Decent too fast?

[k4sdi]

I was wondering,,,,,,

I have never had any problems clearing my ears. Neither has my dive buddy. We tend to go straight to the bottom as fast as possible. Is this a bad habit?

 

[voidware]

probably not, as long as you equalize enough (remember your mask!). Some tables include the descent in their calculations, other assume an instant descent. If you use a computer you're okay, but if you use tables you are probably going to lose some conservativism (not enough to really make a difference).

brandon

 

[Fetch]

Er, what tables assume a non-square dive profile?

Just curious, I hadn't heard of this before.

Jeff

 

[jbd]

k4sdi--we had a discussion about descent rates last year I believe. Try a search. If I recall correctly there was no problem with fast dscents as long as you can equalize properly. Also it seems like I have read a recommendation of not descending faster than 75 ft/min. Just can't remember where I saw that though.

 

[Walter]

jbd,

Look in volume 2 of the US Navy Diving Manual Chapter 7-6.4

"The rate of descent will generally be governed by the ease with which the divers will be able to equalize the pressure in their ears and sinuses, but it should never exceed 75 feet per minute."

The NOAA Diving Manual Chapter 17.5.1 states, "The rate of descent may be the same as dives from the surface(60fsw/minute)."

 

[BILLB]

NAUI uses the NAVY recommendation of 75 fet per minute maximum. I also use it for teaching dive planning especially when calculating air consumption. What I do not know is the medical reasoning for this rate of decent.

Of course there is the ingassing and pressure equalization that is unique to everyone diving. I have seen many divemasters who "set the hook" simply fall at an decent rate with the hook probably faster than 75 feet per minute.

Where is Bruce Weinke when we need his opinion?

 

[Walter]

When you set the hook, you often drop at over twice the recommended descent rate. It results in more intense narcosis.

 

[BILLB]

Walter,
I have been up all night working and I am narced. However, can you expand the thread on the increase in narcosis when decending too fast?

 

[jbd]

I was going to ask the same thing BillB. I would like to see a discussion about descent rates beyond 75 feet per minute.

 

[DocRCH]

Some people may get somewhat disoriented during fast decents, but I do not really see a significant problem. I would say if you have to switch gas mix, I would be sure to follow the dive plan.

Robert:doctor: