Predator question

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cocoajoe

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Messages
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Location
Cape Canaveral Fla
# of dives
200 - 499
I'm just a rec diver but love my Predator. Why is the choice of 'last stop' 10' or 20' ? I have been advised to set it at 10' I know that this is in the 'deco' part of 'system set up' but why not have a choice at 15' ?
 
Must take Advanced Nitrox and Deco class... :D :D :D

The short answer... because no deco tables or software that I know of has 5' stops. All stops are in 10' increments. The longer answer really is covered in a good class.
 
Deco planning software generally has the stops broken down into 10' increments. So I would assume the software is written to follow what is standard practice. The reson for the choice in a last stop depth is that 100% O2 is commonly used to finish deco and it is at 1.6 Po2 at 20'. The final stop being 20' or 10' has a lot to do with conditions. Why hang out at 10' doing a deco stop getting beat up by wave action when you could drop down to 20' and be a lot more comfortable. Some caves don't lend themselves well to a stop at 10' or 20' so one or the other may be preferable for a long hang.
 
I would do the 10' stop if you are diving recreationally , and as stated above, the 20' stop is only suitable as a last stop is doing deco on 100% O2.
 
If you have a Shearwater Predator, why not take Tec 40/Advanced Nitrox??
 
I'm just a rec diver but love my Predator. Why is the choice of 'last stop' 10' or 20' ? I have been advised to set it at 10' I know that this is in the 'deco' part of 'system set up' but why not have a choice at 15' ?

More realistically, you can set it for 10' and sit at 15'. As a rec diver, it really will never make any time difference at all whether you're at 10' or 15' for that last stop.
 
LMAO...it was you who advised me to set it at 10' but I wondered why. Tried several times to meet up at FB as you suggested.....had the feeling I was bothering you too much with many 'basic' questions.
 
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It doesn't matter what you set it at as along as you have NDL time remaining as it won't be used anyway.

Imagine the scene:
Recreational diver makes 250 dives using a recreational computer and occasionally entered a bit of deco. Perhaps the diver had a minute or two minutes here, and couple minutes here, no big deal. This same diver purchases a Shearwater and excited about the ability to program a bunch of gases, programs and makes active 21, 32, 36, 50 & 99% because they've heard of those mixes. This diver grabs his new recreational sidemount kit (just sparking some thread interest, could be a big steel) and makes a dive riding the computer. Sure enough as before, a couple minutes of deco accumulates. No worries, we'll ascend, complete the deco, and surface. Upon ascent, OC 21/00 suspisciously turns a yellow color, and our hapless diver thinks, huh never seen that before. Reassured by previous untrained deco adventures the diver thinks, I will follow the computer and make a stop at 20ft for :10 minutes. After the diver completes :10 minutes of deco, :07 minutes are still remaining on the computer. The diver double checks available gas and he's now overdue for the dive boat, but the decompression time just is counting down properly. The diver is very confused and eventually runs low on gas and maybe even omits deco. Shearwater says "CONFIRM' and that's the end of it.

While the Shearwater products are very easy to use, there is a risk is changing factory settings if you don't understand the information you're being provided. The above scenario is something you could very easily fix underwater, but like the 10ft vs. 20ft stop as a recreational diver it really shouldn't matter.
 
I thought the manual for the Petrel/Predator was very clear about how the 'radio station gases' feature works, how important it is that you only ever turn on gases you are actually carrying, and why that's so. The Shearwater manual is one of the best written, easiest to understand manuals out there (AA's Cobalt manual is also great, but it's such a different computer that it's hard to compare the two), so there's no excuse for not reading and understanding it before jumping in the water.

Cocoajoe, were you referring to me? If so, I haven't been ignoring you intentionally but FB isn't something I understand all that well with the new features/settings/message restrictions...feel free to PM me on here.
 
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More realistically, you can set it for 10' and sit at 15'. As a rec diver, it really will never make any time difference at all whether you're at 10' or 15' for that last stop.


Agreed.
If you have your 20' stop as your last stop on the predator and you are at 19' your computer will start showing "missed stop, confirm or error". But, if you set your last stop for 10' and you are at 19', it doesn't change your time much and you can not get so beaten up by waves. Or if you are in a cave, you've got some flexibility in depth, where 20' might not be possible.

The other thing is, if you are at a very high CNS... moving to 10' for your last 40 minutes of deco brings a little relief from 1.6ppo2 on pure oxygen. :)

---------- Post added November 6th, 2013 at 05:49 PM ----------

LMAO...it was you who advised me to set it at 10' but I wondered why. Tried several times to meet up at FB as you suggested.....had the feeling I was bothering you too much with many 'basic' questions.


Nah, just my busiest month of the year. I'll probably work 460 hours in October -November 8th. Some might notice the reduced number of posts on SB too. Most will enjoy that. :)

---------- Post added November 6th, 2013 at 05:52 PM ----------

It doesn't matter what you set it at as along as you have NDL time remaining as it won't be used anyway.

Imagine the scene:
Recreational diver makes 250 dives using a recreational computer and occasionally entered a bit of deco. Perhaps the diver had a minute or two minutes here, and couple minutes here, no big deal. This same diver purchases a Shearwater and excited about the ability to program a bunch of gases, programs and makes active 21, 32, 36, 50 & 99% because they've heard of those mixes. This diver grabs his new recreational sidemount kit (just sparking some thread interest, could be a big steel) and makes a dive riding the computer. Sure enough as before, a couple minutes of deco accumulates. No worries, we'll ascend, complete the deco, and surface. Upon ascent, OC 21/00 suspisciously turns a yellow color, and our hapless diver thinks, huh never seen that before. Reassured by previous untrained deco adventures the diver thinks, I will follow the computer and make a stop at 20ft for :10 minutes. After the diver completes :10 minutes of deco, :07 minutes are still remaining on the computer. The diver double checks available gas and he's now overdue for the dive boat, but the decompression time just is counting down properly. The diver is very confused and eventually runs low on gas and maybe even omits deco. Shearwater says "CONFIRM' and that's the end of it.

While the Shearwater products are very easy to use, there is a risk is changing factory settings if you don't understand the information you're being provided. The above scenario is something you could very easily fix underwater, but like the 10ft vs. 20ft stop as a recreational diver it really shouldn't matter.

I can show you 4 multigas computers all under 500 bucks that could do the same thing. Sometimes personal accountability comes into play. I had a corvette that had 476 horsepower at the wheels. Was it the corvettes fault if I wrecked the corvette at 190mph? You have to know your limitations, because the gear you are using might not have any. That's just common sense man.

---------- Post added November 6th, 2013 at 05:53 PM ----------

Cocoajoe, were you referring to me? If so, I haven't been ignoring you intentionally but FB isn't something I understand all that well with the new features/settings/message restrictions...feel free to PM me on here.

No he was talking to me.
 

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