horizontal ascents

[ekewaka]

Any yahoo can do a vertical ascent, because they're used to being vertical all day long. None of us move around on our bellies all day so being horizontal takes a lot of getting used to.

I have never understood this. In my OW class, I always tried to stay horizontal, even though no one had ever told me that I should. It just seemed more natural that way. It may just be because I have been in the water my whole life, and I learned to swim about the same time I learned to walk.

 

[ScubaMilo]

Any yahoo can do a vertical ascent, because they're used to being vertical all day long. None of us move around on our bellies all day so being horizontal takes a lot of getting used to.

The entire point of the dive slate is that it doesn't have propulsion attached. It shows how much easier it is to remain in a fixed location in the water column, not moving, by being horizontal as opposed to vertical.

See what I'm getting at?

I really wish I had a copy of the video...it's actually really good. You can let the horizontal dive slate get almost 3/4 of the way down the pool (takes a good while) and then put in the vertical slate and it will beat the horizontal one to the bottom.

No, don't get me wrong I understood you perfectly.
and I for one am 100% for doing horizontal ascents.
I just don't think "because its easier to remain fixed in the water column" is the main reason we do horizontal ascents.
Maybe one of the reasons, but not the main reason.

I think mobility is the main reason for horizontal ascents.

Milo

 

[FishTaco]

If you want to make that argument you need to be arguing for a vertical, head down attitude during ascent.

Yeah, hanging upside down, you can pretend you're a bat durring deco.

 

[lamont]

if you are head-up vertical and have a runaway inflator or otherwise need to propel yourself downwards you need to do nearly a 180.

if you are head-up vertical you can't swim into a current effectively

if you are head-up vertical you can't swim to your buddy without dropping to horizontal

if you are head-up vertical you are probably not neutrally buoyant and will drop if
you stop kicking.

if you are head-up vertical and you start kicking due to stress you'll ascend.

and then there's the reason that you are "pre-flared" and presenting the maximum surface area to ascents or descents.

most of the time when diving you want to be only slowly ascending or descending in control with neutral buoyancy. horizontal trim is optimized for that in ways that vertical trim isn't.

so, yes, the primary reason is "because it is easier to remain fixed in the water column" but there's a whole lot of sub-reasons behind that.

 

[globaldiver]

A few reasons for horizontal ascents that I have heard and thought of are the following:

1. You are in a ready position to assist a team member in need.
2. You present a smaller contact surface to a current compared to when vertical.
3. As mentioned, you can easily kick against current during stops if needed when horizontal and still maintain your desired depth.
4. Easier to keep the team formation intact during deco, utilizing the different kicks at our disposal.
5. Being vertical, the squeeze on the blood vessels in the legs increase, especially when diving a dry suit (air in suit moves up toward chest), thus decreasing blood circulation. This can potentially negatively affect the off gassing rate in the exposed tissues.

I have not seen any scientific evidence on any of this, but to me it makes a whole lot of sense, especially when having compared the two (horizontal/vertical position) during diving. As a mater of fact, I think each of these points are strong enough by themselves to clearly advocate maintaining a horizontal position during an ascent toward the surface.

Anders

 

[nadwidny]

Hi Brian,
I'm not saying you're wrong, and it seems logical, just curious as to why you believe its the main reason. Could you direct me to a scientific study on the subject?

No I can't and I doubt there is one. I read the physiology behind it several times a long time ago on techdiver (has to do with there being a pressure differential in the lungs if one is vertical, and none if one is horizontal). If you have access to the Quest archives the explanation may be in there as well.

 

[Thalassamania]

if you are head-up vertical and have a runaway inflator or otherwise need to propel yourself downwards you need to do nearly a 180.

While that seems to make sense I’ll have to test that next time out to see what the real difference in time and effort is.

if you are head-up vertical you can't swim into a current effectively

Very true.

if you are head-up vertical you can't swim to your buddy without dropping to horizontal

A red herring I think, why is your buddy out of reach on ascent?

if you are head-up vertical you are probably not neutrally buoyant and will drop if you stop kicking.

Divers with no buoyancy control skills are most often seen in a vertical or near vertical attitude, but that does not mean that all divers that are vertical have no buoyancy control skills.

if you are head-up vertical and you start kicking due to stress you'll ascend.

If you're sufficiently stressed to have it controlling you then you are likely in no position to maintain horizontal to begin with.

and then there's the reason that you are "pre-flared" and presenting the maximum surface area to ascents or descents.

”Pre-flared” is kind of a bizarre concept, but I get the idea and you're right.

most of the time when diving you want to be only slowly ascending or descending in control with neutral buoyancy. horizontal trim is optimized for that in ways that vertical trim isn't.

Neutral buoyancy is key and that is not dependent on horizontal or vertical position except that it is likely easier to make a very slow ascent in a horizontal attitude, but it is still quite possible to do so in a vertical attitude.

so, yes, the primary reason is "because it is easier to remain fixed in the water column" but there's a whole lot of sub-reasons behind that.

I agree, “easier” but not “the one and only way.”

A few reasons for horizontal ascents that I have heard and thought of are the following:

1. You are in a ready position to assist a team member in need.

Only if your team member is so far away that you must swim to him or her.

2. You present a smaller contact surface to a current compared to when vertical.

Yes.

3. As mentioned, you can easily kick against current during stops if needed when horizontal and still maintain your desired depth.

If you’re on a stop and have to maintain station due to current and don’t have a down line you’ve a whole lot of other problems that you should have solved first.

4. Easier to keep the team formation intact during deco, utilizing the different kicks at our disposal.

Horse pucky.

5. Being vertical, the squeeze on the blood vessels in the legs increase, especially when diving a dry suit (air in suit moves up toward chest), thus decreasing blood circulation. This can potentially negatively affect the off gassing rate in the exposed tissues.

No data (that I know of) to support this contention.

I have not seen any scientific evidence on any of this, but to me it makes a whole lot of sense, especially when having compared the two (horizontal/vertical position) during diving. As a mater of fact, I think each of these points are strong enough by themselves to clearly advocate maintaining a horizontal position during an ascent toward the surface.

Anders

To be honest I find diving horizontal to be easier and more comfortable in most cases. My descents are either horizontal or head down, my dives are mainly horizontal or slightly head down for benthic work (very rarely feet down, that’s blue water stuff) and my ascents are horizontal or head up depending on the situation (e.g., when using a line). Horizontal is more “mechanical” (submarine like), while head up or angled up, is more “biological” and intuitive.

With all due respect, I do not think that any of the five items you list are “strong enough by themselves to clearly advocate maintaining a horizontal position during an ascent toward the surface.” I think that Lamont’s first (maybe) and sixth reasons are the only ones I see as standing up. The whole discussion of being horizontal to swim against a current means (to me) that you’re advocating a procedure based on the need to recover from a screw-up and that’s not Doing It Right. I’d advise that one avoid the screw-up in the first place, and if caught in it be prepared to deal with as an emergency.

 

[TSandM]

A red herring I think, why is your buddy out of reach on ascent?

I don't know about you, but I don't ascend nose to nose with my teammates. We are nicely positioned where we can see each other, most likely several feet apart. If someone has a problem, it will take only a couple of kicks to get to them. But it does take a couple of kicks.

We often ascend along a buoy line or anchor line in light current, sitting horizontal and kicking gently to maintain station. I've actually tried hanging onto the line and kicking into the current, and the latter is more comfortable and more stable. I would imagine past a certain current velocity that wouldn't be true any more.

Personally, I have read the arguments for a horizontal position to improve offgassing during deco, and find them less than compelling.

 

[Thalassamania]

I don't know about you, but I don't ascend nose to nose with my teammates. We are nicely positioned where we can see each other, most likely several feet apart. If someone has a problem, it will take only a couple of kicks to get to them. But it does take a couple of kicks.

We often ascend along a buoy line or anchor line in light current, sitting horizontal and kicking gently to maintain station. I've actually tried hanging onto the line and kicking into the current, and the latter is more comfortable and more stable. I would imagine past a certain current velocity that wouldn't be true any more.

Personally, I have read the arguments for a horizontal position to improve offgassing during deco, and find them less than compelling.

I'll grant that we likely dive a bit closer than most, a "few kicks" would be considered far, arm's length is a beter description. If one insists on being a "few kicks" away that does make horizontal more important.

Our answer to ascend next to a line in a current is a "Jon Line."

 

[MonkSeal]

I'll grant that we likely dive a bit closer than most, a "few kicks" would be considered far, arm's length is a beter description. If one insists on being a "few kicks" away that does make horizontal more important.

Our answer to ascend next to a line in a current is a "Jon Line."

Exact distance depends on environment (visibility, current, bottom configuration, etc.).

Response to current depends on conditions but it can be:
- light kicking
- swiming
- drift deco
- hanging on the line (by hand)