Presentation on theme: "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."— Presentation transcript:
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 Boyles 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 Boyles Law Volume of a gas is inversely proportional to pressure Depth 0 feet 33 feet 99 feet 66 feet 2 ATM 3 ATM 4 ATM Air Volume Absolute Pressure 1 ATM 1 1/2 1/3 1/4
Pressure and buoyancy Diver in a dry suit is surrounded by air Air changes volume as pressure changes As diver sinks … –pressure increases –air compresses –volume gets smaller –buoyancy reduces –sinks even faster As diver rises … pressure decreases air expands volume gets bigger 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 youre 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* Additional weight 125 lbs. 4 lbs. 155 lbs. 5 lbs. 186 lbs. 6 lbs. 217 lbs. 7 lbs. *includes weight of diver plus equipment
Estimating Weight Requirements Check the manufacturers 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 80ft 3 Luxfer and Catalina tanks become approximately 6 lbs. more buoyant –Faber steel 98ft 3 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 dont get tangled Insert legs, making sure that your socks/booties dont 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 isnt 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 owners 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 free- flow. 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 Boyles 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 (cant turn off the air) What do you do if you are rising with your feet above your head?