Diving Suits

* See also Real Physics
* See also Big Daddy
* See also UnderWater_Construction
* See also Depth
* See also Maintenance
Do a Pressure Graph of under water ( one atmosphere every ~30 feet ) - the Hypoxia pix though illustrated that spectrum of effect.
The "Death Zone" for Divers ... 150-200 feet ( That range of Depth is above what the TOPS of Rapture's building need to be at to avoid being sheared off by icebergs. )
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Canvas Diving Suits - Used for shallow depths down to ~200 feet ( 'Scuba' gear only being developed post WW2 )
Modern Hardsuits - Required for greater depths ( 'Atmospheric diving suit' allows very deep dives of up to 2,000 feet )
Scuba Gear - Similar limitations to the canvas suits ( with ambient pressure acting upon the body )
BD Suits - Big Daddies ( wearing similar to canvas suits ) use ADAM abilities to handle pressure changes
Saturation Diving - Using esoteric gas combinations avoiding Nitrogen ( Heliox, etc ... )
Early Attempts - Breathing an Oxygenated Liquid 
Systemry Involved for realistic Deep Diving : the complexity adds expense, risk, inflexibility ( reason why they made the Big Daddy/Sea Maintenance Cyborgs )
The BendsThe Bends : https://www.emedicinehealth.com/decompression_syndromes_the_bends/symptom.htm - One of the things which can kill you when deep water depths are involved in Diving - rising (decompressing) quickly has bubbles form in your blood system. Painful - causes the subject to 'double over' in pain ( "Bends" - bending over in extreme pain ).
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Standard Diving Suit - It Is NOT A (Modern) Atmospheric 'Hard Suit' 
* "The standard diving dress has been used to depths of 600 feet" of sea water ( which would be the base depth of Rapture's seabed area and where divers are expected to operate ). That very deep depth would not be routine and would be only for short lengths of time ( and likely only in great desperation ).
* Some City construction could be carried out using this simpler (but riskier) technology at its depth limit of safe capability ( The diver is subject to Nitrogen Narcosis beyond 100 feet ). 300 feet is the normal 'safe' limit for a 'limited time at depth' ( Shallower - is the more typical non-emergency/routine application ).
* Diver impairment varies with the individual ( and some training can overcome some disorientation/dizzyness ).
* Special gasses can be used to lessen effects, but start to surpass the cost of Hardsuit technology.
* A 600 foot depth requires pressurizing to near 13 atmospheres (~280 psi), with severe effects for anything longer than short durations ( Divers frequently die from going to 400+ depths ).
* Would be more useful at significantly lesser depths (100 - 200 feet) - like the industrial zone on Mt Ryan.
* Hard Suits would have been used for Foundation work depth in Rapture.
* Big Daddies/Maintenance Daddies use liquid filled suits ( and the occupants have Plasmids/Tonics/genetic modification ) so that they can resist much greater depths ( 3000 + feet ) without being in a technically complicated 'Hardsuit' type diving rig. Such ADAM 'mods' did NOT exist yet when most of Rapture's Construction took place.
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Real Diving Suit of the Type Modified For Big Daddy :
"Standard Diving Dress" first developed in the 1820s and 1830s, predominating into the era of the Aqua Lung ( divers wearing air tanks, developed Post-WW2 ).
Rubberized canvas ( rubber sandwiched between cotton twill Canvas ). Other stronger 'clothish' materials might be used, but they cannot be too stiff, and need to resist salt-water corrosion and puncture. Metal ring seals are used for limbs and head, but dont require strong pressure sealing ability.
The Air is pumped into the suit thru a tube from a compressor on the water surface. The air pressure was kept at a slightly higher pressure than of that of the depth's water ( so the air would not be squeezed out of the suit, and the body pushed into the helmet ). The interior of the suit always is regulated to be kept at a slightly higher pressure than of the waters. The diver can breath normally at that pressure within the inflated suit. The diver is subject to 'The Bends' ( and other pressure related effects ) at any deep water pressure encountered. 
Generally, they (normal humans) did not dive in those suits much below 100-150 feet for any length of time ( otherwise they would face Nitrogen narcolepsy/nitrogen narcosis ).
Weights were added to the suit which were sufficient to offset the suit's buoyancy, which made them clumsy and burdensome. You effectively were slogging around with an encumbrance the equivalent of the suits volume filled with water. Some of the weights were on ropes which could be cut with the diver's knife to quickly bring the diver to the surface in an emergency. Normally a cable hoist umbilical was used alongside the air tubes, and often divers had a phone line inside the suit connecting to the crew above.
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Big Daddy Diving Suit :
Canvas - Not the greatest material to block bullets - Maybe the BDs had some limited regenerative capacity and or resistance to damage trauma.
The damage resistance might be similar to the Brute Splicer's, but with the thicker covering and some projectiles might bounce off the various metal bits ( covering 1/3 their surface ? )
The Big_Daddy suits are heavy and with the over-sized helmets and devices on the back ( which real human divers did not have, as their air supply/pressure is pumped thru an air tube from surface/elsewhere ... ) do add even more weight ( add also tools/weapons ). They would require a lot of strength to carry all that outside of the water. 
So it is likely the BD needed a combination of Brute strength Plasmids/Tonics, as well as handling Pressure changes. The Pressure differentials varied from sea level (1 atmosphere) to beyond the 600 foot depth I estimate as typical for Rapture environs ( about 19 atmospheres ). So some additional Big Daddy Plasmid/Tonic enhancements would allow them to work at that pressure and much deeper -- and survive constant pressure transitions back into 1 atmosphere when re-entering Rapture ( via Airlocks ) -- which is when you would get "The Bends" ( Bubbles forming in your blood - Embolism when the pressure is quickly lowered ) and die horribly.
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==Hard_Suit==
Diving Hard-Suit :
Diagram : http://img841.imageshack.us/img841/2103/divinghardsuit.png
Used for depths in excess of 100 feet for non-modified human ( no 'depth' Plasmid or Big Daddy modifications )
Above that depth the conventional diving suits and scuba gear can be used ( with the required timed ascent schedule because of the pressurization ).
Typical Rapture Diving Hard-suits were sufficient for depths to about 1000 feet ( usable for all city construction ). The diver is kept at 1 atmosphere air pressure ( suit holds out the massive water pressure ) so diver may exit the suit immediately ( no depressurization delay ).
Equipment :
* Work Lights on chest ( half a percent of the Ocean surface light reaches a depth of 100 meters (330 feet) )
* What is that over the shoulder thingee ?? Spotlights or camera (or both). Probably not a gun.
* Air tanks to keep a diver going for many hours, if Oxygen for even longer.
* Utility recharge hookups ( battery charging, air charging, fuel charging for hydraulics )
Weight ~850 lb including the diver ( to achieve near neutral buoyancy ), hydraulic assist would be useful to move that mass. Pressure at 1000 ft down is 31.3 atmAtmospheres - measure of Pressure defined by air pressure at Sea Level - ~14.7 pounds per square inch (459 psi) which takes thick steel construction and carefully fitted joints to keep the water pressure out. That special advanced material 'Ryanium' might be used, but the required structure is still bulky and cumbersome.
You can see why alot of the construction was done from the mini-subs and structural sub-assemblies were assembled near the surface ( < 100 feet on the shallow side of Mt Ryan) when possible to allow use of simpler conventional diving suits. Even with the thousand-odd construction workers much of the Construction was done with machinery ( and Hard-Suit Diving is a specialized skill ).
The construction scenes depicted in Ryan Amusements Rapture Memorial Museum are men wearing the conventional diving suits and thus are at a fairly shallow depth. The concept art had them wearing Big-Daddy-like hard-suits. []
Advanced deep hard-suits can protect the diver down to more than 3000 feet depth (Abyss depths), but are much bulkier (weigh more), complex (more maintenance), and have much more restrictive movement ( Example - claws instead of gloved hand for manual manipulations ). One advantage to the bulky deep hard-suits is that you can pull your arms in to scratch your nose while wearing it.
Later Plasmid-assisted divers may have been able to use the conventional diving suits ( via a Depth Tonic ) and used simpler hardsuits without hydraulics (strength tonics) and possibly go to the Abyss depths without the complicated deep suits. But for the city's construction there were no ADAM enhancements yet existing.
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Diving Suits (Hardsuits) Used As Tools ( Players have access, own or borrow ) :
Players usually aren't Big Daddy mutants, so cannot use the Canvas and Brass Big Daddy diving suits. So 'Hardsuits ...
* Require recharging both compressed air and batteries. The infrastructure needed to support the unit must be brought along when the unit is deployed at a remote location ( ie- in 'the Border' where external building repairs are being done ).
* Heavy enough to requires a small crane to lower you into water ( volume of suit displaces something like 850 lb water and to have near neutral buoyancy -- it has to weigh about that ).
* Human diver units must've had power assist hydraulics ( The suit Jack put on must've (?) had these hydraulics - They shoulda had Tenenbaum have him find 3 or 4 'Sports Boost' Plasmids as part of that game sequence ).
* Big Daddies and Maintenance Daddies have the genetic modifications that give them the strength required ( will have to talk about how many calories they burn ).
* The suit has to be stored someplace when not in use ( bulky and along with all the support equipment ).
* Heh - A scenario for Player who finds an abandoned 'Diving Suit', and then figures out that they can't move it by themselves and have to leave it ...
* The shear bulk/encumbrance/unwieldiness of suit out of water makes sure it cannot become a loophole being used in 'battle'. Underwater on the other hand ...
* The suit has to be maintained.
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Artificial Gills - Hmm, Doesn't Sound Promising ( For Machine Or Even Plasmid ):
http://en.wikipedia.org/wiki/Artificial_gills_(human)
Major factor is the huge amount of water that has to go thru the 'gill' system to exchange enough Oxygen FROM the water ( and 'CO2' TO the water ). Fish, because they are cold blooded, have a slower metabolism, so they can deal with a slower intake of Oxygen ( Remember that saying about Sharks having to 'Swim or Die' - That has to do with processing enough oxygen with the amount of water passing over their gills ).
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My Big Daddy Hunt Trophy Room :
 
With a few of the more unusual ones
 
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Real Diving Hard Suits :
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Diving Technology 1930s - Though the Brass and Canvas Suits were already existing - Better designs and improvements were still being made.
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