First dive computer for a newbie

[dmaziuk]

Nope. At least for the Giotto which I believe runs the same algorthmn. My Bonaire dives are typically 4 a day for 5 days. We will often do a shore dive headed one direction, say North. Finish the dive, switch the gear, maybe a quick snack and head back in to dive South. Sometimes as little as 30 to 40 min SI's. Have yet to go into deco in Bonaire.

In reality, no one really knows the absolute zingers that make some divers have relatively longer BT then others. But its much more complex then just SI time.

Well that has been my experience as well: I rarely see anything less than '99' on the NDL display. Though we usually take an hour between the tanks and 2+ for lunch.


If it's not short SIs, then all those people screaming "too conservative" must have very large tanks and very small lungs.

 

[uncfnp]

Well that has been my experience as well: I rarely see anything less than '99' on the NDL display. Though we usually take an hour between the tanks and 2+ for lunch.


If it's not short SIs, then all those people screaming "too conservative" must have very large tanks and very small lungs.

I think it really is multifactorial. Depth, BT, ascents, length of SS all play a role. In Bonaire, the second half of my dive is essentially a long SS, usually spent between 30 to 20 feet then a slow swim to shore. My opinion is that this is the primary reason I can make so many dives without deco there.

In Florida, my dives are deeper with drift 3 to 5 minute safety stops and have notably shorter NDL's then my old Veo running DSAT no matter how long the surface interval.

Interestingly, my last Florida trip, I set the Petrel on 30/70 and the NDL's were pretty close to the Giotto.

 

[dmaziuk]

I think it really is multifactorial. Depth, BT, ascents, length of SS all play a role. In Bonaire, the second half of my dive is essentially a long SS, usually spent between 30 to 20 feet then a slow swim to shore.

Yes, we tend to do that too. OTOH your "as little as 30 min SI" might be somebody else's "had to wait entire half hour", who knows...

Ultimately the DC has only two variables to operate on: time and pressure (not counting %O2 on nitrox dives), and underwater they are a) interdependent and b) more importantly, have hard limits: the black squares in table 1 (edit: or air, whichever limit you hit first). Once you start hitting those limits, there's only one variable you can manipulate: time at 1 atm. Hence my belief it's gotta be SIs.

I think somewhere among the links posted in the GF thread I saw one mention how off-gassing at the surface is less efficient than off-gassing at 20'. I wonder if I can find it again and actually read it this time. So it looks like that's what's coded into cressi's algorithm as well.