goin' down ... descent tips for newer divers

[Blackwood]

Nitrox has no effect on buoyancy...

Well, if we really want to spit hairs, it does. Since O₂ is ever so slightly more dense than N₂, it should have helped 'Joe' rather than hindered him.

 

[Rick Inman]

Nice post, as usual, Bob.

Yeah, I'm with those who use the skydiver descent. You can easily see down where you're going, above you if you need to, your buddy, and you won't spin and lose directional perspective. Plus the water resistance against your body gives you more control. Also, the auto-kick factor Bob referred to is reduced in that position, because any kicking pushes you forward and not back up.

I also like dumping from my butt dump on the surface to begin the descent. That has a tendency to keep you in that skydiver position and not put your feet down.

 

[sabbath999]

I also like dumping from my butt dump on the surface to begin the descent. That has a tendency to keep you in that skydiver position and not put your feet down.

I've been doing that the last few of dives, nice to know what I was doing makes sense to others...

 

[Blackwood]

Another addition:

Many divers dump as much gas as they can. The makes them really negative from the get go, and uber negative as they reach depth.

A [-]better[/-] different idea is to dump just as much as you need to in order to break the surface, and to then continuously add gas to your BC throughout the descent to maintain as close to neutral buoyancy as possible. Descending at a constant rate makes the whole thing much easier to control, and you can stop on a dime if you need to.

On the other hand, if you are negative throughout the descent, you will be accelerating downwards (at least until you hit terminal velocity), and you'll have to add a ton of gas to stop.

 

[Garrobo]

Personally I prefer to descend head first. I just flip over when I leave the buoy and drop down, sometimes finning, clearing my ears now and then. When I get close to the bottom or wreck I give the BC a short blast of air to stop the descent if necessary.

 

[letterboy]

Good post... Thanks... but I can't resist telling a very funny (at least it was at the time) story.

I used to work at an LDS (now partly owned by the guy I'm referring to in this story.) The name has been changed to save him the embarrassment... but he was supposedly a Navy Diver and according to the website.. instrumental in the recovery of the Atomic Bomb off Rota Spain.

In any event, I was "in charge" of the quarry on this particular day. I was standing at the top of the hill (talking to a couple of people) overlooking the entry beach when I heard a bunch of splashing and grunting. It sounded like someone was in trouble... so I looked over the edge of the hill and saw this diver flailing around on the surface in what appeared to be an attempt to descend. I quickly noted that His BCD was fully inflated. I waited for him to pop his head up out of the water then yelled down to him...

"Hey Joe, what are you doing down there." He turned around and yelled back "I'm testing out this Nitrox I just got certified on."... So I yelled back... "Why are you splashing around on the surface?"
To which he replied, "I can't get down... I think it's something to do with this Nitrox or something!"

To which I replied..." Joe, let some air out of your damn BC!"

He let some air out and down he went... We can all sleep better knowing Joe now teaches students to dive... and maybe even teaches them the benefits of Nitrox!

Sorry... that's another thread ...

Nitrox has no effect on buoyancy... but as Bob pointed out... kicking your fins does, having a partially inflated BCD does, anxiety does (just relax,) improper weighting does, type of water (salt vs fresh does,) the thickness/material of your wetsuit/drysuit does, type of tank does (steel vs Aluminum,) etc..

The "skydiver" descent is the best descent to use... been teaching that for years from pool one...

Thanks again Bob for a great post.

I heard this rumor, pretty scary considering the Dive Con class we were in together . . .

 

[Silverback784]

Thanks Bob I will have to try this technique. Saturday makes sense.

 

[jwc3]

I also like dumping from my butt dump on the surface to begin the descent.

Eww. And I thought those were sea slugs!

 

[dumpsterDiver]

Another good post Bob.
.

Frankly, I'm surprised at the number of divers that still descend in a vertical or heads up position.

While I totally agree with the recommendations given in this thread, they pertain to new divers who are having trouble descending. All the people that I dive with basically swim down head first (at least to start the dive).

The method of descent described is slower than necesary and may not be appropriate for dves that are time sensitive or free descent dives that might involve swimming down to a wreck in a current without any visual reference. Also the method described would not be what I would use to go down on a mooring bouy or secure anchor.

 

[eponym]

Good piece, Bob, solid and clear.

I advise new divers to plan (at the surface) to pause their descent at around ten feet to check in with each other and make sure equalization, gear, etc. are all working before continuing to the planned depth.

What was new to me in your article (and what I plan to try) is the "ballerina" image:

Once you've gotten down a few feet [ . . . ] simply extend your legs and point your fins back (think ballerina). As you descend, the motion of your body in the water will push on the tops of your fins and naturally start rotating your body.

It complements and reinforces Larry Taylor's "barbie" imagery which can be found on the U.Mich site (Visualization For Improved Swimming Efficiency & Increased Bottom Time).

Great work,
Bryan