DeepThought said:
If spearhunters practice "agachon" (it means lurking for the fish to come immobile at the bottom - 30 m or so -) then he or she is heavily weighted...
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Preventing Blackout
- Thread starter fishon
- Start date
Thread Status: Hello
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If spearhunters practice "agachon" (it means lurking for the fish to come immobile at the bottom - 30 m or so -) then he or she is heavily weighted...
I was talking about freediving, spearfishing is the exception usually since it's much more case-dependant. Also, I'de assume that aspetto at 10m of depth will require more weight than at 30m.subaquaticus said:
DeepThought said:I was talking about freediving, spearfishing is the exception usually since it's much more case-dependant. Also, I'de assume that aspetto at 10m of depth will require more weight than at 30m.
aspetto = "agachon" ?
you are right... a spearhunter doing "aspetto" at 5-10 m depth... is more prone to sink after a BO than that whoes does it at 30 m depth...
though I suppose (not being a spearo myself) that a spearo wanting to do "aspetto" will minimize his efforts to reach whatever depth...
He will be more heavily weighted than the "pure" freediver doing solely the retur trip...
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The point of taking the snorkel out of the mouth when diving is for the mouth to be able to be closed in case of a BO and it's easier for recovery breathing as well, not having to make the effort to blow away water when one should be breathing in air upon breaking the surface. That little effort could bring on a BO if one's already at the hypoxic limit.
As far as the diver not sinking, that's what the buddy is there for, to hold your airways clear of the water if you have any difficulties!
Adrian
As far as the diver not sinking, that's what the buddy is there for, to hold your airways clear of the water if you have any difficulties!
Adrian
My opinion has always been: take that snorkel out of your mouth and never start to exhale underwater (because of a conditioning of the subconsciousness). I have changed my mind in the latter point because pretty much everybody does lung packing these days and the last part of the ascent after having packed leads to rapid overinflation of the lungs. But I haven't changed my mind when it comes to using a snorkel. when I simply go fun diving I always use a snorkel. But for each dive I do a last full exhale and after the full inhale I take the snorkel out of my mouth and stick it upsidedown under my belt in the back area. This way it doesn't bother me dangling on the side of my head and I get a more streamlined shape as well. Besides of that it sort of "shifts me into diving mode" :hmm . It's a little every-time-the-same-routine which sets me at ease.
doesn't matter what depth you are hunting, if you are negative even on the surface you can not hunt at all. Because you have to swim on the surface to spot the place to dive if you are negative at the surface you can not do this for sure. Even most shallow aspettos i did not see diver including me negative on the surface. In most hevaily wiegheted extreme scenario for below 3-4 meter aspettos i am still positive on the surface and negative only when i exhale all the air in my lungs, and let me remind again this is the only for 4 meters and less deeper diving situations. I don't think anybody is stupis enough to have blackout
while doing aspettos at 3-4 meters deep.
while doing aspettos at 3-4 meters deep.
Murat, I agree but if U have a blackout U'll most likley let the air out of ur lungs bacuse the incrised presure of the water will force it out without ur mucles operating and keeping the road closed. So if U exhale what are u then...? Negative of course.
If a person is diving from a boat, it seems they could be negative on the surface and hold on to the boat when they surface. For that matter i have heard of people pulling a large balloon type buoy with them with a weight on the bottom. Some of the weight could be attached to the buoy on the way out, and the buoy could be held on to when on the surface, and they could still be negative on the surface.Murat said:
efattah said:
I think the urge to breath just comes sooner. Yes your dives may get shorter with lower rests but I don't think that it increases the risk of blackouts.
What research shows that more blackouts are caused by short rests between dives.
efattah said:
I am confused why you would want to keep higher levels of carbon dioxide in your system. Could these 60 second statics in the recovery phase increase your risk of DCS?
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hi,
after a short rest you will do the next dive without being recovered from the last one, meaning your body still consumes a lot of o2 so you will run out of o2 sooner. the risk arises if a diver thinks he can stay just as long as on a dive which he did after a good rest.
a short static before a dive will elevate your co2 levels, therefore you will get the urge to breathe earlier. an early urge to breathe means you have more time left until bo. you get an earlier warning signal and acidic blood helps you remain conscious longer (bohr effect).
that would be my interpretation of these statements.
roland
after a short rest you will do the next dive without being recovered from the last one, meaning your body still consumes a lot of o2 so you will run out of o2 sooner. the risk arises if a diver thinks he can stay just as long as on a dive which he did after a good rest.
a short static before a dive will elevate your co2 levels, therefore you will get the urge to breathe earlier. an early urge to breathe means you have more time left until bo. you get an earlier warning signal and acidic blood helps you remain conscious longer (bohr effect).
that would be my interpretation of these statements.
roland
immerlustig said:
So from your interpretation it would seem that the risk does not increase. It increases only if the person does not listen to their normal urges.
immerlustig said:
If you know you are getting the urge to breath sooner you may push harder because of it thinking you have more time to stay under. Can you please explain how acidic blood helps you remain conscious longer?
most bo's could be avoided if the diver would pay more attention to details, especially in evaluating his condition before a dive. all divers i know who ever bo'd uw could afterwards name various factors that were leading up to the event (lack of sleep, stress, environmental conditions, attitude, etc). so in principal it should be possible to realise these factors beforehand as well and make a change in the dive plan. divers who claim they have absolutely no idea why they bo'd are, in my opinion, not very aware. awareness is therefore one of the more important skills to learn and improve.
regarding an increased risk of bo after short recoveries, the less time you have from when you get an urge to breath until you do run out of o2 the less time you have to do something about it and ascend. so in a way one could argue the risk does increase.
http://www.chemsoc.org/networks/LearnNet/cfb/transport.htm
the "bohr effect" causes a change of o2 affinity to haemoglobin. when the blood is acidic o2 will come off the haemoglobin more easily. a diver will eventually bo with lower levels of o2 in the blood. a diver who hyperventilated beforehand and whose blood was therefore more alkaline will bo with high levels of o2. this has been measured many times and explains to a degree why the slow breathe-up approach is so effective. on a max static, for example, one can expect contractions to come at around or shortly after the total dive time.
cheers
roland
Too short rests DEFINITELY increase your risk of blackout. Your creatine phosphate stores will take 5 minutes to recharge, this cannot be accelerated no matter how fast you breathe. Similarly, lactic acid, which itself drains oxygen, must be cleared from your system and this can take MANY minutes (or even half an hour). As a result, if you start your next after a short interval, you are guaranteed to be starting your dive with a lower-than-normal store of energy, meaning you will run out of energy sooner, and when you run out of energy, you black out...
Increasing your CO2 levels do not have any effect on DCS... but they help you avoid a blackout by increasing O2 release from hemoglobin, and by causing earlier vasoconstriction (and hence sparing of O2).
Increasing your CO2 levels do not have any effect on DCS... but they help you avoid a blackout by increasing O2 release from hemoglobin, and by causing earlier vasoconstriction (and hence sparing of O2).
efattah said:
So your not more at risk, your dives just become shorter. If we look at top spearfisherman we see lots of one to one ratios of breathup time to dive time. Just like any other physical activity your body will become used to it and adapt.
