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Shearwater V65 Update

Discussion in 'Shearwater Research' started by Norwegian Cave Diver, Jan 26, 2019.

  1. Norwegian Cave Diver

    Norwegian Cave Diver Barracuda

    # of Dives: 200 - 499
    Location: Calgary Alberta Canada
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    I just updated to the newest Shearwater version 65 software. What it the difference between "Delta + 5" and "@ + 5" ?
    Thanks
     
  2. Shearwater

    Shearwater Dive Equipment Manufacturer

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    Hi, @Norwegian Cave Diver . Delta will report just the difference in TTS if you were to stay at the current depth for 5 more minutes. @+5 will report the total modified TTS if you were to stay at current depth for 5 more minutes.

    Example:
    current depth = 20 m
    TTS = 15 mins
    Delta + 5 = -3 mins
    @+5 = 12 mins (15 - 3 = 12 or TTS+Delta = @+5)

    I hope this helps.
     
    Dive Cochran likes this.
  3. rhwestfall

    rhwestfall Solo Diver

    # of Dives: 200 - 499
    Location: "La Grande Ile"
    11,742
    10,225
    113
    you lost me completely....

    TTS = 15 min
    @+5 = 12 min

    how could TTS go down if you stayed at depth longer?
     
  4. Norwegian Cave Diver

    Norwegian Cave Diver Barracuda

    # of Dives: 200 - 499
    Location: Calgary Alberta Canada
    350
    187
    43
    I think the explanation is good - but the example is confusing with "-3"
     
  5. tmassey

    tmassey Barracuda

    # of Dives: 200 - 499
    Location: Shelby Township, MI USA
    372
    367
    63
    VERY roughly speaking, if your current depth is lower than your average depth, you are offgassing. So, staying at depth can and will result in a lower TTS at the end. Think of it as deco at a less than optimal depth...

    The question is, how much are you offgassing? Sometimes it matters. For example one of my favorite wrecks is the Duane. It's very upright, with the crow's nest at half the depth of the deck. So, if I've spent 20 minutes on the bottom and make my way up to the crow's nest, I still have really cool things to see and do. But I'm either near deco or maybe even in it. Will exploring the crow's nest cause me to need to stay longer on deco, or less?

    Delta+5 or @+5 tells me. Not only does it tell me whether I'm offgassing or not, it tells me how *well* I'm offgassing.

    So, using the example given above: I'm currently at the crow's nest at 20 meters. My current Time to Surface is 15 minutes if I leave *right* *now*. That's the *fastest* I can get there under ideal circumstances. But I've got plenty of gas, and want to keep looking at the crow's nest. If I stay an extra 5 minutes here, what does it do to my TTS?

    Delta+5 = -3 minutes. That means that after 5 minutes at my current depth, my Time to Surface will be three minutes less than it is now. That means that at my current depth, I'm offgassing 60% as fast as if I moved directly toward the surface (following any stops, etc.). Nice! That means it will only cost me *two* minutes to spend *five* minutes at my current depth. Seeing as I have the gas, I'll exchange 2 minutes of deco for 5 minutes of fun dive time.

    The *only* difference between Delta+5 and @+5 is how those numbers are shown to the diver. Delta+5 shows only the CHANGE in TTS if I stay where I am for five minutes. If I'm currently below the average depth of my dive, that number will be positive: I'm on-gassing, and I'll take more time to get to the surface and the number will be positive. If I'm currently *above* the average depth, I'm off-gassing, and the number will be negative.

    For some people, that's confusing. They'd rather simply know what the absolute TTS will be in 5 minutes. That's what @+5 is. It's a prediction of what the TTS will be five minutes from now if you don't change depth. And like was said, it's simply Current TTS + Delta+5. Same number, different presentation.

    By the way, my use of average depth is certainly not correct. It's merely a rough approximation. Of course, the computer is doing a lot more careful calculations based on a large collection of tissue compartments with different parameters. There's m values and tissue speeds and gradient factors, and I'm sure a whole lot more. But it gives you the general concept! :)
     
  6. Norwegian Cave Diver

    Norwegian Cave Diver Barracuda

    # of Dives: 200 - 499
    Location: Calgary Alberta Canada
    350
    187
    43
    That is a much better explanation. Not sure if your work for Shearwater ? - but they should either hire you or send you a gift. Thanks.
     
    Divingblueberry and tmassey like this.
  7. rhwestfall

    rhwestfall Solo Diver

    # of Dives: 200 - 499
    Location: "La Grande Ile"
    11,742
    10,225
    113
    @tmassey - thanks. I really wasn't thinking of multi level, so I get what you are saying. If you are on a square profile, and stay, the results aren't going to show that way... hence my confusion.
     
  8. tmassey

    tmassey Barracuda

    # of Dives: 200 - 499
    Location: Shelby Township, MI USA
    372
    367
    63
    Still, even then it's immensely useful. "If I spend 5 more minutes here, what will it cost me in TTS?" is a really nice question to know the answer to. I've used that more than a few times when we're near the end of a dive and I spy something to look at... is it worth it? Maybe 5 minutes will only be two extra minutes of deco: worth it. Or maybe it'll be *8* more minutes... in 50 degree water... with surge... Not worth it!
     
  9. michael-fisch

    michael-fisch Manta Ray

    # of Dives: 2,500 - 4,999
    Location: Germany
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    I updated all my Shearwaters today, the 2 Petrel 2s went to version 65, the 2 Predators only updated to version 63.
    Any ideas why?
     
  10. lynnpartridge

    lynnpartridge Dive Equipment Manufacturer

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    V63 is the final firmware version for the Predator. There is no available code space for further updates.
     
    michael-fisch likes this.

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