Scubadoc’s Ten Foot Stop

June 27, 2009

Problems With Moving Water

Filed under: Article — admin @ 10:47 am
Problems With Moving Water


Avoid this Disaster

Accidents caused by divers being carried away by currents have been reported since the early days of diving in the 1950’s. Most of us have heard about the horror story of the five Japanese divers, who came up after a very beautiful and enjoyable current dive off Peleliu, only to find that they had not only missed their boat but had missed the end of the island. All of these divers died after a prolonged float in what must have been a strong current. The current was not at fault, however, but poorly qualified dive operators and faulty equipment, an uncertified diving guide, a small faulty single engine vessel without a radio and novice divers –all pointed toward this disaster. See Guidelines for the Abandoned Diver

Diving in currents is easily one of the most enjoyable – but can be one of the most dangerous dives that a diver encounters. It is a low energy high speed trip that allows you to see much more of the rapidly passing reef. The flip side of this is that you miss a lot of small life, and the hazards of loss of control and any efforts to work against the currents are high energy and stress producing. Recognizing that a problem exists is the first thing a diver has to face. Divemasters usually are on top of the problem and brief you appropriately.


Signs of A Current

Each diver can detect signs of current, such as:

1). fast moving surface water;

2). which way the boat is facing (depending on whichever is the stronger, the current or the wind);

3). movement of floating material on the water or in the water;

4). movement of divers away from the boat rapidly on entry;

5). bubbles moving away from a diver at an angle underwater;

6). if the plant life and soft coral underwater are laying down.

The contour of the ocean bottom will change currents, often dramatically. A diver can adjust his speed by moving to the bottom, slowing behind coral heads and outcroppings or holding on to permanent objects, all the time presenting the smallest frontal surface area to the current. Because of a “boundary layer” condition, water molecules that are closest to a surface move the slowest due to their nearness to the surface. Other areas of calmness are areas behind obstacles and the sides of walls. Getting close to the bottom and using your finger or dive knife to stabilize you is usually all you need to hold your position.

As the diver moves through the water column he encounters resistance-and this increases by the square of the velocity of the current as it passes over the body. As a diver works against the current along the bottom, a good indication of the amount of work being performed is by monitoring the respiratory rate, this rising exponentially as exertion increases. “Bottom crawling” is a technique that may have to be used when the swimming exertion level rises. This is easily done in rocky areas but can be a real challenge in sandy bottoms-where a good dive knife comes in handy as an anchor.

If conditions exist so that exertion levels continue to rise, it’s better to surface, inflate and wait. Here is where a safety sausage comes in handy. This is an inflatable, long red plastic tube that juts above the water 6-7 ‘ and can be easily seen as much as a half a mile or more. Shining a flashlight in the bottom of the sausage at night provides a long red light that can be seen at a great distance.

Surface floats are other techniques used in diving in currents. A line attached to a float and to a diver give two advantages; the dive group is marked for the boat operator and any tired or nervous divers can hang onto the line and rest. When drifting free without a line, the boat operator relies on visualizing the diver’s bubbles for location; a surface chop can make it difficult for the boat operator to see the divers bubbles,

Strong currents can rip away a mask or snorkel when turning sideways or looking up. Snorkels do better stored in the BC or under a leg strap underwater so as to reduce drag on the mask. Place a little extra tension on mask straps if strong currents are expected.

The dive group should have a clear understanding of exiting and entering the water in conditions of current. Divers should try to let the current work for them by initiating dives into the current on the first part of the dive and planning the return with the current. Float lines are essential for an orderly entry for the divers to hold position for descent and ascent, otherwise divers will be strung out too far apart for a safe dive. Entries should be timed so that there will be no stragglers and the descent be made under control. Exits are also planned so that the float line can be used to pull against the current rather than having to swim against it.

Currents are usually generated by wind and tides or a combination of the two. Predicting what you will encounter generally depends on using information from the local weather service combined with tide information from local dive operators. In certain areas, such as “The Great White Wall” in Fiji and “Blue Corner” in Palau, the currents are almost always due to tidal action and are fairly predictable. One should always go with local experience in making decisions regarding diving into currents.


Surges

Underwater motions occur in areas where swells are forced against a barrier of some sort, such as a beach, wall, rock, or wreck. A surge is a to-and-fro action complicated by indentations such as caves, rocks or large holes in wrecks. Surges can be used to aid in your movement, carrying you forward in one direction where you can stabilize yourself as the surge retreats, and move forward again with the next surge. They are also dangerous since they create huge forces that can carry you into places that you don’t want to go. Divers should remain distant from diver-size holes in wrecks and caves and learn to use surges as a method of aid in movement, either upward to get back into the boat or to move onto a ledge.

WRECKS

Wrecks create special problems with currents. Frequently the boat will anchor on the wreck, playing out enough scope so that divers can easily descend on the line. A tag line is helpful placed between the anchor line and the stern of the boat, facilitating the descent from the dive platform. Divers who lose contact with the line run the risk of being swept away from the wreck and the diveboat, sometimes requiring rescue after coming up predictably exhausted from fighting the current.

Adapted from Glen Egstrom, Ph.D.
Medical Seminars, Inc

Diving In Polluted Waters

Filed under: Article — admin @ 10:46 am
Diving in Polluted Waters

The Problem
Over the past ten to fifteen years the diving population has become sensitized to the potentially hazardous presence of pollution in the sea.  The ocean has been a traditional dumping ground for many types and degrees of pollutants.  Several years ago a Los Angeles Times article indicated that 2000 U.S. beaches were closed due to sewage spills.(1993).  California, as usual a leader, had 745 closures with 588 occurring in Southern California.  Consistent and regular monitoring would have probably  fond many more contaminated beaches needing closure.  There is a definite lack of any standardized program for monitoring our waterways; particular areas of concern are harbors and similar areas which do not “flush” well, rivers, especially those with high levels of industry on the shores, sewage outfalls which go out to sea but are often overloaded and areas which have the deposits of soft, silty materials dropped as the currents reduce their velocities in dispersal areas.  It has been estimated that there are on the order of 15,000 chemical spills that enter our water areas each year in the U.S. alone.  The contaminated areas are growing and now include many recreational diving areas as well as scientific study sites and search and rescue operations.

The health consequences of the water pollution have not been quantified by careful study but many local health professionals are concerned with infectious and carcinogenic disease potential for patients who are ocean swimmers, lifeguards and divers. Until adequate epidemiologic data is available the recourse would appear to be logically focused upon conservative practices in selecting dive sites and conditions.

This increase in areas of pollution is a worldwide problem and has affected many diving operations. Diving in polluted water requires that certain precautions be taken, and, in some instances, the use of sophisticated equipment and procedures.  Avoiding diving in areas with high potential for pollution, particularly after heavy rains is fundamental in urban or industrialized areas.


The main problem centers around the fact that bacterial, viral and chemical hazards can affect the human body by skin contact and entry through orifices.   The following list was produced in the NOAA Manual and the details were obtained from the medical literature.

Vibrio – 34 species of this family of bacteria are known and cholera and El Tor vibriones are among those known to be pathogenic to man.  Cholera vibriones have recently been found in Santa Monica Bay in California and have raised concerns although it is not known to have produced any disease. Other vibriones may be anaerobic and produce disease states such as purulent otitis, mastoiditis, and pulmonary gangrene.  V. Proteus found in human fecal material is a common cause of diarrheal disease.  V. Vulnificus is found in sea water.

Enterobacteria
Escherichia – found widely in nature, occasionally pathogenic to man, produces carotenoid pigments and can often be recognized by the orangish pus.  E. Coli,. which has some pathogenic strains is often found in fecal material: and can produce urinary tract infection and epidemic diarrheal disease.

Shigella – produces dysentery

Salmonella – 1000 serotypes, ingestion can produce gastroenteritis including food poisoning, typhoid and paratyphoid.

Klebsiella – can produce pneumonia, rhinitis, respiratory infection.

Legionella- causes Legionnaires disease and Potomac fever.  Perhaps inhibited in salt water.

Actinomycetes – causes a “ray fungus” actinomycosis, an infectious disease in man which inflames lymph nodes, develops abscesses, can drain into the mouth causing damage to the peritoneum, liver and lungs.

Pseudomonas- pathogenic to man, “blue pus” formed by some pseudomonas infections. This can lead to a wide variety of infections including wound sepsis, endocarditis, pneumonia and meningitis. It is known to flourish in dark, warm, damp places, i.e., inside hoses, bladder compartments and similar places that are not cleansed after being infiltrated by contaminants.

Viruses – infectious agents which can result in fevers (frequently severe), mononucleosis, and a wide range of disease states.

Parasites – many types with all manner of effects, all bad, can are found in polluted water.

Chemicals -  There are over 15,000 chemical spills in the U.S. waterways each year and many of these are releasing chemicals that are incompatible with man and the equipment that is worn.


Prevention
As detailed information becomes available on this issue divers will become sensitized to the need for preventive measures before, during and after diving.  At present the scientific and public safety diving communities are developing techniques for isolating the diver from the potential problems and decontaminating all exposed elements of the diving equipment.  It appears eminent that the recreational community will feel the need to exert greater care in the future.

It is becoming increasingly important to develop an understanding of the variations in the local conditions to which individuals expose themselves.  Some areas become particularly hazardous following heavy rains, hot weather and windstorms.  Local health authorities can usually be called for advice regarding any tests that have been performed and the results.  They should also be able to identify areas of high concentrations of pollutants that should be avoided.

When diving in areas where pollution is suspected or expected the following issues are worthy of evaluation.

1. The individual diver should consider the need for appropriate vaccinations and inoculations.  Many of the diseases can be avoided if the individual has taken the appropriate “shots”.  A few that appear worthy of consideration:
Hepatitis A and B
Cholera
Polio
Tetanus
Typhoid, Smallpox and Diphtheria

2. Pollution and filth are often associated. If the water contains obvious trash and garbage it is quite probably an unhealthful diving environment and another location should be selected.  If the water looks nasty it probably is nasty!!

3. Many diseases have an incubation period before they exhibit symptoms.  Medical advice is as close as the phone and early diagnosis and treatment can sometimes be improved if the Doctor understands that an individual may.have been submerged in polluted water.

4. Information on chemical spills can be obtained from the Chemical Transportation Emergency Center (1 800 424 9300 US).

5. “When in doubt- Check about”

A basic procedure if one feels they must dive in high risk water involves reducing the exposure of the diver.  NOAA has pioneered a sophisticated SOS (suit over suit) system that will virtually isolate the diver from any contact with the water.  This system is somewhat complex inasmuch as it requires complete system integrity from the times the diver dresses out until the system has been decontaminated following the dive.  Strict procedures are followed to ensure that the divers body does not contact the fluid in which it is immersed.

Previously, many public safety divers wore a  single dry suit and a full face mask during their dives. However, Stephen Barsky now states that Full-face masks only provide minimal protection and should only be used in environments where the pollutants are known, and do not pose a threat of death or permanent disability. In environments where the pollutants are not known, or where they lead to death or permanent disability, a helmet should be worn connected to a mating dry suit with mating dry gloves. This is considered the standard today.” (See Reference below)

If good seals are involved and the diver is effectively rinsed, scrubbed down and rinsed again prior to breaking any existing seals, the probability of exposure to the pollutants can be minimized.  Special care must be taken to clear hoses and fittings that interface with the life support system.  A failure to rinse bladders and hoses which may later be linked to the divers mouth or lungs could provide a path to the host days after the dive.  The use of snorkels, alternate air sources, oral inflation devices and hose connections should all be given careful attention since the can carry contaminants directly into the mouth.  Positive pressure, “self bailing” breathing systems have definite advantages in that they resist flooding.

Recreational divers maybe well advised to place their regulator in their mouth and their mask over their nose before entering suspect water and keeping it there until they have safely exited the water where they can remove the regulator without needing to replace it.

Polluted water is a fact of our lives.  The degree of pollution can only be mitigated through education and the “upstream” elimination of the sources of the contaminants.  The attitude that careful rinsing of diving gear is a waste of time “cuz its just going to get wet again next time it is used” should probably be replaced with the attitude that one should begin every dive with clean gear.


LINKS To Pollutant Testing

Utah Bureau of Environmental Chemistry and Toxicology
http://hlunix.hl.state.ut.us/els/chemistry/

Adapted from Glen Egstrom, Ph.D
Medical Seminars, Inc. 1992

Other References:
Colwell, et.al. Microbial Hazards Of
Diving In Polluted Waters, Maryland Sea Grant
Publication UM-SG-TS-82-01.

Diving in High-Risk Environments, 3rd Edition
by Steven M. Barsky
Amazon.com
Paperback – 197 pages 3rd edition (December 15, 1999)
Hammerhead Press; ISBN: 0967430518

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