Re: [PSUBS-MAILIST] PSUB Fatalities...View Ports...Shatterproof

["Karl & Shirin Fuller" <fullerk@voyager.co.nz>]

Doug,
My understanding is that bullet proof glass is made of laminated
polycarbonate (lexan) and glass, very hard to duplicate in the viewport
scenario, unless flat and hugely thick to compensate for the inferior
strength of a flat port.
I've heard some talk that polycarbonate is inferior to acrylic as it can
'cold flow' or creep under sustained pressure. Is there other reasons or the
only reason, as it rarely seems to get used.

Because a view port seems to be one of the most talked of safety concerns, I
would still consider a second view port inside the other, to be a huge peace
of mind. View port failure, being far more likely than hull failure it seems
form what I've read, is, as has been mentioned the most likely failure that
will, shock, injure or kill you instantly. Most of the other failures or
problems would give more time to prepare for an escape to the surface.
In my opinion, no matter how well tested or how big the safety margin,
because of the nature of the material, it will always be the most likely
failure due to the effects of sunlight, accumulated cycles, it's low impact
resistance and Murphy's Law.
Yes it would cost more...... less than the cost of a coffin maybe ?
Karl.



>                 It sounds to me that if you were down fairly deep in a
PSUB
> and a plastic view port blew completely it would more than likely end in
your
> fatality. I guess this is when you get into the math of probabilities to
base
> your design on (i hate math). If view ports are the weak link in a sub how
> can this be eliminated? Personally I do not believe in betting my life
with
> procedural barriers. I prefer the protective barrier is built into the
> design. We talk about view ports shattering. Why not move away from the
> plastic ports and move towards the material used in bullet proof glass? I
am
> not familiar with this technology but there is that technology to
> investigate. Now just think , Would you go in a PSUB whose glass was
bullet
> proof? Maybe yes, maybe no. Are most PSUBs view ports now shatter proof?
Nope.
> Doug
>