1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

What’s the current trend in gradient factors?

Discussion in 'Technical Diving' started by Zubar, Jan 8, 2020.

  1. Dave Whitlow

    Dave Whitlow Super Moderator
    Staff Member

    Joined:
    Oct 27, 2010
    Messages:
    1,360
    Likes Received:
    545
    When I did use v-planner it was just using VPM but perhaps things have moved on. However, when he started posting, and disagreeing with established medical wisdom, I concluded I'd rather not trust his programming.
     
  2. adiverslife

    adiverslife New Member

    Joined:
    Feb 11, 2021
    Messages:
    4
    Likes Received:
    2
    I have only gone through my first course and bought my gear. This was the the GF that was recommended by my instructor and it matches what I can set on my Shearwater Perdix and my Baltic software. As I said I am very new to Tech. The setting is not based on any extensive experience of my own. I start my second tec course next week. What do you recommend and why? I would love to hear more from more experienced people.

    I should say my interest in Tech is twofold - Film places that many people cannot go for our YouTube channel and to discover historic artifacts and to share history. One life goal is to dive and film the wrecks at Bikini Atoll. I am a long way from that but it is my goal. One of the things that really got me to look toward tech was we were the first to discover an 1800s Salt Ship anchor off of Bonaire. I realized I needed to go deeper. Bonaire used to use slaves to mine sea salt for the Netherlands. It is part of our history. You might find it interesting.

     
  3. jb2cool

    jb2cool Moderator
    Staff Member

    Joined:
    Jan 20, 2008
    Messages:
    3,413
    Likes Received:
    590
    It wasn’t any criticism i was just interested.

    I’m using very similar values to you where I started off on 30/85 (most people did) but after I’ve had some shoulder pain on a few occasions I now prefer 30/80 to lengthen the 6m stop. Changing from 85 to 80 usually mean another 5 mins at 6m for the dives I do. I’ve not played with changing the GF- low very much as I don’t pay very close attention to it, being a GUE diver I mainly use ratio deco and what GUE call pragmatic deco to come up with the ascent plan within the team, this does largely follow a GF-low of 35 but not exactly. To me this consistent approach where all my prospective teammates will be doing a similar thing is more valuable than each person finding their own perfect values.
     
  4. Wibble

    Wibble Fish don't talk
    UKD Supporter

    Joined:
    Apr 7, 2014
    Messages:
    6,546
    Likes Received:
    1,516
    Couldn't agree more. It's embarrassing seeing him, the amateur, taking on Simon Mitchell, the well-known deco doc and published researcher. It does seem that there's a massive gulf in understanding.
     
  5. Wibble

    Wibble Fish don't talk
    UKD Supporter

    Joined:
    Apr 7, 2014
    Messages:
    6,546
    Likes Received:
    1,516
    Love the vids.

    For me, the point about technical diving is not the badge, but it's a whole attitude to diving. Recreational diving's very much kept within tight guidelines: no deco (or very limited deco), no overheads therefore not deep nor long. This is purely for safety where people don't have the skills to do the planning, use the additional kit, and safely perform all the new procedures. Therefore a simple "no", you can't do an hour at 40m or dive to 60m or go into that cave.

    Learning technical diving's a gradual process. Firstly the new kit which includes redundancy. There's lots of skills to learn here. Actually, well before that, there's the core skills to sort out as you've got to be able to keep a deco stop and be in control on the bottom. Then there's the mixed gasses to work out; learning decompression theory; the initial move into using accelerated decompression with oxygen rich gasses; the discipline to plan and execute these dives; to work in a team (at first). Then the subsequent skills development; multiple stage cylinders and gasses; ensuring that you've always able to recover from an 'incident'.

    In essence, it's a journey and quite a long one. At the end of it every dive you do is a technical dive! For instance your videos; using these improved skills to hold you position, for much longer.

    Waiting for the day where we're all released from lockdown hell and can actually travel to foreign locations. Will be interesting to see what it would be like to do a random "unprepared" holiday dive where one rocks up at the dive shop, rents pretty much everything and is thrown in with a DiveMASTER and a bunch of novices...


    Gradient Factors.
    I was taught by a well known instructor that's published books on decompression (good instructor too). We went though the theory of what 50:80 means (gf-low, gf-high) and all sorts of calculations using other gradient factors. 50:80's about the most efficient (unless using 100:100), it's safe as many divers use it. When asked what he used for deep, normal and shallow dives, he replied 50:80. Good enough for him, so good enough for me.

    I do extend the top duration sometimes and I do set the plan to be a 3m final stop, so can move up a bit if necessary. Much easier on the rebreather and has a lower CNS / oxygen clock effect.

    Have fun!
     

Share This Page

  • About Us

    Our UKDivers community has been around for many years and prides itself on offering unbiased, helpful discussion among people of all disciplines and abilities. We are working every day to make sure our community is one of the best and friendliest around.
  • Support us!

    The management works very hard to make sure the community continues to run reliably. Care to support us? All donations go to the running costs of the forum: hosting charges, software maintenance, etc. We'd really appreciate it!

    Choose option:  

    UKD Username: