Altitude

[Giggi]

If a person lived at a high altitude, would they still have to take special considerations in what would be considered "altitude diving"?

Do the training agencies who offer OW training, have to offer altititude training before taking the students on the OW cert, if the checkout dives are going to be local?

Also, would that person, if acclimated to altitude, subsequently chose to dive at a lower altitude, what sorts of accomodations would they have to make, if any?

I know it's probably a silly question, but it's strange questions like these that keep me awake at night.

Reading about the Blue Hole in New Mexico got these questions spinning around in my brain.

Even the Holiday Inn Express couldn't help me with this one.

 

[ABQ]

Yes, certain considerations must be made when diving at altitude, nothing startling, (NAUI offers a High Altitude Diver course):

Santa Rosa, NM, where Blue Hole is located, is at an altitude of 4,762 feet, it's a fun dive. Contact either, or all, for information:

Sandia Snorkel & Scuba
(505) 247-8632

Address:

2430 Alamo Ave Se Ste 101
Albuquerque, NM 87106

Cross Street:
Between Columbia Dr SE and Yale Blvd SE

www.sandiasnorkel.com

======

Scuba World Travel
(505) 888-7990

Address:

2715 San Mateo Blvd Ne
Albuquerque, NM 87110

Cross Street:
Between Claremont Ave NE and Phoenix Ave NE

www.scubaadventures.com

======

New Mexico Scuba Center
(505) 271-0633

Address:

7618 Menaul Blvd Ne
Albuquerque, NM 87110

Cross Street:
Between Rhode Island St NE and Pennsylvania St NE

www.nmscuba.com

 

[cmalinowski]

If a person lived at a high altitude, would they still have to take special considerations in what would be considered "altitude diving"?

Do the training agencies who offer OW training, have to offer altititude training before taking the students on the OW cert, if the checkout dives are going to be local?

Also, would that person, if acclimated to altitude, subsequently chose to dive at a lower altitude, what sorts of accomodations would they have to make, if any?

I know it's probably a silly question, but it's strange questions like these that keep me awake at night.

Reading about the Blue Hole in New Mexico got these questions spinning around in my brain.

Even the Holiday Inn Express couldn't help me with this one.

Any time you dive at altitude, you need to understand the issues involved. If you dove the tables at altitude without knowing what to do, you'd more than likely get bent.

That said, I've never taken the course, nor did I stay at a HI last night, but my computer (Oceanic atom) becomes more concervative by pretending it's 3000 ft higher in altitude. Thus, you need to be more conservative at altitude.

it's not a matter of being acclimated to the altitude, it's dive physics.

 

[DA Aquamaster]

The lake I normally dive is at 4600 ft and most people drive up the hill to get here from about 3000.

What this means is that people usually arrive at the dive site with some residual nitrogen time and then apply a "surface interval" in the time between arriving at altitude and actually diving. So essentially, if you are not acclimated to the dive site, the first dive will need to be treated as a repetitive dive.

The second concern is one of theoretical depth. Even if you lived on site and were acclimated, the normal atmospheric pressure is lower, so it would take less 33 FSW of to acquire each additional atmosphere of pressure. For example at 5000 ft, a dive to 100 feet results in a theoretical depth of 120 feet and you would need to plan and execute the dive to 100 feet as if it had really been done to 120 ft for no deco limit and deco purposes.

Gauges are also a potential issue. A mechanical depth gauge needs to be adjustable for altitude, while many electronic gauges and computers will automatically switch to measuring depth in feet fresh water rather than feet sea water.

Most computers allow for altitude diving and will incorporate shorter NDL's and require more deco at altitude. Most however do not account for the drive to altitude or for a potential lack of accomodation to that altitude so some caution is still advised.

 

[ABQ]

All three shops listed above have high altitude dive tables (cards) that one can purchase - all three shops dive at Blue Hole each and every week. They will offer tips and suggestions. All divers here is use a 7000' start for altitude and adjust their tables from there, ie. they treat an 80' dive profile at sea level as a 120' foot dive profile here; and the first dive is always considered a repetitive dive. Don't forget, when diving at high altitude, consider your diving work-load. Stay very hydrated - 10% to 20% humidity here.

Definitely talk to local divers BEFORE diving.

 

[Dive-aholic]

DA Aquamaster answered your first few questions. As far as going to lower altitude to dive, it depends. If you're going to sea level, you don't treat it any differently than a sea level dive. If you're going to anything above 1000' above sea level, you would think you don't have to do the SI that DA mentions, but no one has tested that, so the agencies still recommend the SI or the repetitive dive approach for the 1st dive.

Also, technically, the agencies should be providing the classroom portion of altitude diving prior to O/W checkouts at altitude. The students don't need to complete the dive portion though.

 

[Giggi]

Thanks for all the great replies! I think I may sleep better tonight with one less physics question plaguing me. I love this board!

 

[knotical]

Very slightly different spin on some of the other responses (that all sound good).

“If a person lived at a high altitude, would they still have to take special considerations in what would be considered "altitude diving"? “

Yes. Simplistically: - Nitrogen off-gassing is related to the relative pressure decrease experienced ascending and surfacing. When surfacing at altitude, the atmospheric pressure is less than at sea level, and therefore your risk of DCS is greater.

"Do the training agencies who offer OW training, have to offer altitude training before taking the students on the OW cert, if the checkout dives are going to be local?"

I don’t recall it being a requirement, but all instructors I know provide at least the rudiments.

"Also, would that person, if acclimated to altitude, subsequently chose to dive at a lower altitude, what sorts of accommodations would they have to make, if any?"

None that I am aware of. The diver arriving at lower altitude would have a lesser nitrogen load than those who lived at the lower altitude. As DA pointed out, arriving at higher altitude is a different story.

Keep thinking.