PerroneFord changed my thinking, n maybe even saved my life.

Perrone made two statements in an hour-long discussion that changed the way I'll veiw diving forever. The first was simply this:

“Decompression divers seek to offgas while still underwater where pressure keeps micro bubbles small and safe to pass out of solution. Non-deco divers rely on surface interval for most of their offgassing to take place.” (After a long discussion about physiology, I came to realize that what I do in spearfishing, FOUR back-to-back dives in a single afternoon, depths sometimes to 130-150 feet, bottom times of 20+ minutes…from the standpoint of nitrogen offgassing…one-hour surface intervals simply aren't sufficient to remain safe over the long run!)

Perrone then made a second comment that got me to rethink diving as I currently understand it. He simply said this:

“One day you will achieve the training and knowledge that you are currently seeking and you will look back on this time and recognize it to have been some of the most RISKY diving you ever engaged in throughout your whole diving career.”

I thought about that LONG AND HARD after hanging up the phone. I consider myself a very safe spearfisherman diver. I carry bolt cutters for self extraction (and TEST them before each trip. Yes… I make sure they still can “wack thru a stainless steel cabnit screw even though my cutter is rusty. And I do ALL I CAN to try to urge my fellow spearfisherman that the “paramedic snips” they carry will NOT CUT THROUGH 1/8 steel cable…the cable we use on our guns in the Gulf.) My dive tool is dummy corded so that I can't loose it under stress. I can draw with one hand, use and return to sheath without looking (practiced it many times.) I have NEVER gone into deco…not even ONE time. But I carry a redundant 19cf that affords me (at my current air consumption rates) more than 20 minutes of deco gas at 20 feet at rest. I have that pony mounted such that I can pull it from myself, hold on to it, and ditch the rest of my gear. I have practiced ditching ALL my gear and returning to the surface on that pony (Inverted! Yes... in my 7mil wetsuit, you're going to the surface pretty quick if you ditch your gear...so I have practiced upside down kicking downward to control ascent speed.) I have a host of “self regulating rules” in my head about “depths/remaining air supply” as to shots I am willing to take or NOT take….etc. I utilize a "riding rig" configuration that allows me to "ditch my spear shaft" if a large fish is dragging me to the bottom. I return to the surface at proper ascent rates (faster at depth, slower at the shallows…3 min safety stops ALWAYS…etc.)

Still I have returned to the boat at least ONE time, and begun to feel very “strange” on the surface. I could not put my finger on it but something wasn’t right inside me AT ALL. To be honest…it was scary.

After a LONG talk with Perrone… the night before this last spearfishing trip…I broke out my Aladin Tec2G manual and read PROFUSELY on “micro bubbles” and set it to the highest level of micro-bubble intermediate stops. I was SHOCKED at what my computer told me to do this Saturday. Crystal blue water in the Gulf off Venice, Louisiana with vis beyond 150 feet allowed for four dives (one hour surface intervals)…all depths of 140-150ft… bottom times only in the teens… and here's what my computer told me to do:

“stop at 30 feet for one minute…stop at 20 feet for 3 minutes…stop at 10 feet for SIX minutes!” (We’re NOT talking “deco stops!” I never went into deco. We are talking “micro bubble offgassing stops” that added a FULL TEN MINUTES of time just to offgas before gettin out of the water!)

Summary: According to my nitrogen loading bar on my computer, I left the water with LESS nitrogen loaded than I EVER have in the past! I left the water with CNS leves of 0 or 1%… and I left the water and felt physically GOOD on the boat all day. Most important.. perhaps for the first time since I began spearfishing a year ago (from a standpoint of nitrogen offgassing)…was diving SAFE. Thankyou, Perrone.

I am not a dive instructor. I am not a physiologist, or a doctor of hyperbaric medicine. My only hope was to get you to think a bit differently about what it was you were doing in the water. I am pleased though surprised at what you have come back with.

I do hope your story will help others in the future. But again, this is not medical advice or even sound diving advice. Just a jumpstart on thinking about the dives.

Is there a source for that software that can be run on a home computer? While I tend to do just the kind of ascents you describe when diving deep, long, and repetitive; it would be nice to be able to use that s/w to study micro bubble management options under a wide range of conditions.

Not sure what you are asking exactly. Scubapro has software that goes with the Aladan TecG2 dive computer that allows you to download logged dive profiles. I would assume the prescribed micro-bubble stops you made would be included in that profile. As for "dive planning"...I have not yet looked to see if while in dive planning mode...my computer is NOW going to tell me what my micro-bubble stops will be for future hypothetical dive profile scenarios. Maybe it's something I can check out after I take the computer out of the bathtub along with all the other gear that is soaking after yesterday's diving.

I ran that on V-Planner and it is a deco dive. Even with bottom times in the teens, you still accrue an obligation.
ec to 150ft (3) Nitrox 24 50ft/min descent.
Level 150ft 12:00 (15) Nitrox 24 1.33 ppO2, 143ft
ead
Asc to 70ft (17) Nitrox 24 -30ft/min ascent.
Asc to 50ft (18) Nitrox 50 -30ft/min ascent.
Stop at 50ft 0:40 (19) Nitrox 50 1.26 ppO2, 20ft ead
Stop at 40ft 1:00 (20) Nitrox 50 1.10 ppO2, 13ft ead
Stop at 30ft 1:00 (21) Nitrox 50 0.95 ppO2, 7ft ead
Stop at 20ft 3:00 (24) Nitrox 50 0.80 ppO2, 1ft ead
Stop at 10ft 4:00 (28) Nitrox 50 0.65 ppO2, 0ft ead
Surface (28) Nitrox 50 -30ft/min ascent.
I keep my software fairly conservative, so your Tec2G is pretty close to what my dive would look like, only I would plan it that way and not just ride the computer.
Just my .02

I did not remain at 150 for longer than moments...just long enough to pull the trigger and bang the scamp grouper....the majority of the dive was spent at depths considerably shallower. At this point, I have not been trained to deco dive. So I do not know how to calculate deco dives. I rely on the computer and dive a profile that includes ascending to shallower depths when the computer indicates the "risk of deco" is near. To date, I have never actually "gone over" on any dive. But I am realizing now that all I have truly accomplished is becoming good at diving at the very "edge" of limits. Maybe it is possible that my "less carefull" buddies who accidentally go into forced decos...and have to stop and offgas in the water...are coming up SAFTER with LESS nitrogen in their blood...than me who was trying to follow the rules and stay out of deco, but pushing the limits? All I know is...this past weekend i didn't dive any different than I usually do...other than following these "optional micro bubble stop" setting on the computer and it made a HUGE difference in terms of the reported amount of loaded gas in my system at the end of the dive.

We've been doing 'Half the deepest depth' stops for atleast a full minute (ie 120 deep, stop at 60 for a minute) then complete a normal 3 minute stop at 15-20ft. Alot of doc's have said that half stops show significant improvement in off gassing.

For just me personally, the more work or swimming I do hunting for bugs at 85ft, the better I feel after a dive. I don't know if the increased effort and subseqent blood flow helps in the efficiency of off gassing bubbles, but seems to work.

Since we drift, I usually shoot my SMB at 30 ft and then crawl slowly to the surface as I wrap up the line.

Thanks for posting some good info for readers here!!

I was asking about similar S/W not in a dive computer but that could be installed on a home computer.

Personally, I prefer to use VPLanner. Excellent software, easy to understand, and inexpensive. Even if yiou don't do decompression diving, the information it provides about safety on some of the more edgy recreational dives is excellent.

Ross has a winner with this stuff.

Ok question about the "half stop." We all know that below 20 feet...we are loading nitrogen. Had I stayed DOWN at 120 for a while at that depth...I might have such staturation levels in my blood...that hovering at 60 feet would actually be releasing some amount of nitrogen (hence the usefullness of a 60foot stop on a 120 dive)...but depending on the profile...had I not spent much time "at depth", then i might just as well be LOADING nitrogen during that "1 minute half stop." Correct? I ask this for two reasons. 1, cause it is my "basic understanding" (which may be false) and 2, cause my Aldan Tec2G microbubble stop setting doesnt EVER have you stopping to offgas at that depths that great. It has up to "five levels of protection" and they correspond to 10 foot intervals.... in other words...if I push the limits on the dive (regardless of depth and time) to the very LIMIT of the "L5" setting (the fifth setting and HIGHEST level of protection) the first "micro bubble stop" is going to be at 50 feet. If I push BEYOND the limits of the highest setting of micro bubble stops...I enter my FIRST "obligatory deco stop" scenario. I routinely dive to depths of 130-150...but only if the vis allows it and only for a few moments... to take a quick look and take a quick shot at a scamp or "medium to small" AJ. Then I'm right back up to 90ish or wherever the next main "platform" on the rig might happen to be (anywhere from 75 to 110 somtimes.)

I don't really understand all of this, trully, because it seems to me...it almost becomes a "symantics game" at some point. Call it "micro bubble stop" and claim it to be "OK and within the SAFE limits of recreational non-deco diving" or call it a "decompression stop that is NOT within the safe limits of recreational non-deco diving." Either way... it seems to me the type of diving I am doing REQUIRES that I be STOPPING at intervals and offgassing....Not just doing a controlled ascent and a safety stop as I had been. Until I understand differently and have the training...I will continue to remain OUT of the obligatory deco range. But now realize I am adding about 10 minutes of "off gassing bottom time" to my dives and factoring in HAVING ENOUGH air to do it is another consideration I contemplated this last Sat. Still made it back with 500, but not a pound more. (well...not true...white lie... had 450 on one of the dives.