100ft deep dive, safety stop at a little below 20ft

[jtivat]

I few weeks ago I did a dive to 120' for 20 minutes my charts had me doing 1 min at 20' and 7 minutes at 10' for deco (this is using 50% for deco). I usually start to go for my 50% at 70' and go up slowly from there when I got to 20' my regular air computer had already cleared my deco. My point being that when you come up slowly you do a lot of off gassing (also that Oceanic’s are very liberal). Also note I still did all my deco with the 50% and if we are going to dive again I will hand at 10’ even longer why not it’s hang there or wait and hour or two on the boat.

 

[roakey]

There's a concept called "deep stops" in the technical diving community. An easy way to incorportate this into your recreational diving (technical divers: this isn't perfect, but it's reasonable ) is to ascend to half your depth (rounded up to the nearest 10 feet) hang there a minute, repeat until you get to 20 feet, hang there a minute, then hang two minutes at 10 feet and then *very slowly* ascend the last 10 feet (take at least 30 seconds).

So a 100' dive would be:

Ascend to 50 feet, stop for a minute
Ascend to 30 feet, stop for a minute (50/2 = 25, round up to 30)
Ascend to 20 feet, stop for a minute
Ascend to 10 feet, stop for 2 minutes
Slowly ascend to the surface.

Roak

Ps. This assumes you have a "no stop" dive -- no required decompresson stops.

 

[Doc Intrepid]

There's a concept called "deep stops" in the technical diving community. An easy way to incorportate this into your recreational diving (technical divers: this isn't perfect, but it's reasonable ) is to ascend to half your depth (rounded up to the nearest 10 feet) hang there a minute, repeat until you get to 20 feet, hang there a minute, then hang two minutes at 10 feet and then *very slowly* ascend the last 10 feet (take at least 30 seconds)...

Whereas empirical data regarding decompression can sometimes be hard to find, DAN has been spending quite a bit of time and resources to develop empirically-based studies. One of these is quite interesting, and directly related to this thread:
http://www.diversalertnetwork.org/news/article.asp?newsid=514

To cut to the chase (emphasis added, see about 2/3s of the way through the article):

"Clearly, the best decompression schedule is Profile 6 (see highlights in both tables). With an ascent rate of 33 feet (10 meters) per minute, and two stops at 45 feet (13.5 meters) and 9 feet (2.7 meters) respectively, this profile had the lowest bubble score of 1.76."

FWIW...