[PSUBS-MAILIST] submarine escape procedures

Tue Aug 5 13:56:48 EDT 2014

The problem with selecting a gas for submarine escape is that you are caught between conflicting requirements.  On air, narcosis which is significant enough to impair judgement or behaviour is a possibility even shallower than 100 fsw, and almost guaranteed below 150 fsw. Air reaches a PPO2 of 1.6 (the recommended maximum) at 218 fsw, so beyond that, you have to reduce oxygen and increase inerts. With helium, you think more clearly, but because it has a fast uptake, you incur decompression obligation faster than with nitrogen. Nitrogen gives you a better shot at avoiding bends, but impairs your judgement in an emergency situation when you might need it most. Ascent rate is an issue too, as ideally you would want to escape quickly to minimize your exposure time, and ascend rapidly from depth, but slow yourself as you approach the surface to allow an opportunity for any dissolved gas from depth to escape your body safely.

The bottom line is that drowning is unsurvivable. DCS in many cases can be treated, so it makes sense to get yourself to the surface as rapidly as possible.

If I were selecting a gas for escape purposes, I would mix for a maximum PPO2 of 1.6 at the maximum anticipated depth, because toxicity onsets rapidly and convulsions are debilitating, so you don't want to mess around with too much oxygen. I would also accept a higher nitrogen content than I might for diving, with the understanding that effecting the escape should be quick and get me to lesser pressures rapidly, and I would flare my body or otherwise attempt to slow the ascent somewhat as I approach the surface.

Also, I don't know how practical it would be for a small sub with limited internal space, but the Mustang SC2000 suits look like a sexy piece of kit to have.

Sean

On August 5, 2014 12:33:16 PM CDT, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>Cliff,
>Thanks', I spoke with a diver friend about bailing out at 400 feet.  
>He said it is very doable, but suggested taking a couple of breaths of
>another type of gas, I think it may have been helium.  
>Hank 
>
>
>
>On Tuesday, August 5, 2014 12:00:35 AM, Gregory Cotton via
>Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>  
>
>
>Here is the escape trunk placard from the USS Albacore, the one on my
>boat (USS Torsk) was much the same. Note the bottom times on the
>bottom.
>
>http://www.heiszwolf.com/subs/albacore/escape_trunk_procedure.jpg
>
>
>
>
>On Mon, Aug 4, 2014 at 10:14 PM, Clifford Redus via
>Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>See  http://www.subdb.info/database/   scroll down to R300.  See
>section on emergency procedures in operating manual and second page of
>briefing card. 
>>
>>
>>Calcs show it takes about a minute for hatch to spring open after I
>open the scuttle valve.  During this time I will be using my
>BIBS(second stage scuba reg attached to Boat air supply). I have a
>Steinke hood in protocol but not sure I would use it.  Had a long
>discussion with doctors and tech divers.  As Phil notes ,  issue is
>onset of nitrogen narcosis rather than bends given the short time
>exposed to pressure.  Would be an uncontrolled ascent. 
>>
>>
>>My escape procedure calls for staying in place and waiting for rescue.
> Bailout only given events called out on safety briefing card.
>>
>>
>>
>>
>>
>>Sent from my iPad
>>
>>On Aug 5, 2014, at 8:53 AM, hank pronk via Personal_Submersibles
><personal_submersibles at psubs.org> wrote:
>>
>>
>>Hello all,
>>>We have not talked about escape procedures, that I know of.  Special
>equipment to carry, different gas to breath prior to escape depending
>on depth.  I personally would like to have a check list with escape
>procedures onboard.  Is there such a thing out there? 
>>>Hank
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>
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