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Thread: speigal grove here I come

  1. #51
    Grouper
    Join Date
    07/14/2010
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    Charlotte, NC
    Posts
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    Back on the good subject, watched a food show and they cooked hamburgers until they were partly done and then put batter on them and deep fried them. They looked wonderful!!! They were probably even healthy...

    On the the other subject, Tim just choose to ignore peoples advice. The only reason people even respond is because there are a bunch of good people on here that truly care about other divers and we try to keep people from being a topic of discussion and a statistic at the same time. I truly hope he is trolling and is not serious about doing this dive.
    Lets see, to dive or not to dive? Well that is a stupid question, DIVE, DIVE, DIVE, and then DIVE some more as long as it is safe!!!!!

  2. #52
    Grouper
    Join Date
    05/28/2009
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    Brisneyland
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    Enough with this talk of dog's eyes. You're making me homesick.

  3. #53
    Quote Originally Posted by Clernix View Post
    All this talk about the sac rate which btw makes me chuckle to say, but isn't air consumption variable? So much so that planning for it almost seems like wishful thinking. Of course almost all of my dives have been "dive your tank dives" so I don't really do any planning. Depending on conditions and what activities I'm doing such as photography or just drifting along there is a huge difference.
    SAC rate is variable. Different conditions are going to give you a different SAC rate. However, if you are in good shape you can use a known SAC rate as an approximation. This is why most divers use Rock Bottom Gas Management or Rule Of Thirds. Rock Bottom Gas Management looks at the worst case scenario and puts in enough reserve that you should be safe. Rule of Thirds says to figure out how much gas you need and multiple it by 1.5. This means you'll have 1/3 more gas than you anticipate.

    Drift diving or similar activities are different than a typical gas managed dive. Gas management assumes you are diving out and coming back to the entry point. So if it is a hard dive out, it would be an easy dive back and everything would balance out.

    SAC rate is also great for knowing you have insufficient gas. Let's say you have a SAC rate of ~1.0 and want to do a dive to 110 feet for NDL maximum. You need:

    - gas used on descent (average of final-depth / 2)
    - gas used on the bottom
    - gas used to ascend
    - gas used at a safety stop

    For a dive to 110 fsw it would be:

    110 / 2 = 55 feet = 1.6 ATA ==> 1.0 SAC * 1.6 ATA = 1.6 cu.ft. per minute. If you descend at 60 feet a minute it should take you around 2 minute to get to the bottom. So descent gas will be approximately 3.2 cu.ft. Notice that I round UP to 2 minutes when it is really 1 minute 50 seconds.

    I'm going to stay at depth for 16 minutes (due to NDL I cannot exceed this). 110 feet = ~4.4 ATA. With a SAC of 1.0 that will be 4.4 cu.ft. / minute. 4.4 * 16 = 70.4

    Ascend is going to average to 1.6 ATA as well. Ascending at a slower rate of 30 feet / minute means ~4 minutes travel time. Really it is 3 minutes 40 seconds but again, round UP. This means 6.4 cu.ft. for the ride up.

    This is a deep dive so I need 3 minute safety stop. But I'm also at the limits of NDL so I'm going to make it a 5 minute safety stop at 15 feet. 15 feet = ~0.5 ATA. 5 minutes * 0.5 cu.ft = ~3 cu.ft. of air.

    Total: 3.2 + 70.4 + 6.4 + 3 = 83 cu.ft. * 1.5 for rule of thirds = 124.5.

    I might use an HP119 because it is 123 cu.ft. and I round up a lot on this. Or I can be ultra-conservative and go for something above 125 cu.ft. (HP130, HP100 doubles, AL80 doubles, HP100 with AL30 slung.

    I like the idea of an HP100 with an AL30 slung. If all goes well I dive the HP100 down to 570 PSI and never touch my AL30 unless there is an emergency.
    This signature left intentionally blank

  4. #54
    Funeral Jorunna
    Join Date
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    Lafayette, CO
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    Hey scubadiver888 your ATA's are wrong for 55 feet and 15 feet. Remember 1 ATA is sea level so 15 feet would be ~1.5 ATA and 55 feet would be about 2.7 ATA
    Last edited by chinacat46; 03-01-2012 at 11:22.
    If you get confused listen to the music play.
    To much of everything is just enough.

  5. #55
    Grouper
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    I thought this topic had already been beaten to death. Biggie should just check his own archives before posting:

    http://forum.scubatoys.com/wreck-div...l-grove-34094/
    http://forum.scubatoys.com/wreck-div...e-wreck-35633/

  6. #56
    I missed that one. Just over a year between this thread and the other one. Maybe we should look up subsequent threads he started and start a pool on when he starts repeating them as well.
    This signature left intentionally blank

  7. #57
    Megalodon
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    SAC and more appropriately RMV is indeed variable from dive to dive. Curious is that my first dive is usually about .7 cuft/min and the dives after between .6 and .5 cuft/min. I've been using Oceanic's divelog and it will figure an average SAC for each dive if you enter the PSI and tank size, it's real handy. That's why I chart and keep a good log of each dive's SAC. to help me plan dives similar in the future.

    To be honest, I would probably have at least 1 cuft/min SAC on my first dive on the Grove since I've not dove it and really, really want to. But I would plan accordingly.

    I once saved a man in Wichita just to watch him dive...(inventor)

  8. #58
    Shark
    Join Date
    03/21/2008
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    well we drove down wensday did the morning dive with rainbow reef, did have a very good guide, he is in fact preparing to do his cave instructor class and knew his stuff. In the end me and my buddy called the dive and did not get on the wreck. Big learning experience and hey might not have got on her but there is a point where u say its not a good idea to go down today. I just got home after getting up yesterday morning at 5 and doing the dive trip then the casino down there(won 200 bucks on blackjack lol) and driving back I just walked in the door and going on 30 hours no sleep.

    When I get up ill give u all the full report. IT was a scaring experience but did not panic and took care of everything, kind of like a few tiny things that by their self's where manageable but together caused me to call the dive and return to the boat. But in the end a good diver knows when to abort a dive and knows when if they continue it might be their last, that boat ant going anywhere.

  9. #59
    Shark
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    03/21/2008
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    key largo florida
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    no I had alot of stuff to take care of and got busy. lol
    Quote Originally Posted by Largo View Post
    I just noticed that Big hasn't logged on since Monday.

    I'm beginning to think that he doesn't care about meat pies at all.

  10. #60
    Grouper
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    05/28/2009
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    Brisneyland
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    Good to hear that you recognized the issues that arose and had the sense to call the dive. Keep practicing.

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