Diving Depths

[General Pain]

Well I'm doing some scuba research for my next merc mission, and I was hoping anyone could provide me with a list of :


depth - gear - acciliary gear
1 - 5m none or snorkel - none

etc

so what depth would u need an auxiliary pressure chamber or whatnot etc....after u are back on land/boat

[headquarters]

Thats a question of nitrogen saturation in the blood - and that depends on the TIME you have spent on the DEPTH as well as the DEPTH alone .

At say 2-3 meters you could probably stay under for 90 minutes without other precautions than a cold beer waiting in the boat .But as depths increase , the safe -time on the depth decreases and decrompession times increases . (The need to gradually re-surface ) .

You should go to a diving site to check this out too..

Originally Posted by General Pain

Well I'm doing some scuba research for my next merc mission, and I was hoping anyone could provide me with a list of :


depth - gear - acciliary gear
1 - 5m none or snorkel - none

etc

so what depth would u need an auxiliary pressure chamber or whatnot etc....after u are back on land/boat

[General Pain]

Originally Posted by headquarters

Thats a question of nitrogen saturation in the blood - and that depends on the TIME you have spent on the DEPTH as well as the DEPTH alone .

At say 2-3 meters you could probably stay under for 90 minutes without other precautions than a cold beer waiting in the boat .But as depths increase , the safe -time on the depth decreases and decrompession times increases . (The need to gradually re-surface ) .

You should go to a diving site to check this out too..

well it wasnt actually that I was looking for -

I was more interested in the various equipment needed forvarious depths -

[jester]

Dive phsyics has alot of stuff.

Like Time at Depth

How many other depths you have been that day, how much time topside you have in between and all of that.

As a very general rule one can stay 60 minutes at 60 feet without worry of any decompression.

Remember, for each 10m <roughly> you double the atmospheric pressure.


For gamming purposes 30 feet and under it is a long time without worry of "THE BENDS"

As for gear:

You have the following types:

Compressed air, the traditional method of diving. The standard tanks are 80 cubic feet aluiminums and 72 cubic feet steel tanks. <that is how much air they hold> How long they last varies according the persons phsycical condition, how deep they are, how hard they are working like hauling alot of gear, swimming all out or fighting a current. Each tank will last about an hour to half an hour at between 30 and 60 feet. Again a rough time limit.

Oxygen Enriched Diving or Nitrox: I am not too familiar with this system, it lasts longer and extends your bottom time and reduces your decompression I THINK. This is a mixed gas though, special equipment is needed to fill the tanks so this will not be available everywhere.

REBREATHER; WWII tech and all the highspeed SEAL stuff it is now available on the open market, it takes about 3000-5000 to purchase and that is just the system, not the tanks or other gear that is specialized to it. It uses a bottle of oxygen that is used to reconstituite the air you have already breathed into a tank that filters out the Co2. These can last about 4 to 6 hours, again depending on activity level, condition and depth.

Next:

Wet suite or dry suite so you do not get hypothermia or just end up numberand shivering when you hit the beach.

MASK and SNORKEL

Weights and weightbelt <the human body is bouyant, as is the wetsuite and air tanks, you need roughly 1 pound of led per 10 pounds of body weight> Otherwise you will have to fight to keep submerged and it really won't work to well.

FINS and BOOTIES. Some fins allow the use of regular boots, this can be stressful on the feet if swimming long distances. Or the slip on fins that do not require fins, good for warm water with nice sandy beaches, overall though, not recomended.

Scuba Tanks with a BC and Harness <Buyancy compensator, or tank pack. A Boyancy compensator is an inflatable life jacket looking thing used to stay afloat on the surface, they also have pockets for gear and a built in backpack for your tank> Or you can use the "HORSE COLAR" this is a round inflatable ring that goes around the neck like the old pilots inflatible vests, with these you need a backpack for your tank. Most tanks are carried singly, although they do have twin tank set ups, I can honestly say I have only seen them used once and I have never used them.

Dive knife; there is alot of fishing line, cordage, seaweed, kelp and netting on the bottom of the sea.

REGULATOR: this is the line that connects to the tank and goes to the mouthpiece in which you breathe from. VERY IMPORTANT! These come with at least 2 dials on them, a pressure gauge that tells you how much air is left in the tank. The second guage has a depth gauge that tells you how deep you are. It also has a needle that marks the deepest depth you have gone. Alot of them also have a 3rd dial a luminesent compass so you can do underwater land navigation which is VERY IMPORTANT since underwater visibility varies.

Flashlight; this is helpful when operating at night, or you end up with holes, caves or wrecks.

Dive Tables: this is the waterproof chart that tells you how long you can stay down and how deep after figuring the data from prior dives.

Undersuite: This is a comfort item, normaly a thin nylon type body suite you wear under your wetsuite which helps you stay warm, keeps sand out of every crevice and crack, and makes it much much easier to put on and take off your wetsuite <they are difficuilt to get on or off when wet>

Wetsuite usualy consists of: Top with long sleeves, trousers that are called OVERALLS as they resemble farmer overalls, booties prefferable with hard soles for walking on gravel and sharp coral reefs <walk on a reef barefoot and you will know!> gloves, alot of sharp shells and coral and other stuff to slice the hell out of your hands, they also burn with cold and go numb after a while. HOOD, again keeps the head warm.

That is the basic gear a diver needs, and all of this is good for about 90 feet down, of course at that depth you are looking at a bottom time of about 5 minutes if you do not want to decompress.

As for decompression chambers; they have small portable ones that are are about 30 inches in diameter and 7 feet long, they are made of a soft colapsible material. And then the ones that look like a large propane tank. However, for operations I would suggest not going to depth where you will have to spend time in a chamber, either sit tight at specific depths decompressing before hitting the surface which can be boring. Or just don't go down and stay down long enough where you have to do it, otherwise you will be wasting time that could be best spend on operations. I mean what happens if you are stuck 30 feet down waiting to decompress and an enemy boat rolls by, you will be hating life.

[Eddie]

General Pain,

Jester's list is pretty accurate. Some nitpicks could be made but nothing warranting any real corrections. Most regulators now have dive computers that erase the need for dive tables. It tracks all dive data: depth, time, date, temperature, Nitrogen loading (absorption by your body), O2 loading for NITROX computers, ascent rate, beginning and ending pressures in some models, and a plethora of other information.

For the record, if his is not substantial to answer your questions, I just received my Advanced Open Water Certification on 22 MAR, and am getting NITROX certified this weekend, and have been diving since 2002. I'm fairly knowledgeable or at the very least know the right people to ask any questions you have.

He was right about NITROX. It extends your time at depth and allows you to go deeper.

By pressure chamber, are you meaning a decompression chamber? And, what context do you mean it in? A dive emergency or we just did our planned dive and we're now mandated to go into the DECO chamber for X hours?

If the first manner, you could possibly need the chamber from an ascent from 6 feet. Likely? No. From 50 feet? Much more likely. From 90 feet? Most likely (which happened to a girl in my Advanced Open Water class).

If you mean the second situation, no recreational dive depth (up to 130 feet) will require time in a DECO chamber unless you exceed the Allowable Bottom Time (ABT). As Jester said, the ABT is significantly shorter at deeper depths.

If your mercs are using rebreathers, they can't go below 33 feet, otherwise the oxygen becomes toxic. Below 33 feet (as in 32, 31, 30, etc, not below as in 90 feet), the nitrogen accumulation in the body is negligible and a person can effectively stay as long as he has air, i.e., your tank or rebreather will stop working before it's a danger to you.

For deep diving, you have some special considerations though. At depth, because of pressure, your air in the tank is going to be smaller in volume and the air in your lungs is going to be smaller in volume. You're going to continue breathing your normal breaths though to your full lung capacity. This means you're breathing more air at the same rate you breathe less air at the surface. Your tank goes faster, in otherwords.

Also, if you want to go below 130 feet, you get into what is called Tec Diving. With Trimix gases you can go well below 130 feet. This is extremely hazardous and requires multiple decompression stops along the way up (requiring surface support stations -- essentially extra sets of gear dangling on a buoy at fixed depths), but I don't know what the threshold for chamber time is. My advice, get something reasonable sounding, like 250 feet, and start fudging something from that.

[General Pain]

I was hoping to simplify the whole ordeal into a basic shematic.

0-5meter
5-20meters
20-100 meters
100+ meters

so what equipment should/could be used at the various depths

It's no problem to divide it into more categories offcourse

but anyway thanx for the help