Wisdom-2 Liberal or Conservative???

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cjbikes

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Location
Miami, Florida
# of dives
500 - 999
Greetings...

Wanting to purchase a dive computer, but one with a Liberal Algorythm.

A friend has a Suunto Cobra, however he tells me that it's very conservative, that I should look into the Sherwood or the Oceanic.

Can you share between the three of you manufacturers, which would be more liberal in bottom time...for example, could you give me how much time does the Sherwood allow at 100 feet???

Thanks,

CJ
 
Sherwood and Oceanics are made by the same company, Pelagic Pressure Systems. Most of their computers are rather liberal in that they implement the DSAT/PADI deco model (which is what the PADI table is based upon) without any additional conservatism.

You can easily add additonal conservatism by choosing how far you are willing to push the N2 loading bargraph and/or how far into the yellow you are willing to surface.

You can get the Wisdom 2 manual at Welcome to Sherwood Scuba! , but it requires registration. I haven't registered so I haven't verified it, but if it is like other Pelagic computers, the Wisdom 2 NDLs are very close to those of the PADI table.

The Suunto Cobra manual can be found at http://www.suunto.com/suunto/main/index.jsp under the Customer Service | download area.

Charlie Allen
 
With air the NDL is 19 minutes at 100', 16 min at 110', 13 minutes at 120' and 11 minutes at 130' and in the extreme, 5 minutes at 190'.

In essence, the limits are just a bit less than US Navy table limits and are consequently, liberal by computer standards.
 
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Charlie...

Wow...great detailed information about the puters, you've helped me make up my mind as I read your response.

Thanks again,

CJ
 
AM...

And to you as well, thank you for the other detail which I was looking for as well, this simply zeroes it down for me. As I had mentioned originally, I've doved with a couple of buddies using Suunto and Cressi, and both are very conservative, and they're always wanting to come up sooner than later...I much prefer a liberal puter which has closer limits to the regular tables.

Thanks again,

CJ
 
Well i have a Wisdom and my girl has the cobra 2 so here is the difference i have found between the two.
With her cobra set at the most possible liberal setting, there are differences of a few minutes bottom time. I find the conservatism of the cobra comes more into play on the way up.
If you pass the recommended accent rate you will be penalized with an extra mandatory stop besides your regular safety stop. and also once you finish your safety and ascend to fast it will give more mandatory time so you will have to go back down and do time. Also if you pass your deco time you will be penalized on your safety stop with mandatory time.
On our safety stop my girl always has a minimum of and extra minute of time to do and some times more. The biggest difference was four minutes besides the safety stop.

The scariest time we had was at Cozumel when she had to do three minutes of mandatory time then three minutes safety and on the way up from safety she was penalized one more minute and had to go back down. Mean while we were seeing the boat ladder go up engines start and move then stop. The boat was anxious to leave because of the storm brewing at the surface but other divers on board (who we just met on board)realized we were not on board and warned the crew. This is when i realized that to conserative can have its pros and cons.
 
The scariest time we had was at Cozumel when she had to do three minutes of mandatory time then three minutes safety and on the way up from safety she was penalized one more minute and had to go back down. Mean while we were seeing the boat ladder go up engines start and move then stop. The boat was anxious to leave because of the storm brewing at the surface but other divers on board (who we just met on board)realized we were not on board and warned the crew. This is when i realized that to conserative can have its pros and cons.
That's it in a nutshell.

When I went with a trimix computer I selected one on the advice of an experienced off shore diver who articulated the need for a computeer that is set you get you out of the water in near minimum time in the event you absolutely have to in case the weather blows up, etc.

You can always ascend a bit slower and linger longer at a safety stop than the computer advises, but you cannot tell a computer set on uber conservative mode that you really need to get out now as it will still consider it a violation.

My Cochran allows conservatism settings from 0% to 100% and on 0% it gets you out of the water faster than just about anything else on the planet. For recreational diving I tend to set it in the 30% range and then adjust up or down (usually up to 35%-40% to match the dive buddy's computer so I have a good idea where they are at in terms of NDL's.

In that regard a conservatism settings on a computer can be used to keep two different computers in the same ascent time required ballpark instead of having two that differ greatly.

On decompression dives, my computer is a back up to a computer generated plan on a slate anyway so I set it at 10% to give me a pretty fast trip to the surface if for some reason I have to abort the dive and need to surface quickly or if the weather is closing in.

On many computers, you have a tissue loading bar graph that allows you to see where the controlling compartment is in terms of a red zone (deco), yellow zone (caution-but ok to surface), and green zone. If you have one, you can leave a computer offering adjustable conservatism at a liberal setting and then build conservatism back in by slowing your ascent and adding some time with a slow ascent from 20-30 feet with added time at the safety stop to let the tissue loading bar graph get farther down into the yellow or even into the green.

That approach, combined with using conservatism settings primarily* to match a much different computer in use by a buddy makes more sense than automatically defaulting to an overly conservative setting.

*Deco theory is just theory and your need for conservatism should be driven by your own particular body. If you feel overly fatigued or achy after a dive or series of dives, increase the conservatism a notch on the next diving day. If you then feel better after the next series of dives, make that the most liberal setting you use.

One cautionary note regarding you and your sig other's computers. Your more liberal computer is obviously putting hers into deco mode if it is requiring an additional 4 minutes beyond a normal 3 to 5 minute safety stop. I'd suggest three things:

1. Increase the conservatism of your computer. You can force any nitrox computer to act more conservative even if it is non adjustable by setting a lower nitrox mix than the one you are actually using one, you just have to be aware that any mod warning will be innaccurate so you have to know the shallower MOD of the mix you are really using.

2. If you tend to have longer bottom times, be sure to gear up early and be the first couple off the boat, then with the longer bottom time, you may be the last couple back on the boat, but you will be right behind the other divers and will not be holding up the show. Being slow getting off the boat and then going long on the bottom time is both inconsiderate and annoying to others and as you found out, potentially dangerous.

3. If you do deco dives, get training in deco procedures and configure accordingly with the required level of redundancy and gas planning. Also consider an advanced nitrox course and using a slung 30 or 40 with 50%, 80% or 100% 02 for a deco gas along with tables or a two or three gas computer like the Nitek Duo/Tusa IQ-700. It will get you out of the water cleaner and much faster.
 
That's it in a nutshell.


1. Increase the conservatism of your computer. You can force any nitrox computer to act more conservative even if it is non adjustable by setting a lower nitrox mix than the one you are actually using one, you just have to be aware that any mod warning will be innaccurate so you have to know the shallower MOD of the mix you are really using.

Hi DA Aquamaster,

...also, by 'tricking' the computer by programming in a 'bogus' NITROX %, you're messing up the computer's ability to properly track 'oxygen toxicity', I'm not sure this is a good idea.

...for what it's worth, when I set my Cochrans ( (1)EMC-20H and (2) AI GEMINI'S ) to a '25' conservative rating, they seem to track well with my (4) Oceanic Datamax Pro Plus II's...which is what I want as I see absolutely no point in diving computers providing substantially differing information/deco 'schedules'.

Karl
 
.....I've given my dive buddy one of my Oceanics to dive, and she gave her Sunnto AI computer away...her Sunnto was giving her way shorter dives, needlessly, so now we're both 'on' Oceanics/Cochrans...all I can say is Sunnto makes great computers for snorkeling ! :D

Karl
 
FWIW I have a completly different experience with the Wisdom and the Cobra 2. Before I switched from my wisdom to the Cobra 2 I dove them together so I could compare the NDL. With the Cobra 2 I did set the RGBM to 50%. Every dive the Corbra 2 gave me more bottom time than the Wisdom. In fact I put the Wisdom into deco a couple times while the Cobra 2 was still alowwing a few minutes bottom time. After this real world test I have had a hard tme understanding why the Suunto is supposed to be more conservative. The only thing I have been able to confirm is that Suunto will reward or penalize a diver for a good or bad profile/accent rate.
 
https://www.shearwater.com/products/peregrine/

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