"Bouncing"

[Influx130]

I see a lot of mates on Dive Boats "bouncing to check the anchor, spot, etc". What should I consider when doing this or should I not even attempt it. I dive between 100-50 feet typically.

It seems to me that it wouldn't be a big deal because your not down long enough to ongas that much nitrogen. It would be nice to nail out a couple of spots I have marked but havn't dived.

Thanks.

 

[Blackwood]

IMO, the time to be wary of bouncing is after other dives. The bounce itself may not be significant with respect to ongasing, but it certainly could be with respect to crushing existing bubbles and permitting them to pass into dangerous locations of the body before expanding (on ascent).

 

[deepstops]

IMO, the time to be wary of bouncing is after other dives. The bounce itself may not be significant with respect to ongasing, but it certainly could be with respect to crushing existing bubbles and permitting them to pass into dangerous locations of the body before expanding (on ascent).

Exactly.

 

[Thalassamania]

A bounce (with an appropriately slow ascent, and without a safety stop) as the first dive of the day, or after a significant surface interval, should pose no problem. HOWEVER, right after a dive, it can be quite dangerous. You bubble on almost every dive, especially on the lower pressure venous side. These bubble travel harmlessly to you lungs where they are filtered out in the capillary beds. If you descend with these bubbles trapped in your capillaries, they can be compressed and travel thorough to you arterial circulation. If you ascend just then, that can result in DCS/AGE symptoms.

Woops ... got delayed, Blackwood (bridge player?) already said it.

 

[Teamcasa]

IMO, the time to be wary of bouncing is after other dives. The bounce itself may not be significant with respect to ongasing, but it certainly could be with respect to crushing existing bubbles and permitting them to pass into dangerous locations of the body before expanding (on ascent).

Ditto.

... HOWEVER, right after a dive, it can be quite dangerous.

Ditto - again...

 

[Influx130]

got it...thats kind of what I was figuring myself. Thanks

 

[bleeb]

A bounce (with an appropriately slow ascent, and without a safety stop) as the first dive of the day, or after a significant surface interval, should pose no problem. HOWEVER, right after a dive, it can be quite dangerous. You bubble on almost every dive, especially on the lower pressure venous side. These bubble travel harmlessly to you lungs where they are filtered out in the capillary beds. If you descend with these bubbles trapped in your capillaries, they can be compressed and travel thorough to you arterial circulation. If you ascend just then, that can result in DCS/AGE symptoms.

Speaking purely about theory, I seem to recall from previous posts that fast tissues like blood only take 2-3 minutes to saturate, and since the process is exponential, even one minute at depth gets you most of the way there. Also as Thal pointed out, Doppler studies have showed bubbling on just about any dive. IIRC, other Doppler studies have also found that the maximum number of detectable bubbles seems to be about 50 (to 60?) minutes after surfacing. However, I don't know how true this might be if someone hasn't been under pressure long enough for tissues other than blood to pick up significant amounts of oxygen. Nevertheless, if the former is true, all this might suggest that even with a short dive, an SI of 60+ minutes might be a good precaution. OTOH, if other tissues really aren't offgassing into the blood stream, maybe only 5-6 half times for the blood alone (15-20 minutes?) might be needed. Either way, I'm wondering if after a bounce, even if it's the first dive of the day, a decent SI afterwords might not be a bad idea.

 

[Thalassamania]

A point that I did not make clearly is that a bounce followed by a prolonged dive should be fine, but the opposite (dive then bounce) may be a problem.

 

[Blue982]

IMO, the time to be wary of bouncing is after other dives. The bounce itself may not be significant with respect to ongasing, but it certainly could be with respect to crushing existing bubbles and permitting them to pass into dangerous locations of the body before expanding (on ascent).

This is also the reasoning I've been given not to freedive after scuba diving. I believe it's excellent advice.

 

[TNdiver6387]

This is also the reasoning I've been given not to freedive after scuba diving. I believe it's excellent advice.

I'll second this. On the freediving board I used to frequent that warning was given VERY VERY frequently and discussed in depth, but long story short NEVER freedive with in 24 hours of scuba diving is what they always said. A bounce would have the same dangers associated as freediving I would think.