Rapid Descent Rate

[RobPNW]

When I get in the water, I tend to dump all my wing gas and exhale and descend pretty fast. When I get to depth I add gas to the wing and level off. We always worry about rate of ascent for obvious reasons but is there an unsafe descent rate? The only thing I can think of is maybe higher chance of narcosis?

 

[Jcp2]

Is this with or without a hard bottom?

 

[RobPNW]

With a hard bottom.

 

[inquis]

Descent rate is an issue with VERY deep dives (over 100 m from High Pressure Nervous Syndrome), but I think the main thing for a recreational diver is simply to not plow into the bottom. (It takes a surprisingly long time on the inflator to halt at 100 ft if you have a good head of steam.)

 

[kinoons]

Pardon me if I’m not experienced enough, but if you’re plummeting towards the bottom vs swimming down once you let the air out of your wing, and requiring adding air to the BCD at depth, are you over weighted?

Sure you shouldn’t have to actively swim with effort down, but you shouldn’t drop like a peice of blue ice from an aircraft in flight either.

 

[RobPNW]

You chose to use the term plummeting. I said fast. Fast is a relative term and doesn't need to mean jumping off the Empire State building. It could mean descending at about 60 feet per minute. Also, I barely stay neutral at a safety stop with a near empty tank but at the beginning of a dive with a full tank and exhaling, I can sink easily.

 

[davehicks]

You chose to use the term plummeting. I said fast. Fast is a relative term and doesn't need to mean jumping off the Empire State building. It could mean descending at about 60 feet per minute. Also, I barely stay neutral at a safety stop with a near empty tank but at the beginning of a dive with a full tank and exhaling, I can sink easily.

If you are sinking like a rock on decent you are most likely overweighted. If you can't hold a safety stop you are probably retaining gas in your drysuit, bc, or lungs.

A steel tank will work better as it will still be negative at the end of the dive. Aluminum tends to swing to the positive when it nears empty.

 

[RobPNW]

With 500psi at a safety stop, I have to reach back with my hands and flatten my wing to be neutral. And the only way I sink at that point is to completely exhale or swim down. I'm not overweighted.

 

[GF99/99]

When I get in the water, I tend to dump all my wing gas and exhale and descend pretty fast. When I get to depth I add gas to the wing and level off. We always worry about rate of ascent for obvious reasons but is there an unsafe descent rate? The only thing I can think of is maybe higher chance of narcosis?

Wait until you get a 25+kg rebreather strapped to your back, 7 tanks with 7 first stages so you sink like a rock ohh and then point your DPV down and your doing 40+m/min so that your ADV can barrel keep up that you have to help it out with your MAV.

Do that for 4 min and then trying to slow all that down and level off at 160m is always fun...

 

[kaylee_ann]

Wait until you get a 25+kg rebreather strapped to your back, 7 tanks with 7 first stages so you sink like a rock ohh and then point your DPV down and your doing 40+m/min so that your ADV can barrel keep up that you have to help it out with your MAV.

Do that for 4 min and then trying to slow all that down and level off at 160m is always fun...

first of all- love the username.
second, this is kinda off topic, but yeah. Having a lot of weight by choice or being overweighted makes it harder to stop quick. Like why semis, vans and SUVs take longer- they’re heavier vehicles and usually have more stuff in them than compact cars.