Air Consumption

Handy Formulae

In order to calculate the time (in minutes) at a given depth, with a known volume of air, the following formula may be used:

VOLUME       
(DEPTH plus 1) x .75 equals Time in minutes.
The figure. 75 represents the consumption of air of the diver (cubic ft/minute) at the surface.

In order to calculate the remaining volume of a partially used tank, another formula may be used:
GAUGED PRESSURE OF TANK x RATED VOLUME OF TANK RATED PRESSURE OF TANK

For instance, a rated 70 cu. ft. tank has 1125 psi and its rated pressure is 2250 psi. Using the above formula:

1125 x 70                                78750
                2250            equals               2250   which equals 35 cubic feet

Therefore, if we wished to know how long a 70 cubic foot cylinder rated at 2250psi but containing only 1125 psi would last us at 66 feet, we would use both formulae. For instance, having already computed the new volume, we could use it in the first formula to determine time at depth:

            35                                equals 15. 5 minutes
( 66 plus 1 ) x   .75
  33
 
As a diver you will derive tremendous enjoyment in later years if you keep a log of your dives. In addition to supplying you with data concerning your past dives, a log enables you to enjoy at your leisure some of your past experiences. For this reason, it is suggested that the "Comment" section of the log be kept in the manner of a diary, to be filled out as soon as returning from the dive as is practical, so as to recapture the spirit of the dive for later perusal.

For best results, it is suggested you keep your log in a small, looseleaf notebook, or you may purchase a commercially prepared log.

SUGGESTED DIVERTS LOG BOOK

DATE:                                           LOCATION OF DIVE:
COMPANIONS:                           NUMBER OF TANKS:
AIR TEMPERATURE:                  WATER TEMPERATURE:
VISIBILITY:                                  AVERAGE DEPTH:
WEATHER CONDITIONS:         TIDE:
COMMENTS:

The best acquatic training for skin diving is done either in a swimming pool or in sheltered waters. For the benefit of those persons who wish a progressive training program in acquatic skills, the following program and schedule is presented. It is broken down into eleven subdivisions, so as to facilitate a step-by-step program.

I. Prerequisites:
II. Skin diving skills

1. Introduction to fins.
2. Introduction to mask. (Clearing)
3. Introduction to snorkel. (Clearing)
4. Flutter kick
5. Swim 200 yards using flutter kick.

III. Skin Diving Skills

1. Swim 500 yards using flutter kick
2. Clear mask, two methods
3. Dolphin kick
4. Trudge on kick
5. Introduction to surface dives

IV. Skin diving skills

1. Swim 500 yards using flutter kick
2. Surface dive, head first
3. Surface dive, feet first
4. Recover and clear mask and snorkel, ten feet of water.
5. Introduction to step-in entry.

V. Skin Diving Skills

1. Swim 500 yards using flutter kick, trudgeon, and dolphin.
2. Step-in entry
3. Swim 25 yards under water using mask and fins.
4. Using mask, fins, and snorkel, carry 10 pound weight belt 50 yards.
5. Clear mask and snorkel, 10 feet of water.
6. Review all skin skills.

VI. Scuba Skills

1. Introduction to scuba. (Assembly, pre-dive check, donning, post dive check.)
2. Safety hitches
3. Review AIR EMBOLISM
4. Use scuba in four feet of water.
5. Clear mask while using scuba.
6. Equalizing
7. Adjust bouyancy by breathing
8. Swim 50 yards using scuba, accompanied by experienced diver.

VII. Scuba Skills

1. Clear hoses
2. Surface dives using scuba
3. Step-in entry using scuba
4. Slither-in entry using scuba.
5. Swim 50 yards using scuba, no mask.

VIII. Scuba Skills

1. Basic lifesaving
2. Tow scuba equipped buddy 100 yards
3. Alternate between scuba and snorkel for 100 yards

IX. Scuba Skills

1. Fundamentals of Buddy Breathing, two methods
2. Buddy breathe 50 yards using each method.

X. Scuba Skills

1. Fundamentals of Ditch and Recover
2. Ditch and Recover, 5 feet of water
3. Ditch and Recover, 10 feet of water

XL Scuba Skills

Demonstrate each skill.

I. Prerequisites

The prerequisites are to demonstrate the acquatic proficiency of the would-be diver. Skin diving equipment is not a substitute for swimming ability, and should not be considered as such. These prerequisites are minimum standards, and should be able to be satisfactorily performed by anyone considering taking up skin diving.

1. Swim 300 yards, any style, no time limit. Forward motion must be maintained. The purpose here is to demonstrate a minimum ability of survival swimming, not competitive style.

2. Tread water using hands and feet for five minutes. Again, a demonstration of survival swimming.

3. Tread water for one minute using feet only.

4. Swim underwater for 25 feet.

5. Swim 25 yards, any style, with a ten pound weight. This is again a demonstration of survival swimming ability.

6. Surface dive in ten feet of water and retrieve object from bottom.

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