Surface Interval

[PRL]

I,m guessing you are talking about recreational diving to NDL
IMO,You might want to set hard limits for your self, if you choose to dive to NDL than thats your limit, if you want to be more conservative and have at least 2 pressure groups buffer (or what ever) than that would be your limit. If your dive plan is well within your limits than a "guestimate" will do, but if you are close or pushing your limits than there is no way of getting around planing for a more accurate SI.

BTW, If your buddy is more conservative than you, than he/she is your limit

Guesstimate=EDUCATED guess. If you don't have the experience to know when your plan is well within your limits than follow the table recomendations

 

[MikeC]

Exactly, there are many things to consider. You did forget - what is the depth of the next dive? and what is your objective?

Walter, if you were "talking" to me regarding the depth of the next dive, I meant that in my specs comment.



Remember, the increased time on the surface may not add to your bottom time on the next dive, but it may help you get warmer or add fluids to your body or other positive things.

 

[s7595]

useing my computer and tables .I like 1hour or longer between dives . I always dive deep first ,some times deep second ,most times shalower on second dive ,if doing third 1.5 hour or longer.always watch my comp and stay well inside the no stop limits.

 

[eod]

The rdp are calculated using half time compartments. That means the nitrogen loading in a compartment is exponential vs time, that goes for both on gassing and off gassing. So to answer one of your questions in this thread, yes, the first hour gives your more bottom time than the next.

Personally I tend to have a surface interval in the region 2 hours. That gives us time to get out of our gear, warm up, have some lunch, talk some and then kit up again.

 

[Diver0001]

Right, but what I was really wondering is if something like this is the case:

"After X minutes of surface interval, staying on the surface any longer than that doesn't give you much incremental bottom time on the next dive".

For example, does, say, the first hour of SI give you the biggest bang for the buck in terms of NDL for then next dive, or is it a linear function, where 20% more SI gives you 20% more NDL.

[reply removed after realising that it was total nonsense]

 

[android]

My preference is to get back to the A group on the PADI RDP. Easy to plan for lake shore dives, more problematic on boats.

 

[Walter]

On the PADI tables, three hours will take you from group Z to group A.

Scary, isn't it?

 

[Don Burke]

On the PADI tables, three hours will take you from group Z to group A.

Scary, isn't it?

Not at first.

Then I realize that people are going to be trying to do four dives a day for a week or so on these and then the beads of cold sweat start building.

The idea of people breathing 100% on the surface just to keep from doing required stops does not give me a warm fuzzy feeling either.

If that second dive is that important, do five minutes at twenty feet and ten minutes at ten feet on EAN36 after each dive. Better yet, get the right gear and training and make them staged decompression dives.

 

[voop]

Not at first.

Then I realize that people are going to be trying to do four dives a day for a week or so on these and then the beads of cold sweat start building.

The idea of people breathing 100% on the surface just to keep from doing required stops does not give me a warm fuzzy feeling either.

If that second dive is that important, do five minutes at twenty feet and ten minutes at ten feet on EAN36 after each dive. Better yet, get the right gear and training and make them staged decompression dives.

I can only agree with that sentiment: get the gear and training and make them staged deco dives. 100% O2 is more efficient at -6m than at the surface

That said, I know at least one agency teaching surface-O2 as a way of offgassing. I agree that it has limited useability (but, nonetheless, that it can be usefull).