Driving to altitude after 3 days of diving

[Lriemann]

Hi All!

I'm planning three days of diving in Sharm El-Sheikh in the Red Sea soon.

The dives will be to no more than 30 meters (100 ft) and I assume about 45-55 minutes long.
We will be using Nitrox 32.

I thought I'd head to Dahab, by bus or taxi, straight after coming back to port from the third dive, which should end by 4 PM.

But it turns out that the drive from Sharm to Dahab involves going up a mountain range that's 650 meters (2130 ft) before descending again.
The dive club said I should wait 4 hours before taking a bus or taxi.

This really surprised me, as I didn't think such an altitude would be a problem.
I also didn't realize it was that high

I did some searching in the forum, but would still like your input about how many hours to wait between finishing the dive and driving over that range.
4? 10? 24?
Any input would be welcome!

Cheers.

 

[inquis]

Need more info. For NDL dives, deeper is actually safer as far as the drive since the fast tissues dominate. However, if you do several dives on day 3 where you ride the NDL time (loading your slower tissues), the 4 hr timeframe may be prudent.

 

[Lriemann]

Thank you.
We will do three NDL dives per day.
The third one should end by 4 PM.

 

[Endler's]

If you are using local dive shop, ask for their advice.

If you are not using LDS, call one of the many surrounding Dahab. Looks to be close to a dozen dive shops there. 'Almost certain, they have answered that question many times.

 

[Rearviewmirror]

You might find this thread helpful - Ascent To Altitude From Santa Rosa

 

[inquis]

I've done some analysis on the Navy ascent tables in conjunction with time-to-fly and have found their guidance correlates with a surface GF of about 13.5% at flight altitude of 8000 ft. (SurfGF is a tissue-loading metric that is available on Shearwater, Garmin, and perhaps some other computers.) Given the pressure reduction associated with 2130 ft, a sea-level surfGF right at 0% would increase to that tolerable value of 13.5% at altitude (with an instantaneous ascent).

Based on that, I would wait to depart until my surfGF read 0%. (The drive time will add further margin.) How long that takes will be dependent on your earlier dives. If you don't have access to the surfGF metric on your computer, your best bet is to go by the shop's advice.

 

[Scared Silly]

I would be inclined to wait a bit. As you arrive back at port at ~4pm wander around Sharm for a bit, have dinner, perhaps another stroll, then head over the hill.

 

[Edward3c]

Working on a worst-case scenario. Using the BSAC 88 Altitude Transfer Table, and assuming the air pressure is 1,000mbar.

You will be moving between Level 1 to Level 2, starting with surface code of G/1 from the end of the last dive:

• After 60min the code is D/1 you would move to G/2 then to E/1 on return to sea level with 4hr before getting to B/1 for flying.
• After 90min the code is C/1 you would move to D/2 then to D/1 on return to sea level with 3hr before getting to B/1 for flying.
• After 4hr the code is B/1 you would move to C/2 then to C/1 on return to sea level with 2hr before getting to B/1 for flying.

However, if you’re not flying straight away from Dahab it really doesn’t matter which option is chosen.

 

[broncobowsher]

Don't forget to factor in the boat ride time and the unloading from the boat time. Depending on how things go you could be 2 hours out of the water before you are ready to leave the dock. Stop for a nice sit down meal for a little extra buffer. A drive is a slow ascent, not rapid aircraft style.

So much stuff is based on worst case scenerios, add in theoretical modeling, adding safety buffer on top of safety buffer. The recommendations just keep growing and growing. 24 hours you will be so clear you can do 99% of your dive profile all over again.

The driving part is nice, slow ascent. Boat ride is nice, it's time. I would add in a nice meal once on shore and hit the road.

Back of my head, 1000' of elevation is roughly equal to 1' water depth. Ascending to 2000' elevation is ascending -2' of water.

 

[Lriemann]

Thank you.
I will ask a couple of guides in the area and make my decision.