Dayo Scuba - Cavern Study Guide

NAUI Tec Cave

Cavern Diving Limitations:

1. Maximum Depth 70-100'ft (depends on agency)
2. Minimum Visibility 20' (30' feet for some agencies)
3. Maximum Linear Penetration 200'ft (130ft for some agencies) or to the edge of the lighted zone
4. No Decompression Diving
5. 1/3 Air Rule for all single tanks.
6. Minimum Starting Pressure 2000 PSI. Minimum Ending Pressure 1200 PSI

Cavern Diving Equipment Requirements:

1. Minimum tank size is 72 cu ft
2. K Valves, Y Valves, or H Valves allowed. No J Valves.
3. 2 Lights per diver. The Sun is the primary light
4. Small Cutting Device
5. Slate with Pencil
6. Decompression Tables & Bottom timer or Dive Computer
7. 7ft hose is required for alternate air source
8. Cavern or Primary Reel
9. All other equipment required for open water diving. No Snorkels! No Gloves!

Conservation:

You are there by choice; the cave is not, so respect the environment that you are entering into.

1. Do not remove anything, the ecological balance of a cave system is very fragile
2. No Graffiti!
3. No Trash. Remove it if you see any
4. Cave are geological windows to the past
5. Caves are home to both animal and plant life-respect it!

Landowner Relations:

1. Land is either privately or publicly owned. Do not abuse the privilege of being there.
2. Make sure you have permission to be there.
3. Time Considerations:
a. Plan dives to coincide with the owners desires
b. Gate privileges
c. Noise considerations
d. Develop good relations with the landowners so that others may dive there also
e. You are representing other cavern and cave divers, do not give us a bad name because of your actions.

General Terminology & Geology:

1. Geology is defined as the scientific study of the origin, history and structure of the earth.

Geologists Terminology/Definitions:

1. Cave: A cave is defined as a naturally occurring room or passage in bedrock, large enough to be entered by a human.
2. Cavern: A cavern is defined as two or more such interconnected underground rooms or passages.

Divers Terminology/Definitions:

1. Cavern: A cavern is defined as the initial room of an underwater cave system, which is illuminated by natural daylight.
2. Cave: A Cave is defined as an underwater passage or room that is not illuminated by natural daylight.

Types of Caves & Their Formations:

1. Sea Caves (Littoral Caves)
   a. Formed by wave (hydraulic) action
   b. Typically not extensive
   c. Special Considerations:
      i. Marine Growth
      ii. Marine Animals
      iii. Tides & Currents
   d. Located along California Coast, New England, SW Pacific, Sea of Cortez, Great Lakes, Bahamas

2. Coral Caves

a. Formed by coral polyps that grow together to form living coverings over coral canyons which one can swim through
b. Typically not extensive
c. Special Considerations:
   i. Marine Growth (Coral is very sharp)
   ii. Marine Animals
   iii. Tides & Currents
d. Located in areas that are favorable to coral growth. South Florida, Bahamas, Caribbean, South Pacific

3. Lava Tubes

a. Formed when the outer surface of a lava flow hardens while the inner core continues to flow. If the flow of lave is cut off suddenly, this inner core may empty out, leaving a hollow tube
b. Typically very extensive
c. Special Considerations
   i. Marine Growth
   ii. Tides & Currents
   iii. Rock color is black which absorbs light very quickly
   iv. Very Dangerous
d. Located along the Pacific Rim of fire. Hawaii and every other volcanic island or land mass.

4. Solution Tubes

a. Solution caves are formed by the dissolution of limestone (calcium carbonate) or dolomite (calcium magnesium carbonate) by water containing carbonic acid. These are the most commonly dived caves. Rain falling through the atmosphere and percolating through the ground picks up Carbon Dioxide (CO2) and forms a mild solution of carbonic acid. As this carbonic acid flows through the ground it forms tiny solution tubes which over time become bigger. Eventually, these solutions tubes from an underground cave system. This process takes thousands of years.

b. Other Factors in Cave Formation

       i. Rise & Fall of the water table
       ii. Changes in the direction of water flow
       iii. Breakdowns (Cave-ins)

c. There are two types of Sink Holes
i. In-Line Sinks. In-Line Sinks are defined as sinks in which the flow of water is constantly moving in direct relation with the cave system which connects too.
Example: Olsen Sink & Challenge Sink @ Peacock State Park
ii. Off-Set Sinks. Off-Set Sinks are defined as sinks in which there is no significant water movement with relation to the cave system, which it connects too.
Example: Cat Fish Sink @ Manatee State Park

d. Karst Terrain. Karst Terrain is defined as a distinctive landscape in which caves are likely to occur. Characteristics include sinkholes, sinking streams, large springs and rolling landscapes.

e. There are two types of solution cave formations:

1. Phreatic: Phreatic is defined as a limestone passage that has been carved out by flowing water

2. Vadose: Vadose is defined as a limestone passage which is at present completely filled with water, but at one time was once partially filled with air, due to a lowering of the water table. At that time the erosion process virtually stopped in the air filled section, but continued in the water filled section thus creating a V type cut through the limestone where the underground stream continued to flow.
Solutions Caves are very extensive and maze like. It is very easy to become lost if you are not trained.

Some special considerations:

    a. Direction of the flow can change very quickly
    b. Visibility can change very quickly
    c. Every cave has its own dangers and formations

Solution Caves are located throughout North-Central Florida, the Ozark Mountains of Missouri, the Yucatan Peninsula of Mexico, Texas & the entire Caribbean.

Entrance Descriptions:

1. Spring:

A spring is defined as the entrance to a cavern or cave system in which the water flows out of the ground.

a. Usually have a surface boil present and a pool of water (spring basin) and a stream of water, which leads to the river. This is called a run.
b. Considered the safest type of cavern/cave to dive in
c. Reversing the flow. During locally heavy rains springs may reverse their flow.

2. Siphon:

A siphon is defined as the entrance to a cavern or cave system in which the water flows into ground.

    a. Usually have many of the characteristics of a spring except the water flows into the ground. It may have a whirlpool like appearance instead of a boil.
    b. Usually considered unsafe for cavern diving
    c. There is no set rule for diving siphons; you adjust your air according to the intensity of the flow.
    d. Reversing the flow. During locally heavy rains siphons may reverse their flow. After the rains have subsided, this is the best time to dive a siphon because if the flow has reversed it has become a spring for a short period or time.

3. Spring-Siphon:

A Spring-Siphon is defined as a single basin (Sinkhole) that contains both a spring and a siphon.

Sinkholes are the most common form of karst window. They form when the ground collapses over an underground river. When this happens the upstream side of the flow is forced to flow up and over the breakdown to get to the downstream side. This forms a spring at the upstream side and a siphon at the downstream side. There may be no visible water movement at the surface of the sinkhole.

4. Sumps:

Sumps are defined as water filled sections of a cave within an otherwise air-filled passage. These are very complex dives that require much more advanced training than is afforded during this course.

Bottom Compositions:

Cave divers define silt as fine, naturally occurring particles that may affect visibility. Cave Divers rate silt according to its immediate effect on visibility; the rating goes from least concern too most serious.

1. Sand:

    a. Least Serious
    b. Large Particle Size
    c. Settles quickly out of solution
    d. Clean appearance

2. Mud:

    a. Serious
    b. Easily Disturbed
    c. Can stay in solution for several hours

3. Clay:

    a. Most Serious
    b. Very Easily Disturbed
    c. Very fine particles that are electrically charged when agitated; will stick to a cave divers body, equipment, and exposure suit
    d. Can stay in solution for several days

Silt Locations:

    1. Floor (most common)
    2. Walls (Less Common)
    3. Ceiling (in less frequented cave systems)

Chemicals, Gases, & Related Terminology:

1. Hydrogen Sulfide (H2S)

        a. Rotten egg smell
        b. It is a poison and may be absorbed through the skin. This can cause a diver to feel sick to the stomach.
        c. May cause equipment to turn black or cause electrolysis
        d. Hydrogen Sulfide layer creates a milky cloud effect when it mixes with water. There may be limited visibility within the cloud and no light usually penetrates through the layer.
        e. Hydrogen Sulfide usually occurs when salt and fresh water interface with each other; usually near the coastline. Example: Hospital Hole, near Tampa, Fl

2. Tannic Acid

        a. Formed by decomposing vegetation, often associated with cypress tree stumps.
        b. Gives the water the color of a strong cup of tea.
        c. Usually produces poor visibility, but can provide some dramatic effects when it mixes with clear spring water.

3. Hydrocarbons, Methane & Other Gases

        a. These gases are formed as a by-product of decomposing material.
        b. They are odorless and tasteless but they are potentially lethal gases.
        c. The presence of these gases in caves is rare but do not breathe them.
        d. Usually found in small gas pockets on the ceiling of underwater caves.

4. Stale Air

a. This is a result of the exhaust bubbles from divers regulators. It has a very high Carbon Dioxide concentration and may be potentially lethal if inhaled. It is usually located in ceiling pockets throughout the caves.

5. Halocline

a. A halocline is formed when layers and concentrations of salt and fresh water interface with each other. The result can be impaired visibility as you travel between these layers. Haloclines are very common in caves that are located close to the coastline. Example: Yucatan Peninsula Caves in Mexico are renown for their many haloclines.

6. Thermo clines

a. Thermo clines occur when there is a dramatic change in temperature between two different layers of water. The ability of sound travel can be affected because of the different densities of these layers of water.

Hazards of the Environment:

1. Water

a. You cannot breath it
b. Hypothermia; water conducts heat away from the body 20 times faster than air. This is because water is 800 times denser than air. We loose 45% of body heat from our head, and another 25% from our armpits.

2. Ceiling

No direct access to the surface

3. Limited Space

    a. Minor Restrictions: Divers must traverse the restriction in a single file manor
    b. Major Restrictions: Divers must remove their gear to navigate through the restriction. Major Restrictions are not allowed during any level of cavern diving.
    c. Small spaces may cause a feeling of claustrophobia, and also makes it harder to maneuver through.
    d. Line Traps: these are cracks or spaces, which the line may be pulled into but it is much too small for a diver to navigate. This could become a serious problem in a loss of visibility situation. Line Traps are discussed in great detail during the Land Line Drills portion of the course.
    e. Mazes: It is very easy to become lost in the many convoluted tunnels that a cavern/cave diver may encounter in underwater cave systems. Lack of training has caused the deaths of many open water divers who got lost with a limited air supply.

4. Currents/Direction of Flow

Remember that the direction of flow can change very quickly, and does very often.

5. Darkness

    a. Can cause loss of direction
   b. Increase Stress & Task Loading
    c. Increase the amount of time to perform routine tasks

Anti-Silting Techniques:

1. Body Positioning (Trim)

    a. The preferred anti-silting body position is a slightly head down/fins up position, so that thrust from the fins is directed away from the silt on the floor of the cave/cavern.
    b. When your buoyancy is not under control it can cause you to become off balance and cause you to silt up the cave. Buoyancy control is the hardest skill to master in scuba diving. The only way to master it is practice the proper techniques perfectly by practical application-Go Diving! Buoyancy can be affected by many factors to include the following:
        i. Over-Weighting
        ii. Ill-Fitting Equipment
        iii. Poor Breathing Techniques
        iv. Poor Equipment Positioning
        v. Lack of Experience
        vi. Utilizing Improper Training Techniques

2. Propulsion Techniques:

    a. Modified Flutter & Baby Modified Flutter
    b. Frog Kick & Baby Frog Kick
    c. Pull & Glide
    d. Ceiling Walk

Propulsion Techniques will be discussed in great detail during the Land Line Drills portions of this course. Combinations of the propulsion techniques are normally used.

Ambient Awareness:

Ambient awareness is defined as being conscious or mindful of your environment, and completely cognizant of all stimuli that have a direct, and indirect effect on you and your surroundings. When you are diving in an overhead environment, this is one of the fundamental traits of a great cave/cavern diver. Perceptual Narrowing can lead to many problems and even be fatal. Always be aware of where your buddy is, check you gauges, line protocol, fin placement, gas management; add all these factors into one equation and you have ambient awareness.

Underwater Communications:

There are three levels of underwater communications:

Command Signals require a response from the buddy diver; the buddy diver repeats the signal to assure the other diver that the signal was received and understood. Example: If an OK is given to a diver, he must respond in kind with an OK. We have video examples of all these: Link

1. Light & Hand Signals. These are used to communicate general ideas easily and quickly.

Light Signals:

            a. OK (Command Signal)
            b. Attention
            c. Emergency

2. Hand Signals:

        a. OK (Command Signal)
        b. Stop (Command Signal)
        c. Surface/Terminate the Dive (Command Signal)
        d. Turn the Dive
        e. Back up light is on
        f. Wrap the line
        g. Entangled in the line
        h. Question
        i. Something is wrong
        j. Slate
        k. Out of Air/Share Air
        l. Cut the line
        m. Reel up the line
        n. Look
        o. Silting
        p. Small Bubble Leak
        q. Big Bubble Leak
        r. Slow Down
        s. Low on Air
        t. Decompression

3. Slate: Slates are used to communicate complex messages

4. Touch Contact: Physical contact that is used when loss of visibility prevents visual communication.

        a. Forward
        b. Backward
        c. Stop
        d. Line Entanglement
        e. Emergency/Out of Air
        f. Cross the Line

General Rules while in a Cavern:

1. Team leader is the first one into the cavern since that person is running the reel. The team leader is the last one out since all others would need to be on the line. Diver 2 is most responsible for making sure that the team leader's line placements and ties are secure. Diver 2 and 3 are responsible for communicating information back from the team leader. Divers 2 is most responsible for aiding the team leader with light, ie: helping to light up ties and placements. All divers are responsible for making sure the line is tight and secure on placements and tie-offs. Any team member can help with another that is tangled, but the diver that is tangled should lie still.

2. The primary tie-off is done in open water or even at the surface. After that, you must do a secondary tie-off just inside the cavern. These tie-offs are done with a 'tie' and a double wrap. You will be trained on this technique during class.

3. In the event of a light failure, deploy your backup, call (end) the dive, and exit with the guide line. Note, because the backup light might be MUCH dimmer than the other team member's lights, it is recommended to put the low light person in front, but if that person is the team leader (with reel), take special care to watch for the low light in case of emergency signaling.

Psychological Considerations for Cave & Cavern Diving:

1. Why do people enter into underwater caves and caverns?

        a. Discovery-to explore new aspects of diving
        b. Enjoyment-peaceful environment
        c. Ego Gratification (Positive & Negative)

Positive: A new challenge, a person who wants to improve their diving skills and explore new environments

Negative: Star Trek Syndrome-To boldly go where no man has gone before. This can be detrimental to your health

2. Do not dive beyond your skill level and ability. Know your limits and evaluate yourself; do not get over confident. Do not do anything you feel uncomfortable doing.

Psychological Stress Factors:

    1. Time Pressure: "Aren't you ready yet"
    2. Ego Threat: Peer Pressure. "Everyone else dives this cavern, don't be a wimp" "If he says I'm ready, he must be right." Or Self doubt. "What am I doing here"
    3. Task Loading: Run the reel, hold the light, anti-silt techs, watching gauges, communications, line protocol, directional requirements, body position. All these requirements can create an information overload.

Physical Stress Factors:

    1. Temperature: Cold water can impair thinking and physical performance.
    2. Exertion: Over exertion can cause a diver to become disoriented and affect his mental and physical performance.
    3. Ill-Fitting Equipment: A diver that is fighting with his gear may loose focus on other aspects of the dive.
    4. Buoyancy Control: correct weighting and equipment placement is critical for safety in an overhead environment.
    5. Loss of Visibility: Loss of visibility can cause stress to lead to panic.
    6. Adequate Air Supply: Ensuring that you have this and a back-up is the most important part of your gear.

Recognizing Stress:

1. In yourself: Discomfort, Fatigue, Lack of Concentration, Frustration

2. In others: Perceptual Narrowing, Clumsy Behavior, Frustration, Constant Equipment Monitoring, Lack of Equipment Monitoring, Pupil Dilation

3 Stages of Stress:

        a. Masking
        b. Flight or Fight
        c. Panic

Coping with Stress:

    1. Accept that a certain level of stress will always exist during a cave or cavern dive.
    2. Practice all cavern and cave diving skills until their proper execution is second nature.
    3. Only clear minded, thoroughly self-aware divers can effectively cope with stress.

Golden Rule of Cave & Cavern Diving:

Any diver can call any dive, for any reason, at any time!

In-Water Pre-Dive Checklist:

    1. Head to Toe: Check you and your buddy for all the required equipment required to conduct this level of diving.
    2. Bubble Check: Check you and your buddy's manifold underwater for leaks.
    3. S-Drill: check you and your buddy's alternate air source underwater to ensure that it is turned on, and working correctly.
    4. Review of the Dive Plan:
        a. Who is the reel man
        b. How many people are in the team, and what is the order
        c. Estimate the maximum depth
        d. Review the dive tables or computer
        e. Minimum starting pressure allowed, 2000 PSI
        f. Minimum ending pressure allowed, 1200 PSI
        g. Calculate your Critical Air Supply (CAS). 2/3's Air Rule

Formula for CAS Calculation:

    P=Starting Pressure
    P1=Starting Pressure rounded down to nearest number divisible by 3
    P2=P1/3
    CAS=Critical Air Supply
    P1/3=P2
    P-P2=CAS

    Example: Starting Pressure (P) = 3200 PSI
    Round down starting Pressure to nearest number divisible by 3 = 3000
    (P1)=3000 PSI / 3 = (P2) 1000 PSI
    (P) 3200 PSI - (P2) 1000 PSI = 2200 (CAS)

Dissimilar Tank Turn-around Formula:

Step One:

1. You must first determine the cubic ft per 100 psi for your tank or as it is called the "Baseline."

Formula: (Tank Size/Tank Working Pressure) x 100 = Baseline

Example: (104 cuft/2640 psi) x 100 = 3.9 cuft per 100 psi.

For Doubles multiply baseline by 2.

Step Two:

1. Now you take the cuft consumed (1/3 of starting pressure) by the smaller tank and divide the number by the baseline of the larger tank then multiply the answer by100.

Formula: (Small Tank cuft consumed/Large Tank Baseline) x 100 = Allowable consumption of Larger Tank.

Example:

a. Diver A is diving a single Steel 95 @ 3000 psi
b. Diver B is diving a single Steel 104 @ 3000 psi

Diver A consumes 1/3 of starting pressure =1000 psi
1000 psi of steel 95 = 36 cuft

(95 cuft/2640 psi) x 100 = 3.6 cuft per 100 psi. This equates to 36 cuft per 1000psi.

Diver B can only consume the same amount of cuft not psi.
Divide smaller tank cuft (36cuft) by larger tank baseline (3.9 cuft) then multiply by 100.

(36 cuft/3.9cuft) x 100 = 923 psi

Turn-around for Diver B would be approximately 2073 psi. This is obviously to small to register, so for conservatism Diver B would round up to 2100 psi and this would be hi adjusted dissimilar tank turn-around.

Supplemental Formula:

Sometimes you may wish to figure out how many cubic feet you have in your tank at any given pressure. To do that you can use to following formula:

(Baseline x Tank Pressure) /100

Example: Let us say that you are diving a steel 104 @ 3600 psi. The baseline for a 104 is 3.9 cuft.

(3.9 cuft x 3600 psi) /100 = 140 cuft.

Baseline Quick Reference List:

AL = Aluminum Tank. AA = Steel Tank. GEN = Genesis Tank.

    1. 50 cuft AL = 1.66 cuft. 2 Tanks = 3.3 cuft
    2. 71.2 cuft AA = 2.9 cuft. 2 Tanks = 5.8 cuft
    3. 80 cuft AL = 2.7 cuft. 2 Tanks = 5.4 cuft
    4. 80 cuft GEN = 2.3 cuft. 2 Tanks = 4.6 cuft
    5. 100 cuft AL = 3.0 cuft. 2 Tanks = 6.0 cuft
    6. 100 cuft GEN = 2.8 cuft. 2 Tanks = 5.6 cuft
    7. 95 cuft AA = 3.6 cuft. 2 Tanks = 7.2 cuft
    8. 98 cuft AA = 3.7 cuft. 2 Tanks = 7.4 cuft
    9. 104 cuft AA = 3.9 cuft. 2 Tanks = 7.8 cuft
    10. 108 cuft AA = 4.1 cuft. 2 Tanks =8.2 cuft
    11. 120 cuft GEN = 3.4 cuft. 2 Tanks = 6.8 cuft
    12. 120 cuft AA = 4.5 cuft. 2 Tanks = 9.0 cuft

Accident Analysis:

1. Training:

95% of cave and cavern diving fatalities involve divers with no formal training in overhead environment diving. 10% of these fatalities were open water instructors.

2. Continuous Guideline to Open Water/Surface:

Failure to run a continuous guideline to open water or the surface is the leading cause of fatalities in underwater caves and caverns.

3. Air (2/3's Rule)

Failure to keep sufficient air in reserve is the second leading cause of cave and cavern fatalities. The rule of thirds is as follows: One third in for me, one third out for me, and one third out for my buddy. Remember, this reserve still may not be enough to allow an entire dive team to make it safely out of a cave or cavern. Dive conservatively; it will save you life!

4. Depth (Diving below 130 ft on Air)

Divers should not dive below 130 ft of depth on air. This is the leading cause of death for certified cave/cavern divers. It has been suggested by many cave divers that any cave dive below 130 ft should be conducted on trimix for safety purposes.

5. Lights (2 per cavern, 3 lights preferred)

Lack of adequate lighting is a major contributing factor to cave and cavern diving fatalities. Always have at least 3 lights per diver. In cavern diving the sun is the primary (3rd) light.

The following accident analysis rule was added in recent years and is very debatable.

6. Solo Diving

Solo diving is very dangerous if you are not properly trained and equipped. Solo diving has killed numerous certified cave divers over the past few years. It is suggested that you always dive with a buddy. We have redundant equipment for emergencies; we should also have a back-up brain. You never know when your buddy may save your life.

Web Resources:

Cave Diver's Forum www.cavediver.net

Cave Conservation: www.cavekeepers.com

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