Dry Suits
Sources

Barsky, S., D. Long, B. Stinton. 1992. Drysuit
Diving – A Guide To Diving Dry. Watersport
Publishing, Inc., San Diego, California.
 T. Joiner (ed.). 2001. NOAA Diving Manual Diving for Science and Technology, Fourth
Edition. Best Publishing Company, Flagstaff,
Arizona.
Thermal Protection

Some measure of thermal protection is necessary
for diving - even in warm waters
– Average body temperature is 98.6°F

To one degree or another, the body will lose heat in water
cooler than body temperature. Hypothermia can occur in water
as warm as 91 °F
– Hypothermia occurs when the core body temperature is
lower than 95 °F. However, A diver can become
incapacitated by chilling - without ever becoming
hypothermic.
Chilling

Chilling:





Increases fatigue
Reduces dexterity
Affects short-term memory and the ability to think
clearly
Increases air consumption (a diver’s metabolism
increases as the body burns more calories in an
effort to maintain temperature)
May increase the risk of decompression sickness
Wetsuits

Wetsuits are made from foam neoprene. The
neoprene has thousands of closed cells containing
nitrogen. These cells provide insulation.
– Wetsuits work by trapping a thin layer of water next to
the diver’s skin. This water is warmed by the diver.

Wetsuits come in a variety of thicknesses – one
mm up to 7mm. The thickness of the wetsuit
determines its insulating capacity.
Wetsuits VS Dry Suits

Wetsuits are most effective at 60°F and above diving in water temperatures 50°F and colder
usually requires a dry suit.
 Table 1 (next slide) indicates that the efficiency of
wet suits declines at a much faster rate than that of
dry suits during multiple dive days.
 Dry suits are the most efficient form of passive
thermal protection for the diver – they can greatly
increase the amount of time a diver can stay
underwater.
 Dry suits afford greater protection against
contaminants in polluted water
Table 1. Thermal Efficiency of
Wetsuits vs. Dry Suits
WETSUITS
DRY SUITS
Water Temperature 1st dive 2nd dive 3rd dive
70°F
100% 100%
60°F
100%
50°F
1st dive
2nd dive
3rd dive
100%
100% 100%
100%
90%
80%
100% 100%
100%
80%
70%
50%
100% 100%
100%
40°F
50%
25%
*
100%
85%
75%
32°F
*
*
*
100% 75%
55%
Table is based upon 30-minute dives at 50 fsw, with one hour surface intervals between dives.
The * indicates an exposure not recommended unless involved in a contingency situation.
Wetsuits VS Dry Suits

The initial cost of a dry suit is greater than
that of a wetsuit
 Dry suits require more maintenance
 Dry suits are more bulky and more buoyant,
requiring more weight than wetsuits
 More care is required to manage buoyancy
in a dry suit
Dry Suits – What Are They?

One piece suits with a waterproof zipper for
entering the suit, attached boots, and seals at the
diver’s wrists and neck.
 Water does not enter the suit.
 Undergarments are worn under the suit for
insulation. The type and amount of
undergarments worn determine the level of
insulation.
 Suits have inflator valves – generally located on
the chest - for putting air into the suit. They also
have exhaust valves – generally located on the
upper left arm – for venting air from the suit.
Dry Suits – 2 Entry Styles

Shoulder entry suit
– Zipper for entry located on back. You must
have assistance to get in suit.
Dry Suits – 2 Entry Styles

Self-donning suit
– Zipper for entry is located across front of suit,
So assistance entering suit is not necessary.
However, these suits are generally more
expensive than shoulder entry suits
Dry Suit Types

Foam neoprene (compressed neoprene)
– The same material wetsuits are made of
– Advantages
 The material stretches well, and can be tailored to fit
the body closely.
 Has good insulating properties
– may require less or even no undergarments
– beneficial in the event of a leak


The only type of dry suit that is inherently buoyant.
Most inexpensive type of suit.
Dry Suit Types

Foam neoprene
– Disadvantages
 Loses buoyancy and insulation value as depth
increases
 Tends to develop leaks over time as cracks develop
in the bubble layers and water migrates through the
material
 May be difficult to patch and repair
 May not last as long as other types of dry suits
Foam neoprene dry suits (note
inflator valve on chest and
exhaust valve on upper left
arm)
Dry Suit Types

Crushed neoprene
– Advantages
 Very tough and flexible
– Can be tailored into a suit of outstanding fit
• Good for swimming


High insulation value
Long lasting
Dry Suit Types

Crushed neoprene
– Disadvantages
 May be difficult to repair
 May be heavier than suits made of other materials
 More expensive than foam neoprene
Crushed neoprene dry suits
Dry Suit Types

Urethane coated nylon
– Composed of nylon to which urethane has been
applied in order to create a waterproof barrier.
– Advantages


Lightweight
Low cost
– Disadvantages
 Little stretch, so fit is loose and baggy
Urethane coated nylon dry suits
Dry Suit Types

Trilaminate (TLS)
– Composed of two layers of tightly woven nylon
with a layer of rubber in between

Originally designed for chemical warfare
– Advantages
 Lightweight, yet very strong
 Flexible material, Easily repaired
– Disadvantages
 Little stretch
Trilaminate dry
suits
Dry Suit Types

Vulcanized rubber
– Advantages



Easily repaired
Dries quickly
Excellent for diving in polluted waters
– Easier to decontaminate than other dry suit types
– Disadvantages


Has some stretch, but not as form fitting as neoprene suits
Heavy
Vulcanized rubber dry suits (good
for diving in polluted environments)
Dry Suit Seals – 2 Types

Latex – the most common type
– Advantages
 Good stretch, so more comfortable – puts less
pressure on neck and rests
 Quick to repair
 Not as likely to leak
– Disadvantages
 More easily punctured or torn
Dry Suit Seals – 2 Types

Neoprene
– Advantages
 Rugged – harder to tear and longer lasting
– Disadvantages
 Difficult to repair
 Individuals with skinny necks may have difficulty
getting a proper seal
 Do not stretch as well and may feel uncomfortable
 May fit looser as neoprene becomes permanently
stretched
Dry Suit Undergarments

Undergarments increase insulation by
trapping air against your body – different
materials are better at insulating than others.

Undergarments also affect
buoyancy, mobility, and
comfort
Dry Suit Undergarments

Open cell foam
– Similar to a sponge in cross section
– Loose fitting, baggy and bulky
– Fairly resistant to compression
– Maintains some insulating properties when
damp, but not when soaked
– Will lose all of its buoyancy if suit floods
– Less popular today than competing synthetics
Dry Suit Undergarments

Thinsulate
– Lightweight and quick drying
– excellent insulating properties even when wet
– Repels water
– Is bulky, does not stretch or breathe, and is
more uncomfortable than some other materials
Dry Suit Undergarments

Synthetic pile garments
– Generally made of polyester
 Has a tendency to form lint which may block
exhaust valves
 Buoyant
 Loses insulating characteristics when wet
Dry Suit Undergarments

Polartec®
– Good insulating characteristics with little bulk
– Lots of stretch – easy to don and swim in
– Does not retain its insulation capabilities once
wet
Dry Suit Valves

Most dry suits today have separate inflator
and exhaust valves
– Inflator valves
 Push-button, connects to a low pressure inflator
hose running from the 1st stage
 Typically located on the center of the chest, but can
be located elsewhere depending on the manufacturer
 Must be accessible while diving and easily
disconnected with heavy gloves
Typical Inflator valve with push-button operation
located on the chest.
Dry Suit Valves
– Exhaust valves
 Generally located on the upper left arm, but may also
be situated on the wrist or chest
 Most exhaust valves today are “automatic exhaust
valves” – that is, they will vent automatically when
positioned at the highest point on the dry suit
 May also be vented manually
 Generally, dry suit exhaust valves do not vent air as
rapidly as a buoyancy compensator (BC)
Typical dry suit automatic exhaust valve positioned
on upper left arm. Note the manual vent button in
center of valve.
Dry Suit Weighting

Where weighting is concerned, your goal is to
dive with the minimum amount of weight possible
and, associated with that, the minimum volume of
air inside your suit. This will simplify buoyancy
control – a diver with excess weight will have to
put a great deal of air into a dry suit to become
neutral. When this air shifts in the suit it can
create buoyancy control issues for the
inexperienced dry suit diver.
Dry Suit Weighting

You should wear only enough weight to
allow you to make a safety stop at the end
of your dive (15 – 20 ft) when you have 500
psi left in your tank.
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 tank you use

All tanks become more buoyant as the air inside the tank is used
– 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
Divers weight
125 lbs.
155 lbs.
186 lbs.
217 lbs.
Additional weight
4 lbs.
5 lbs.
6 lbs.
7 lbs.
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 are
approximately 2 lbs negative when full and 4 pounds
positive when empty
– Faber steel 98ft3 tanks are approximately 8 lbs negative
when full and neutrally buoyant when empty
Checking Buoyancy

After removing air from dry suit (see slide 38) and entering
water – perform the following:
– 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.
Donning a Dry Suit

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.
 Once lower body is in suit, put on and adjust
suspenders. They should be taut, supporting the
lower part of the suit, but not tight. There should
still be some stretch in them.
Donning a Dry Suit

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
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.
 Insure no undergarments extend through seal.
 Ideally, at least two inches of seal should be in
direct contact with your skin.
Donning a Dry Suit

Neoprene wrist seals
– May be either cone-shaped or designed to fold
under.


If the seal is cone-shaped, insure that it is pushed far
enough up the arm to insure a seal
If the seal is meant to be folded under, then insure
that at least 2 inches of material is folded under the
top layer of neoprene
Donning a Dry Suit

Latex neck seals
– To spread the neck seal, reach through the seal
with both hand 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.
– Insure that long hair
and collars are not
caught in the seal.
Donning a Dry Suit

Neoprene neck seals
– Position your head at the base of the seal, then,
with your hands on the outside of the seal, pull
the seal over your head. When the seal reaches
your chin, fold the material inside itself.
Donning a Dry Suit

Insure both inflator and exhaust valves work
before entering water.
 Vent the suit.
– After closing all zippers, it is necessary to remove the
air from the suit. This will both make the suit more
comfortable to wear on deck, and prevent 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.
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 any leak is found, take the time
to fix the problem – a small leak on the
surface may get worse at depth, and will
certainly continue throughout your dive.
Diving a Dry Suit – Venting air
From the Suit

To start the dive, vent all the air from your BC
then vent the air out of your dry suit via the
exhaust valve.
– If you have an automatic exhaust valve, open it all the
way and leave it open throughout the dive. If your
automatic exhaust valve is located on your upper left
arm, then lift your left elbow out of the water (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.
Diving a Dry Suit –
Descending and controlling
buoyancy

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.
 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
when you have air in 2 separate compartments –
controlling both air compartments simultaneously
is an advanced skill and is not recommended for
the novice dry suit diver.
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
Diving a Dry Suit - Ascending
If you have an automatic exhaust valve – insure
that it is open before ascending.
 If valve is located on upper left arm (the standard
location) – then raise it 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.
 If you are not using an automatic exhaust valve,
then, again, raise your arm so the valve is at the
highest point and use your other hand to push in
on the valve to vent air.

Diving a Dry Suit

If you are using an automatic valve and 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.
 Inflate your BC at the surface – it is more
comfortable to move on the surface this way rather
than inflating your dry suit.
Dry Suit Leaks

Small amounts of water may enter your dry
suit through seals. 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.
Diving a Dry Suit – A Warning

Do not lift heavy weights by inflating your
dry suit or BC – if the weight drops you will
become dangerously buoyant
Diving a Dry Suit –
Emergency Techniques

Stuck inflator valve
– An improperly maintained inflator valve can
stick open – this will cause your suit to inflate
continuously.

You should attempt to disconnect your inflator hose
immediately, and vent excess air through the exhaust
valve at the same time (this can only be done if you
have an automatic exhaust valve if you have a
manually operated valve then disconnect the hose
first, then vent the manual exhaust).
Diving a Dry Suit –
Emergency Techniques

Improperly functioning exhaust valve
 An improperly maintained valve, or a valve that
has become clogged during a dive 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. Little
can be done to get a manual valve to work properly
once clogged.
– If your valve still does not function properly try to
ascend an anchor line or some other fixed object while
venting air by opening a neck or wrist seal – you will
get wet doing this. If doing a free ascent, be prepared
to vent air rapidly through the neck or wrist seals.
Diving a Dry Suit –
Emergency Techniques

Losing weight belt at depth
– Will cause you to become very buoyant with an
extremely fast ascent - It is doubtful you will be
able to vent enough air through the exhaust valve to
get control of the situation

Work to stop your ascent and be prepared to vent air
from your suit from the wrist seal or neck seal.
Diving a Dry Suit –
Emergency Techniques

Rapid ascent
– 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.
Diving a Dry Suit –
Emergency Techniques

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 such a 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.
Diving a Dry Suit –
Emergency Techniques

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.
Removing a Dry Suit

Remove a latex neck seal by sliding the fingers of
each hand down between your neck and the seal,
grasping firmly, spreading the neck seal with your
hands, and lifting up.
 Remove a fold-under neoprene neck seal by first
unrolling it, then firmly grasping the edge of the
seal and pull the seal up and over the head.
Removing a Dry Suit

To remove a latex wrist seal, insert 2 fingers
under the wrist seal with the fingernails
against the wrist, slide the fingers down past
the seal, grasp the sleeve of the suit, and
pull your arm out of the sleeve.
 To remove a neoprene wrist seal – simply
unfold it and follow the instructions above
for wrist seals.
Maintenance of Dry Suits
Rinse dry suits thoroughly – especially the
valves and zippers. Close the zipper and the
seals with rubber bands to prevent water
entry. Operate valves as you run water over
them – rotate automatic valves and push the
inflator button several times.
 Dry a suit out of the sun – you may need to
turn the suit inside-out if it is wet inside.

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

Storage of Dry Suits





Follow manufactures recommendations
Store away from electric motors and other
producers of ozone – ozone deteriorates latex
Avoid storing in direct sunlight
Never use metal hangers – they cause creases and
rust
Do not bend zipper in storage – roll suit with
zipper open
Dry Suit Accessories

Gloves
– Wet gloves are most common – essentially
wetsuit gloves pulled over the tops of wrist
seals
– Dry gloves



Connected to suit with cuff rings
Warmest gloves, but prone to flooding
Work only with latex seals
Dry Suit Accessories

Hoods
– Wet hoods are most common
 Can be attached to suit or separate
– Semi-dry hoods
 Neoprene – attached to suit and seal around face
Dry Suit
Accessories
–Dry hoods

Warmest hoods
Latex hood attached to suit that
seals around face

Requires separate insulating
hood worn underneath latex hood


Will not work with a beard
Insulating hood
Dry Suit Accessories

Ankle weights
– ½ - 3 pound weights attached to each ankle
– Help to keep feet down and retain trim
underwater
– May help for beginners, but NOT a necessary
item for dry suits
– Fatiguing during long swims
Dry Suit Accessories

P – valves
– Allows for underwater urination
– Most convenient for males with condom
catheter
– Available for females, but not as convenient or
easy to use – requires shaving and lots of
adhesive
– Adult diapers are the alternative
Dry Suit Accessories

Pockets
– Many styles and attachment points available
– Creates drag underwater
Dry Suit Accessories

Argon inflation systems
– Requires separate inflation
bottle and 1st stage
– Argon is more dense than
helium or air, and provides
better insulating qualities