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Re: [PSUBS-MAILIST] K250 to K400 modification
Maybe an ROV would be a better alternative .
> [Original Message]
> From: Alan James <alanjames@xtra.co.nz>
> To: <personal_submersibles@psubs.org>
> Date: 7/4/2010 6:11:58 PM
> Subject: Re: [PSUBS-MAILIST] K250 to K400 modification
>
> Hi Carsten,
> Firstly it looks like it could be a Germany - Netherlands final.
> NewZealand could be the only unbeaten team in the world cup!
> Re the buoyancy issue-- You would have to go down heavy &
> use your thrusters as you could always add air to become more
> buoyant, but if you emptied 10 x 90 cubic ft tanks to equalize your
> hull this would make you about 100 lb lighter by the time you
> expelled the air coming to the surface.
> ( a scuba tank is about 10lb lighter when empty ).
>
> >>>By the way what shall a K250 do in 400ft on a stricken sub?
>
> Maybe offer moral support. Assess the situation.
> Or take a grapnel down & hook it on the sub.
> Or locate it for some tech divers.
> Alan
>
>
>
> ----- Original Message -----
> From: <MerlinSub@t-online.de>
> To: <personal_submersibles@psubs.org>
> Sent: Sunday, July 04, 2010 11:23 PM
> Subject: Re: [PSUBS-MAILIST] K250 to K400 modification
>
>
>
> Hi Alan - In General you can go that way.
>
> A sub designed for 150 ft max dive deepth can double there operation
depth
> with that way.
>
> The only real problem is if the boat is in this condition and you pop up
> (surface fast).
>
> There are two possible failtures:
>
> - Overpressure vale to small and hatch and windows pop out.
>
> - Over pressure vale has the right huge size and crew gets heavy
> decrompression tickness, blown ears etc..
>
> - In case of a fire or anything else in the sub - you can not surface in
> short time and probably get problems in it.
>
> We discuss this way some years ago but never go this way.
> Its a way only for crew with real expierence with there sub and also real
> scuba divers with expierence with decompression dives.
>
> If you double the cabin pressure just with air this means you double the
> amount of o2 atoms per volume.
> The fire risk increase.. If you increase the pressure with helium this
will
> work. The problem starts than when you lower later the pressure - you
have
> to feed o2 back.
>
> By the way what shall a K250 do in 400ft on a stricken sub?
>
> vbr Carsten
>
>
> "Alan James" <alanjames@xtra.co.nz> schrieb:
> > Hi Jon,
> > The emergency I was thinking of was along the lines of
> > a stricken sub entangled at 400ft & the nearest help was
> > a sub capable of 250ft depth.
> > Alan
> > ----- Original Message -----
> > From: Jon Wallace
> > To: personal_submersibles@psubs.org
> > Sent: Sunday, July 04, 2010 5:41 PM
> > Subject: Re: [PSUBS-MAILIST] K250 to K400 modification
> >
> >
> >
> > Sorry Alan, I missed the "emergency situation" part. So yes, in an
> > emergency where you are
> > sinking in water beyond your normal operating depth you could certainly
> > counter some amount of
> > outside pressure by increasing the pressure within. That may delay
> > (possibly prevent depending
> > upon depth) hull failure but of course has the potential for some other
> > nasty biological side
> > effects and I'm guessing in such an emergency you're probably going to
be
> > at the increased ambient
> > depth well beyond no-decompression limits. We had a similar discussion
a
> > few years ago about
> > standardizing on a specific valve so that divers could feed air into
the
> > cabin of disabled sub that
> > did not have life support capability, until that sub could be raised.
I
> > believe the discussion
> > started with "schrader" valves (tire valves) which were determined to
be
> > too small to be useful.
> > Many of the same issues were raised at that time ie...decompression
upon
> > surfacing, additional
> > pressure in the cabin affecting instruments, etc.
> >
> > Jon
> >
> >
> > On 7/4/2010 12:29 AM, Alan James wrote:
> > Thanks Hugh & Jon for the vote of confidance.
> > I did qualify this with " In an emergency situation". I think I
have
> > been misunderstood.
> > You take your sub down to its 250ft limit with several extra dive
> > tanks on board.
> > At this point the outside of your hull is experiencing round 125psi.
> > For every 33ft further you go down you add 14.7psi. The hull would
> > always be experiencing
> > 125psi from the outside as the pressure you're adding would be
> > countering the additional
> > pressure from additional depth.
> > So no pressure as such from the inside would be pushing your view
> > ports out.
> > The reason I said to increase the O2 flow into the hull is the
> > "bellows add" system based on
> > sensing a drop in pressure wouldn't work. In that system the O2
flow
> > is set below the users
> > normal O2 consumption & then topped up from the bellows add system
> > because if the O2
> > was set too high there would be a continual pressure build up & 02
%
> > increase.
> > You could safely bump up the O2 a tad as it would be safer to have
too
> > much O2 than not
> > enough. This, as Jon said wouldn't matter much because your time
would
> > be constrained by
> > decompression tables, & there would be enough air in the hull to
> > breath from.
> > So in a life or death emergency you could take several air tanks
into
> > your hull & a set of
> > dive timetables, open the tanks by hand at the 250ft mark & go to
> > 400ft.
> > Alan
> >
> >
> >
> >
>
>
>
>
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