[PSUBS-MAILIST] onboard gear

Mon Apr 22 15:36:12 EDT 2019

Rick - Be careful with using mixed gas in a submarine escape application.  Helium is not typically used to reduce decompression obligations, but rather to alleviate inert gas narcosis.  Often this is at the expense of an increased decompression obligation in comparison to an equivalent nitrox.  Helium is a fast-diffusing gas, and on short exposures like submarine escape will likely increase the risk of bends as compared to nitrogen.  On the basis of oxygen content alone, air can be breathed down to about 218 fsw.  Below that, you have to reduce the oxygen content, but you don't want to reduce it to the extent that you end up with a dangerously hypoxic gas at the surface.  16% is about as low as you can go without guaranteeing a surface blackout.  A 16% oxygen gas would be good down to about 300 fsw.  Deeper than that, and you run a severe risk of oxygen toxicity convulsions (single breath and go scenario notwithstanding) without further reducing the oxygen content.  Of course, at 300 fsw, the narcosis would be huge, but given that your task load during a submarine escape is hopefully both of short duration and of simple nature, the risk imposed by having to lock out under the influence of the narcosis is likely far less than the risk of incurring a greater decompression obligation during the lockout and ascent by using a helium based gas for this application as opposed to nitrogen which has a slower uptake.  Of course, an escape scenario lets you get away with a lot more than if you were planning an ambient pressure dive, as a result of the limited duration lockout and rapid ascent, so YMMV.  In any case, give these issues some careful consideration.  At the end of the day, bends can be treated. Drowning, not so much.

Sean

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Monday, April 22, 2019 12:38 PM, Rick Patton via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

> Shanee
>
> Depending on the depth that you have to flood the sub and make a free accent to the surface, it really depends on how fast you need to equalize to try and get to the surface before exceeding the nitrogen uptake limits for getting bent on course. Only the air cavity's are affected in a rapid pressurization I believe but my sub has a rated working depth of 350' and as I remember from the old navy tables, you only have about 5 minutes at 165' before you have to make a stop at 10' so due to that fact, I would have to flood the sub as fast as I can to minimize the nitrogen uptake to make it to the surface before getting bent and the negatives to that are that most people can't clear their ears that fast so you are looking at possibly blowing your ear drums which in turn is really painful and screws up you equilibrium which is going to hamper your safe accent to the surface in a timely manner. I am going to have mixed gas in my bailouts to buy me time for getting to the surface and keeping the nitrogen uptake as minimal as possible.
> Rick
>
> On Mon, Apr 22, 2019 at 7:15 AM Shanee Stopnitzky via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>> Doesn't feel like it compared to Hank! Also, forgetting food, water, blankets and a first aid kit. Forgetting those has been my specialty for my whole life!
>>
>> Steinke hoods are probably a good idea, although I'm terrified of them myself. Does anyone have any information on what pressure change effects happen physiologically during an emergency escape? I'm a diver so I'm very familiar with what happens when you descend and ascend on scuba, but I'm not sure what happens with a sudden and extreme pressure increase. Other than all your organs getting squished, of course.
>>
>> Thanks for your input everybody!
>>
>> On Sun, Apr 21, 2019 at 6:58 PM Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>
>>> Hi Shanee,
>>>
>>> That's a pretty comprehensive list you have, and I couldn't fit all that. But how about a pair of Steinke hoods? Oh, and one very simple thing... a flashlight.
>>>
>>> Best,
>>> Alec
>>>
>>> On Sun, Apr 21, 2019 at 4:35 PM Shanee Stopnitzky via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>>
>>>> Hi all,
>>>>
>>>> I'm wondering what everyone's onboard safety/repair kits contain, or what 'loose' gear you carry on dives with you. Ours are (so far):
>>>>
>>>> CG requirements
>>>> air horn
>>>> whistle
>>>> life jackets
>>>> fire extinguisher
>>>>
>>>> safety
>>>> fire blanket
>>>> 2x scuba masks
>>>> 2x spare air
>>>> primary gas analyzer
>>>> backup gas analyzer
>>>> spare CO2 scrubber - battery powered
>>>> handheld radios
>>>> uw radio system
>>>>
>>>> repair kit
>>>> gorilla tape
>>>> electrical tape
>>>> butyl tape
>>>> zip tie assortment
>>>> spare battery terminals
>>>> spare wire connectors
>>>> spare wire
>>>> splash zone
>>>> JB weld
>>>> steel tie wire
>>>> steel strap
>>>> e6000 glue
>>>> hose clamp assortment
>>>> screwdriver set
>>>> adjustable wrench
>>>> multi-tool
>>>> hammer
>>>> scissors
>>>>
>>>> What's in your kits?
>>>>
>>>> Best,
>>>> Shanee
>>>>
>>>> --
>>>> Institute for Emergence//Community Submersibles Project
>>>>
>>>> :::::
>>>>
>>>> 'The fact remains that political frontiers are impervious to our verbal cultures, while the substantially nonverbal civilization of playfulness crosses them with the happy freedom of the wind and the clouds.' ~ Primo Levi
>>>>
>>>> :::::
>>>>
>>>> 'Caught up in a mass of abstractions, our attention hypnotized by a host of human-made technologies that only reflect us back to ourselves, it is all too easy for us to forget our carnal inherence in a more-than-human matrix of sensations and sensibilities. Our bodies have formed themselves in delicate reciprocity with the manifold textures, sounds, and shapes of an animate earth. Our eyes have evolved in subtle interaction with other eyes, as our ears are attuned by their very structure to the howling of wolves and the honking of geese. To shut ourselves off from these other voices, to continue by our lifestyles to condemn these other sensibilities to the oblivion of extinction, is to rob our own senses of their integrity, and to rob our minds of their coherence. ' ~David Abrams
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>>
>> --
>> Institute for Emergence//Community Submersibles Project
>>
>> :::::
>>
>> 'The fact remains that political frontiers are impervious to our verbal cultures, while the substantially nonverbal civilization of playfulness crosses them with the happy freedom of the wind and the clouds.' ~ Primo Levi
>>
>> :::::
>>
>> 'Caught up in a mass of abstractions, our attention hypnotized by a host of human-made technologies that only reflect us back to ourselves, it is all too easy for us to forget our carnal inherence in a more-than-human matrix of sensations and sensibilities. Our bodies have formed themselves in delicate reciprocity with the manifold textures, sounds, and shapes of an animate earth. Our eyes have evolved in subtle interaction with other eyes, as our ears are attuned by their very structure to the howling of wolves and the honking of geese. To shut ourselves off from these other voices, to continue by our lifestyles to condemn these other sensibilities to the oblivion of extinction, is to rob our own senses of their integrity, and to rob our minds of their coherence. ' ~David Abrams
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>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
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