OP
dkktsunami:
Can you explain this a little more to me?
Thanks
Suunto Vyper questions
- Thread starter jim2386
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Can you explain this a little more to me?
Thanks
The Cobra and the Vytec (the two the above poster referenced) are "air integrated" units (HP hose is connected to computer in the case of the Cobra, and hoseless transmitter in the case of the Vytec), so they measure tank pressure and compute SAC from your gas usage during a dive. The Vyper is not an air integrated unit, so it won't calculate your SAC. IIRC, if you use the Suunto Dive Manager software, it can roughly calculate your SAC if you input your tank size and starting pressure into the dive log.
All you need to figure your SAC is your average depth, time and volume used.
SAC = volume used / (pressure-at-avg-depth * time).
Knowing those 3 numbers (which the Vyper will record for you), you can calculate your SAC over the entirity of the dive.
I believe that's what Suunto meant. Now a Vytec, Cobra or D9 will be able to tell you what you SAC has been over the past minute say or whatever time interval they use.
SAC = volume used / (pressure-at-avg-depth * time).
Knowing those 3 numbers (which the Vyper will record for you), you can calculate your SAC over the entirity of the dive.
I believe that's what Suunto meant. Now a Vytec, Cobra or D9 will be able to tell you what you SAC has been over the past minute say or whatever time interval they use.
OP
Boy I feel really dumb. I guess I've never had to calculate my SAC. Heck I just found out it means surface air consumption. The only reason I could see to calculate it was to see how long the tank would last at a certain depth. But why would you want to know? Evidently in order to get it if I understand you guys correctly, you dive and the vyper calculates your average depth. It also will give you your total dive time. If you know your starting and ending pressure you know how much PSI you used so you could calculate your SAC AFTER the dive. Why would I want to know how long the tank should last after the dive? Wouldn't it be nice to know beforehand?
You guys are all probably banging your heads...bear with me! I'm always up for learning something new
Jim
You guys are all probably banging your heads...bear with me! I'm always up for learning something new
Jim
SAC is useful as a gas planning tool, but you have to determine what it is before you can use it. SAC will also change based upon conditions, stress, your fitness level, and any number of other variables. Not all divers plan a dive as "60 feet until the first of us hits 800 psi, then we surface."
Over a series of dives, calculate your SAC and record it in your log. Also, record temperature, diving conditions, your level of fitness, exposure protection, and stressors during the dive. After many dives, you start to develop a baseline for what your gas consumption is like in varying conditions.
Once you have determined your SAC for the various diving conditions, you can then plan how much gas to bring with you for a particular dive. Say, for example, you want to dive a wreck at 110 feet in cold water with heavy current, you want to stay "X" minutes on site, and you're diving thirds (1/3 for descent and ingress, 1/3 for egress and ascent, 1/3 for your buddy in case his equipment fails). If you know your SAC for the stated conditions (and your buddy's SAC in this case), adjust it for the planned depth and determine your gas needs. You can also use SAC to determine turn pressures (tank pressure reading at which you terminate the bottom of the dive and start to ascend), and can analyze your consumption on the fly to determine whether you need to revise the dive plan. If you need 250 cubic feet of gas to safely make the planned dive, you drag out your doubled 104s or 108s and carry a stage. If you don't have doubles or stages, you rethink and re-plan the dive. Or don't do it at all. Or better yet, buy a set of doubles.
Hope that helps.
Over a series of dives, calculate your SAC and record it in your log. Also, record temperature, diving conditions, your level of fitness, exposure protection, and stressors during the dive. After many dives, you start to develop a baseline for what your gas consumption is like in varying conditions.
Once you have determined your SAC for the various diving conditions, you can then plan how much gas to bring with you for a particular dive. Say, for example, you want to dive a wreck at 110 feet in cold water with heavy current, you want to stay "X" minutes on site, and you're diving thirds (1/3 for descent and ingress, 1/3 for egress and ascent, 1/3 for your buddy in case his equipment fails). If you know your SAC for the stated conditions (and your buddy's SAC in this case), adjust it for the planned depth and determine your gas needs. You can also use SAC to determine turn pressures (tank pressure reading at which you terminate the bottom of the dive and start to ascend), and can analyze your consumption on the fly to determine whether you need to revise the dive plan. If you need 250 cubic feet of gas to safely make the planned dive, you drag out your doubled 104s or 108s and carry a stage. If you don't have doubles or stages, you rethink and re-plan the dive. Or don't do it at all. Or better yet, buy a set of doubles.
Hope that helps.
hoopstar2323
Registered
love my vyper. one thing to consider is the conservative nature that all suunto computers contain. now i know i dont mind being safe especially with my experience level but some people really prefere to be able to set their own limits, and suunto is on the very conservative side of the spectrum. have fun be safe.
Scared Silly
Contributor
The new Suunto (Cobra 2, Vytec DS, Vyper2) allow you to use the algorithm at 100% or 50% which takes out some of the conservativeness.
OP
hoopstar2323:
When you say conservative...how conservative are we talking. My uncle and I dive with US Divers Matrix master computers (well until mine crapped out.) Are we talking mine would put me in deco maybe a minute earlier or are we talking like 10 minutes difference? I've been to deco and if it's just being on the safe side I can account for that. I just don't want to cut my buddy's dive short by 10 minutes because my computer is putting in a factor of safety of 3 lol
That's probably a very vague question, but maybe someone knows.
wfmiller
Contributor
Suunto's are very conservative, I like that about them. That being said I would not worry about cutting anyones dive short. I have two Cobras and the Vyper and have never had to cut short a dive with my buddy.
hoopstar2323
Registered
its tough to say exactly how much it would be, but ive never had to come up more than 1 or 2 minutes before any of my buddies using different computers.
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