Imperial users abroad?
- Thread starter asherlc
- Start date
Please register or login
Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
- Ability to post and comment on topics and discussions.
- A Free photo gallery to share your dive photos with the world.
- You can make this box go away
Scared Silly
Contributor
If one can not convert between metric and imperial one should head back to 5th grade.
3 meters == 10 feet (actual 1 meter ~= 3.3 feet)
1 bar ~ 15psi (actual 1 bar ~= 14.7psi)
C x 2 + 30 ~ F (actual C x 1.8 + 32 = F)
3 meters == 10 feet (actual 1 meter ~= 3.3 feet)
1 bar ~ 15psi (actual 1 bar ~= 14.7psi)
C x 2 + 30 ~ F (actual C x 1.8 + 32 = F)
TONY CHANEY
Contributor
I do not want to be the A%% in this but it really does matter about your buddies gas. Not very often with rec. diving but much needed in tech. diving. GAS MATCHING! i.e. When I was assisting with a full cave class, the student was from Finland and used bars and the rest of us used PSI. We discussed our turn pressures and more importantly, gas matching. You owe it to yourself and your team that everyone knows their turn pressure so there is enough gas available to get your butt back to the surface / exit should something goes wrong.
According to some others in this thread, we should be able to do the math, at least using approximation tricks.
I suck at doing mental arithmetic. In rec diving, it shouldn't be that critical, though. In tech, of course it is.
Kevrumbo
Banned
- Messages
- 5,659
- Reaction score
- 1,366
- # of dives
- 1000 - 2499
Let's see . . .I have a full 200bar tank and normally consume 30 bar in five minutes at 18m depth:
Five minutes elapsed time and I know my SPG should read 170bar -check! It does.
Another five minutes for total Ten minutes elapsed time and my SPG should read 140bar -check! It does.
Fifteen minutes elapsed time and my SPG should read 110bar -check! It does.
Twenty minutes elapsed time and my SPG should read 80bar -check! It does,
and then start a multi-level ascent to the shallows & eventual safety stop. . .
Is it that hard to perform the simple iterative subtraction operation above of remaining gas during the dive? (Hint: It's actually easier to do the mental arithmetic in Metric bar units than in US Imperial psi units).
My gauge set (Suunto) came from the US so it is in imperial units, but have been living in Europe for a number of years. I simply took a sharpie marker and a calculator and did the conversion math for 50 Bar, 100 Bar, 150 Bar, and 200 Bar and then made tick marks around the bezel of my SPG at the corresponding PSI measurements.
If my buddy or a dive guide asks me how much air I have and I am between 100 and 150 Bar I just indicate which ever the needle is closer to...if I am slightly above the 100 bar tick mark I may indicate 120.
In recreational diving the idea of asking someone how much air they have is mostly to ensure they are keeping aware of it and to know when it is time to start heading to the surface. When diving with less experienced divers I will often ask them how much air they have every few minutes as I expect a new diver to burn through their tank fairly quickly. When diving with more experience divers I ask much fewer times...we usually discuss on the surface to indicate 100 Bar (or half tank) and when we have reached our Rock Bottom pressure for the depth we are diving at.
The reality is that for recreational diving it is not critical to know or indicate the exact number of PSI/Bar one has in the tank...a good general idea of tank pressure is all that is needed....in fact most SPGs are not particularly accurate at lower pressures. And one can indicate they have 150 bar one moment and a few moments later can easily find themself at 100bar if there breathing rate increases due to things such as swimming against a current, being overweighted and trying to swim upwards without having added air to their BC to compensate for depth, or just plain being stressed out.
Tick mark your gauge and enjoy....save your cash for more necessary dive related purchases such as a compass if you don't have one, or put it away for when you need to replace your booties, gloves, etc.
-Z
If my buddy or a dive guide asks me how much air I have and I am between 100 and 150 Bar I just indicate which ever the needle is closer to...if I am slightly above the 100 bar tick mark I may indicate 120.
In recreational diving the idea of asking someone how much air they have is mostly to ensure they are keeping aware of it and to know when it is time to start heading to the surface. When diving with less experienced divers I will often ask them how much air they have every few minutes as I expect a new diver to burn through their tank fairly quickly. When diving with more experience divers I ask much fewer times...we usually discuss on the surface to indicate 100 Bar (or half tank) and when we have reached our Rock Bottom pressure for the depth we are diving at.
The reality is that for recreational diving it is not critical to know or indicate the exact number of PSI/Bar one has in the tank...a good general idea of tank pressure is all that is needed....in fact most SPGs are not particularly accurate at lower pressures. And one can indicate they have 150 bar one moment and a few moments later can easily find themself at 100bar if there breathing rate increases due to things such as swimming against a current, being overweighted and trying to swim upwards without having added air to their BC to compensate for depth, or just plain being stressed out.
Tick mark your gauge and enjoy....save your cash for more necessary dive related purchases such as a compass if you don't have one, or put it away for when you need to replace your booties, gloves, etc.
-Z
Last edited:
Similar threads
