First off I must ask "What is the most important rule in scuba diving ? That's right. Breathe continuously and never hold your breath while using scuba. We teach you this in the basic course and watch you often to see if there is bubbles coming from your regulator. We may even point to our mouths to remind you to do it underwater. There are some divers who do it while at depth to conserve air. This is know as skip breathing, not a good thing to do at depth. There are better ways to increase air time underwater, which I may cover in a later blog.
Why is this rule important ? For one, If you hold your breathe while ascending you could die. But why ? What happens ? If you hold your breath you create a "closed bag" if I may with your lungs. No place for air to go. As you ascend your lungs will increase in size by nature of the ascent. You could get a lung rupture as a result. This rupture forces bubbles into the bloodstream, blocking blood flow to the brain and other parts of your body, leading to paralysis, serious injury, or death. If you hold your breath for even 1 meter or a few feet, your lungs could over expand, just like the small bag.
If you feel discomfort in your ears while ascending, stop, go down a few feet and wait for it to clear. Afterwards, continue to ascend. Remember it is never a good idea to dive while having a cold, and on decongestants. They could wear off, trapping air in the ears and sinuses. If they do wear off you could get a "reverse Block."
Now the S.A.F.E. part. This stands for Slowly Ascend From Every Dive.
This is really the PADI motto, so to speak. But how ? The rate of ascent should be no faster than 60 feet per minute, but slower is better. Your body needs time to adjust to the changing pressures, time to regulate your buoyancy, keep track of your buddy, and to watch for obstructions.
The best way to ascend is to use a dive line if diving from a boat, or follow the bottom contour, to make a slow trip to the surface. Make sure you start up with plenty of air.
One last note, it is always a good idea to stop your ascent at 15 feet for 3 minutes, again to offset more pressure gases. This is known as a safety stop..
Think of the 60 feet per minute as a speed limit. It is fine to go slower, slower is better. Be a S.A.F.E. diver: Slowly Ascend From Every dive
Tuesday, March 31, 2009
Wednesday, March 25, 2009
In my last lesson, a discussion was made on how to do the 5 point descent. Let's do a quick review, 1) signal your buddy you are ready to "go down" with the OK sign, 2)look for a reference point for your location, 3) look at your dive watch for the start time of the dive (very important if you are not using a dive computer), 4) do a snorkel and regulator exchange, 5) lift the manual inflator from your BCD and deflate the air. This will allow you to be heavier than the water you displace (negatively buoyant) causing you to sink below the surface. From this point we will talk about how to do a comfortable descent.
As soon as your head goes under water you should equalize your ears. There are many ways to equalize your ears.
1. Equalize your ears early and often as you descent, every few feet. Don't wait for discomfort, that is too late. If you equalize often, you shouldn't feel discomfort.
2. Block your nose and gently blow through it. If you blow too hard, damage could result to your ear drums. This will not only end your dive, but could take months to heal. So, "gently" blow through your nose.
3. Swallow and wiggle your jaw from side to side.
4. Could do both of the above at the same time.
5. One thing that helps me at times is to lean my head to the side of the blocked ear, while pulling on my ear. This "loosens" up the space and may allow the pressures to become equal.
6. Add air to your mask through your nose. This prevents uncomfortable mask squeeze. In fact, you should do this procedure many times while at depth. This also helps keep water out of the bottom of the mask.
There are a few procedures you can do should you feel discomfort.
Ascend up a few feet till you feel no discomfort. At this depth, gently try to equalize your blocked ear. If you air space equalizes continue diving to depth while continueing the procedure. If you can not equalize, discontinue the dive. Signal your Divemaster or buddys that you are having ear problems and must ascend, and end the dive.
If you have cold, allergy or other congestion problems will cause you to have trouble equalizing your ears. Blocking off the air space with ears plugs or a tight fitting hood can cause problems. If your are wearing tight hood, as you descend reach in and allow some water to enter, this will prevent this from being the problem. I do not recommend diving while taking cold medications. If during the dive the medications wear off, you may have what we call a "reverse block". This is where you have a ear/air block on the ascent. Not a good thing. You need to exit the water, and the futher up you go causes more pain. So if you have cold, allergy....DO NOT DIVE AND DO NOT TAKE MEDICATIONS FOR IT WHILE DIVING.
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Sunday, March 22, 2009
In order to make a comfortable decent there are a few things you need to do first. You and your buddy need to put together your equipment and preform the pre-dive safety procedure B.W.R.A.F. Once that is completed, enter the water and put air into your BCD to about 1/4 fill, or just enough to keep your head above water. Do not over fill your BCD. Next, put in your snorkel in your mouth, it should come from the left side, while the regulator comes from the right. Swim to your desired dive spot, doing a snorkel swim. At this point, if you use your regulator you will be using precious air that you could be using while under water. Conserve your air.
Once at your site, the 5 point procedure begins.
Step 1: OK
While facing your buddy, give the OK to go down and start the dive. You and your buddy need to agree to "go down". This first step insures that both of you are ready to begin the dive, and insures both are on the "same page".
Step 2: LOCATION
This simply means that you pick out a point somewhere on shore, or a anchored boat. By doing this you start out having a reference point. If you make a straight down descent, once on the bottom and at depth you know which direction the reference is. This, of course, is based on a non-compass dive, which I DO NOT recommend. You need to learn how to use the compass, and always dive with one. Trust me, you NEED the Compass.
Step 3: TIME
Take a look at your watch and make a mental note of the time. This time is what you will use to calculate your final dive profile. Later I will go over how to calculate a diver profile, but for now a time is defined as the start of the descent to the start of the ascent. Like I said this start time is important for this reason.
Step 4: SNORKEL / REGULATOR EXCHANGE
At this point you have your snorkel in your mouth, and need to remove it and place in your regulator. You do this by holding the snorkel in your left hand while the regulator is in your right. Now, take out the snorkel and place in your regulator. Make sure you clear your regulator of water before breathing thought it.
Step 5: LET THE AIR OUT OF YOUR BCD
With your left hand place it on the manual inflator button. Raise it above your head, so as gravity and water puts a force on the BCD which allows air to be released. This makes you negatively buoyant, because now you weigh heavier than the water you displace, and therefore you sink.
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