• Welcome to ScubaBoard

  1. Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

    Benefits of registering include

    • Ability to post and comment on topics and discussions.
    • A Free photo gallery to share your dive photos with the world.
    • You can make this box go away

    Joining is quick and easy. Login or Register now by clicking on the button

Is UTD still a "fringe" organization?

Discussion in 'Technical Diving' started by onepointfivethumbs, Mar 24, 2021.

  1. rjack321

    rjack321 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Port Orchard, Washington State
    He has frequently sold his share of companies he started. None of them are publicly traded to my knowledge but after a decade or so he usually gets out.
    Sold his share in DiveXtras
    Sold his share in Red Sea Explorer
    Sold his share in UTD

    He's a starter not a finisher. Moving on from UTD is not a shock to me
    diver42 likes this.
  2. StefinSB

    StefinSB ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Santa Barbara, CA
    Rjack answered. You obviously have nothing to add.
  3. boulderjohn

    boulderjohn Technical Instructor ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Boulder, CO
    Decompression theory for NDL dives has been studied for over 100 years, and countless divers were tested in coming up with the standard NDL dive profiles used today.That approach is enormously successful--only about 0.02% of dives end in DCS. So it makes sense to you to try a "what the hell, let's do something different and see if we like it" approach? You call it a "thoughtful" approach to throw out all that research and do something instead that has never been tested.

    By the way, this debate is really about a hundred years old. Haldane liked the staged ascent approach; others liked a continuous ascent approach? While the UTD approach is technically staged, it is closer to continuous.
  4. helodriver87

    helodriver87 Contributor

    # of Dives: 500 - 999
    Location: New Mexico
    This is one of the reasons UTD is still fairly fringe. Ratio deco is very much a ballpark guess best suited for the backup to your backup plan. GUE still teaches a version of it, but it's secondary to tables (and realistically, tertiary with the general acceptance of computers across the community). The ascent technique taught in fundies is geared more towards building proficiency for T1 than actual deco efficiency, even though its roots may still be based on outdated deco research. Relying on ratio deco is like choosing to navigate by the stars. You can manage ok if you really know what you're doing, but there are better, easier, more accurate ways.
  5. ginti

    ginti Contributor

    # of Dives: 200 - 499
    Location: Lyon, France
    I never discussed this point with anyone, but it's my personal opinion that it has to do with the pressure gradient. The shallower you are, the higher the pressure gradient relative to a fixed change of depth. For example, if you move at 10m/min (30ft/min) from 40m (130ft) to 30m (100ft), you are reducing the pressure from 50bar to 40bar in 1minute, which is a reduction of 20%. Do that from 15m (45ft) to 5m (15ft) and the pressure is reducing from 2.5bar to 1.5bar in the same amount of time, which is a reduction of 40%!

    Being the pressure gradient one of the key factors in decompression strategies, it makes sense to plan the ascent so as to never surpass some critical levels - which is why I think GUE breaks the ascent into two different phases (it's just the easiest way to do it)

    I guess most of you already knew these simple facts, but it is worth underlining it I guess, especially for newer divers

    I am really surprised to hear this, and I'd like to understand more - so I have two questions:
    1) What does "significant" mean for you?
    2) I couldn't find any study online concluding that the percentage of divers getting DCS is relevant, but maybe I am just not as good as I want to believe in internet research :) Could you send us a link to this study?

    Being tired is a symptom of DCS. But being tired does not mean having DCS...
    Wibble likes this.
  6. KevinNM

    KevinNM Contributor

    The GUE non-stop ascent is actually 3 phases. Fast to 50%, then 10 feet per minute to 10 feet, then as slow as practical to the surface from 10 feet.
  7. Wibble

    Wibble Contributor

    # of Dives: 500 - 999
    Location: UK
    I answered in reading order to your specific question.
    Your replies do seem rather aggressive
  8. AfterDark

    AfterDark Contributor

    # of Dives: 1,000 - 2,499
    Location: Rhode Island, USA
    IMO it is fringe because they don't allow for solo diving but that's just me.
  9. kensuf

    kensuf ScubaBoard Sponsor ScubaBoard Sponsor

    Add mild hypothermia with the subsequent caloric expenditure and dehydration from diving (breathing compressed air dries you out), plus sun on the boat and I'm ready to take a nap just thinking about it.
    tbone1004, grantctobin and ginti like this.

    CAPTAIN SINBAD Contributor

    # of Dives: 200 - 499
    Location: Woodbridge VA
    To reiterate my earlier point, Doppler technology found bubbles running inside in each and every one of us. The most important statistic to start with is that 100% of people who dive are bent. If there is anything that we can say with Doppler certainty it is the fact that everyone is bent.

    "This (discovery of bubbles in divers within NDL) provides a significant challenge to the traditional view of decompression theory. If bubbles are formed well within our M-Value limit then what use are M-Values? And if bubbles form, and yet there are no signs or symptoms of decompression sickness then how can we say that bubble formation causes decompression sickness?" (Mark Powell, Deco for Divers page 110)

    How do you determine where the NDL is when bubbles have started to form so much earlier than established NDL limits and the point at which silent bubbles become symptomatic varies so much for person to person? For reference purposes, here are NDL limits for a 100ft dive on various dive tables ...

    Buhlmann ZHL-16 B (PSAI) - 16 mins
    US Navy Table (SSI) - 20 mins
    RGBM (NAUI) - 22 mins
    NOAA - 25 mins

    We can see the dilemma that a decompression modeler has. All of the above tables have been used quite extensively with safety levels that are still acceptable today. The guy who is diving on NOAA table may get bent 23 minutes into the dive, have severe headache that knocks him out and, on his table it is an "undeserved hit" but you could pull out the Buhlmann table and say, "No you were 7 minutes into decompression according to Buhlmann so you deserved it." This is why DAN writes the following:

    "Many divers are also unaware of the fact that dive computers make use of many different mathematical models, or versions of different models; there is no universal standard. A single manufacturer may use more than one model, possibly in a single type of computer. This makes it extremely difficult to assess the nuances of every system." (Dan.org > Decompression Sickness, Chapter 2: Effective Use of Dive Computers)

    UTD trains divers to treat every dive as a decompression dive. As for the half stops, I have also found details of the study that DAN did to come up with their deeper stop recommendations for recreational diving. I will try to post it later during the weekend. It gives some validity to UTD's approach.

    Had my vaccine so I have my own symptoms right now that are not that different from DCS.

Share This Page