New feature for computers

[jimclarke]

After diving twice a day over a weekend I would like to drive home through some hills.
(If I could do this without waiting 24 hours I could dive on the east coast of Malaysia instead of the west!)

All it would need is a setting on the computer which assumed that I start the dive saturated at sea level but must end the dive at altitude.

The algorithm is the same an altitude setting that does not require/expect aclimatisation.

Would anyone else find it useful?

Going a stage further it could be possible to put in an intended flight time and direct diving accordingly. The algorithms are not an issue, but rather the user interface manual etc

Any thoughts ?

 

[cerich]

how would you account for assent speed as you drive thru the mountains?

 

[jimclarke]

Cerich,
Agreed for a perfect system you would need to put in the planned altitude ascent profile.
Perhaps the sytem could be based on assuming an immediate ascent to altitude on ending the dive. (Tissue compartment tensions as for surfacing at altitude). This would be conservative but still gain on the wait 24 hours approach after multiple dives.

A two hour before begining altitude ascent assumption would be better still in terms of the reality with boat dives.

I suppose the training would be aan issue. I have talked to plenty of certified divers who ignore the hill risk or don't even know what I am refering to.

 

[SeaHorseWoman]

How do I figure hill risk?
About 2 hours after diving I drive about 2 hours at sea level, then 1 hour 300m below sea level (Dead Sea area) then over the course of about 40 minutes to about 300m above sea level. The diving is generally two 10m-30m dives per day for 3 or 4 days. Is this risky?

 

[cerich]

How do I figure hill risk?
About 2 hours after diving I drive about 2 hours at sea level, then 1 hour 300m below sea level (Dead Sea area) then over the course of about 40 minutes to about 300m above sea level. The diving is generally two 10m-30m dives per day for 3 or 4 days. Is this risky?

My gut tells me yes, esp. if dehydrated/tired or didn't do optimal assent and/or profiles during dives.

 

[TeddyDiver]

How do I figure hill risk?
About 2 hours after diving I drive about 2 hours at sea level, then 1 hour 300m below sea level (Dead Sea area) then over the course of about 40 minutes to about 300m above sea level. The diving is generally two 10m-30m dives per day for 3 or 4 days. Is this risky?

Nope! 300m is OK. Anything higher=higher risk

To original question: Just set your computer to the altitude you going after the dives, like you would be doing altitude dives. This way you be on the safe side..
And for flying no no no. You can't know the cabine pressure in particular flight bcs it varies...

 

[pupdiver]

The FAA requires cabin pressures to be no higher than the equivalent of 8000 ft altitude (about 2400 meters). Most aircraft have cabin pressure around 5-6000 ft. 300 m is significantly below that, so I wouldn't think it would be a huge problem but why not ask DAN?

Better yet, set your dive computer at 300 m/1000 ft to be conservative.

 

[cerich]

Read her post again you guys, there is a 600M differential, not 300M.

Setting the computer for 300M won't allow for actual calculations based on pressure swings that she actually experiences.

The only tables that I can think of that would allow her to really calculate this is the BSAC 13 tables.

This falls into the "normally be OK but can bite you category"

 

[jimclarke]

How do I figure hill risk?
About 2 hours after diving I drive about 2 hours at sea level, then 1 hour 300m below sea level (Dead Sea area) then over the course of about 40 minutes to about 300m above sea level. The diving is generally two 10m-30m dives per day for 3 or 4 days. Is this risky?

300m air is equivalent to 30cm water.
First you surface at sea level. After a surface inteval of 2 hours you drive though the dead sea area and you have effectively dived to 30cm for an hour. Hardly worth the discussion. You then go to 'altitude'. This 300m is discounted by all tables I have ever seen.

Atmospheric pressue regularly fluctuates by 0.3m either side of standard.

My computer gives 700m as the lowest altitude to be taken into condideration.

There is no such thing as zero risk.....but here is not where you need to worry.

 

[jimclarke]

Nope! 300m is OK. Anything higher=higher risk

To original question: Just set your computer to the altitude you going after the dives, like you would be doing altitude dives. This way you be on the safe side..
And for flying no no no. You can't know the cabine pressure in particular flight bcs it varies...

Teddy I checked with Zak of Mares. (Unfortunately in this aplication), the algorithm that Mares uses assumes that you aclimatise at altitude before diving. This means you have less nitrogen when entering the water than you would if entering at sea level.

To use the compter at sea level but set in altitude mode ignores this extra nitrogen loading. I never did the sums but remember reading that this can be equivalent to a couple of pressure groups.

If Mares set it up to account for sea level loading it would be ultra conservative for those lodging at altitude.