Minimum Surface Intervals When Not Using Tables

[ResortDiver850]

I was curious how divers are calculating their proper surface intervals when not using tables or square dive profiles on repetitive dives. For example, if I go on a 3 tank dive, and I am using a dive computer on a multi level dive. I stay within the NDL according to the computer.

How do I know what are safe surface intervals for my next dives? I an calculate the SIs when using tables but, the table profiles don't represent my dives.

Also, I am using an Oceanic computer that gives me an 02 saturation number. I am unsure how to use this information. I am using EAN 32%.

Thank you in advance. I am a novice.

 

[Addicted2H2O]

Generally speaking, as long as you take at minimum a 1-hour surface interval in between, you should be fine doing multiple dives. And your Oceanic computer calculates your NDLs based on several factors, SI time included. It should have two different algorithms built in, one that's pretty conservative (DSAT) and one that's a little more liberal (Z+). Either will keep you within your NDLs but if you're concerned about it, stick to the standard conservative algorithm and you'll be fine.

 

[rhwestfall]

doesn't it (your PDC) scroll NDL's for subsequent dives? Every computer I have owned shows this in one way or another during the SI after dive each dive....

We have watched them to make sure we are "in a good place" for dive #2....

 

[Basking Ridge Diver]

I am a novice.

Oceanic is very good about posting User Manuals on the internet. Do yourself a favor and read the manual. Then come back with specific questions - you will learn a lot more from manual than you think. YMMV and RTDM

 

[ResortDiver850]

I believe my Geo 2.0 does show NDLs when using the Planning feature. On my last dives I was staying within NDL that was always recalculating as I was changing depths. I took an hour for an SI.

 

[ResortDiver850]

Oceanic is very good about posting User Manuals on the internet. Do yourself a favor and read the manual. Then come back with specific questions - you will learn a lot more from manual than you think. YMMV and RTDM

I have read the manual a couple times. I am going to sign up for the DIV Nav class when I get a chance. I did not see the topic addressed. The manual is very detailed.

I guess I am used to using the PADI tables.

 

[Basking Ridge Diver]

I did not see the topic addressed.

It is called Plan Mode - look again it will give you information that you need to plan your next dive.

 

[ZzzKing]

Your Oceanic computer will give you a running NDL dive time when you go to the PLAN screen. The longer you sit on the boat or shore, the more NDL it will show. After you have used it for a few dives, you will get a handle on the SI impact on NDL time. As stated above, about an hour is a good starting point for typical recreational dives. You can use 45 minutes. Heck, you could use 10 minutes. Just check the PLAN screen and see what you can expect at depth before submerging.

If you want to plan a day of diving, another option is to use whatever the PADI electronic planner that my son just used for his certification. It seemed pretty easy and straightforward.

 

[jlcnuke]

It is called Plan Mode - look again it will give you information that you need to plan your next dive.

This. The plan mode on my Oceanic will tell me my NDLs based on depth for a subsequent dive if I dive in "right now" of the surface interval. Ensure your NDL on the plan, for the depth you plan to dive, is adequate for the planned dive time before jumping in. The longer the SI, the longer the NDLs will be in the plan mode.

 

[uncfnp]

Couple of things.

First Shortbus got it backwards DSAT is one of the most liberal recreational algorithms while Z+ is their version of Buhlmann ZHL-16C which is moderately conservative.

Second. There is no “safe” surface interval. It is generally recommended to wait an hour but there is nothing magical about that number. However, the longer you wait between dives, the longer your NDL time for the next dive. Theoretically you could do your second dive 10 minutes after the first but it could be a very short dive. Waiting longer would give you more time at depth.

As others have said, at any time after your dive you should be able to use the dive plan feature to see what NDL you would have at a particular depth if you jumped it at thatmoment during your SI.