Re: [PSUBS-MAILIST] Tympanic membranes

[Jon Wallace <jonw@psubs.org>]

I was headed down that path as well. The best defense is a good offense, 
or follow ABS/PVHO rules and build it right and you won't have much to 
worry about. If you design, build, and rate the sub correctly, and only 
dive in water no deeper than the sub rating you should never have a 
reason to bail from the sub. The Seaker100 accident (read the web site) 
is factual evidence that the likelihood of surviving a catastrophic 
failure is slim to none. That vessel failed in 30 feet of water 
resulting in one dead and one critical who survived, but by his own 
admission had no time to "react" and has no idea how he reached the surface.

However, building true to ABS/PVHO specs won't guarantee you don't get 
yourself into an entanglement situation. This seems to be a valid reason 
to discuss escaping a sub and having some kind of plan for it. The video 
clip of Alec hitting that underwater cable with snoopy is a perfect 
example that there are underwater obstacles out there that can ruin your 
day, even though it didn't ruin his. Had that cable gotten caught within 
the claw arm on the front of Snoopy it would have been a far different 
situation. I don't recall if that was a private dive or one that he made 
at the 2006 convention, but we should look at that situation sometime in 
the future and imagine the cable ensnared the sub, then discuss, "Ok now 
what?"

Last year we started some discussions about equipment, parts, or 
placement thereof that we might build on our subs as "standards" so in 
case an entanglement situation arose an outside support team and/or 
rescuers could understand how to get us additional air, locate lift 
hooks, etc. We've let that discussion falter and should get back to it 
since it represents an opportunity to deal with a situation without 
forcing the occupant to escape. And lastly, directed to everyone, Jay 
Jeffries has a lot of practical knowledge on issues surrounding sub 
escape and has spent two consecutive conventions discussing the topic. 
He should be listened to.

Jon



Greg Cottrell wrote:
> I also agree with Dan. No offense, but I think that it is very 
> interesting that some folks would say that following the PVHO is “over 
> kill” on safety and not necessary but then spend all their energy 
> planning to escape from their sunken sub. An escape plan is a fine 
> idea, but it would be nice to see more of that energy spent on safe 
> building practices that are proven than “internet innovation with a 
> great escape plan”
>
> Greg C



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