Descent Rate Limitation of 75 ft/min

[boulderjohn]

Some people teach that for deep dives planned on tables--including tables generated by software programs--a certain descent rate is assumed. On a shallow dive, it won't make much difference if you exceed it. On a very deep dive, a faster ascent rate means you spent more time at the deepest part of your dive than the dive plan expected. Roughly calculating the case James described above, the program/table might assume the diver spend the first 3 minutes of the dive at an average depth of 100 feet, when in reality those 3 minutes were at an average depth of 170 feet.

I don't know if that is the reason in this case, but I do know that people who dive tables and descend significantly faster than the assumed rate might want to consider themselves as having had more bottom time than normal.

 

[mathauck0814]

Point the scooter at the bottom and pull the trigger.

 

[TSandM]

Point the scooter at the bottom and pull the trigger.

I did that on Little Brother in the Red Sea. It was pretty fun . . . (gotta be careful with those ears, though!).

 

[Basking Ridge Diver]

Hope you don't hit a mud hole either at a fast clip. I have heard folks can get stuck in the mud and can not get out with out help of "dive buddies"... Could be just a story or could be true - either way I dont want to hit the bottom like a lawn dart.

 

[chillyinCanada]

I don't hit the bottom because I have control but still buzz down as fast as my ears will let me. This only works when I don't have a buddy to stick with.

 

[TSandM]

In the Red Sea, we could see the bottom at 140 feet, when we put our heads in the water. It was great fun!

 

[azhar]

I think that deco tables are worked with this assumption therefore it is limited.
However this is a guess anyone have a definitive answer, with reference from there veteran instructors/ mentors?
You can look at up at US Navy Manual Rev.6 Chapter 9.

 

[Crass3000]

If I really want to get down I don't watch my ascent rate. After my deepest dive and having to come up 20ft to equilize and then went down to about 182ft on a bounce dive, my ears don't work as well. used to be able to equalize without any problem. Possibly I have ear infections. When they find them I never know I have them. For some reason I never get pain from ear infections. But that goes to show I never know so I might have them pretty often. Word of advice. There's really no reason to do bounce dives. It seemed fun at the time and seemed like I was progressing which I always want to do but now that I think about it they are just dumb. While they might be easy to control and pull off -- it's just a matter of time until you hit deco. Not that deco is that big of deal (it is for me) and NDL as they go up pretty quick as you rise. I feel pretty dumb. But I know I can pull it off.

I guess my point is that sooner or later if you do deep bounces it may catch up with you.

 

[Steve_C]

It can depend on if you have a hard/soft bottom under you or for practical purposes no bottom. In the second case you need to be able to control your descent so that you can stop over open water at the desired depth. That is best done adding air on the way down which also means you are slowing your descent. If it is only 70 or 80 ft then the drop rate is controlled by how my ears and my buddy's ears are doing since I want to be within reasonable distance (visual contact) of buddy. I have a couple of buddies that need to do slow descents and sometimes go up a bit before continuing down. I can usually drop pretty fast if I want to and am already 15-20 ft down which is the case with NC diving since we usually follow a line to the anchor at about 15 ft.

 

[Hatul]

It can depend on if you have a hard/soft bottom under you or for practical purposes no bottom. In the second case you need to be able to control your descent so that you can stop over open water at the desired depth. That is best done adding air on the way down which also means you are slowing your descent. If it is only 70 or 80 ft then the drop rate is controlled by how my ears and my buddy's ears are doing since I want to be within reasonable distance (visual contact) of buddy. I have a couple of buddies that need to do slow descents and sometimes go up a bit before continuing down. I can usually drop pretty fast if I want to and am already 15-20 ft down which is the case with NC diving since we usually follow a line to the anchor at about 15 ft.

That's my thinking too. If you're diving in an area with a bottom much deeper than the max depth you want to dive, it's not a good idea to rocket down as you may end up with runaway descent that you may not be able to stop, especially when diving with a thick wetsuit and no redundant buoyancy. Descending into an area with "no bottom" it's safest to stay close to neutral buoyancy throughout the descent.