As mentioned in the last blog and talkcast, the way to avoid is to limit the factors that predispose divers to DCS. Some factors are unavoidable. So make the others of more importance. Physiologists still don't understand all factors that may predispose an individual to DCS, but the list is a start to what they do know. No matter what you do, DIVE CONSERVATIVELY. NEVER DIVE TO THE LIMITS OF A DIVE TABLE OR COMPUTER. They may be wrong for you at that time.
Following is a short list of these factors and a brief explanation.
FAT TISSUE
Fat tissue is slow tissue, holding a high amount of dissolved nitrogen. A lot of fat tissue increases the nitrogen retained in the body. Divers that have a higher fat ratio to lean muscle are more likely to have more nitrogen after a dive and therefore have a slightly higher risk of DCS.
AGE
The circulatory and respiratory system works less efficiently in the older population. This interferes with gas exchange. Remain fit by reducing the fat content and exercising regularly to counter this factor.
DEHYDRATION
Dehydration reduces the quanity (volume) of blood available for gas exchange, slowing nitrogen removal from the body. Comsumption of diuretics (caffine), profuse perspiration, and even the dry scuba air tend to dehydrate the diver. During metabolism of alcohol uses a great deal of water. Thus a diver with a hangover is more likely to be partially dehydrated. To do: Make sure you drink plenty of water before, during and after the dive. More than you normally would do.
INJURIES AND ILLNESS
Any condition that affects normal circulation can potentially affect nitrogen elimination. Healed conditions may reduce local circulation difficulties. Also any illness can produce a general reduction in circulation. Make sure you do not dive if you have any injuries or illnesses. It is simply not worth it. Better to heal and dive a different day.
ALCOHOL
Alcohol consumed before or after a dive alters physiology, we all know that but in favor of DCS. Alcohol tends to accelerate circulation and can cause tissues to carry higher amounts of nitrogen. After a dive, alcohol dilates capillaries, possibly increasing the rate of nitrogen release and bubble formation.
CARBON DIOXIDE
Elevated carbon dioxide from skip breathing or improper breathing may interfere with the gas transport by the circulatory system by dilating the capillaries, and again increasing nitrogen uptake.
COLD WATER
During a cold dive, inadequate exposure protection in moderately warm water, changes normal circulation, as the body trys to stay warm. At start of dive, circulation carries nitrogen to all parts of the body, but as heat is conserved, this reduces circulation to the hands and feet. There is less blood to carry away dissolved nitrogen during ascent.
HEAVY EXERCISE
Exercise while diving increases blood circulation, carrying nitrogen to all parts of the body faster than normal. After resting, circulation returns to normal, and so there is no corresponding circulation to accelerate nitrogen elimination.
ALTITUDE AND FLYING AFTER A DIVE
Reduced atmosphere pressure at altitude increases the pressure gradient between tissue and the ambient pressures and can possibly cause larger bubble formation. Once DCS occurs returning to sea level does not usually correct the problem
Sunday, May 10, 2009
Sunday, April 19, 2009
Wreck Diver (Part 3)
Basic Diving Techniques 2
In the last Blog on Wreck Diving (Part 1), I covered navigation and evaluation, deep wrecks, and mapping techniques. This blog will cover wreck penetration, and special situations.
WRECK PENETRATION
1. Have all necessary equipment
Have at least 2 dive lights per diver--to make sure no one will be without a light inside the wreck. Have a wreck reel and line to provide penetration line marking your way in and out. A slate comes in handy to make interior map as you navigate around. A pony is needed in case of an out of air situation.
2. Observe the limits established for diving in overhead environments
Stay within the natural light zone -- you always have a guide to the outside should the light fails. Limit your penetration to the linear distance of 100 feet. Follow the "Rule of Thirds". Use no more than 1/3 of your air entering. 1/3 for exiting, and 1/3 for reserve. (See www.diverjamesten.com for show on diving to you limits)
3. Before entering the wreck, attach the end of the line to a sturdy piece of the wreck
Put the line through a hole and tie using a secure knot. Consider creating a loop in the line and pass the entire reel through it.
4. After entering, secure the line to another point just inside the wreck
Check the entry for possible hazards. Look to the ceiling and see if your air bubbles are causing too much silt to rain down. If this happens, abort the penetration.
5. Move slowly through the wreck while maintaining neutral buoyancy
Keep light tension on the line as you move through the wreck. Wrap the line around non-sharp objects. Use gentle sculling kicks to avoid silting up the bottom. When pracical, pull yourself along the wreck - do not pull on the penetration line.
6. Use the penetration line as a guide
Swim along with the line just below your chest level, and to one side. Stay close to line to reach out and grasp if at any time. Gently make and "O" around the line with your thumb and fingers.
SPECIAL SITUATIONS
1. Stress
If problem occurs - Stop, Breathe, Think, and Act (see Stress Underwater at www.diverjamesten.com)
2. Silt Out
Stop all activity, and wait a few minutes to see if it calms some. If continues, immediately make loose contact with penetration line. If it does not settle, signal "up" and abort the dive and turn to exit. DO NOT LET GO if the penetration line. Leave the reel in place as you exit- you can retrieve it later, unless you know all divers have exited the wreck.
3. Lost or cut penetration line
If you can not find the line, or cut, stop and look for the natural light from the exit. If necessary, cover your light to help you see (DO NOT TURN IT OFF), and let your eyes adjust. Follow natural light to exit, using the map as a guide.
4. Light failure
Go to your backup light. If this is your only back up, you should abort the dive and exit the wreck. Do not dive with only one working light.
5. Air supply loss
If air is low, switch to your pony bottle, and exit the wreck immediately. If you have no pony, secure your buddy's alternate air source and exit the wreck with the donor leading.
Visit my sponsors links for good stuff.
WRECK PENETRATION
1. Have all necessary equipment
Have at least 2 dive lights per diver--to make sure no one will be without a light inside the wreck. Have a wreck reel and line to provide penetration line marking your way in and out. A slate comes in handy to make interior map as you navigate around. A pony is needed in case of an out of air situation.
2. Observe the limits established for diving in overhead environments
Stay within the natural light zone -- you always have a guide to the outside should the light fails. Limit your penetration to the linear distance of 100 feet. Follow the "Rule of Thirds". Use no more than 1/3 of your air entering. 1/3 for exiting, and 1/3 for reserve. (See www.diverjamesten.com for show on diving to you limits)
3. Before entering the wreck, attach the end of the line to a sturdy piece of the wreck
Put the line through a hole and tie using a secure knot. Consider creating a loop in the line and pass the entire reel through it.
4. After entering, secure the line to another point just inside the wreck
Check the entry for possible hazards. Look to the ceiling and see if your air bubbles are causing too much silt to rain down. If this happens, abort the penetration.
5. Move slowly through the wreck while maintaining neutral buoyancy
Keep light tension on the line as you move through the wreck. Wrap the line around non-sharp objects. Use gentle sculling kicks to avoid silting up the bottom. When pracical, pull yourself along the wreck - do not pull on the penetration line.
6. Use the penetration line as a guide
Swim along with the line just below your chest level, and to one side. Stay close to line to reach out and grasp if at any time. Gently make and "O" around the line with your thumb and fingers.
SPECIAL SITUATIONS
1. Stress
If problem occurs - Stop, Breathe, Think, and Act (see Stress Underwater at www.diverjamesten.com)
2. Silt Out
Stop all activity, and wait a few minutes to see if it calms some. If continues, immediately make loose contact with penetration line. If it does not settle, signal "up" and abort the dive and turn to exit. DO NOT LET GO if the penetration line. Leave the reel in place as you exit- you can retrieve it later, unless you know all divers have exited the wreck.
3. Lost or cut penetration line
If you can not find the line, or cut, stop and look for the natural light from the exit. If necessary, cover your light to help you see (DO NOT TURN IT OFF), and let your eyes adjust. Follow natural light to exit, using the map as a guide.
4. Light failure
Go to your backup light. If this is your only back up, you should abort the dive and exit the wreck. Do not dive with only one working light.
5. Air supply loss
If air is low, switch to your pony bottle, and exit the wreck immediately. If you have no pony, secure your buddy's alternate air source and exit the wreck with the donor leading.
Visit my sponsors links for good stuff.
Monday, April 6, 2009
Wreck Diver (Part 2)
Basic Diving Techniques I
As a wreck diver there are many different techniques that you must consider. An attempt will be made here to bring out what would be consider basic techniques. They could be divided in the following sections. Keep in mind that what is written here is just the basics and a highlight of these techniques.
NAVIGATION AND EVALUATION
1. Follow the wreck's layout
Use natural lines to navigate, ie swim along the hull or along one side. Go up one side and back the other. If the wreck is fragmented, pick some prominent points and swim in a relative track. On occasion, look back to see what the return trip will look like.
A FANTASTIC underwater
photo of the
HILMA HOOKER.
A must see.
2. Establish a baseline for widely scattered wrecks
Use a compass heading and swim in that direction, being carefull to note that some compasses may not work if close to the metal hull of the ship. In low visibily or current, use you wreck reel tied off to a point as a return line to your starting point.
3. Evaluate the wreck for possible hazzards and stability
How is the wreck sitting ? Does it look stabile ? Look for sharp objects and entaglements. Check to see if walls and structure appear stong and intact. If considering to penetrate this wreck, check for possible entry ways that are free from hazards.
Click on the photos for more pictures about the Hilma Hooker.
DEEP WRECKS
1. Be a trained PADI Deep Diver.
2. Have proper deep diving equipment available
Hang a tank at 15 feet to assure ample air for a saftey stop. Set a reference line for orientation for descents and ascents. Have a first aid kit available.
3. Take the effect of nitrogen narcosis into account
Plan the dive to keep objectives at or below 100 feet. Avoid changing your dive plan on deep wreck dives. Stay close to your ascent point so if you need to come up you know where it is.
MAPPING
1. Use a large slate to draw more accurate details.
Note distances, angle, directions, depths, points fo interest. Try to make true to scale. The more accurate the better.
This is a sample of a wreck map. This is The Emerald wreck. See article here by the New Jersey Scuba Diver for more maps and history of this wreck.
2. Compass use
Use compass and navigational aids to determine angles between prominent points of the wreck.
3. Distance determination
Use kick cycles and arm spans to estimate size and distance. For more accurate measuraments, use a marked rope or measuring tape. (See the above link for a map grid of this wreck...this is a good site to study wrecks, esp on the east coast.)
NAVIGATION AND EVALUATION
1. Follow the wreck's layout
Use natural lines to navigate, ie swim along the hull or along one side. Go up one side and back the other. If the wreck is fragmented, pick some prominent points and swim in a relative track. On occasion, look back to see what the return trip will look like.
A FANTASTIC underwater
photo of the
HILMA HOOKER.
A must see.
2. Establish a baseline for widely scattered wrecks
Use a compass heading and swim in that direction, being carefull to note that some compasses may not work if close to the metal hull of the ship. In low visibily or current, use you wreck reel tied off to a point as a return line to your starting point.
3. Evaluate the wreck for possible hazzards and stability
How is the wreck sitting ? Does it look stabile ? Look for sharp objects and entaglements. Check to see if walls and structure appear stong and intact. If considering to penetrate this wreck, check for possible entry ways that are free from hazards.
Click on the photos for more pictures about the Hilma Hooker.
DEEP WRECKS
1. Be a trained PADI Deep Diver.
2. Have proper deep diving equipment available
Hang a tank at 15 feet to assure ample air for a saftey stop. Set a reference line for orientation for descents and ascents. Have a first aid kit available.
3. Take the effect of nitrogen narcosis into account
Plan the dive to keep objectives at or below 100 feet. Avoid changing your dive plan on deep wreck dives. Stay close to your ascent point so if you need to come up you know where it is.
MAPPING
1. Use a large slate to draw more accurate details.
Note distances, angle, directions, depths, points fo interest. Try to make true to scale. The more accurate the better.
The Emerald
This is a sample of a wreck map. This is The Emerald wreck. See article here by the New Jersey Scuba Diver for more maps and history of this wreck.
2. Compass use
Use compass and navigational aids to determine angles between prominent points of the wreck.
3. Distance determination
Use kick cycles and arm spans to estimate size and distance. For more accurate measuraments, use a marked rope or measuring tape. (See the above link for a map grid of this wreck...this is a good site to study wrecks, esp on the east coast.)
Monday, March 30, 2009
Wreck Diver (Part 1)
Ways to Protect the Aquatic Realm
and Equipment List
Lets start off first by listing ten ways the wreck diver can protect the aquatic realm.
1. Dive carefully on wrecks, especially in fragile aquatic ecosystems.
2. Be Aware of your body and equipment placement when wreck diving.
3. Keep the wreck diving skills sharp with continuing education.
4. Consider your effect on aquatic life through your interactions.
5. Understand and respect underwater creatures who have made wrecks their home.
6. Resist the urge to collect souvenirs while wreck diving. Wreck artifacts and debris may be protected by law, but are also the home of the attached or shy aquatic life.
7. If you hunt and/or gather game while wreck diving, obey all local fish and game laws.
8. Report environmental disturbances or destruction of your dive sites.
9. Be a role model for other wreck divers when interacting with the aquatic environment.
10. Get involved in local environmental activities and issues.
STANDARD EQUIPMENT
**Exposure Suit
Wrecks often have sharp, rough edges. Your suit should be thick enough to help prevent cuts or abrasions. On deeper dives the temperature will be colder, your suit should also be based on the bottom temperature of the dive, not what the temp of the surface is.
**Gloves
Gloves will not only protect your hands, but wearing sturdy gloves can be used to help pull you along a wreck.
**Knives / Dive Scissors
Wrecks often have monofilament lines or fishing nets on them. You need a way to cut free if you get entangled. Carry a knife that is easily accessible. Carry the scissors in the holder at about chest level. Consider carrying 2 knives and a pair of scissors, making sure you put them in different locations.
**Dive Lights
Ambient light may be dim in and around a wreck. Carry a dive light to look in the crack and crevices. If penetrating a wreck, carry a primary light and at least 1 additional light per diver. More backup lights the better. Before the dive, ensure that all batteries are changed and the lights are in working order. Check the O-rings and make sure that the light is well closed and sealed.
**Slates
Slates are used for mapping the wreck as well as communication. Consider carrying a grid slate for mapping and a smaller one for communication.
**Clips
The extra equipment you carry on a wreck dive makes clips useful. Choose clips that are sturdy and easy to use underwater. Consider putting clips on the BCD.
SPECIAL EQUIPMENT
**Penetration Lines and wreck reels
Only make penetration dives with proper lines and reel for visual / tactil reference.
The lines should be strong, durable, and made from a non-biodegradeble material -- nylon is best. The reel should have 3 times the lenght as you would need and easy to operate. Inspect lines and reels BEFORE each dive.
**Pony Bottles
Having a complete independent air source in addition to the standard alternate air source is highly recommended. Maintain a pony bottle with a separate attached regulator. Pony bottles come in a variety of sizes as shown below. The size you need is how much extra air you want to carry and of course, your physical size as well.
Check bottles that it is filled and system is operating with no flaws. Attach pony bottles with a special harness and put 2nd stage in a place that can be easily accessed.
This is only one type of band attachments for the pony bottles. Click on above picture to go to products page.
READY, SET, GO ...
Evaluate your readiness for wreck diving.
1. Get familiar with local laws concerning wrecks. Know what you can and can't do on the dive. The local dive shop should help you with this.
2. Develop a dive objective for exploring the wreck. Determine what you want to see and do the dive depending on it's size.
3. Get familiar with the wreck's position underwater so you can formulate a navigation plan.
4. Determine your physical and emotional readiness. Be ready to dive. Are you trained to dive on this wreck, and at this depth. If not, take a guide with you.
5. Check your Recreational Dive Planner - confirm No Decompression time.
6. Use familiar Equipment. Do not dive with new equipment till first you made a dive that was not so chalenging.
1. Dive carefully on wrecks, especially in fragile aquatic ecosystems.
2. Be Aware of your body and equipment placement when wreck diving.
3. Keep the wreck diving skills sharp with continuing education.
4. Consider your effect on aquatic life through your interactions.
5. Understand and respect underwater creatures who have made wrecks their home.
6. Resist the urge to collect souvenirs while wreck diving. Wreck artifacts and debris may be protected by law, but are also the home of the attached or shy aquatic life.
7. If you hunt and/or gather game while wreck diving, obey all local fish and game laws.
8. Report environmental disturbances or destruction of your dive sites.
9. Be a role model for other wreck divers when interacting with the aquatic environment.
10. Get involved in local environmental activities and issues.
STANDARD EQUIPMENT
**Exposure Suit
Wrecks often have sharp, rough edges. Your suit should be thick enough to help prevent cuts or abrasions. On deeper dives the temperature will be colder, your suit should also be based on the bottom temperature of the dive, not what the temp of the surface is.
**Gloves
Gloves will not only protect your hands, but wearing sturdy gloves can be used to help pull you along a wreck.
**Knives / Dive Scissors
Wrecks often have monofilament lines or fishing nets on them. You need a way to cut free if you get entangled. Carry a knife that is easily accessible. Carry the scissors in the holder at about chest level. Consider carrying 2 knives and a pair of scissors, making sure you put them in different locations.
**Dive Lights
Ambient light may be dim in and around a wreck. Carry a dive light to look in the crack and crevices. If penetrating a wreck, carry a primary light and at least 1 additional light per diver. More backup lights the better. Before the dive, ensure that all batteries are changed and the lights are in working order. Check the O-rings and make sure that the light is well closed and sealed.
**Slates
Slates are used for mapping the wreck as well as communication. Consider carrying a grid slate for mapping and a smaller one for communication.
**Clips
The extra equipment you carry on a wreck dive makes clips useful. Choose clips that are sturdy and easy to use underwater. Consider putting clips on the BCD.
SPECIAL EQUIPMENT
**Penetration Lines and wreck reels
Only make penetration dives with proper lines and reel for visual / tactil reference.
The lines should be strong, durable, and made from a non-biodegradeble material -- nylon is best. The reel should have 3 times the lenght as you would need and easy to operate. Inspect lines and reels BEFORE each dive.
**Pony Bottles
Having a complete independent air source in addition to the standard alternate air source is highly recommended. Maintain a pony bottle with a separate attached regulator. Pony bottles come in a variety of sizes as shown below. The size you need is how much extra air you want to carry and of course, your physical size as well.
Check bottles that it is filled and system is operating with no flaws. Attach pony bottles with a special harness and put 2nd stage in a place that can be easily accessed.This is only one type of band attachments for the pony bottles. Click on above picture to go to products page.
READY, SET, GO ...
Evaluate your readiness for wreck diving.
1. Get familiar with local laws concerning wrecks. Know what you can and can't do on the dive. The local dive shop should help you with this.
2. Develop a dive objective for exploring the wreck. Determine what you want to see and do the dive depending on it's size.
3. Get familiar with the wreck's position underwater so you can formulate a navigation plan.
4. Determine your physical and emotional readiness. Be ready to dive. Are you trained to dive on this wreck, and at this depth. If not, take a guide with you.
5. Check your Recreational Dive Planner - confirm No Decompression time.
6. Use familiar Equipment. Do not dive with new equipment till first you made a dive that was not so chalenging.
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