horizontal ascents

[JeffG]

- hanging on the line (by hand)

a Jon line is a better solution than hanging on by your hand.

 

[GreenDiverDown]

And then there are times when you have no choice but to ascend vertically. Do you practice for that? Do you do the vertical ascent drill?

 

[Charlie99]

This thread is in the DIR forum, so the simplest answer as to why horizontal instead of vertical ascent is preferred is simply that horizontal is what is taught and is what is expected by your buddies.

Since there is less resistance to vertical motion when one is vertical, it requires MORE skill, not less to do stops while vertical. A skilled diver can closely hold a stop while motionless and vertical, but someone less skilled will be bouncing up and down. Staying horizontal is much easier.

I often recommend horizontal ascent to insta-buddies that are having trouble bouncing up and down at safety stops. Most find it helps a lot, partly because of the increased resistance to vertical motion, and also because it forces the diver to get neutral (when vertical, the tendency of new divers to stay negatively buoyant and then fin gently to offset that. You don't have that option when horizontal).

 

[JeffG]

Since there is less resistance to vertical motion when one is vertical, it requires MORE skill, not less to do stops while vertical. A skilled diver can closely hold a stop while motionless and vertical, but someone less skilled will be bouncing up and down. Staying horizontal is much easier.

I often recommend horizontal ascent to insta-buddies that are having trouble bouncing up and down at safety stops, and most find it helps a lot.

LOL...To bad thats not how they do it. They usually are negative and just keep finning to keep themselves in place.

But nice try.

 

[Blitz]

LOL...To bad thats not how they do it. They usually are negative and just keep finning to keep themselves in place.

But nice try.

Exactly. I have yet to see someone do a controlled vertical ascent with any precision.

 

[Soggy]

Exactly. I have yet to see someone do a controlled vertical ascent with any precision.

You need to get out more.

Step 1) Grab line forcefully
Step 2) Pull self to stop
Step 3) Hold on tight

Actually, we often move from horizontal to vertical to horizontal. It's the smart thing to do when you have a Carolina rig with 30 lb weights on the line bouncing up and down at 25 ft and 60ft.

Concussion underwater = not so good

 

[Blitz]

You need to get out more.

Step 1) Grab line forcefully
Step 2) Pull self to stop
Step 3) Hold on tight

Actually, we often move from horizontal to vertical to horizontal. It's the smart thing to do when you have a Carolina rig with 30 lb weights on the line bouncing up and down at 25 ft and 60ft.

Concussion underwater = not so good

Ahhhh Thanks for the tip, Aaron!

I haven't dove in New England in so long I forgot what it like to dive in real waves. We don't have that here.

 

[cdennyb]

The DIR reason for horizontal positioning during deco is this:

Besides all the cool stuff, looking around for objects (?) and the like, consider this.
If you're not horizontal, you're not decompressing. The reason is that the vertical pressure differential from your head to your toes is considerable. Dive a dry suit? Remember the squeeze at your ankles, vs the bubble at your neck? The lungs are the only place for the gas exchange between blood bubbles and the off gassing air volumn. This means that the during the 2 minutes it takes for a complete blood passage between your lungs and the farthest location on your body any time spent at a deco stop less than the 2 minutes is pretty much worthless.
The pressure gradient across the lungs as well as the gas being brought out of solution requires a common pressure. If it doesn't have that same pressure gradient then the feet (or blood in the feet) is under a higher pressure and the gas stays inn solution (blood) whereas the blood in your brain area is at a lesser pressure and off gasses more easily.
If you use the entire surface area of the lungs (somewhere around a football field in sq ft !) you want to utilize the entire area available at any given time. If you're horizontal, you've maximized this surface area for offgassing. If you are vertical, the capillaries in your lungs are seeing different pressure gradients and therefor not all of the blood passing through these "beds" are 'cleaned' of the nitrogen, etc.
Keep in mind that if you dive Trimix and have a helium content to your gas, then it will off gass quicker since it is a much smaller molecule.
Forget being able to react betterto an emergency, forget stirring up silt (You're in the open water column right?), and forget how cool it looks. It's all about the maximum decompression benefit and you aren't decompressing if you aren't horizontal.
With respect to bouncing up and down on a rope, that's what a John Line is for. I use an endless loop of 1/4" and just throw a hitch around the anchor line (if I'm hanging there coming up in a current) and swing away from the line going up and down in the rough seas. I control my buoyancy with my BC wing by holding the inflator about "head level" and allowing the air inside to equalize. This stops you at that depth "cold". Neither up or down. I don't understand why it's so hard for divers to float horizontal motionless becausse if they just did that one little manuever, they'd soon find that if they hold the inflator lower, they rise, higher to vent the BC and the sink. Oh well, that's why they call it "diver education".
I hope I've clairified this a bit for all here. I'm surprised that you DIR divers don't know this, but I guess now you do, huh.

db

 

[Thalassamania]

The DIR reason for horizontal positioning during deco is this:

If you're not horizontal, you're not decompressing. The reason is that the vertical pressure differential from your head to your toes is considerable. Dive a dry suit? Remember the squeeze at your ankles, vs the bubble at your neck? The lungs are the only place for the gas exchange between blood bubbles and the off gassing air volumn. This means that the during the 2 minutes it takes for a complete blood passage between your lungs and the farthest location on your body any time spent at a deco stop less than the 2 minutes is pretty much worthless.
The pressure gradient across the lungs as well as the gas being brought out of solution requires a common pressure. If it doesn't have that same pressure gradient then the feet (or blood in the feet) is under a higher pressure and the gas stays inn solution (blood) whereas the blood in your brain area is at a lesser pressure and off gasses more easily.
If you use the entire surface area of the lungs (somewhere around a football field in sq ft !) you want to utilize the entire area available at any given time. If you're horizontal, you've maximized this surface area for offgassing. If you are vertical, the capillaries in your lungs are seeing different pressure gradients and therefor not all of the blood passing through these "beds" are 'cleaned' of the nitrogen, etc.
Keep in mind that if you dive Trimix and have a helium content to your gas, then it will off gass quicker since it is a much smaller molecule.
Forget being able to react betterto an emergency, forget stirring up silt (You're in the open water column right?), and forget how cool it looks. It's all about the maximum decompression benefit and you aren't decompressing if you aren't horizontal.

There is no data that I know of to support your kool-aid induced hallucinations of either how decompression works or lung size (about 75 sq meters, that's a really small football field).

 

[JeffG]

I hope I've clairified this a bit for all here. I'm surprised that you DIR divers don't know this, but I guess now you do, huh.

db

LOL...Yep sure do.

You would almost want to believe that deco is like falling into a black hole. If your vertical, the gravitational forces will tear your body apart.