Surface Intervals

[samdive]

What surface interval do you give yourself between freedives? do you even think about this? After a recent DCI hit I have been recommended to keep 10 minutes between dives and from the groups of I have been training with this seems quite a long time, to me it seems sensible though and I think my dives are of better quality because of it. Just wondered what everyone else is doing.

Sam

 

[Alun]

...depends on the depth.

if you're talking about max effort dives, then i would want to click a 15mins+ category, but there isn't one.

 

[Jon]

I agree with Alun.

When it comes to the deeper stuff I always do twice my bottom time.

Last Saturday, when Ted and I went out spearfishing, it was more like 45 seconds- max depth 35'.

Jon

 

[Jersey Jim]

I also go with twice my prior breath-hold time. Was real inconvenient timing this with the Apneist computer. For this reason I went with a D3 this year. It times surface interval down to the second.

Jim

 

[Jersey Jim]

Forgot to mention, different body composition will vary the need for longer off gassing, as body fat retains N2 longer, and maybe CO2, but not certain about the latter.

Jim

 

[efattah]

This is the self-made table that I have used for the past 2 years:

[DISCLAIMER: I don't claim this table is accurate! Find more sources!]

This is assuming you are inhaling & packing before you go down:

Depth Dive Time Surface Interval
20m Any Any*
30m 1'30 4 min
30m 2'00 6 min
30m 3'00 10 min
30-35m 4'00+ 15 min+
35m 2'00 6 min (could be too short)
40-50m 2'00-2'20 8 min (could be too short)
55-65m 2'00-2'20 12 min (could be too short)
70m+ 2'00+ 15 min+ (could be too short)

*there was that study where a guy dove to 20m in a tank enough times to get bent, so in theory there is some minimum interval for 20m as well.

This is the table I've used over the last few years, and I haven't been bent yet....

This table only considers DCS, and it doesn't consider recovery from a hypoxic incident or extremely difficult dive, in which case you might need 20-30min (or a day off), to recover before you go down again.

Eric Fattah
BC, Canada

 

[derelictp]

Hello!

Did you get bent from a freediving session Sam?

In that case it should be interesting to know your number of dives, the depth of the dives, the duration and the surface intervals. (Offcourse approximately )

 

[samdive]

no I got bent from scuba diving, but only from 11m. Had both pain and neurological symptoms so they are trying to advise me to be conservative on my freediving as I may be susceptible. 10 minutes is working well for me, but yes Alun, 15-20 is better before a max
thanks guys, we may be doing some more research on this, I will keep you posted

Sam

 

[Erik]

Sam, I can't remember if you had ever stated that you have a PFO....do you have a PFO?
Dive safe,
Erik Y.

 

[efattah]

Seb Murat was telling me that if you have PFO, and you adopt FRC diving, not only do you reduce your risk of DCS, but the PFO actually gives you an advantage in the FRC realm vs. a diver who doesn't have PFO. Personally I haven't thought of the physiological implications.

But FRC diving for Sam would definitely seem the way to go. Wouldn't even need to worry about any surface intervals.


Eric Fattah
BC, Canada

 

[derelictp]

PFO???

Can Erik or Eric tell me what PFO is?

Am I stupid or

 

[Erik]

PFO stands for Patent foramen ovale, which is a heart defect that greatly increases the risk of DCS (decompression sickness) for those that are born with it. I believe it is a hole that allows a small amount of blood to bypass the lungs (where nitrogen would be off-gassed) and thereby promote DCS.
Cheers,
Erik Y.

 

[efattah]

Keep in mind that crocodiles and alligators have an extra valve in their heart, which deliberately causes blood to bypass the lungs during apnea. If you exhale before going down, then pumping blood past the lungs is a waste of energy.


Eric Fattah
BC, Canada

 

[samdive]

I don't have a PFO, got checked out a couple of weeks ago.

What's FRC diving? am I being dumb?

 

[Alun]

FRC = functional residual capacity... basically diving after exhaling.

 

[samdive]

tried that and it scared me...... did weird things to my ears and made me panic

no thanks!

Sam

 

[bluecape]

On an average session, I dive plus minus 7-15 meters, collecting muscles or spearfishing, and surface intervals probably average at about 1m 15 sec. This topic is really interesting, as it seems as though I need to give myself more recovery time. ( Only since using my D3 have I watched surface time.)

This may sound crazy, but if I had to ask myself what causes me to rush surface time a lot ...it' would probably often be on days that something has triggered my concience to be thinking of our Great White friends. They are far more like to hit you on the surface. A buddy of mine who has done a bit of research into their behaviour believes they will watch you for sometime, before deciding that you are not a 'scuba diver', but rather a seal ????
Nothing like these thoughts to get you scurrying back down into the deep blue !

 

[efattah]

Originally posted by samdive
tried that and it scared me...... did weird things to my ears and made me panic

no thanks!

Sam

As with anything in life, you get out of it what you put into it. In the end it all depends how much you want it. If you're not willing to learn a new style of diving to overcome a physiological problem, then I question how badly you want to dive at all.


Eric Fattah
BC, Canada

 

[efattah]

Keep that negative karma coming! Sometimes the truth hurts.

Eric Fattah
BC, Canada

 

[ash]

I am a still very much a newbie but my freediving "journey" has been as much about overcoming problems as it has been about discovery.

For example, my first negative dives weren’t much fun and it took some concentration and a lot of effort before I was 100% comfortable with the new sensations I was feeling.

The same goes for pushing through all the statics. Initially I wasn’t enjoying them at all but with enough work, I managed to get to a point where I was very happy doing longer statics and managing the contractions.

The end result of pushing through these (and other) little barriers that made me uncomfortable was of course worth the effort and I believe that’s the point Eric is making.

IMHO I certainly wouldn’t say he deserves any negative karma for his comments in this thread.

Thanks

Ash