Ascending from shallow dives

[Eric Sedletzky]

If you are neutral at 20’ and are able to cruise around horizontally, AND you do not have to dump air to go up
then it sounds like you don’t have any air in your BC at 20’ which means you are just about perfectly weighted, maybe even a tad on the light side
How refreshing it is to hear this!

 

[Diver0001]

I am ascending according to PADI's "safe" rate of a foot a second.

This recommendation is out of date. PADI's current recommendation is to follow the instructions of your computer, assuming you are using one.

Almost all computers on the market are set to about 33ft/min (about 1/2 of what you are using) in accordance with the last 15 years or so of deco theory that provided substantial evidence that 60ft/min is far too fast for safety. In addition, you're starting your ascent too deep. 20ft is really deeper than you should be doing a safety stop and 30ft is well too deep. So you are ascending too fast and from too great a depth for optimal safety.

I should note that while very few people are still using the PADI table, the maximum ascent speed applied to testing the table was indeed 60ft/min. Applying an ascent speed of 30ft/min to the table is also quite feasible and, I would say, safer since 30ft/min conforms to current thinking. Therefore, even if you are using the table, you should slow down your ascent through the last 30ft considerably.

R..

 

[KevinNM]

Iirc, study showed that 10ft/min was too slow, and 60 ft/min was too fast. This is for the whole ascent. I’m not sure there is a too slow from safety stop to surface.

 

[TMHeimer]

3 feet pr second??

Not sure what you mean. I posted a foot a second (= 60'/18mtrs. per minute).

 

[TMHeimer]

This recommendation is out of date. PADI's current recommendation is to follow the instructions of your computer, assuming you are using one.

Almost all computers on the market are set to about 33ft/min (about 1/2 of what you are using) in accordance with the last 15 years or so of deco theory that provided substantial evidence that 60ft/min is far too fast for safety. In addition, you're starting your ascent too deep. 20ft is really deeper than you should be doing a safety stop and 30ft is well too deep. So you are ascending too fast and from too great a depth for optimal safety.

I should note that while very few people are still using the PADI table, the maximum ascent speed applied to testing the table was indeed 60ft/min. Applying an ascent speed of 30ft/min to the table is also quite feasible and, I would say, safer since 30ft/min conforms to current thinking. Therefore, even if you are using the table, you should slow down your ascent through the last 30ft considerably.

R..

I'm usually slower than 60'/minute. I didn't know PADI changed that recommendation, but did know everyone else had previously recommended 30'/minute. Thanks for clarifying.
Keep in mind that when I start my ascent from 20' I'm starting from the bottom (so really 18' since I'm usually 2' off the bottom diving). I have read that around that depth is where you could stay down indefinitely and directly ascend. Assume that since the longest I may be down there is 45 minutes, I doubt a safety stop does much of anything. As well, with these simple shore dives (20 or 30'), I probably spend way more than 3 minutes swimming in to shore in depths of 10-15'. I believe a safety stop was once considered best at 10', but was changed to 15 for convenience of getting a little deeper away from wave action or boats.
When you say slow down the last 30', you are assuming I have been deeper than that. I'm ascending from the bottom, not from a safety stop. Are you saying I should begin my ascent from 20 (18)', ascend 3 feet up to 15' depth and do a safety stop?

 

[CuzzA]

For a twenty foot dive I wouldn't even have a computer and wouldn't bother looking at a depth gauge. Just kick up one time off the bottom and float up. There's literally not much to consider other than holding your breath or getting hit by boat.

 

[TMHeimer]

For a twenty foot dive I wouldn't even have a computer and wouldn't bother looking at a depth gauge. Just kick up one time off the bottom and float up. There's literally not much to consider other than holding your breath or getting hit by boat.

Yeah, no computer. I still go up slowly, but I doubt speed matters much. I look at depth gauge--gotta put something in the log book.

 

[ScubaWithTurk]

I try to keep my ascent rate at 9 meters per minute. When looking at my computer it has an ascent speed graph. If I keep it right in the middle of the graph I am dead nuts on the 9 meters a minute.