Dangerous gear?

[ThomasScherrer]

>You will find you can't avoid breathing out.

that may be true for the experiment you mention.
BUT when scuba diving ALOT more pressure from inside the loungs can block the exhale function,
that is why it is so important to exhale BEFORE the pressure gets too high, when you accent.
this is also why lung over expansion is a known illness most likely to cause death.
breating compressed air under water and swimming up as fast as you normally do when snorkeling is a VERY bad ide !!
also another thing is air bubbles in your blood, they expand too.
it is NOT a problem when the last air you got was from the surface, then you do not make bubbles in blood
and you can not over expand lungs, but offcourse you get a bit limited underwater time.
my best advise is to keep snorking, snorkling,
and keep scuba, scuba, do not mix them, specially at depths you mention.

 

[John C. Ratliff]

Thomas, I agree with much of what you say, but a few things need clarification.

>You will find you can't avoid breathing out.

that may be true for the experiment you mention.
BUT when scuba diving ALOT more pressure from inside the loungs can block the exhale function,
that is why it is so important to exhale BEFORE the pressure gets too high, when you accent.

I had not heard this, and I have been reading about underwater physiology for quite some time. What my understanding say can happen is that a portion of the lung can collapse when breathing out too much, then as you ascend expand again without a means of releasing this pressure. Obviously this could only happen on a free ascent using scuba or compressed air at depth.

A lot of breath-hold divers "pack" their lungs with air prior to the dive. There is now some information that this could result in an embolism to the brain (cerebral arterial gas embolism).

this is also why lung over expansion is a known illness most likely to cause death.
breating compressed air under water and swimming up as fast as you normally do when snorkeling is a VERY bad ide !!

Agreed!!! Thanks for mentioning that.

also another thing is air bubbles in your blood, they expand too.
it is NOT a problem when the last air you got was from the surface, then you do not make bubbles in blood
and you can not over expand lungs, but offcourse you get a bit limited underwater time.
my best advise is to keep snorking, snorkling,
and keep scuba, scuba, do not mix them, specially at depths you mention.

Your advise is correct. But there is one exception, and one clarification too. Lung over-expansion will cause the air sac (alveoli) to rupture, and allow air from the lung to enter the blood stream. This "air embolism" is extremely dangerous, and can be fatal if not treated correctly (Trendelenburg position, oxygen administration, etc.). This is where air can get into the blood stream. And yes, these can expand as the pressure lessens.

But snorkel and breath-hold divers can get decompression sickness. This was discovered years ago when a disease called "Taravana" was investigated. These were South Seas pearl divers who had unusual symptoms, which turned out to be decompression sickness. This was discovered by diving pioneer E.R. Cross, and he wrote about the condition. They breath-hold dived deep enough, and stayed long enough, to absorb nitrogen into their blood stream. With enough dives, there was supersaturation and bubble formation, resulting in "taravana" or decompression sickness in breath-hold divers. U.S. Navy divers in submarine tanks have also experienced taravana. Most recently, Robert Wong has documented decompression sickness in breath-hold divers. While it is most unusual, this problem occurs to very accomplished breath-hold divers, and must be understood as a potential problem for deep descents while breath-hold diving.

Thank you for mentioning these areas. In this forum, we don't discuss breath-hold diving that much, and we need to understand some of the unique physiological differences between breath-hold diving and scuba diving.

SeaRat

 

[Nemrod]

I was just over in the Basic Scuba section reading the posts about the diver with older gear that was getting back into diving.
http://www.scubaboard.com/forums/ba...k-diving-after-20-years-what-do-old-gear.html
There were a few "that old stuff is dangerous, replace it all", type replies, but most respondents basically told him it was still fine and that he should just get it serviced.

This brought to my mind a question though. What gear from either the past or the present really was dangerous and shouldn't be used? I know Fred Roberts condemned the homebuilt doublehose regulator conversions in Basic Scuba, but certainly in the past 60 years of diving there must have been a few real lemons produced.

So what gear was out there that was badly designed or built and that they couldn't pay you enough to dive?

This being the vintage forum and not the "old" gear forum I am not sure how to answer the question. "Old" gear to many divers today is anything more than five years. That concept is hardly applicable to vintage gear which is pre-73(ish). I think, and could be wrong, that one difference is that those who collect and dive old gear, especially those who used the gear or similar types of gear when it was NEW gear at least understand the performance or characteristics of that gear and it's strengths and shortcomings. Of course, not all vintage gear divers are themselves vintage gear so for them it is useful to be mentored or to take seriously their questions (forum, virtual) and provide them realistic answers.

Yes, some vintage or other era gear is dangerous, the items that come to mind are any old deco equipment and especially the SP Bendomatic, old depth gauges and especially the watch type from USD as they are notoriously inaccurate and not consistent and quite a large number of older regulators both single and double hose that just do not perform adequately. Of course, using such equipment, if you know the limitations and plan the dive to stay within those limitations, then all is probably OK. Is this a place for a Bendomatic:

The other category of "old" dangerous gear is that equipment for which there are no parts available and those divers who then may rationalize or talk themselves into using the gear (regulators in particular) anyways. But, people often know their limitations even if they do not admit them, down deep (pun) they know them and avoid those limits whether personal or equipment. The fact is that many older regs are like sucking air through a straw and simply should not be used on a dive like the Spiegal for example where there are currents combined with depth are taxing even for experienced divers with modern equipment. Like here:

There is one other area of concern that comes to mind, mixing older gear, that being gear from one era with another era that was never intended or designed to be used together and which are therefore incompatible. Example, using a vintage harness that has a sternum strap with a horsecollar BC that makes it nigh impossible to reach the sternum strap and then having the sternum strap nearly choke the life out of me. Of course, I was carrying a 4,000 dollars camera in what, near 200 feet of water and dropping it was not an option (yes it was tethered but----but) so I only had one hand and it was on the tag line due to current and waves where it should have been so I had, mixed incompatible gear from multiple eras. A Navy Harness, early vintage, horsecollar BC, late vintage, camera, brand new and a dive that could easily reach 130 feet and known for current and rough seas. A modern era dive profile, a hodgepodge of dive gear and my focus on my camera toy led to a less than desirable experience. Sans BC, the Navy Harness is great, heck, it even works fine with a Mach V wing but not with a horsecollar, oil and water:

Yes, there is dangerous scuba gear out there, the trick is knowing what and when. Yeah, a old Healthways double sucker may be completely safe on a 20 foot dive on a rock pile in Table Rock lake and completely dangerous on the Spiegal Grove or Oriskany. Know your limits, know your equipments limits. We all got limits. Heavy Iron tour, Duane, Bibb and Spiegal in one day, two weeks ago, bow of Duane:

Of course, if the diving is on a reef here, use any kind of gear you want, lol, I think this is where more (vintage) diving occurs than any other locale :

N

 

[DaleC]

Excellent write up N. That is my phylosophy exactly. I have lots of funky gear and will try almost anything (once) but I scale the exposure to the risk of malfunction/poor performance.

 

[Nemrod]

Excellent write up N. That is my phylosophy exactly. I have lots of funky gear and will try almost anything (once) but I scale the exposure to the risk of malfunction/poor performance.

Thanks, it occurs to me I have not been paying y'all any mind of late .

Yeah, I know you know;

"You got to know when to hold 'em, know when to fold 'em,
Know when to walk away, know when to run.
You never count your money when you're sittin' at the table,
There'll be time enough for countin' when the dealin's done.”
(Kenny Rogers)

Safety is way overrated, but, I would not underrate either!

N

 

[John C. Ratliff]

Nemrod,

I like everything you said except the thought that the military harness is incompatible with the horsecollar BC. I was taught to use the military harness with a horsecollar BC (or life vest) by the U.S. Navy School for Underwater Swimmers. It is how it is used that makes the difference. Here's a photo I made of me with a horsecollar BC (Dacor this time):

Note that the chest strap is under the vest, so that it can inflate without harming the diver by pushing against the harness. The harness is inside, but the end of the quick release webbing is outside where it can be grabbed easily. Here are a few photos from our class in 1967 which illustrate this method of use of the military harness:

Note that all the divers were using a vest-style life vest, CO2 inflated with an optional oral inflation tube.

This photo shows a Navy instructor with the vest and a military harness.

Finally, here's a U.S. Navy photo of divers in a submarine lock, using a military harness and a horsecollar-style vest. This photo comes from the book, The Business of Diving, by John E. Kenny (gpc, book division, gulf publishing, houston texas,, Library of Congress Catalog Card Number 74-114693, ISBN-0-87201-183-5), Copyright 1972, page 196. The caption reads,

Figure 8-4 (Left). These combat swimmers are prepared to lock out of a fleet submarine. Figure 8-5 (above). Probably the most efficient fighting machine ever developed, the U.S. Navy SEAL Team has changed concepts of marine special warfare. Trained first as combat swimmers, then as long-range assault troops, SEAL teams are suited for antiguerilla warfare. (Photos U.S. Navy.)

The effectiveness of the SEAL Teams is what Osama bin Laden recently found out too. It is with great sadness that I also found out today that we lost 30 people in Afghanistan, some of whom were members of SEAL Team 6. We all need to say a little prayer tonight for them and their families.

SeaRat

 

[Thalassamania]

Team 6, a tragedy, a horrible tragedy.

Note the Swimaster Wideview MOF on the diver locking out ... my favorite mask. Anyone got one for sale?

 

[DaleC]

Sorry, not for sale but I did just get one a couple of weeks ago in uber good condition.

 

[Thalassamania]

You are breaking my heart and my spirit. If you ever find another ...

 

[DaleC]

You never know! If I do it will be yours.