44 replies to this topic

[annasea]

However, 50 ft is not exactly 15 meters. As Walter said, 50 ft is 15.24 meters...

50 feet converts to 15.24 meters.

Thank you for the clarification, gentleman. In reality, since I plan on completing my OW in the States it will be 50 feet, but in my mind (and Canada!), I prefer to think of it as 15 M. It makes it seem just a wee bit less daunting.

Thank you to everyone who has responded publicly and privately thus far!

[Basslet]

Poor Walter. He's always misunderstood. Razor wit does go over a lot of people's heads. I have no advice for you Annasea on top of what others have suggested. But, I wish you luck.

[WreckWench]

Poor Walter. He's always misunderstood. Razor wit does go over a lot of people's heads. I have no advice for you Annasea on top of what others have suggested. But, I wish you luck.

Yes Walter's wit is far to razor like for this blonde...it just 'ripped' thru me!

But now that you all have explained it...I can see where he must of been seeing the humor in her rounding off the fraction.

Sorry Walter....ya gotta sometimes explain these things...or gosh forbid use one of those evil *smilie/emoticon* things!

[Walter]

Stop trying to cheat, you have to swim 15.24 meters or 50 feet.

It was a joke, wasn't it?

Of course.

On a completely different topic (it's my thread and I can hijack if I want to...sang to the tune of "It's My Party" ), I just figured out what the "Quote" button is for!

If you want to quote 2 people from different posts in your reply, hit the "Quote" button for the first post. You'll notice the + sign turns into a - and the button turns red. Scroll down to your second post and hit the "Quote" button again. Once again, you'll see the + turn to a - and the button turning red. Now, hit the "Add Reply" at the bottom of your screen. You'll now be taken to the page that allows you to enter your reply. Notice how both quotes appear in your reply box?

The nice thing about quoting this way, rather than cutting and pasting in a second quote as I used to do, is that when others are viewing your response with more than one quote, if they click on the red arrows seen in both quotes, they're taken back to the original post.

Also, you can even add from other forums this way.

(I'll post this as well in the Feedback forum.)

How do you do it if the two posts you want to quote are on different pages?

Sorry Walter....ya gotta sometimes explain these things...or gosh forbid use one of those evil *smilie/emoticon* things!

But I don't understand them, how would I know which one to use?

[annasea]

How do you do it if the two posts you want to quote are on different pages?

Very easy! As you can see, I've quoted myself below from assorted threads I've started here in the New and Non-divers forum...

I've just started searching around for beginner diving classes and have discovered that some facilities offer classes utilizing wetsuits only while others offer both wet and drysuit diving.

After my OW debacle here in Vancouver, I've decided to refer my ocean dives elsewhere. I've considered California, Florida, and Hawaii.

Since my certification process is on hold until June, a few questions have come to mind.

A very wise bird suggested to me recently that I may be better off learning to dive in a backplate and wings set-up rather than the jacket-style BC I was using in the confined dives portion of my ill-fated PADI OW course.

If you click on the red arrow that appears in the *header* of each quote (go ahead, don't be shy! or lazy! ), you'll be taken back to the original post even though it's in a different thread. (Did you click? Worked, didn't it? )

All you need to do is run around the board and click on the QUOTE button that appears at the bottom right of the post you'd like to quote. As mentioned above, as long as the QUOTE button turns red, you're in business! Once you've selected all the posts that you'd like to quote, return to the thread that you'd like to post your response in and hit ADD REPLY. All the quotes that you've selected will appear in their entirety.

[Mermaid Lady]

Walter was joking. However, 50 ft is not exactly 15 meters. As Walter said, 50 ft is 15.24 meters, if you only swim 15 meters, you are cheating.

Only 50 feet?? We had to swim 60 feet (20 yards) in my NAUI OW class.

But seriously, There's a lot of good ideas here. The main point I would add would be to relax and not try to rush. Paradoxically you can go farther by going slower. Your body builds up CO2 more quickly when you are exerting yourself.

Here's my particular advice FWIW. Take graduated steps:

Try simply practicing holding your breath for short periods and work your way up. If you can only do 10 seconds at first, no problem. Just practice that until you are comfortable. Once you are, then you can start increasing your time in 2-5 second intervals. (CAUTION: Always have a friend or lifeguard nearby when you are practicing in the water!!!). For example first you go under for 10 seconds. Then you rest whie breathing normally for several minutes. Then go under and try for 12 seconds. By the 3rd or 4th try, you will likely be doing 25-18 seconds and you will be surprised at how easy it is now to get to your original 10. In a single session, you will likely double or triple your time.

Once you are comfortable holding your breath for 30-45 seconds you can start trying for distance. A friend can help immensely here as they can "mark" the distance. You can estimate by using body lengths. You can start by simply trying to swim 2 body lengths underwater. Once you are up to 30 seconds of comfortable breath-holding this should be a snap. Once you are comfortable you can try for 3, and then 4 lengths. Try do increase by at least 2 "steps" in each session. Once you are swimming 5 lengths, you will notice how effortlessly you are doing 2. When you arre up to 7 , 5 will be easy. When you get to 11 lengths, hey, you're home free because you are now going 55 feet (if you're 5'6", a little less if you're shorter) and you've passed the test!!! Woo Hoo!! congratulations!!!

Hope this helps!!

PS. Merry Christmas and Happy Hanukkah

Edited by Mermaid Lady, 25 December 2005 - 09:43 AM.

[Hipshot]

Here's my particular advice FWIW. Take graduated steps:

Try simply practicing holding your breath for short periods and work your way up. If you can only do 10 seconds at first, no problem. Just practice that until you are comfortable. Once you are, then you can start increasing your time in 2-5 second intervals. (CAUTION: Always have a friend or lifeguard nearby when you are practicing in the water!!!). For example first you go under for 10 seconds. Then you rest whie breathing normally for several minutes. Then go under and try for 12 seconds. By the 3rd or 4th try, you will likely be doing 25-18 seconds and you will be surprised at how easy it is now to get to your original 10. In a single session, you will likely double or triple your time.

Teresa has given you a lot of good suggestions in her post. I'd only add one thing for safety during this exercise. If you're not swimming, but holding your breath underwater, always hold something small that floats (e.g., champagne cork, ping pong ball, floating key ring, etc.) in your hand. This way, you're protected if you experience shallow-water blackout. An unconscious person would let go of what they're holding, which would signal the topside observer that it's time to make a rescue. BTW, that's probably NOT going to happen, especially to someone who's just starting out, but it can't hurt to be safe.

Rick

Edited by Hipshot, 25 December 2005 - 11:02 AM.

[ScubaDadMiami]

Shallow water blackout is actually something different. Yes, holding breath for too long could cause one to black out in shallow water or even in open air. However, the term "shallow water blackout" connotes something different.

Normally, there is a certain amount of carbon dioxide in the lungs. Your lungs have strong sensors built into them that monitor the level of carbon dioxide. When the CO2 level gets too high, these sensors send a message to the brain, instructing the brain to breathe.

Your body also monitors oxygen levels, and will also send a message to the brain for it to instruct the lungs to breathe. However, the oxygen sensors to not control the breathing nearly as much as the CO2 sensors do. Only when oxygen levels get pretty critically low do the oxygen sensors kick in when compared to the CO2 sensors.

By hyperventilating before doing a free dive, the skin diver is removing the carbon dioxide from the lungs by breathing faster than the body can manufacture it (as well as breathing deeper, allowing a better exchange deeper in the lungs). So, after the skin diver hyperventilates, the CO2 levels take a while to come back to the point where the sensors trigger a message to the brain that it is time to take a breath. This delays the urge to breathe.

After hyperventilating, when the free diver descends, the oxygen partial pressure in the lungs rises, compacting lots of oxygen molecules together. The body gets plenty of oxygen. In fact, initially, it gets more than it does at the surface due to more molecules entering the bloodstream. So, the oxygen alarms are kept from firing.

Since the body is used to dealing with oxygen in normal atmospheric pressure, the oxygen alarms do not trigger when the percentage of oxygen in the lungs starts to drop. This is because the few molecules of oxygen that are left are compacted together so tightly that the body is receiving enough oxygen to sustain life. In other words, the fraction of gas will become too low to support life at the surface but it will be fine at depth. (This is why partial pressure is not the same thing as gas fraction. You can have a very low fraction of oxygen but put enough pressure around it to compact the molecules tightly enough together to sustain life. This is why deep trimix contains low fractions of oxygen, otherwise known as hypoxic mixes.)

However, by this time, the carbon dioxide is starting to build up to the point where this alarm is now activated, prompting the urge to breathe. So, the diver starts to ascend. During this ascent, what is happening to the oxygen in the lungs? The partial pressure drops. In fact, it can get so low that it is insufficient to sustain consciousness. By the time the oxygen alarm goes off, it is too late. The brain, deprived of oxygen, blacks out.

Since the blackout happens as the diver is ascending through the shallows, the event has come to be known as "shallow water blackout."

Edited by ScubaDadMiami, 25 December 2005 - 11:27 PM.

[Walter]

Howard, very good explanation.

[Hipshot]

Shallow water blackout is actually something different. Yes, holding breath for too long could cause one to black out in shallow water or even in open air. However, the term "shallow water blackout" connotes something different.

Normally, there is a certain amount of carbon dioxide in the lungs. Your lungs have strong sensors built into them that monitor the level of carbon dioxide. When the CO2 level gets too high, these sensors send a message to the brain, instructing the brain to breathe.

Your body also monitors oxygen levels, and will also send a message to the brain for it to instruct the lungs to breathe. However, the oxygen sensors to not control the breathing nearly as much as the CO2 sensors do. Only when oxygen levels get pretty critically low do the oxygen sensors kick in when compared to the CO2 sensors.

By hyperventilating before doing a free dive, the skin diver is removing the carbon dioxide from the lungs by breathing faster than the body can manufacture it (as well as breathing deeper, allowing a better exchange deeper in the lungs). So, after the skin diver hyperventilates, the CO2 levels take a while to come back to the point where the sensors trigger a message to the brain that it is time to take a breath. This delays the urge to breathe.

After hyperventilating, when the free diver descends, the oxygen partial pressure in the lungs rises, compacting lots of oxygen molecules together. The body gets plenty of oxygen. In fact, initially, it gets more than it does at the surface due to more molecules entering the bloodstream. So, the oxygen alarms are kept from firing.

Since the body is used to dealing with oxygen in normal atmospheric pressure, the oxygen alarms do not trigger when the percentage of oxygen in the lungs starts to drop. This is because the few molecules of oxygen that are left are compacted together so tightly that the body is receiving enough oxygen to sustain life. In other words, the fraction of gas will become too low to support life at the surface but it will be fine at depth. (This is why partial pressure is not the same thing as gas fraction. You can have a very low fraction of oxygen but put enough pressure around it to compact the molecules tightly enough together to sustain life. This is why deep trimix contains low fractions of oxygen, otherwise known as hypoxic mixes.)

However, by this time, the carbon dioxide is starting to build up to the point where this alarm is now activated, prompting the urge to breathe. So, the diver starts to ascend. During this ascent, what is happening to the oxygen in the lungs? The partial pressure drops. In fact, it can get so low that it is insufficient to sustain consciousness. By the time the oxygen alarm goes off, it is too late. The brain, deprived of oxygen, blacks out.

Since the blackout happens as the diver is ascending through the shallows, the event has come to be known as "shallow water blackout."

Okay, perhaps hypoxia would have been a better choice of words. However, the potential danger of passing out during an attempt to hold one's breath for a time, especially after hyperventilating and incrementally letting out one's air, is a valid concern.

Rick


Spero nos familiares mansuros. (Latin for I hope we'll still be friends.)

Edited by Hipshot, 26 December 2005 - 02:20 PM.

[Mermaid Lady]

Teresa has given you a lot of good suggestions in her post. I'd only add one thing for safety during this exercise. If you're not swimming, but holding your breath underwater, always hold something small that floats (e.g., champagne cork, ping pong ball, floating key ring, etc.) in your hand. This way, you're protected if you experience shallow-water blackout. An unconscious person would let go of what they're holding, which would signal the topside observer that it's time to make a rescue. BTW, that's probably NOT going to happen, especially to someone who's just starting out, but it can't hurt to be safe.

Rick

Thanks for mentioning that. I'd forgotten. (D'oh!!)

I use the ol' ping pong ball myself. For my long breath-hold attempts I would have a spotter right next to me holding the stopwatch. Who was also ready to pull me up in case I let go of the ball.

[6Gill]

Caetlonn,
Not sure of you exact location but FYI the West Vancouver Aquatic Center runs stroke clinics for $15 and its an hour long.Last one I went to was just me so it worked out as a great deal.The other plus it is a brand new facility that doesn't need to cholorinate the water to keep it clean(I hate pool chlorine).
I think that being comfortable in the water will go along way to making swimming underwater easier along with the better your physical fittness the less effort required thus the longer your breath will last.
If you need a spotter let me know cause I should also work on my breath-holding and we could trade off.

Eric

[Walter]

Caetllonn,

That sounds like a great idea.

[jholley309]

* I don't even know what underwater swimming (really) is! How does one position oneself within the water and maintain that position as opposed to swimming on the surface?

Most of my underwater swimming (other than diving, which doesn't really count in the context of this discussion) is done with fins while skin diving, with fins. I extend my arms in front of me, palms down flat, with fingertips overlapping to form a "V" with my arms. I then use my arms like a plane to control my vertical position; just raise to go up, lower to go down. Not sure how that would work without fins, though, since it takes a fair amount of water flow to make it work for me. Someone less naturally bouyant may require less effort.

Cheers!

Jim

[finley]

annasea...come visit..I will give you lessons