Re: [PSUBS-MAILIST] a 1atm dry sub or a potential coffin?

[Ian Roxborough <irox@ix.netcom.com>]

Hi Robert,

you bring up some very good points about 1atm subs.  But I think you'll
find that you can get into much as trouble with a 'seat of the pants' wet
or dry ambient sub as you can with a 1atm.  In my eyes ambient pressure
subs will always be frought with more risk than the 1atm - do you have a
decompression chamber?

You're happily exploring in your wet/dry ambient sub at 100feet, suddenly
your sub get's caught on fish nets/line/dredger cables/whatever,  the
exit from the vehicle is resticted by the lines, before you can start on
freeing youself the cables/ropes/lines go tight and you are being hauled
to the surface faster than your decompresion chart says you should.  This
happened to a friend of mine who was out diving (no submarines needed) -
the Navy would not allow him access to a decompression chambler (they had
the only decompression chamber for 100s miles and where later successfully
sued for not allowing him access), now his leg's don't work any more, and
he get's to be luck he's a live.

As I see it, the biggest issue with wet/dry ambient designs is once something
has gone wrong you've only got a short rescue time - with a 1atm design,
your rescue time can be as long as you design it to be...  Time will never
be on your side - but you can buy a little (days?) extra with a 1 atm design
(better remember to being enough cat litter for 3 days as well).

As far as psubs being coffins, whether it's a 1atm or ambient doesn't matter
too much if you've planning everything out properly.  The idea of
a 'seat of the pants' design does strike me as having more coffin potental
than any well thought out design.

Wouldn't you have a prelaunch checklist for ambient subs as well?
(It would like of suck to get to the bottom and realize nobody
filled the air flasks....)

Thanks,
  Ian.

On Tue, 23 Dec 2003 23:23:03 +0000
maxxx1@comcast.net wrote:

> Hello All,
> In my opinion,designing and building wet subs or ambient dry subs from the seat 
> of the pants could be a very rewarding accomplishment.However,building a 1atm 
> dry sub is another matter,especially one which decends in excess of 150 feet.Now 
> your dealing with life support in your self contained environment even if its 
> just a bounce dive.Are the O2 and CO2 levels monitered correctly?
> Do you have and use a Dragger tube periodically to confirm the gas meters are 
> working correctly?.If only one person is in the sub and he blacks out because of 
> incorrect gas ratios,then what? Should we carry enough O2 and Soda Zorb to allow 
> for a possible rescue from above in case we are hung up on something protruding 
> from the wreck we are observing and we can't release ourself, mabee if we could 
> see what we were caught on we know what direction or angle to move the sub to 
> release ourselves.Could the rope on the wreck be wound around our propeller,no 
> way, because we remembered to totally encase the prop and shaft in a wire 
> housing.Do we have enough reserve buoyancy to lift the object we are caught on? 
> Can we evacuate the sub after equalizing the pressure from 150 feet? 300 
> feet?,600 feet? Do we need 2 pony bottles to take with us during out ascent to 
> the surface,one air,one a tri-mix with a lable DEEP? What is the record depth 
> anyone ever sucessfully evacuated from a sub?
> If you go really deep say for example over 600 feet,you may as well be on the 
> moon, will you have enough life support for a rescue allowing time for a 
> submersible to be flown in,mabee they can spot our bouy which floated to the 
> surface and is attached to the sub because we decided to build one on our sub.
> Did we decide to spend the $600+ for the underwater phone so we can keep in 
> contact with someone on shore.Did we remember to dress with static resistant 
> clothing in a potentially O2 enriched environment,and are the lead acid battery 
> gasses kept out of the potentially O2 enriched environment cabin? Did we try  to 
> eliminate all gear outside the sub which can snag things and hang us up.How many 
> volts is that switch we are touching while our knees are immersed in water?.
> Did we remember to build an emergency drop weight because we didn't take enough 
> scuba air with us to make up for the extra 70lbs we brought aboard,will the drop 
> weight work when it is burried in mud? over one cubic foot at say 1000 feet 
> depth is how much at  sea level? Did we incorporate any trim weights rather than 
> soft ballast tanks? What will happen when the acrylic window hits a submerged 
> log while we are decending?
> In other words did we remember everything?Do we have prelaunch checklists?
> I hope nobody out there is performing manned test dives,in anything but very 
> shallow water.Do we have a system for sending the sub down unmanned in excess of 
> our maximum dive depth for our test dives? I know we can't think of every 
> eventuality, but lets do our homework and find out whats what before we put a 
> man inside his potential coffin ie: a 1atm dry sub.
> Take Great Care All! 
> Robert Rogala
> maxxx1@comcast.net