Standard vs Metric

[gcarter]

When I did my first few dives, my rental gear was imperial. As soon as I bought my own gear, it was metric all the way. My observation of other divers around Vancouver is that imperial is more common. Perhaps it is because of our proximity to the USA.

An interesting note - Canada went metric in 1978 (I think). I only learned metric in school so I tend to think in metric. My wife, 9 years older than me, learned mainly imperial in school so she still thinks in imperial. I am trying to convert her

Sounds about right. I finished high school in 1976.

 

[billmas]

Akimbo - you are scary brainy ... I always feel stupid after reading posts like this from you. A friend of mine that I did a couple of reef boat dives with was shocked that I could set the O2% on my computer . He said " You commercial divers always have some guy doing that S**t for you". I laughed ... but I am not so far from that. I am techno illiterate.

I disagree. Whilst the numbers may be accurate, I question their usefulness on a "New Divers Forum". For the purposes of shallow, recreational diving, 1 bar = 1 atmosphere. 1 bar = 15 psi etc etc.

There are undoubtedly situations where accuracy to 10 decimal places might be helpful, but I doubt it is on this forum. I imagine they would serve only to startle the average new diver.

Regards
bill

 

[DuboisP]

easier than converting Tank volume by psi to liters
just playing with 32, 9 and 5.

do you really need more precision in Temp when diving ?
i have at least 1°C of difference between my 2 computers;
I will switch them to farenheit, one day, to see if the difference will be 1°F

 

[RTee]

Notwithstanding what has been said by others, do not sweat the small stuff. I first got certified in 78 in Quebec(Canada) and I have been using ft, psi and Fahrenheit since that time when it comes to diving. However, I would have no problem using metrics if I had to.

Based on my personal experience, DMs are really looking for specific triggers when it comes to gas remaining such as half tank and reserve. Knowing that a standard AL 80 cft tank is full at 200 bars (3000 psi),then half tank can easily be established at 100 bars (1500 psi) and reserve at50 bars (750 psi). If he wants additional or different triggers then you folks can set them up prior to diving. If both are using the same units of measurement, it becomes a moot point because you revert to the briefed number. If using different units, then just revert to the ratio I described earlier for the proper hand signal.

Gas consumption(RMV/SAC) vs gas management: Historical numbers are really only good to provide you with ball park figure for planning purposes ie howmuch gas should I carry or how long will this tank probably last me based onthe dive profile I have in mind. Having said that, one of the first things you should do once established at the desired depth is to initiate a gas consumption calculation base on a five min period. It does not matter if you do so in bars orpsi…as it is simply a quantity you derive and then based on how much you have left before reaching the minimum you established to support your ascent and so forth, you should be in a position to come up with how long you should be goodfor at that depth from a gas perspective. Tables and dive computer will provide you with NDL.

Depth vs dive computer set-up: Nowadays most brands,if not all, provide you with the option of choosing between metrics or imperial as part of the set-up menu. I leave mine to feet because really what is of interest to me is…NDL remaining. If the DM briefs meters then I can easily get the equivalent in feet just by multiplying by 3.3 and I can then quickly check the associated NDL by either consulting my imperial dive tables or using the dive planner function of my dive computer.

Temperature…(C X9)/5 + 32 = F or vice versa.

Bottom line, usewhatever you are comfortable with as there are easy ways to derive the equivalencies that may be of interest to you for comparison sake.