Tank Slap - Motorcycle Forum

kiwikrasher wrote:

Mac wrote:

kiwikrasher wrote:
Altitude dive by any chance Mac? I love freshwater diving for a change. If you haven't already, you should see if you can do a river drift dive somewhere, so much fun!!

Not really an altitude dive as our elevation is ~ 2,500'. Visibility sucked today due to recent rains with average being about 3-5', and she did well considering her experience and conditions. She did find out today that her birthday pressie in two weeks will be diving with whale sharks at the worlds largest aquarium (the Ga. Aquarium), and she was understandably psyched beyond belief!

http://m.youtube.com/watch?v=30sunLoAoTU" onclick="window.open(this.href);return false;

I had to work about 5 days off duty for this, but completely worth it for her reaction today

Lucky girl! And top dad!!

Just with your dive Mac, any dive at 1000' or more is classed as an altitude dive in that you need to adjust your pressure group in dive planning. So if your diving off a dive planner chart it's worth looking at the adjustment. If your diving on a computer, no dramas as it will automatically adjust nitrogen loading values.

As for today's conditions, it will add tons to her confidence having handled that. Makes for a much more rounded diver on my experience.

Thanks for the advice and support, it's much appreciated

This thread is now making me want to get back in the water.

Definite top Dad award!

What does the atmospheric pressure change? Depth gauges? Do you have to come up slower because the pressure delta P is higher?

Monty wrote:Definite top Dad award!

What does the atmospheric pressure change? Depth gauges? Do you have to come up slower because the pressure delta P is higher?

Yep and yep.

The pressure gauge issue is also compounded by the fact freshwater is less dense than seawater. Diving off charts you tend to add an extra pressure group (or more depending on factors) to compensate.

The rate of change in pressure ascending is also greater ( delta P as you put it) and increases the nitrogen bubble formation (bends) so by reducing dive time and depth limits you reduce time at higher partial pressures (nitrogen loading) and give a margin if safety to counter the increased risk.

If you are planning on altitude diving regularly, it is offered as a speciality course and worth the education.