things in our lives that we could actually do
without but, because we want to be more comfortable, we decide to obtain the
item or convenience. Diving, for most people, is an exhilarating experience and
if those in wetsuits realized how much more enjoyable their dives would be if
they were warm and comfortable most would invest in a drysuit immediately.|
Another thing that many people don’t realize is that if a diver is warm they
are much more efficient. Even those who claim they don’t get cold suffer a
decrease of efficiency by losing body temperature to the environment.
In almost every dive accident recorded, cold can be identified as a factor. The
first thing a diver loses as a result of a drop in body temperature, is mental
acuity. The recognition of a potential problem can go unnoticed because being
cold slows the mental process. The second symptom of temperature drop is the
loss of physical dexterity. The ability to take proper action to avert the
results of a problem is lost. Many divers lose dexterity without even knowing
they are being adversely affected by a loss of temperature.
Drysuits are for professionals and advanced divers only!
People who express this opinion need only analyze the statement. Of course,
those who know most about diving and who are doing it most frequently will
gravitate to the most efficient and most comfortable way to achieve the desired
results.
If I wanted to improve my methods I would first look to see how those who do it
best are doing it. The best reason for professionals or advanced divers to dive
in drysuits is that they know most about it and do it more frequently. An
endorsement of this type by a professional should be viewed as an
unquestionable testimony. Simply stated, the fact that professionals and
advanced divers use drysuits is the best reason for all divers to use
drysuits.|
If the suit floods it will drag you to the bottom!
In the past people were warned, "never wear hip boots in a boat or around deep
water. If you fall in the boots will fill with water and drag you down." To
dispel this myth in training lifeguards one of the exercises used is to have
trainees don hip waders and swim lengths of the pool. Although the boots make
it more difficult to swim gracefully there is no need for additional effort to
remain afloat.
If you remember that if an object displaces an amount of water weighing more
than the object, the item will float. If the item immersed in water is water
the displacement is exactly equal and the result is neither positive nor
negative buoyancy. Recreational divers should always wear a Buoyancy
Compensation Device (BCD). Regardless of the method employed to maintain
temperature equilibrium the BCD would be used for surface support and in the
event of any emergency.
There is no such thing as a drysuit. The best you can
hope for is a "Semi-Dry"!
In the past this statement was more credible than it is today. First, there is
no such thing as "semi-dry." Just as there is no such thing as "semi-pregnant",
a person is either dry or they are wet.
Modern drysuits are made to totally exclude water. If the system is properly
operated it will keep the diver dry. If the suit is poorly maintained, ill
fitted, improperly donned or incorrectly used there is a chance that the user
will get wet. In almost every case where the diver in a drysuit gets wet one of
the aforementioned items is at fault.
Proper training, including donning, diving techniques (including emergency
procedures), removing, care and storing, are all part of the complete package
that makes up the responsibilities when purchasing a drysuit system.
It is the responsibility of the person selling the product to ensure that the
purchaser is either qualified to use the equipment properly or will get
instruction in its proper use. It is the responsibility of the purchaser or
user of the drysuit to ensure that they are properly trained to use the product
safely and correctly.
Drysuits cause a lot more drag and require a lot more weight!
The additional drag caused by the modern drysuit is nearly undetectable. The
drag caused by the scuba equipment itself far outweighs any drag caused by the
suit that the typical diver would be hard-pressed to detect any change.
This is not to say that an expert who is accustomed to swimming in a current
would not be able to detect a difference. More important than the drag in some
drysuits, is the fact that the diver’s "range of motion" is adversely effected.
When selecting a drysuit the purchaser should be asked to perform a series of
exercises designed to assess the ability to perform some simple motions: raise
the leg so that the foot is level with the knee of the other leg perform a
"figure four" (such as the figure four used to don fins) reach the back of the
neck with both hands touch hands together stretched overhead in a kneeling
position, sit back towards the feet The above "range of motion" exercises
should be performed with the divewear and again with the divewear insulation
and the drysuit together.
None of the equipment should impede the diver’s ability to do the "range of
motion" exercises. A high-quality drysuit will allow the diver to do all of
these exercises unencumbered. One of the greatest advantages to a drysuit is
that on each dive the diver is allowed to take into consideration: 1)
temperature of the water 2) the diver’s metabolic rate at the time of the dive
and 3) the rate of exercise performed on this dive. As these items vary, so
does the diver’s ability to vary the divewear insulation under the drysuit.
Generally with a wetsuit the diver is either too warm or too cold.
As far as weight is concerned, the drysuit diver is able to adjust the amount
of weight in accordance with their thermal needs. The more thermal protection
they use the more weight is necessary. It is impossible to generalize weight
requirements. For example, one diver wears twenty pounds of weight with a 6.5
mm wetsuit. In a drysuit, comfortably equipped for temperatures between 50 and
70 degrees F, this diver will use twenty-two pounds of weight. If a vest is
added (giving an additional 5 degrees of warmth) this diver will wear
twenty-six pounds. Due to the wide variation of body composition there is no
general rule of thumb. Each diver must weight themselves according to their
needs. However, to say that a diver needs much more weight with a drysuit is
incorrect.
Drysuit are only for extremely cold water!
In the entry-level course the students are taught that water conducts heat 25
times faster than air. This means that if a body is immersed in water colder
than body temperature heat is being drawn away from the body 25 times faster
than if the body were surrounded by air. In cold climates windows are installed
with "twin panes" since it is generally accepted that a dead air space
insulates most efficiently. Household insulation, cold weather sleeping bags
and numerous other heat retention items base their insulatory value on their
ability to trap air. It simply makes better sense to select the most efficient
method to retain heat in any endeavor.
Based on this logic it is easy to conclude: if there is a need for thermal
protection while diving, a drysuit, since air is the insulator, is always a
better choice than a wetsuit. One of the best attributes of a high quality,
well fitted wetsuit is that it excludes water from most of the body and
prevents the "flushing" of water in areas where water is not excluded. This is
more evidence indicating that if the diver totally excludes water from the
system it would be more efficient.
Since the divewear the diver wears under the drysuit provides the thermal
protection and the amount of protection is variable according to the three
things mentioned earlier, the chances of a drysuit diver being uncomfortable
are minimized. This is true for all temperatures of water from ice diving to,
in some cases, eighty-degree water.
Drysuit diving is too technical for the recreational diver!
Nothing is farther from the truth! Early on all scuba diving was thought to be
too complicated for recreational divers. In all facets of scuba diving the
proper procedures must be followed. Drysuit diving is no different. It is no
more or less complicated than diving with a BCD. When the first BCD was
introduced, many people in the dive education community pointed and laughed at
the new divers showing up in BCD’s. Many thought they were cumbersome,
complicated, bulky and dangerous. To introduce them to a new diver would be
task loading and asking for trouble.
Today the training organizations all require the use of a BCD in dive training.
Entry level students trained in drysuits tend to accomplish buoyancy skills
with much less trouble and much more accuracy. Divers trained in drysuits tend
to dive more often, take more courses, purchase more equipment and are less
likely to become an "occasional" or "dropout" diver.
For more information visit Diving Unlimited International's website at
http://www.dui-online.com.
*Thinsulate™ is a trademark of 3M
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