Thread: Diving Depths
View Single Post
Old 04-01-2009, 07:51 AM
jester jester is offline
Registered User
Join Date: Sep 2008
Location: Equaly at home in the water, the mountains and the desert.
Posts: 919

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.


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


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.
"God bless America, the land of the free, but only so long as it remains the home of the brave."
Reply With Quote