Diving low but driving high

[janeothejungle]

Hey all,

Long time no see. I have recently moved to the big island of Hawaii and am grappling with an interesting dilemma. I live near Hilo, on the east side of the island, I am wanting to take the PADI Instructor course, but the only dive shop offering it is in Kona, on the west side of the island. In between us are a couple of volcanoes and connecting roads that climb up and over (4500ft elev at high point). Basically, from reading a lot of the older threads here and pouring over the navy dive tables, I am leaning towards going by the NDT to estimate the interval time before I could potentially drive home after diving in Kona. Staying overnight in Kona is not appealing because a: I'm not rich enough to afford a room twice a week and b: napping overnight in my car sucks if I have to do it on a regular basis. I have no problem hanging out after my dives and killing some time, but the "standard" of 18 hours to wait post-dives before driving home seems excruciatingly over cautious. Have there been any newer studies or are there currently any research projects going on this subject? I'm a biologist by trade, so I plan on documenting my intervals and experiences, but it'd be even better if the data could be of use. Thoughts? Cheers, Kat

 

[runsongas]

i drove up through waimea, but padded the time by having dinner in kona and not leaving till 10pm. it was pitch black on the road and i didn't get to hilo till very late though. the waimea route on 19 tops out around 2750 ft iirc.

 

[rsingler]

Buy the PADI Altitude Diver specialty course crewpak. You'll get specific guidance in this regard. It's not 18 hrs.

 

[Oldbear]

Suck on some 100% O2.

 

[Lorenzoid]

You mentioned reading some older threads. Here are a few I found.

Driving to Elevation after diving question

Altitude?

Driving to altitude after diving

Ascent To Altitude From Santa Rosa

drive to 5000ft. after diving.

 

[broncobowsher]

Surface, hang out near sea level a few hours. Load gear up, get lunch/dinner, drive home.

Not Hawaii specific problem. I have the same thing coming back to Arizona from San Diego. A 4,000+ mountain pass or hours long detour through LA. The passes are about an hour from shore, so they do come up fairly quickly. But also they are still a slow climb compared to what an aircraft does. An hour to climb 4,000 feet by car is a lot slower then the few minutes in a plane. So there is no sudden pressure changes as well.

I had the Shearwater out and watched the tissue profiles after I surfaced. Kept it in the front seat and watched them as I drove over the mountain. This was after a weekend of light deco diving. By the time lunch was over the tissues were nicely unloading. Going over the mountain they still unloaded. After keeping an eye on doing that I am a lot more comfortable doing it. So much better looking at real info instead of generic "don't fly" blanket response only backed by worst case scenerios.

 

[KevinNM]

Saddle road goes to 6500 or so, so don't go that way. But you don't need 18 hours to go via the less direct routes if you are not doing crazy deep or long dives. It's also not a huge issue if you are spending the day in the pool. You do need some time after actual diving, so if you can arrange it so you can get done diving in the afternoon, do all the post diving stuff, eat dinner and then drive home it shouldn't be a problem. But the altitude diver course material should provide a methodology to determine how long to wait given the altitude you will reach.

 

[Edward3c]

These tables will enable you to calculate changes in altitude from sea level to 3,000m.

BSAC - Shop-Decompression Tables 88 Level 1-4 (with slate)

 

[boulderjohn]

Driving to altitude has not been well studied, and no experts are willing to go out on a limb and offer advice on something that has no real scientific backing. The US Navy ascent to altitude table offers you some idea, although you will need to use the Navy tables to be perfectly in tune with them. Here is the table:

To give a sense of what the numbers on this table mean, here are some examples of specific single dives to specific depths and the resulting US Navy pressure groups using the current US Navy tables. Divers wishing more precise information should get a copy of the US Navy tables and use them for their dives.

Group C: 35 feet/11 meters - 32 minutes; 60 feet/18 meters - 17 minutes; 100 feet/30 meters - 9 minutes

Group E: 35 feet/11 meters - 52 minutes; 60 feet/18 meters - 28 minutes; 100 feet/30 meters - 15 minutes

Group F: 50 feet/15 meters - 41 minutes; 80 feet/24 meters - 24 minutes; 100 feet/30 meters - minutes

Group G: 50 feet/15 meters - 48 minutes; 80 feet/24 meters - 28 minutes; 100 feet/30 meters - 21 minutes

Group J: 50 feet/15 meters - 71 minutes; 80 feet/24 meters - 39 minutes

Group L: 35 feet/11 meters - 148 minutes; 50 feet/15 meters - 89 minutes

Group N: 35 feet/11 meters – 195 minutes; 45 feet/15 meters - 125 minutes​

Here are some untested, unproven things you can consider. (Nothing I write after this should be considered advice.)

• Most organizations say that a 2,000 foot ascent is safe at any time.
• If you make a safe ascent while driving over the space of an hour, you will off-gas faster than you would staying at the original altitude for that hour because of the lower PPN2 you are breathing during that hour.
• Before making the ascent of a liftoff or before taking a spacewalk, astronauts breathe oxygen to eliminate nitrogen from their tissues.