Need answer to something I've always Wondered About - Page 3 - SailNet Community
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post #21 of Old 07-19-2013
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Re: Need answer to something I've always Wondered About

The problem isn't the resistance in the snorkel. Its the water pressure preventing your lungs from expanding and drawing in air.
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post #22 of Old 07-19-2013
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Re: Need answer to something I've always Wondered About

I think our lungs are accustom to a curtain surface level pressure then, for every foot below the suface level you add between 0.43 - 0.445 or 7. psi depending on salinity; At 3' below surface level in saltwater you have a additinal 1.33 psi working against you.

That would be like exhaling all the air out of your lungs, then wrapping your chest in a elastic ACE bandage then trying to breath

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post #23 of Old 07-19-2013
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Re: Need answer to something I've always Wondered About

Instead of a long snorkel or an expensive hookah, attach a scuba tank securely to the dock or boat. Then connect a first stage to a high grade, 20 to 25-foot hose with sufficient PSI rating (my hoses say they're rated to 400 psi) and a second stage to breath. While breathing compressed air at 10-15 feet isn't likely to be dangerous as long as you know how to clear your ears and don't hold your breath when coming to the surface, you'll often be asked to show a scuba certification card for the fills or whenever the tank needs to be inspected.
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post #24 of Old 07-19-2013
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Re: Need answer to something I've always Wondered About

I clean my boat on a regular basis as I am in the Caribbean. I use a scraper [or brush if the fouling just scum] mounted on an 8 ft handle. This allows me to work from the surface, I wear snorkel gear but do not need to dive down.

I can do my 44 ft mono in an hour the prop takes me the most time.

Do not be tempted to extend a snorkel as you can not clear your exhaled CO2 from the tube.
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post #25 of Old 07-19-2013
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Re: Need answer to something I've always Wondered About

A guy I know just cleaned all but his fin keel with a regular snorkel at the surface and a brush on a handle. Pretty good.


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post #26 of Old 07-19-2013 Thread Starter
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This is what I was hoping for. Good general discussion. I had also thought of the one way valve idea, just hadn't mentioned it yet. As far as water pressure and being able to breathe, isn't that why we have a rib cage? I would think the ribs would maintain room for some volume of air at minimal depths?

Med, you are right, I was only talking about being under a couple feet just to be able to inspect and maybe clean without having to surface at regular intervals.

Thanks guys!
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post #27 of Old 07-20-2013
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Re: Need answer to something I've always Wondered About

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Originally Posted by TQA View Post
Do not be tempted to extend a snorkel as you can not clear your exhaled CO2 from the tube.
Not a problem. I sell an Oxygen analyzer to scuba shops as part of some of my compressor stuff. One of my dive shop customers did a check to see how much oxygen was left in an exhaled breath. Normal air has approximately 21% O2. Our exhaled breath came in at about 19% which makes a lot of sense. After all, we blow our exhaled breath into the lungs of others when doing mouth to mouth!

This whole thing has nothing to do with the resistance of air flow in a long snorkel or breathing your exhaled breath. It is all about the difference in pressure on the lungs. You just can't breathe in when water pressure is squeezing your body.

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post #28 of Old 07-20-2013
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Re: Need answer to something I've always Wondered About

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Not a problem. I sell an Oxygen analyzer to scuba shops as part of some of my compressor stuff. One of my dive shop customers did a check to see how much oxygen was left in an exhaled breath. Normal air has approximately 21% O2. Our exhaled breath came in at about 19% which makes a lot of sense. After all, we blow our exhaled breath into the lungs of others when doing mouth to mouth!

This whole thing has nothing to do with the resistance of air flow in a long snorkel or breathing your exhaled breath. It is all about the difference in pressure on the lungs. You just can't breathe in when water pressure is squeezing your body.
Hmm well you should look up hypercapnia [excess CO2] which is a known problem with long snorkels.

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Additional sources of carbon dioxide in diving[edit]

There is a variety of reasons for carbon dioxide not being expelled completely when the diver exhales:
The diver is exhaling into a vessel that does not allow all the CO2 to escape to the environment, such as a long snorkel
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Hypercapnia normally triggers a reflex which increases breathing and access to oxygen, such as arousal and turning the head during sleep. A failure of this reflex can be fatal, as in sudden infant death syndrome
Please note the word FATAL.
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post #29 of Old 07-20-2013
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Re: Need answer to something I've always Wondered About

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Hmm well you should look up hypercapnia [excess CO2] which is a known problem with long snorkels.
I am afraid that you are a victim of Wikipedia bunk. That particular little argument from a 1952 Navy study was debunked back in the 80s ... again by the Navy. A snorkel that is too long will starve a diver simply because of the pressure difference ... not the CO2.

The CO2 question was studied extensively because of commercial hard hat diver incidents that occurred. Because the air circulation in the hat was not sufficient to expel the diver's breath, the diver would slowly but surely go to sleep and if not tendered properly, could die. I was an expert witness on a trial where a diver died for that very reason.

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post #30 of Old 07-21-2013
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Re: Need answer to something I've always Wondered About

Hm the diver died. Sounds fatal to me.

My knowledge of hypercapnia comes from using skip breathing to extend my underwater time using scuba. It certainly had an effect on me.
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