Ascent Rate (SSI vs PADI)

[Omisson]

I second this statement. It was teached in my school. Smallest bubbles ascent slower than big bubbles.
Bubbles ascend at a rate of 20 mts/min (65 ft/min). You should ascend at a lower rate than this. Slower means safer.

Slower doesn't ALWAYS mean safer, the longer you are at an on gassing depth the closer you move to decompression. So it's more accurate to say there is an optimum ascent rate of between 30-60 feet per minute which should not be exceeded... But also should not be deceeded/subsceeded.


Dan-O

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[Ricky B]

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A ScubaBoard Staff Message...

The topic of this thread is Ascent Rate (SSI vs PADI). Please keep posts on topic.

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[johnnyblackau]

My two cents worth ... TDI recommend ascent rates of 10m/ min... Slower is safer if you pay attention to bubble
Models


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[Omisson]

My two cents worth ... TDI recommend ascent rates of 10m/ min... Slower is safer if you pay attention to bubble
Models


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SLOWER IS NOT SAFER.

I don't know how many more times people saying this is needed before people get it.

You must be at an optimum speed in deco dives to limit on gassing during ascents and prevent additional tissue loading.

It must be NO LESS THAN 30 feet per second and NOT MORE THAN 60 feet per second. BUT CLOSER TO 60 limits on gassing the best- AND is the US Navy standard because it works in tens of thousands of dives.




Dan-O

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[Diver0001]

There is such a thing as "too slow" but it's not a major problem. If you're diving with tables you just need to add the ascent time to your bottom time if you're going under 10m/min.

If you're diving with a computer then it will calculate your deco time for you.

In terms of recreational diving "riding" the computer will tell you where you are on the map. It might not be "beautiful" in the sense of "looking good while you do it" but the computer *will* tell you where you are on the map.

R..

 

[knotical]

While “slower is safer” is a simplification, so is “between 30 and 60 fpm”.

In reality, we can never know the optimal ascent rates. They will vary with depth, individual physiology and previous profile(s).

The guestimates of optimal ascent rate (to reduce tissue on-loading while also minimizing risk of DCS) vary from model to model. At depth speeds greater than 60 fpm can be OK. In shallower water slower can be safer.

And what I just said is also simplification.

 

[Steve_C]

So I am coming up the line say from 100 ft. Around 50 or maybe 40 or maybe 60 the viz improves and there is some interesting stuff in the water. Assuming I am within NDL I will stop and watch the critters for a while. Then I will head on up. This is just a multilevel dive except a level occurs in mid water. I understand the point that if you are at a certain depth and hang there for a while you will on gas. But again that is just muiltilevel diving. I see no problem with this on Rec dives. Folks stop ascents all the time for various resasons.

 

[johnnyblackau]

I understand that too slow of an ascent rate is an issue (still on gassing of compartments) however my intention of that statement was a relative one. I didn't state numbers, but I believe that 10m a min rate is ideal ( tdi manual) ... Slower is an issue...


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