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Too Deep, Too Often, Too Soon?

Discussion in 'Safety' started by ricki, Aug 9, 2007.

  1. ricki

    ricki Well-Known Member

    I was speaking to Paul Kotik this morning about a minor lightness (I noticed no other symptoms), I perceived at the top of my head during some of those scooter dives a few days ago. I wondered if it might have been the product of an improper breath up and recovery (seemed normal), inadequate surface interval (went to ten+ minutes), inadequate hydration (could have drank more) or ???

    One of his points was that unless I was used to going to that depth on breath hold dives in that frequency the attendant stresses could bring out something like that perhaps something worse as well. He described some serious instances of lung squeeze and trachea problems. He strongly advised going slow with depth increments over weeks to allow things to acclimate to the increasing rigors of depth. Makes good sense.

    Unlike having to swim down and back which might take some time and repetition to achieve, a scooter or sled can allow a person in a near quiescent state to rapidly reach depths. Going down to 120 to 150 ft. repetitively seems readily within reach but may not be that great an idea, too soon anyway. The experience has felt good (more accurately great) to date but then again, strange problems can set in suddenly with minimal warning at times.

    What physiological hazards and precautions come to mind in doing something like this? I wonder if new sled divers have had issues like this?

    Thanks,
    Rick
    Last edited: Aug 9, 2007
  2. harbour seal

    harbour seal Well-Known Member

    not exactly addressing the depth issue directly but....

    in the event of scooter malfunction, i would consider not going deeper than you are able to swim back to the surface under your own power.

    also i have read of freedivers experiencing serious DCS symptoms from repeated deep dives using a scooter. kirk krack comes immediately to mind (although at the time i don't think that DCS in freediving was considered a big issue).

    i expect that lung squeeze and co2 narcosis would be threats in any dives to 50m+, not to mention the dcs, especially if you haven't allowed time for gradual physical adaptation. those divers who have experience with these depths are obviously the best sources of info on these matters.

    cheers,
    sean

    ps. not sure why you needed to start another thread as your previous thread from 2 days ago addressing basically the same issues
    Last edited: Aug 10, 2007
  3. laminar

    laminar Well-Known Member

    DCS definitely would be a concern, especially given the potential for shorter recoveries and VERY rapid ascents. The latter being probably the most important for avoiding DCS and the former for avoiding a blackout.

    Kirk did do a silly deep dive on the scooter a long time ago...

    Pete
  4. ricki

    ricki Well-Known Member

    I had no intent to launch a redundant thread, in my mind it was not. Here's why, I just picked up an Oceanic Geo, plan on 10 minute or more surface interval between dives, plan to ascend slowly in the upper 33 ft. and depending on circumstances may even do an O2 safety stop at some point(s) in the day. So, at least I have a starting plan for trying to manage DCS which is fairly familiar from study and misadventures over several decades.

    Lung squeeze aside from a theoretical issue that almost never impacts SCUBA divers or shallow free divers, different story. The same goes with trachea issues, new and unfamiliar ground for me. It seems like there may still be other issues. In constant ballast free diving you get there on your own and it is usually with smaller depth increments and down intervals over time allowing some acclimatization. This acclimatization could be cut short in scooter free diving exposing the body to rigors that it may not be ready for with limited warning.

    Scooter diving can be easy, perhaps too easy to undertake deeper dives and a fair quantity of repetitions. Sounds like the making of some possible strange physiology experiments, hence my original question, which I could use some more input on.

    I totally agree on going no deeper and longer than you have air to return from. Probably for around 115 ft. perhaps a bit more currently I think it should be doable. I am used to gear failures from kiteboarding and to a lesser degree diving. Over time, things can happen, just the way it is. So, I setup a 13 cft. pony bottle to carry horizontally in the small of my back. I wouldn't want to routinely free dive with it but with a scooter it may fall within a negative pressure area limiting drag. This is a fair amount of specialization of gear, procedures and precautions apart from regular free diving, still a good scooter session can be pretty intriguing.

    Rick
    Last edited: Aug 10, 2007
  5. ricki

    ricki Well-Known Member

    Thank you for your input. You can be tempted to just go and short cut recovery time. Still, with a good handle on possible consequences and a plan for residual nitrogen management it should be easy to observe reasonable precautions. How fast an ascent is too fast promote an untoward risk of BO, are there depth intervals which are more critical than others in this regard, like ? ft. to the surface? Subjective questions, still input on this is welcome. Was that deep scooter dive on a wreck in the Caymans?

    Rick
    Last edited: Aug 10, 2007
  6. harbour seal

    harbour seal Well-Known Member

    rick,

    safety issues aside, scooters sound like a lot of fun.

    keep us updated on your progress.

    cheers,
    sean
  7. ricki

    ricki Well-Known Member

    Hello Sean,

    Will do, hope to learn some more this weekend. It will interesting to see how wearing the bailout bottle works out and the Geo in tracking SCUBA combined with free dives over time. I usually avoid SCUBA diving entirely anymore but this weekend may unavoidably involve a mix.

    Does anyone have any stories or experiences about physiological problems that have come up for new sled free divers?

    Rick
  8. fcallagy

    fcallagy Well-Known Member

    Hi ricki,
    Be careful about that mix others have got dcs freediving after scuab even if relativly shallow. There are no tables to base it on so the best advise is dont mix it. Obviously surface snorkelling aint an issue but even to maybe 15m there may be some micro bubbles in some of the slow dissues. In effect you are recompressing them again and then ascending very fast. Do this over a period of time and !!!!. I know one person on this board suffered from dcs while freediving after scuba.
  9. ricki

    ricki Well-Known Member

    thank you for the warning. I spoke to tech support at oceanic yesterday about the geo's advertised ability to handle deco planning for both activities combined. the say it will do it but I will be conserative anyway. no longer a good deco test dummy choice.

    I met a guy about 15 yrs. ago. he did some repetitive scuba on the cayman wall the day before. the next day he free dove to 100 ft. three times. had a real nasty type II dcs hit that didn't fully respond to recompression. the story sticks with me.

    rick
    Last edited: Aug 10, 2007
  10. kelp princess

    kelp princess depthfinder Staff Member Forum Mentor

    i am extremely curious abou this theory with micro bubbles and freediving after scuba. in fact it may be the clue to a mystery i haven't had resolved for myself and an apparentt dcs case.

    any insight any of you guys have would be extremely useful:

    my situation:

    9 day expedition to monitor lemon sharks and pick up geological samples in the exumas (bahamas) about 3 weeks ago. freedving (snorkelling to max 15 meters) everyday, some days freediving before and after scuba diving and mixed gas rebreather diving. no erractic profiles, no rapid ascents, no overexertion. most scuba dives were recreational, no days of multiple scuba dives.

    -last scuba dive on 7/29 at 12 noon
    -flight home out of miami to SF on 7/31 at 8:30 pm (more than 48 hours later)
    -no pain or syptoms on plane
    -8/1 exhaustion and weird tingling (symmetrically) in calf muscles, swollen hands and pins and needles
    -8/2 still sorta tired and still weird tingling in legs ( feels like lack of circulation), sporadic cramping from tingling inlegs
    -8/3 2 quick flights back and forth from SF to San Diego, random leg tingling (both legs) through out the day
    -8/4 leg cramps extreme call DAN get no good information or help (unbelievable). go to emergency room and see a hyberbaric docotr who doesn't know or have answers so to be sure sends me to chamber for pressure test: 3 atms for 1.0 hrs., 2 atms for 1.5 hrs, surface up to 1 atm 30 mins

    -8/5 thru 8/7 3 more chamber rides
    -8/6 hands noticeably not tingly and not swollen
    -8/6 tingling in legs transitions to what i would assume is a more typical dcs symptom of achey writst, hip and back of knee ares (no tingling but extreme aches in joints)
    -8/7 last chamber visit and no aches and no tingling

    -8/10 today go to regular doctor (internal medicine) and she takes blood sample to see if everyone is crazy and perhaps i just had a virus?

    (btw i never had a headache, dizziness, vision blur or fever...)

    what do you guys think?

    kp
  11. cdavis

    cdavis Supporter Supporter

    Ricki,

    If you are still diving half lung or close, that is very relevant to deep scooter diving. It greatly increases the chance of encountering squeeze injuries, but decreases the chance of DCS and intensity of n2 narcosis, not sure about c02 narcosis. Eric F has some experiance and comments on this that are appicable to what you are doing. Seach FRC for his threads.

    I will follow your experiance with great interest. Jon and Longfins introduced me to scooter diving last month and it is a major Wow. I plan on doing lots more.

    Connor
  12. Jon

    Jon Dairyland diver Supporter

    Any time your freediving after scuba your opening yourself up to a DCS hit- and most of those hits will be type II due to the rapid ascent rates experienced in freediving. The general rule of thumb is freedive first and scuba second- never the other way around.

    Kelp Princess,
    from your profiles it sounds like you got bent. I've read that the WKPP don't even let their divers go back in to retrieve their own deco bottles after a big cave push because too many got hit from that simple dip back down to 20' after decoing out. A simple freedive after a rebreather/mix/deco dive should have the same effect- whether or not your breathing off a tank when it happens. I would separate your activities a lot more, but that's just me.

    Ricki,
    I wear a spare air when scootering. I know all the bad points about them for scuba, but it's all I need in case of a scooter flood at depth. I've worn one for 8 years now and never had to use it once- but it's always there just in case. Your idea of wearing a 13 cuft bottle has some merit, but I just never wanted anything that bulky on me while diving- the spare air is bad enough.

    I've been wreck diving with mine to 105' with repeated excursions and never had an issue with DCS- sub-clinical or otherwise. I've always stuck with the rule of keeping my surface interval at least 2-3 times as long as my bottom time and it's worked so far.

    I have seen some examples of the freediving DCS tables put together by some Spanish doctors. I think that they were published in Freediver magazine a few years ago- which has since gone out of business. They were based on longer surface intervals for deeper depths and longer bottom times at those depths. None of them had any safety stops, or ascent rates, built into them. they were all based on proper surface intervals.

    There's no computer that I ma aware of that has any kind of a proven deco algorithm in it for freediving- let alone mixing freediving and scuba together. IF there was one we'd have heard a LOT more about it on here. I don't think I would trust that thing as far as I could throw it.

    Just my $0.02;)

    Jon
    kelp princess likes this.
  13. ricki

    ricki Well-Known Member

    I am still evaluating diving with fully filled lungs, new to me but not to lots of other free divers. Thank you for your thoughts about relative risks of the two approaches and the direction for more info.

    I came over to Andros for a couple of days. Unfortunately, my new scooter has some serious drive shaft linkage problems so no powered dives for me this trip. I was looking forward to checking out the wall and blue hole with it, next time. Went to the "dark side" using tanks for a wall and shark dive today. So, I am probably screwed up for free diving with residual nitrogen for a while. May get some in Monday but perhaps not even then out of caution.

    Scooter free diving is a trip, with all the mobility and expanded capacity. I thought it was more established than it might be. Like anything new, folks may get hurt learning what works and what is best avoided.

    Rick
  14. island_sands

    island_sands Erection Supervisor ;) Supporter

    Just the title of this thread attracted my attention.

    Can never be too deep or too often rofl
  15. samdive

    samdive Lady of the Lake

    KP/Ricki

    Don't think it's a secret that I got a nasty DCS freediving after scuba - it was the day after a 40m scuba dive - 16 hours in between and I was only freediving to 15m

    My docs, and now AIDA Education, agreed that freediving after scuba should be treated like flying - don't do any until your dive computer is cleared. If you don't have a dive computer, wait 24 hours.

    it's hard to put a depth on "what is freediving, what is snorkelling" so I'd say, just stay on the surface until your totally bubble-free

    S
    kelp princess likes this.
  16. kelp princess

    kelp princess depthfinder Staff Member Forum Mentor


    well now you are not alone in that club lady of the lake - thanks so much for sharing your story- it helps me answer these nagging "why's" that have been roaming around my head.

    also of note to everyone, i have been doing alot of rsch since this happened (am going to a advanced decompression physiology course offered at USC next wknd too because i felt the MD's i spoke with didn't have enough precise info) but in my research i also found an obscure 2006 DAN study that was conducted by a control group of recreational wesuit divers in the caribbean, cold water divers in dry suits, and US navy divers in dry-suits that purposefully held warm water.


    the net net of the study was that warm skin in warm water CONSISTENTLY absorbed significantly greater amounts of nitrogen at depth!

    that was the other variable on my trip - the water was HOT! 88 degrees farenheit and i was hot the whole time too.

    i'm feeling more sure that i was actually experiencing DCS (even though it took 3-4 days to manifest symptoms) and that i was not only absorbing more nitrogen than usual but that i compounded it with my freediving after scuba.

    thanks much to you Jon and Sam for your insights - tis much appreciated.:inlove

    kp
  17. ricki

    ricki Well-Known Member

    Hello Jon,

    Thanks for your comments. I was sorely tempted to get a 6 cft. tank as it is smaller. Then I ran some calc's dealing with consumption at depth, say around 150 ft. perhaps with a slightly delayed ascent and bought the larger bottle. It isn't that large a tank however and I hope it won't be that annoying given where I plan to wear the thing. I wanted to get a Spare Air unit initially but the air calcs turned me towards something larger. I've free dove with dpv's since the late '70's without a worry for emergency air. Then again, I never went below 100 ft., much less repeatedly until quite recently. If I work down to something approaching the max depth on the scooter, emergency air would be a nice precaution. Your ideas for minimizing DCS hazards make sense. I think I am going to try to have a minimum 10 minute surface interval. As to the utility of the Geo in free diving deco planning, I'm going to have to take some time and caution evaluating that. It is quite new, however the discomfort of DSC is quite old. Would like to try to avoid a refresher.

    Rick
    Last edited: Aug 14, 2007
  18. ricki

    ricki Well-Known Member

    Normally, I would agree with you, terminal O2 toxicity and acute narcosis aside. Still, all this talk of here to fore rare barotrauma related to deep breath hold diving has me wondering.


    See what happens?! I get fixated on something and miss the obvious, sigh.
    Last edited: Aug 16, 2007
  19. ricki

    ricki Well-Known Member

    What were your DCS symptoms and response to recompression? How deep and long did you SCUBA dive the day before? Sorry that you went through it but thanks for sharing the experience. The more I hear of unusual DCS hits to free divers following SCUBA sessions that result in substantial residual nitrogen, the more your approach makes sense. If you want to avoid "getting hit from left field, stay out of the field until you are ready." It is a burden to avoid free diving after SCUBA at times then again it is an incentive to avoid SCUBA in general if feasible.

    Thanks again,
    Rick
    Last edited: Aug 15, 2007
  20. trux

    trux ~~~~~ Supporter

    I am afraid you did not explore yet the depth of Sara's (Island Sand) soul, otherwise you'd know that she does not joke when she tells it can never be too deep or too often for her. On the other hand, it is true she might be disappointed if it were too soon.

    Excuse me for the off-topic answer, but I though it needed some explanation. Let's stop at it, avoiding yet another off-topic runaway.

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