Diving on tables

[cummings66]

I'm not DIR but I respect the thought process behind it and someday when a class is offered nearby I just may jump on it to gain more knowledge, but since it's not and I have a burning desire to know the answer to this question.

I've seen the tables and understand the process of how that works, but I've seen many divers post that they like to dive at least x long per dive and I'm wondering how that works because I've seen them post depths that should mean a shorter dive than x.

I.e. I'm doing a dive to 100 feet to check out something for a couple minutes but the majority of the dive will be around 60 feet, normally on tables I've been taught that the 100 foot level is what you based everything on. So even if I'm there 1 minute the dive must be of a much shorter duration than if I did it all at 60 feet.

Is this the same with the DIR method or is there some sort of average they use to account for that? How did those divers do the longer dive in other words without violating the NDL?

 

[PerroneFord]

I.e. I'm doing a dive to 100 feet to check out something for a couple minutes but the majority of the dive will be around 60 feet, normally on tables I've been taught that the 100 foot level is what you based everything on. So even if I'm there 1 minute the dive must be of a much shorter duration than if I did it all at 60 feet.

Is this the same with the DIR method or is there some sort of average they use to account for that? How did those divers do the longer dive in other words without violating the NDL?

You are basing your conclusions on a faulty premise. It is not necessary to avoid NDL.

 

[PerroneFord]

I'm not DIR but I respect the thought process behind it and someday when a class is offered nearby I just may jump on it to gain more knowledge, but since it's not and I have a burning desire to know the answer to this question.

If you don't mind, I have a question for you. And it's something I've seen repeatedly so...

I have seen divers travels the ends of the earth going to dive destinations and vacation spots. Yet, those same divers sqawk at the idea of traveling to take a diving course. Why is that? Suppose a DIR course is NEVER offered near you? Is it not worth the time and effort to travel somewhere to gain the knowledge you seek?

 

[cummings66]

I don't go far to dive, in fact I keep it within one state of me or about 300 miles or so. If a DIR course come up in that range I'd be inclined to take it, if not I'll wait and just keep picking up tidbits here and there. For me when I dive I take my family along and we do family things afterwards, it's not necessarily fun to travel by car halfway across the country with a 4 year old, soon to be. So for now I stay within a few hundred miles to keep things easy on myself and the wife. There's only so much car time a little girl can put up with. I'd fly myself but then you have the issues of not flying after diving, so that's out and I'll have to drive. I hope that explains why I won't go halfway across the country to dive anywhere for anything. Someday in a few years time that may change.

For what it's worth I'm aware it's not necessary to avoid the NDL and such, but possibly I made an incorrect assumption in how a DIR diver dives the tables. I know that you work the times, pressure groups and do mandatory stops which I somewhat incorporate into my diving style because I've found it helps me feel better after the dive, IMO of course. In fact after starting those additional stops I've never felt tired or had a headache after a dive. Could be coincidence, but I don't think so.

I know I'm probably wording it badly since the terminology is slightly different than other agencies, but I hope you get the point of what I'm asking.

 

[MonkSeal]

Deco calculations are based on average depth rather then on maximum depth.

 

[PerroneFord]

Monkseal has answered your question directly. I hear you on the family travel issues. I think you ought to fly and take the class. Flying after diving is not as big a deal as you might think, especially since the DIRF class probably won't have you in more than 25-30ft of water.

-P

I don't go far to dive, in fact I keep it within one state of me or about 300 miles or so. If a DIR course come up in that range I'd be inclined to take it, if not I'll wait and just keep picking up tidbits here and there. For me when I dive I take my family along and we do family things afterwards, it's not necessarily fun to travel by car halfway across the country with a 4 year old, soon to be. So for now I stay within a few hundred miles to keep things easy on myself and the wife. There's only so much car time a little girl can put up with. I'd fly myself but then you have the issues of not flying after diving, so that's out and I'll have to drive. I hope that explains why I won't go halfway across the country to dive anywhere for anything. Someday in a few years time that may change.

For what it's worth I'm aware it's not necessary to avoid the NDL and such, but possibly I made an incorrect assumption in how a DIR diver dives the tables. I know that you work the times, pressure groups and do mandatory stops which I somewhat incorporate into my diving style because I've found it helps me feel better after the dive, IMO of course. In fact after starting those additional stops I've never felt tired or had a headache after a dive. Could be coincidence, but I don't think so.

I know I'm probably wording it badly since the terminology is slightly different than other agencies, but I hope you get the point of what I'm asking.

 

[vladimir]

Monkseal has answered your question directly.

He just came right out and answered it?! No interrogation?! No cryptic answers?! Wow, what a novel approach!

 

[MonkSeal]

No interrogation?! No cryptic answers?!

That's just not my style

 

[Charlie99]

That's just not my style

Since you actually answer questions, here's a follow-up question.

When going first to 100'/30m for a while, then afterwards to 60'/18m it makes sense to average.

How about the case where you are at 60'/18m for say, something like 15 minutes, and then head on down to 100'? (Just assume that there IS a valid reason for such profile, such a 60' shelf and a 100' shelf on a shore dive). Let's further assume that you are using a minimum deco table with limits of 30 minutes at 80'/24m and 20 minutes at 100'/30m.


Do you do the very conservative "treat it all as 100'/30m'" and figure you have 5 minutes left at 100'/30m / 20 minutes total bottom time to stay within minimum deco limits?

It seems that doing just a simple average and figuring that you have 15 minutes left at 100'/30m, for total bottom time of 30 minutes is too aggressive or liberal. Agreed?

Or do you just kind of fudge it and figure that some where around 10 minutes is about right?

Thanks in advance,

Charlie Allen

 

[MonkSeal]

Since you actually answer questions, here's a follow-up question.

When going first to 100'/30m for a while, then afterwards to 60'/18m it makes sense to average.

How about the case where you are at 60'/18m for say, something like 15 minutes, and then head on down to 100'? (Just assume that there IS a valid reason for such profile, such a 60' shelf and a 100' shelf on a shore dive).

Do you do the very conservative "treat it all as 100'/30m'" and figure you have 5 minutes left at 100'/30m / 20 minutes total bottom time to stay within minimum deco limits?

It seems that doing just a simple average and figuring that you have 15 minutes left at 100'/30m, for total bottom time of 30 minutes is too aggressive or liberal. Agreed?

Or do you just kind of fudge it and figure that some where around 10 minutes is about right?

Thanks in advance,

Charlie Allen

Here's good article that I believe contain answers to your questions:

http://www.dir-diver.com/en/knowledge/average_depth.html