Introduction To Skin Diving

Since man first began scratching pictures upon the walls of his cave to depict his daily life, there has been a continuous record of his attempt to explore and exploit the sea. We find references to man's propensities as a diver from the time of early historic man down to the present day. Man's culture has, of course, been influenced strongly by his adventures above and below the surface of the sea.

However, until fairly modern times, man was limited to short sojourns beneath the surface. In the early 1800's the conventional "Hard Hat", or helmeted diving dress was invented, which enabled man for the first time to successfully submerge for long periods of time with comparative safety. He was still, however limited in his scope by the length of his hoses and lines. Envisage a "Hard Hat", diver, if you will, still a creature of the surface, as attested to by the umbilical like lines running from him to his boat, leaning at a precarious angle and plodding laboriously across the bottom. Hardly a thing of poetry and grace; but nonetheless, utilitarian and successful.

Some several years after the advent of the helmeted divers appearance upon the scene, there appeared a breed of men who called themselves "sport divers", or "skin divers". These men, equipped only with bathing suits, goggles, and frog-like flippers upon their feet, and depending upon their ability to hold their breath, plunged beneath the surface for brief glimpses of the underwater world.

In 1943, two men, Jaques Yves Cousteau and Emile Gagnan perfected a piece of equipment that was the forerunner of the Aqualung, or as we now know this type of equipment, SCUBA, Self Contained Underwater Breathing Apparatus. Its obvious advantages were complete freedom from the surface, unhampered by hoses, lines, etc., limited in time beneath the surface only by the knowledge of the diver and the quantity of his air supply. For the first time, man was truly FREE beneath the surface of the water, virtually a manfish, for he combined the equipment and skills utilized in skin diving, as well as the physics learned by the "Hard Hat" divers.

First it is necessary that you learn the basic equipment and the reasons behind its use. It is axiomatic to say that a mastery of the skills utilized in skin diving is fundamental. The basic equipment used by the skin & Scuba diver consists primarily of three items; Mask, Fins, and Snorkel. Let us deal with each of these in turn.

MASK - Purpose

The mask is used to provide an air space between the eyeball and the water. Man's eye is a very imperfect organ when exposed directly to the water. However, when an air space is introduced between the eye and the water, the eye functions normally. Due to the refraction of the water, objects viewed through the mask under water will be magnified by approximately 25%.

MASK - Construction

A mask should have a shatterproof glass lens, for obvious reasons. It should have a fairly soft rubber body with a live rubber skirt. It should have a stainless steel band around the lens, to maintain a water tight seal between the lens and the body of the mask.

MASK - Fit

The mask should fit snugly, but not so tightly that it is uncomfortable. A good method of checking the fit of the mask is to put it in place, not using the head band, inhale slightly through the nostrils, and remove your hand. If the mask fits properly, the mask will remain in place until the slight vacuum you have created is released. If the mask leaks air around the face, it will also leak water. Selection of the proper mask is purely an individual affair, due to different facial contours, and taste.

MASK - Fogging

Due to the temperature differential between the diver's face and the water, unless preventive steps are taken, the mask will fog while being used. This is the primary reason Lucite, or plastic masks are not suitable for skin diving, for there is no effective method of keeping them unfogged. However, with a mask which has a glass lens, several methods are available for preventing fogging. The lens should first be washed out in the water, then tobacco, potato, sea weed, or saliva should be rubbed on the inside of the lens. Both because of its effectiveness and availability saliva is the most often used anti-fog compound. However, there are commercially prepared products for this purpose. After the lens has been rubbed with one of the above-mentioned, it should again be rinsed out, and then may be worn fog free.

MASK - Clearing

While in use underwater, the mask is frequently flooded, due to being dislodged on the face, or due to an imperfect seal. This, however, is merely an inconvenience, and should be treated as such. The mask may be cleared while the diver REMAINS UNDER WATER. There are, essentially, two methods of clearing the mask, one method differing but little from the other.

1. The diver grasps his flooded mask by the skirt, pressing the skirt to his face with thumb and forefinger above the right eye.

2. He then assumes a position in the water about 45 degrees from the horizontal, head up, and tilts his head back and to the left.

3. He then rolls over to his left side and exhales through his nostrils. The incoming air, unable to escape the mask at the top, due to the divers pressing the skirt against his face, is forced out at the bottom side of the mask, thus carrying the water out before it.

FINS - Purpose

The purpose of the fins is to increase the surface or propelling area of the foot, thereby enabling the diver to greatly increase his thrusting force without an equal increase in effort.

FINS - Construction

Fins are roughly placed in two major categories, the open foot, and the full shoe types.

For the most part, those fins which are constructed in a fashion similar to a shoe, in that they possess a heel, sole, etc. are of the type of fin called the full shoe type. The open foot type is that type of fin which has a strap going behind the heel to hold them in place. Whichever type is preferred, the fin should be chosen with an eye toward certain features.

A good fin has a fairly rigid blade, of moderate size. It should be rigid enough to provide a good firm thrusting base, but should not be so rigid nor so large as to put undue strain upon the divers legs. Professional type fins should not be worn by novice divers, but should rather be worked up to, due to the increased strain they place upon the divers leg muscles.

FINS - use

When the fin is put on the foot both it and the foot should be wet. The foot should be thrust well forward, and then the heel or strap (depending upon which type of fin is being used.) stretched up over the heel, much in the same manner one dons a pair of rubbers.

There are essentially three different strokes or ''kicks" used with fins. Trudge on, and Dolphin. They are Flutter,

Flutter Kick

In the Flutter Kick the toes are pointed backward and the legs are pivoted from the hips in an up and down motion, breaking from the knees only very slightly. It is good practice to keep the knees completely rigid while perfecting this kick so as to not develop any bad habits.

TRUDGE ON KICK

In the Trudgeon Kick the diver lies on one side and, holding the knees rigid, pivots from the hips with a sweeping motion of his legs, taking care to keep his toes pointed downward.

DOLPHIN KICK

The Dolphin Kick is, as the name implies, as close an imitation of the porpoises swimming motion as is possible. The diver, lying in a prone position, bends the trunk of his body downward briskly and his legs upward. Then, arching his back and breaking at the knees, he thrusts downward with both legs. This motion forces the trunk upward, completing the cycle. The diver immediately repeats the whole cycle continuously. The proper kick requires good co-ordination, and is usually mastered after a very few trials. Relaxation of movement is the key.

SNORKEL - Purpose

The snorkel has two primary purposes, both of prime importance to the skin diver. The purpose of the snorkel is to enable the diver to breathe without necessitating his holding his head up above the surface. This has tremendous import for the diver. The skin diver is thus enabled to lie prone in the water, his face fastened below the surface, scanning the bottom. If he were to be required to raise his head periodically, he would sacrifice two things, his balance in the water and his acuity of vision into the subsurface world. By the time his eyes become accustomed to the subdued light, it would again be time to raise his head for a breath. The second primary purpose of the snorkel is as a piece of emergency equipment. Obviously, if a diver is able to lie in a prone position without the necessity of raising his head for air, he is much more relaxed and rested. His endurance in emergency situations is greatly extended by the use of the snorkel. The snorkel is simply a J tube, usually constructed of a flexible rubber, with a mouthpiece at the bottom of the J. Snorkels with sealing devices, (ping pong balls, etc.) are not recommended, as these devices often fail to seal, whereupon the diver, assuming his snorkel to be dry, inhales a goodly quantity of water, creating considerable consternation, particularly among novices.

SNORKEL - Use

As mentioned above, the snorkels purpose is to enable the diver to breathe while his face remains underwater. Therefore, the mouthpiece is held in the divers mouth while the straight "stem" of the J is placed between the headband of the divers mask and his head. Upon submerging, the divers breath is held against the snorkel. Upon surfacing, the divers head returns to the horizontal with the open end of the snorkel projecting above the surface. The diver exhales through the snorkel with a short, sharp blast, much as though he were using a bean shooter, thereby voiding the snorkel of water and enabling him to begin breathing normally through the mouth. The optimum length of the snorkel is in the vicinity of 13 inches from the mouthpiece to the open end of the J. Snorkels longer than this have two major disadvantages:

1. They allow too much residual carbon dioxide to remain in the snorkel, causing excessive carbon dioxide build-up in the lungs.

2. Cause a too great expenditure of effort for breathing.

The first disadvantage will be dealt with in future sessions, but a word of explanation is necessary on the second point. As one considers this idea of a snorkel, he's apt to wonder, "Why use Scuba?" As you undoubtedly know, as the depth of water increases so does its pressure. (Pressure being nothing more than the accumulated weight of more water.) If a person is using a snorkel, he's breathing air at surface pressure (14.7 psi), but his body is exposed to the pressure of the surrounding water. If a man submerges to a depth of more than 6 feet, his chest muscles are not strong enough to overcome the water pressure, and so he's unable to expand his chest for an inspiration. It has been found that a snorkel 13 inches in length is long enough to enable the diver to keep its open end above water under the most conditions while lying prone without causing undue effort for respiration.

Medical Aspects

Scuba diving appears to be very simple and uncomplicated, so simple that it appears that all that is necessary is for the novice to don the equipment, submerge, and breathe. Unfortunately, however, there are many changes taking place in the human body as the diver submerges himself, and it is imperative that the diver know what these changes are, how they affect him, and how to prevent or treat these changes.

In order to better undehstand the phenomena of pressures and their effect upon the human body, we have treated these changes as they occur in diving

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