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Ryanh1801
12-12-2007, 12:20
OK have a quick question. In my open water class, they made a point to say that during cold water dives or strenuous dives you should go to the next time on your dive tables. Im planing on diving over the winter up here in a wet suit so im sure on some of the dives I will be a little cold. Is their a way to put this into the computer? Should I just use my tables and use the computer for backup? Or is it nothing to worry about to much and just use the computer? I have a Mares M2 computer. I could not find anything about it in the manual, but I might be reading over it(not the best instruction manual I have ever seen).

Thanks for any insight. :smiley20:

Navy OnStar
12-12-2007, 12:39
Good question. I'm not sure if my computer will get more conservative based on temp. I know I can put in personal changes for physical fitness and such and that would make it more conservative. I'll have to check my manual when I get home.
If it doesn't and you want to dive more conservative then just come up a few minutes early.

adv_diver1
12-12-2007, 12:47
Unless I am wrong, if you don't have a really sophisticated computer, I am pretty sure the computer will not adjust accordingly for the physiological portion of the equation. I would go with the Dive Tables and use the computer as backup and just stay within the limits of the tables no matter what. Better safe than sorry. I would not trust my life to a computer that is for sure.

MSilvia
12-12-2007, 12:48
I dive in the winter in New England, without a computer, and only worry about the extra conservatism if I'm diving beyond rec limits. I wouldn't lose any sleep over it if you're diving in Texas.

cummings66
12-12-2007, 17:36
I dive year round and don't adjust anything for cold temps. I know I was told in class you should but in practice I have yet to find somebody who does modify. I am pretty sure my dive computer doesn't modify the times based on cold.

wheelman
12-12-2007, 19:42
You might check to see if you can set a personal adjustment on the computer to make it more conservative. That's what I do. Otherwise, use the tables and make your adjustments.

Puffer Fish
12-12-2007, 19:44
You raise an interesting question....

A lot of computers will allow you to change how agressive the profile is...and you can obviously just adjust how much time left on the dive you decide to allow.

Mine, you can adjust a lot of the calculation values, and put extra safety margins in, however, I would doubt they would ever exactly match the same as jumping to the next time group... and doing so means that you would have to remember to put it back..

If you are going to do that, I would suggest just calculating how much less time you want the dive to be and call it at that point...

Ryanh1801
12-12-2007, 19:53
Thanks for all the suggestions guys. Guess if I feel like I get really cold on a dive Ill just use my tables and if not just use the computer. Im gonna read through the manual again and see if I can figure out if there are any adjustments to be made.

CompuDude
12-12-2007, 19:59
The vast majority of computers have settings for extra conservatism. Add a blip of conservatism if you're worried, else don't worry about it.

It's really only a concern (maybe) if you're riding close to the NDLs anyway.

in_cavediver
12-12-2007, 20:12
Stop thinking technically here. Engage your brain! You can and should adjust your profile based on how you feel during each dive and the day in general. If its cold, then don't stay as long. If you uncomfortable, don't stay as long. Just because the computer says you can doesn't mean you have to or that you should!

Computers are like tables, they can only account for time/depth. You have to account for environmental factors yourself. IE, adjust the NDL *you* are willing to stay.

scubajane
12-12-2007, 20:25
Stop thinking technically here. Engage your brain! You can and should adjust your profile based on how you feel during each dive and the day in general. If its cold, then don't stay as long. If you uncomfortable, don't stay as long. Just because the computer says you can doesn't mean you have to or that you should!

Computers are like tables, they can only account for time/depth. You have to account for environmental factors yourself. IE, adjust the NDL *you* are willing to stay.

Thank you!! there is not a formula for everything. some say to not make repetitive dives for more than 4 days without taking a break. We dove in Costa Rica 6 days in a row either 2 or 3 dives a day and we felt great. another time at Key Largo we had 2 days of 2 dives and felt awful so we took a day off and then back for 2 more days of diving., listen to your body. computer algorithms give you a good idea but when you tune in to your body and really listen you'll do even better.
In cold water you need to layer more. maybe a skin suit under your wet suit or add a vest to your 5ml add a hood for repetitive dives. and as always stay WELL hydrated

Hollywood703
12-12-2007, 20:27
I dont adjust my computer for Ice dives even. I dive my standard table, and if my air consumption is higher my computer will show it, if I get cold, I stop the dive, If I get more tired than normal, I stop the dive. I dont plan to stop early, I adjust if something feels uncomfortable.

fisheater
12-12-2007, 20:32
I had the same question about my Sherwood Wisdom. I emailed them and they confirmed that they took (a) low water temperature and (b) increased air consumption into consideration in their algorithm.

Sure would be nice for them to tell us that, one way or the other, in the owner's manuals.

My suggestion is to contact the manufacturer and ask them detailed questions.

Ryanh1801
12-12-2007, 21:14
I had the same question about my Sherwood Wisdom. I emailed them and they confirmed that they took (a) low water temperature and (b) increased air consumption into consideration in their algorithm.

Sure would be nice for them to tell us that, one way or the other, in the owner's manuals.

My suggestion is to contact the manufacturer and ask them detailed questions.

Thanks for the info, ill give them an email.

CompuDude
12-12-2007, 21:20
I had the same question about my Sherwood Wisdom. I emailed them and they confirmed that they took (a) low water temperature and (b) increased air consumption into consideration in their algorithm.

Sure would be nice for them to tell us that, one way or the other, in the owner's manuals.

My suggestion is to contact the manufacturer and ask them detailed questions.

Many models of Uwatec computers can and do take temp into consideration. It's in my computer's manual, and I know it's listed as on the feature list for several other models as well.

CODMAN
12-13-2007, 07:04
Ryan, I have an M2 and I'm pretty sure it doesn,t compensate for temperature. It uses one of the most conservative algorythms out there (RGBM) to which it would be wise for you to add any degree of conservatism you feel you need on any dive by simply staying clear of the NDL limit. That's what I do. I've never been within 5 minutes of my NDL (usually way more than 10 minutes off) and don,t intend to unless something special requires it...

Just my 0.02$:smiley20:

in_cavediver
12-13-2007, 11:48
I just wanted to add this bit about added info to a computer. Just because it know the water temp, it doesn't know its thermal effects. I can be/have been comfortable and warm in a 45 minute dive in 45 degree water (drysuit thick undies, drygloves etc). I have also been chilled in 65 degree water in a wetsuit.

Also, air consumption tells you only so much as well. The variation from diver to diver is signicant. Can it tell the difference between exertion and air share? Even more, can it tell the difference in cft used? 500 psi in capacity is entirely tank dependent.

The only good computer you can truly rely on is the one between your ears. (well, if it crashes, you have other more important problems). Pay attention to it and your body and you can adjust the 'NDL' for the dive based on the raw time/pressure data the computer gives. For instance, a chilled diver in 65 degree water will want to pad the NDL. A diver doing strenous swimming, irregarless of temp, will want to pad the NDL. Its that easy.

cummings66
12-13-2007, 14:36
I agree that it's a feel thing in many cases. For me I don't normally get cold diving in the Winter in my drysuit and so I don't make changes. The few times I have got cold I did change things around to improve my comfort.