Dry Suits. Sources Barsky, S., D. Long, B. Stinton. 1992. Drysuit Diving – A Guide To Diving Dry. Watersport Publishing, Inc., San Diego, California

Dry SuitsDry Suits

SourcesSources

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 ProtectionThermal 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.

ChillingChilling

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

WetsuitsWetsuits

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 SuitsWetsuits 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 Table 1. Thermal Efficiency of Wetsuits vs. Dry SuitsWetsuits vs. Dry Suits

WETSUITS DRY SUITS

Water Temperature 1st dive 2nd dive 3rd dive 1st dive 2nd dive 3rd dive

70°F 100% 100% 100% 100% 100% 100%

60°F 100% 90% 80% 100% 100% 100%

50°F 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 SuitsWetsuits 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 wetsuitsMore care is required to manage buoyancy

in a dry suit

Dry Suits – What Are They?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 StylesDry Suits – 2 Entry StylesShoulder entry suit

– Zipper for entry located on back. You must have assistance to get in suit.

Dry Suits – 2 Entry StylesDry Suits – 2 Entry StylesSelf-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 TypesDry 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.


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)


Crushed neoprene– Advantages

Very tough and flexible – Can be tailored into a suit of outstanding fit

• Good for swimming

High insulation value Long lasting


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


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


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


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 TypesDry 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 TypesDry 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 UndergarmentsDry 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


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


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


Synthetic pile garments– Generally made of polyester

Has a tendency to form lint which may block exhaust valves

Buoyant Loses insulating characteristics when wet


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 ValvesDry 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 ValvesDry 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 WeightingDry 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 WeightingDry 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 Estimating Weight RequirementsRequirements

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 Table 2. Adjusting weight from fresh to saltwaterfrom fresh to saltwater

Divers weight Additional weight

125 lbs. 4 lbs.

155 lbs. 5 lbs.

186 lbs. 6 lbs.

217 lbs. 7 lbs.

Estimating Weight Estimating Weight RequirementsRequirements

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 BuoyancyChecking 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 SuitDonning 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 SuitDonning 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.


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 SuitDonning a Dry SuitLatex 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 SuitDonning a Dry SuitNeoprene 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.


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 Diving a Dry Suit – Check for LeaksLeaks

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 Diving a Dry Suit – Venting air From the SuitFrom 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 – Diving a Dry Suit – Descending and controlling Descending and controlling

buoyancybuoyancy 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 Diving a Dry Suit – Controlling buoyancybuoyancy

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 - AscendingDiving 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 SuitDiving 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 LeaksDry 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 WarningDiving 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 – Diving a Dry Suit – Emergency TechniquesEmergency 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).


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.


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.


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.


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.


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 SuitRemoving 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 SuitRemoving 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 SuitsMaintenance 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 SuitsMaintenance 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 SuitsStorage 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 AccessoriesDry 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


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 Dry Suit AccessoriesAccessories–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


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


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


Pockets– Many styles and attachment points available– Creates drag underwater


Argon inflation systems– Requires separate inflation

bottle and 1st stage– Argon is more dense than

helium or air, and provides

better insulating qualities

Documents

Dry Suits. Sources Barsky, S., D. Long, B. Stinton. 1992. Drysuit Diving – A Guide To Diving Dry. Watersport Publishing, Inc., San Diego, California