How to Know When To Start Heading Up

[Dr Wu]

When the ads for Zeagle and Halcyon gear that keep popping up around your head on Scubaboard make you nauseous, it's time to head for the surface.

 

[D_B]

the whole idea is to have plenty of air for you, and enough extra for a buddy if that is needed .. a good way to do that is to have an idea of what the pressure is when you need to start up
For me, recreational diver, ... I like Lamont's Rule Of Thumb because it's so easy to remember and I can implement it even if my average depth ends up being different than planned .. my depth + a 0 and 300 psi is easy

It doesn't work for extremes but remember, it's a just thumb rule ... if I need to I'll plan more throughly with exact calculation

 

[marine9]

Sounds like a good plan.

 

[boat sju]

ReadyDiver,

I've been using Lamont's rule of them as D_B suggests for a while now. As a newer diver you may want to use a factor of safety of +500 psi until you get comfortable with it.

 

[ptyx]

Here is another excellent article on the subject:NWGratefulDiver.com

 

[ianr33]

My simple rule of thumb using Al 80's:

Ascend when pressure is 10 times depth +300

e.g ascend from 100 feet at 1300 psi. 80 feet at 1100 psi and so on.


If you do this all the way up then a direct ascent from safety stop depth (20 feet) even gives you 500 psi on the surface to keep boat crews happy.

Its actually fairly conservative but thats not a bad thing, as it gives a fair bit of slack to allow for stress and high SAC rates.
Has the HUGE advantage of being really easy to remember.

Edit: Just seen this is the same as Lamont. Not sure who came up with it first but that does not matter.

 

[Teller]

How do you know when to start heading up on a dive? I understand people use up air at different rates and the deeper you are the faster you use up your air supply. I never know at what psi I should start heading up to end my dives. I am always with an instructor or my Dad and they seem to know when to head up to the surface. I guess i just haven't dove enough to estimate how much air I will need to reach the surface ending my dive with still around 500psi left in my tank. I have an uwatec aladin prime dive console that I love but can't understand how to know when to head up. Is there a general rule of thumb on when to head up?
Any help would be greatly appreciated.

To be safe use the rule of thirds. One third of your air out, one third back, and one third just in case. Always take into consideration your safety stop and your buddy's air supply as well.

 

[ReadyDiver]

Thank you to everyone who has responded to my question. You all have been a huge help!

 

[H2O 70]

I tend to follow the rule of 1/3's. 1/3 to get there, 1/3 to get back and 1/3 for whatever.

Since I'm not using the rule of 1/3's for cave diving, I make sure that the end of 2/3's a tank I'm back at the anchor line. Since I'm typically diving to my NDL or I end up with no more than 10min deco obligation. I'll end up getting back on the boat with 1100psi left using a HP130 in typical NC wreck dives.

 

[The Chairman]

Good stuff! You guys covered it well!