How high after diving?

[aquayle]

All the tables & surface intervals have, I guess been calculated at sea level. But, if you have to go home over a mountain, then how high before the pressure gradient becomes too high & bubbles form.
In other words, when should we start to become concerned about how high to go (not flying of course) whilst still off-gassing?

Andy

[Adrian Kelland]

BSAC Multilevel tables anyone?

Its not a sea level issue, but an atmospheric pressure issue Andy. However I've not seen a particular pressure mentioned anywhere.

Adrian

[Scuba Monkey]

Originally Posted by aquayle

All the tables & surface intervals have, I guess been calculated at sea level. But, if you have to go home over a mountain, then how high before the pressure gradient becomes too high & bubbles form.
In other words, when should we start to become concerned about how high to go (not flying of course) whilst still off-gassing?

Andy

I've wondered the same thing a few times, usually when in Tenerife. Would setting your computer to say you're diving at the altitude you're planning on going to after compensate for this perhaps?

[PW1664]

BSAC multi level tables give atmospheric pressure/altitude conversions and adjustments.

As already said, atmospheric pressure (during really bad storms) are as much of a problem, however you'll probably not be diving then!

[aquayle]

But- some of the restaurants in Tenerife are quite high (& no I don't own an altimeter) La Conception is a good example..

Don't know how the BSAC multi-level tables would help - its not a 'diving at altitude' problem - its a 'post-diving' problem

Andy

[Lynne]

I've been told to avoid anything in excess of 300m above sea level - lots of the restaurants are out of bounds unfortunately Andy - I know a nice Tapas bar you can try at sea level lol

[aquayle]

This thread came about from reading about Vivian quarry:

http://www.ukdivers.net/sites/vivian.htm

"Vivian Quarry is borderline with regard to altitude diving, it is recommended that if the atmospheric pressure is less than 1000mb at sea level then you should use BSAC level 2 tables or equivalent. It is also recommended that when returning home, avoid any increase in altitude and head towards Bangor and the A55."

[Janos]

Originally Posted by aquayle

Don't know how the BSAC multi-level tables would help - its not a 'diving at altitude' problem - its a 'post-diving' problem

BSAC tables do help in this case. The transfer tables will forbid a change of level (ie pressure / altitude) until you've undergone a suitable surface interval. A typical exam question is: "Two divers dive in the Sea for x mins to y metres. How long must they wait before driving over a mountain z metres tall"


Janos

[Janos]

Originally Posted by aquayle

This thread came about from reading about Vivian quarry:

http://www.ukdivers.net/sites/vivian.htm

"Vivian Quarry is borderline with regard to altitude diving, it is recommended that if the atmospheric pressure is less than 1000mb at sea level then you should use BSAC level 2 tables or equivalent. It is also recommended that when returning home, avoid any increase in altitude and head towards Bangor and the A55."

Also Stoney can be a Level 2 dive if the weather is really bad. I would just plan it as an altitude dive. If you're asking me about this in an exam context then I would obviously use Level 2's and transfer tables.

In reality I would just spend a little longer eating a post-dive butty and having a post-dive drink before heading home.

Janos

[PW1664]

The BSAC 88's transfer tables give you a tissue code at any point of your surface interval, this is adjusted to the altitude/atmospheric pressure you are exposed to at any point in time.

Generally an altitude meter would not be of much use as it may be too late to use the info. Normally you would plan your surface interval (incl. any climbs) before acting.

A map is better for this...

Bad storms (low atmospheric Pressure) can also be a problem, however in most cases it is unlikely that you would be diving, well at sea! Although Janos has a point.... inland sites and altitude sites may be different.