Dry Suit Diving
Part 2: Techniques
With emphasis on the use of the
CF200 dry suits manufactured by
Diving Unlimited International, Inc.
(DUI)
Photo by Steven M. Barsky
Training Goals
Upon completion of this session, the student will be able to:
• Discuss the importance of Boyle’s law with respect to dry suit
diving
• Describe how to determine proper weighting
• List normal predive procedures.
• Describe how to inspect, prepare, and don the dry suit.
• Describe the proper way to enter the water
• Describe how to begin the descent and how to control the
descent.
• Describe how to control buoyancy at depth
• Describe how to control buoyancy during ascent
• Describe how to maintain buoyancy at the surface
Training Goals, Continued
Upon completion of this session, the student will be able to:
• Discuss dry suit leaks, their cause and prevention
• Describe how to remove a dry suit
• Describe normal post-diving procedures and proper storage of
dry suits.
• Describe proper maintenance of dry suits
• Discuss the problems associated with diving in extremely cold
water
• List and describe emergency procedures
–
–
–
–
–
Inflator and exhaust valve problems
Lost weight belt
Flooded suit
Uncontrolled ascent
Inverted ascent
A dry suit is not just a piece of
clothing to be worn; it is a buoyancy
device that the diver must control.
Review of Boyle’s Law
Depth
0 feet
Volume of a gas
is inversely
proportional to
pressure
33 feet
Air Volume
1
Absolute
Pressure
1 ATM
2 ATM
1/2
66 feet
3 ATM
1/3
99 feet
4 ATM
1/4
Pressure and buoyancy
• Diver in a dry suit is surrounded by air
• Air changes volume as pressure changes
• As diver sinks …
• As diver rises …
– pressure increases
• pressure decreases
– air compresses
• air expands
– volume gets smaller
• volume gets bigger
– buoyancy reduces
– sinks even faster
• buoyancy increases
• rises even faster
Pressure and buoyancy
• Controlling the suit …
– Inflate on descent to avoid squeeze and slow rate of sink
– Vent air on ascent to slow rate of rise
• Note how easy it is to lose control …
– Vicious circle during both sinking and rising
– Rate of sink/rise increases if not corrected
– Biggest pressure & buoyancy changes near the surface
Dry Suit Weighting
• The goal is to dive with the minimum amount of
weight possible, resulting in the minimum volume of
air inside your suit.
– This will simplify buoyancy control – a diver with excess
weight will have to put excess air into the suit to become
neutral.
– When this air bubble shifts in the suit it can create
buoyancy control problems
• Wear only enough weight to allow you to make a
safety stop at the end of your dive (15 – 20 ft) with
500 psi of pressure in your cylinder.
Estimating Weight
Requirements
• Generally, you will need 4 to 10 lbs more weight than
you wear with a 7mm wetsuit. How much weight you
need depends on a variety of factors including:
–
–
–
–
The type of dry suit
The type of undergarment
Your personal buoyancy
The type of cylinder you use
• All cylinders become more buoyant as the air inside the tank is used
– How much more depends on the cylinder material and volume
– Whether you’re diving in freshwater or saltwater
• More weight is needed to dive in saltwater (Table 2 – next slide)
Table 2. Adjusting weight from
fresh to saltwater
Diver’s weight*
125 lbs.
155 lbs.
186 lbs.
217 lbs.
Additional weight
4 lbs.
5 lbs.
6 lbs.
7 lbs.
*includes weight of diver plus equipment
Estimating Weight Requirements
• Check the manufacturer’s specifications for
your cylinder to see how the buoyancy
changes from the time the tank is full until it is
empty. This change in buoyancy must be
considered for proper weighting
– aluminum 80ft3 Luxfer and Catalina tanks become
approximately 6 lbs. more buoyant
– Faber steel 98ft3 tanks become approximately 8
lbs. more buoyant
Checking Buoyancy
• Place regulator in mouth and breathe normally. Vent all the
air out of your BC. You should still float.
– Vent any remaining air from dry suit
• In a vertical position – you should float with your eyes at water level with a
lungful of air, and you should begin to sink slowly after exhaling all the air
from your lungs.
– If you sink rapidly you are too negative.
– Add or subtract weights as necessary.
– Now add weight to account for the change in buoyancy of your
tank as you breathe
• Add approximately 2/3 the weight of the buoyancy change of your scuba
cylinder from full to empty (you may find you have to adjust this slightly).
– You should be able to become neutral at a depth of 10 feet when you have
500psi of air in your tank.
• Once you have determined your buoyancy for a given
suit/insulation system, make a logbook entry so you will
know how to weight the next time.
Prediving Procedures
• Prepare suit
– Remove suit from storage bag and unroll
– Inspect body of suit for obvious cuts, damage
– Inspect zippers for corrosion, frayed or cracked rubber
sealing surface, missing teeth
– Inspect seals for deterioration (cracking or gummy
spots on latex), cuts, other damage. If using Zip Seals,
ensure security of cuff/seal interface
– Check inflator button function; if using swivel type
valve, make sure it moves smoothly
– Check that exhaust valve rotates smoothly and push
button to check function
Prediving Procedures, Continued
• Prepare suit, continued
– Lightly rub wax onto outside
surface of zipper
– Lubricate the seals with pure
talcum powder (do not use
scented talcs which contain
oils that can damage seals).
This will allow you to get
through seals easier. Soapy
water may be used as well.
– Remove all watches and
jewelry including earrings,
necklaces, bracelets and rings.
Any of these may tear a dry
suit seal.
Photo by Steven M. Barsky
Prediving Procedures, Continued
• Assemble and inspect other equipment
–
–
–
–
Fins large enough to fit over dry suit boots
BC large enough to fit over dry suit
Dry suit l.p. inflator installed onto regulator
Assemble all undergarment components and
inspect (zippers, Velcro, etc.)
– Rock boots, if used
– Inspect and assemble all other SCUBA equipment
as usual
Review the features
of the DUI dry suits
Donning a Dry Suit
•
•
•
•
•
Put on undergarments
Invert top of dry suit down to crotch
Sit down
Arrange suspenders behind the suit so they don’t get tangled
Insert legs, making sure that your socks/booties don’t fold over
your toes (they will cramp during the dive!)
• If your suit has ankle straps, secure them. If your suit has rock
boots, put them on and lace them
• Put on ankle weights if you choose to wear them.
• Pull up bottom, arrange and adjust suspenders over shoulders
Donning a Dry Suit, Continued
• Extend torso, put arms into sleeves
• When putting hands through wrist seals,
extend fingers (including thumb) and
squeeze them together – this will give
your hand the smallest diameter for
getting through the seal.
• With your free hand, either grab the
outside of the wrist seal and pull it over
the hand inside the suit, or alternatively,
slip two or three fingers of the free hand
inside the opening of the wrist seal and
pull the seal over the hand inside the
sleeve. In either case, do not dig your
fingernails into the seal.
• Ensure no undergarments extend through
wrist seal.
• Ideally, at least two inches of seal should
be in direct contact with your skin.
Photo by Ray Sharf
Powdering the seals greatly eases the donning process.
Donning a Dry Suit, Continued
• To spread the neck seal,
reach through the seal
with both hands and
spread the neck seal by
pulling against the
palms of your hands.
Avoid digging your
fingers into the latex.
• Pull the neck seal over
your head.
Photo by Steven M. Barsky
Donning a Dry Suit, Continued
• Ensure that long hair
and collars are not
caught in the seal.
• Neck seal should lie flat
Photo by Steven M. Barsky
Donning a Dry Suit, Continued
• Close waterproof zipper,
making sure that you check
to make sure that the glider
is fully docked onto the
rubber stop
• If your suit is equipped with
a zipper guard, zip that as
well.
• Fold telescoping torso,
secure and adjust the crotch
strap
Photo by Steven M. Barsky
Donning a Dry Suit, Continued
• Vent the suit.
– makes the suit more
comfortable to wear on deck
– prevents air from escaping
from the neck and creating a
leak upon entering the water.
– Squat down, cross your arms
over your chest and either
manually open the exhaust
valve, or let air out through
the neck.
• Close the exhaust valve by
rotating clockwise until it
stops
Photo by Steven M. Barsky
Entering the Water
• Perform normal buddy checks
• BC should be used for surface flotation
• You will notice 2 things when you enter the water:
– No icy streams of water entering your suit! Nice!
– When vertical at the surface, you will feel the suit
compressing your feet and legs as the air migrates
upwards
Diving a Dry Suit – Check for
Leaks
• Do not dive if your suit is leaking. Upon
entering the water, take a moment to check for
leaks. If you feel water coming in, take the
time to fix the problem – a small trickle on the
surface may get worse at depth, and will
certainly continue throughout your dive.
Diving a Dry Suit – Starting the
Descent
• Vent all the air from your BC.
• Open automatic exhaust valve by
rotating it all the way
counterclockwise. Leave it open
throughout the dive.
• Lift your left shoulder (thereby
making the exhaust valve the
highest part of the suit) while
keeping your arm bent and your
hand pointed towards the bottom.
You will hear air hissing out of
the valve.
• Exhale, and if you are weighted
correctly, you will begin to sink
Photo by Steven M. Barsky
The bubble to be vented must be directly below the exhaust valve.
Diving a Dry Suit – Descending
• As you sink through the water
column you will begin to feel
“squeeze” on your body. Add
just enough air to relieve the
pressure and control your descent
using short bursts.
• Be aware of the position of your
exhaust valve. Lower your left
shoulder to retain air and raise it
to vent air.
• As you near the bottom shift to a
horizontal position to avoid
stirring up sediment.
Photo by Steven M. Barsky
Diving a Dry Suit – Controlling
buoyancy
• Maintain a minimum volume of air
inside the suit – there should not be a
large bubble of air inside your suit,
nor should you notice massive air
shifts as you change position
• Control buoyancy at depth using only
your dry suit. Do not add air to your
BC to control buoyancy – it is very
difficult to control buoyancy in 2
separate compartments
simultaneously.
• Maintain a constant awareness of the
state of your buoyancy
Diving a Dry Suit - Ascending
•
•
•
•
Ensure that automatic exhaust valve is
open before ascending.
As you ascend and gain positive
buoyancy, raise left shoulder so valve is
higher than rest of suit. Keep your lower
arm pointed down -Do not extend the rest
of your arm higher than the valve or air
will rise to your wrist and bypass the
valve.
Control buoyancy by raising and
lowering position of exhaust valve. You
should be able to stop and hover at any
time during the ascent.
If you find you are ascending faster than
you should, raise the valve higher and air
should vent faster. If air still isn’t
venting fast enough, vent the valve
manually by pushing down on the valve.
Photo by Steven M. Barsky
Diving a Dry Suit – On the surface
• Upon reaching the surface, close the exhaust valve
at the surface by rotating it all the way clockwise.
• Inflate your BC at the surface – it is more
comfortable to move on the surface this way rather
than inflating your dry suit.
• If the dive is over, exit the water as normal
• Because of heavier dry suit weight systems, when
diving from a small boat:
– If using a DUI Weight and Trim System or weight
integrated BC, pull each lanyard and hand weights up, or
hook a snap from a boat lanyard and remove entire
system
– Always remove weights before removing air/BC system
Dry Suit Leaks
• All dry suits leak a little.
• When the suit is closed up, the humidity inside raises
to 100%. Even when not perspiring, moisture is
constantly coming from the skin pores. Body heat
moves the moisture to the cool inside surface of the
suit where it condenses. It is common to find
moisture on the inside of the suit after a dive.
• Flexing your wrists and turning your head allow
water to enter around pronounced tendons. This is
normal, and can be avoided with knowledge and
practice.
• Remember, “damp is OK as long as you are warm.”
Removing a Dry Suit
•
•
•
•
•
•
•
•
•
•
If you suspect that you have a leak in your suit, undress carefully and assess where
the wet is as you undress
Unfasten crotch strap
Unzip zipper guard if installed. Unzip waterproof zipper.
Simultaneously tuck your chin to your chest while sliding the fingers of each hand
down between your neck and the seal. Grasp firmly (careful with fingernails!) and
spread the neck seal with your hands, lifting the seal up over your head.
Slide left hand out of seal (insert 2 fingers of right hand under the wrist seal with
the fingernails against the wrist, slide the fingers of left hand down past the seal,
grasp the sleeve of the suit, and pull your left arm out of the sleeve). Carefully
shrug off shoulder and remove arm.
Remove right arm from sleeve.
Invert suit down to crotch and pull off suspenders
Sit down
Release ankle straps if installed, rock boots and ankle weights if used
Gently place the toe of one foot on the heel of the other, point your toe and pull out
of the drysuit leg. Repeat with the other foot.
Post-dive Procedures
• Rinse all equipment in fresh,
warm (if available) water as
normal
• Operate valves as you run water
over them – rotate automatic
valves and push the inflator
button several times.
• It is usually easier to hose the
zipper while wearing the suit, but
if you remove the suit before
washing close the zipper and the
seals with rubber bands first to
prevent water entry.
• If suit or seals have been
contaminated by oil, gently wash
with mild soapy water
Photo by Steven M. Barsky
Post-dive Procedures, Continued
• Hang suit over a large
diameter roller in a dry
location away from direct
sunlight, ozone, high heat,
etc.
• Remember also to turn the
suit inside out to dry (keeps
the mold and smell down)
• When fully dry, roll as per
owner’s manual instructions
and store in dry suit bag.
Photo by Steven M. Barsky
Storage of Dry Suits
• Store in a cool, dry, dark place
• Store away from heat, chemicals, petroleum, solvents,
electric motors and other producers of ozone – ozone
deteriorates latex
• Avoid storing in direct sunlight
• Cover valve stem
• Store rolled in the proper drysuit bag or flat, never
folded (can develop permanent creases) or on a thin
metal hangar (creases and rust)
• Do not bend zipper in storage – store suit with zipper
open to avoid creating a permanent compression set on
the sealing surface and reducing the life of the zipper.
Maintenance of Dry Suits
• Zipper lubrication – zippers should be lubricated
either before or after you dive. Use bees wax or
paraffin wax – never use silicone spray or grease on
your dry suit zipper. (Also, be sure to remove any
excess paraffin wax – otherwise it will cause
deterioration of latex seals if let in contact with the
seal for long periods of time)
• Close the zipper and only lubricate the outside – if
you lubricate the inside dirt will collect and cause the
zipper to fail.
• A thin film of wax is sufficient
Locating leaks
• Close seals with rubber bands and
close zipper.
• Assemble regulator and cylinder
with dry suit inflator attached.
Turn on air. Attach inflator to suit
and push button just enough to
lightly inflate suit.
• Brush soapy water and observe
any bubbles
• Minor leaks can be repaired with
Aquaseal and Cotol. Suit must be
completely dry.
• Major leaks or damage should be
returned to dealer or factory
Photos by Terrence M. Rioux
Lifting Heavy Objects
• Do not lift heavy
weights by inflating
your dry suit or BC – if
the weight drops you
will become
dangerously buoyant.
Use proper procedures,
such as lift bags or lift
lines to raise heavy
objects.
Photo by Steven M. Barsky
Polar and Ice Diving
•
•
•
Water colder than 39°F (4°C) is an
extreme environment
An unprotected person (i.e., falling over
the side, major dry suit leak) will be
rendered helpless within minutes and this
will result in a life-threatening situation.
Equipment problems
–
–
–
•
•
SCUBA regulators and inflator valves may
freeze, resulting in severe free-flow
Lowered battery life (e.g., computers,
lights)
Many materials become stiff or brittle in
extreme cold
Winter (February is coldest month) in New
England approach polar conditions
Diving under an ice ceiling is an advanced
skill and requires special training and
equipment
Photo by Judy Harbison
Regulator Freezeup
•
•
Compressed air released from first and second stage valves is cold because of
adiabatic cooling
The colder the water, the more readily ice forms
–
–
–
–
Exhaled breath is saturated and may freeze on valve
Heavy exertion and breathing increase cooling
Ice forms, preventing valve from seating and creating a free-flow
Free-flow increases cooling, resulting in more ice formation, resulting in uncontrolled
free-flow
– BC and dry suit inflator valves also susceptible to freezing
•
Prevention
–
–
–
–
–
–
•
Second stage must be completely dried between dives
Avoid breathing into regulator until you leave the surface
Adjust any small air leak before beginning dive
Breathe slowly and calmly during dive
Some brands/models have better cold resistance than others
Consider using completely redundant systems in very cold water (‘Y’ valve or pony
bottle) Inflate BC & dry suit using short burst, not long
Abort dive if you detect any leaks
Severe regulator freeze-up
Ice completely filled second
stage due to uncontrolled freeflow. Obviously, the cylinder
was emptied very quickly.
Icing around the first stage,
however, is normal in very cold
water.
Photos by Terrence M. Rioux
Emergency Procedures
• Inflator valve stuck open
– Causes
• Corrosion, silt or sand buildup in valve
• Freezing causing ice to build up in valve
– This will cause your suit to inflate continuously.
• immediately attempt to disconnect your inflator hose
• Assume proper position and vent excess air through the exhaust
valve
• If severe enough, pull neck or wrist seals open (water will enter
suit)
• If air cannot be vented, extend arms and legs in a horizontal
position to create drag (flare position)
Emergency Procedures
• Inflator valve stuck closed
– Cause: poor maintenance and corrosion build-up
– This should be detected during the pre-dive
inspection!
– If it does happen on the dive:
•
•
•
•
Stop the descent and terminate the dive
Use BC as needed to control buoyancy
Return to the surface venting expanding air as normal
Remind yourself to do a better job during the pre-dive
inspection next time!
Emergency Procedures
• Exhaust valve stuck closed or clogged
–
–
–
–
Cause: improperly maintained valve
A very rare occurrence
Result: exhaust valve may fail to exhaust air
If your exhaust valve fails, you should immediately
stop your ascent, if possible. Rotating or manually
operating an automatic valve may get it to work.
– If your valve still does not function properly pull neck
or wrist seals open to vent – you will get wet doing this.
– ascend an anchor line or some other fixed object
Emergency Procedures
• Leaking exhaust valve
– Cause: dirt, lint, sand buildup in valve
– Determine extent of leak, terminate dive if needed
– Use BC to control buoyancy if necessary
Emergency Procedures
• Dropped/lost weight belt at depth
– If unable to recover weights, you will become very
buoyant and ascend very rapidly
– If you are right next to an anchor line or fixed
object, hold on and try to shimmy up.
– Exhaust expanding air as rapidly as possible and
vent from seals.
– If ascending rapidly, use flare position to slow
ascent by increasing drag
– Remember to exhale!
Emergency Procedures
• Rapid ascent
– Flare position: you may slow your ascent
dramatically by holding your ankles rigid with
your fins parallel to the bottom (the fins act as
“water brakes”), arching your back, and holding
your arms out parallel to your body.
– Another technique for slowing a rapid ascent is to
swim horizontally, so your body presents a greater
surface area.
Emergency Procedures
• Righting yourself
– It is possible for excess air to
move to the feet of your dry
suit, potentially making it
difficult to return to an
upright position.
• To right yourself in this
situation, tuck your body into a
ball, give a slight kick, and roll
to an upright position. Once
you are upright immediately
vent your suit through the
exhaust valve to regain
control.
Photo by Steven M. Barsky
Emergency Procedures
• Complete dry-suit flooding
– Occurs only rarely, possibly from
the complete failure of a zipper,
blow out of a neck seal, or the
destruction of a valve. Total
flooding of your dry suit may cause
you to become negative depending
on what kind of undergarments you
are wearing.
• Usually you will be able to achieve
neutral or positive buoyancy by
inflating your BC.
• A flooded dry suit may make it
extremely difficult to exit the water
– someone may have to puncture
the leg of the suit to drain water.
WHOI Dry Suit Rules
•
•
•
•
•
•
•
•
•
•
•
•
Certification from DSO must be obtained before usage.
Advance notice via dive plan must be given.
Dry suits must be signed out – and in - when returned.
Project may be liable for any damage incurred due to user negligence.
Dry Suits will be properly cared for, cleaned and dried before storage.
Always clean at end of diving day, just as you would with personal diving
equipment.
Hang up to dry both inside and outside.
When dry, please store in the proper bag (they are marked) and put away.
Please keep the inflator hoses with the dry suits; do not leave them on the
regulators.
Keep track of all of the components, including booties, hoses inflator plug
Please return the powder bags and wax!
Dry suits may not be loaned out to unauthorized persons.
Review
• Why is Boyle’s Law so important to learning how do
dive in a dry suit?
• How do you determine your proper buoyancy?
• How do you prepare a dry suit for diving?
• List the steps involved in donning a dry suit.
• Before entering the water, what is the position of the
exhaust valve?
• How do you start your descent?
• What is the role of the BC in dry suit diving?
Review, Continued
• How do you control buoyancy while descending?
While ascending?
• What two steps do you take when you first reach the
surface?
• List the steps in removing a dry suit.
• List at least 5 maintenance procedures.
• How can you reduce the incidence of regulator and
inflator valve freeze-up when diving in very cold
water?
• What do you do if your inflator valve gets stuck in
the ‘open’ position (can’t turn off the air)
• What do you do if you are rising with your feet above
your head?
QUESTIONS