How deep is 3 bars
by
thenewage
How deep is 3 bars and could you use a
watch that is limited to 3 bars for any serious diving?
ScubaDivingFanClub Answer:
The answer to your question is: 3bars = 20 meters or 66 feet.
Now we will explain how we came up to this response.
A French philosopher and scientist named Blaise Pascal demonstrated that
the pressure applied by the atmosphere at sea level is equal to the
pressure applied by approximately 10 meters / 33 feet. It means that
for each 10 meters / 33 feet of sea water, we will have to add 1
atmosphere.
When doing calculation on depth and the pressure we
have to take into account that at the surface there is already one
atmosphere. And also to get to the measuring system you feel
comfortable with you have to know that 1 ATM=1.01 BAR and to make it
more simple 1ATM=1BAR.
Depth 
Pressure 
0 
1 ATM/BAR 
10M/33F 
2 ATM/BAR 
20M/66F 
3 ATM/BAR 
30M/99F 
4 ATM/BAR 
40M/131F 
5 ATM/BAR 
50M/164F 
6 ATM/BAR 
60M/197F 
7 ATM/BAR 
70M/231F 
8 ATM/BAR 
80M/264F 
9 ATM/BAR 
90M/297F 
10 ATM/BAR 
100M/330F 
11 ATM/BAR 
150M/495F 
16 ATM/BAR 
200M/660F 
21 ATM/BAR 
Continuing with an answer to your
question  to take a watch
for recreational diving, these watches must be at least minimum
50M/164F or 6 ATM/BAR water resistant.
But I have a little story
for you: I was doing a deep dive (30M/100F) with students doing PADI
Advanced Open Water, and my diving watch had no battery. I needed a
watch just to take the time of the dive and for the mandatory 3 minutes
safety stop.
Going to work that day I decided to buy a cheap 100 meters digital
watch just until I replace a battery in my diving watch.
Everything
went well on the deep dive until we started the safety stop, I looked
at that cheap peace of …100M watch and the crystal was gone, the watch
filled up with water and I had to rely on one of my student’s watch for
the safety stop and dive time.
Most watches have a 200 meters
water resistance. I guess the following proverb applied to my purchase:
"you get what you pay for".
Thank you for visiting our web site.
We hope this answers your question and feel free to send any additional
questions or concerns.
Have fun diving, Sincerely:
ScubaDivingFanClub
Where Scuba Divers share their passion.

Some corrections have being made
We
would like to thank our "Anonymous” visitor for his/her comment (see
comment below). Yes there is some misunderstanding when we were trying
to explain Blaise Pascal demonstration of pressure applied by the
atmosphere. We will try to clarify and make it easier for our visitors
to understand.
A French philosopher and scientist named Blaise
Pascal demonstrated that the pressure applied by the atmosphere at sea
level is equal to the pressure applied by approximately 10 meters / 33
feet. It means that 10 meters / 33 feet will be equal to 1 atmosphere.
Statement:
It means that 10 meters / 33 feet will be equal to 1 atmosphere.
Clarification:
It means that for every additional 10 meters / 33 feet of sea water, we
will have to add 1 atmosphere.
Since at sea level, 0 meter / 0 feet = 1 ATM/BAR.
At 10 meters / 33 feet = 2 ATM/BAR
Hence, at 20 meters / 66 feet = 3 ATM/BAR
Hope this helps.
ScubaDivingFanClub
Where Scuba Divers share their passion.
Visitor's comments
May 07, 2010

Your math sucks! 3x33 does not
= 66. haha
by: Anonymous
Your answer to his question that 3 bars= 66 feet is wrong when you
state in " How you got this" it shows 1 bar / ATM (atmosphere) equals
33 ft. Well 3 ATM multiplied by 33 ft as shown in your shart below
equals 99ft., not 66ft. 

To the guys who didn't get it. (who said your math sucks)
by: Anonymous
Actually he has it right. At Zero(0) depth as in when your head is above the water you are at one(1) Atmosphere. Once you go down 10 meters/33 feet that is equivalent to having another atmosphere above you, adding up to a total of two(2) atmosphere. When you see the chart (See Below) maybe it'll help me explain better.
So 3 Bars = 20m/66F = 3 ATM/BAR
Bar Depth Pressure
1 0 1 ATM/BAR
2 10M/33F 2 ATM/BAR
3 20M/66F 3 ATM/BAR
4 30M/99F 4 ATM/BAR
5 40M/131F 5 ATM/BAR
6 50M/164F 6 ATM/BAR
7 60M/197F 7 ATM/BAR
8 70M/231F 8 ATM/BAR
9 80M/264F 9 ATM/BAR
10 90M/297F 10 ATM/BAR
11 100M/330F 11 ATM/BAR
12 150M/495F 16 ATM/BAR
13 200M/660F 21 ATM/BAR