NDL what are you getting?

[Smiler1968]

Hi, having only just got my 2N I've been playing around with the simulator. For a dive to 30m on air my unit gives a NDL of 13 minutes (30/90). If I set it to 100/100 it gives me 15 minutes. My Vytec ( and Suunto are well known for being conservative) I get 18 minutes. Looking at an 18m dive the 2N gives me 42 minutes. The PADI tables give 56 minutes. That seems like a big difference to me. My CF's are pretty much default other than my last stop is at 4m any I have off set the log book. Am I missing something?

Regards

Jerry

[dmainou]

You can make the 2n as conservative or aggressive as you want.

It's all about how you set the CF's.

If you are NOT planning to do decompression you may wish to set the decompression algorithm to plain Buhlman. If you want it to be more conservative during the dive then increase the speed of the gas intake and to make it even more conservative during the ascent and after the dive decrease the speed of the off gassing.

If you are going to go into deco and wish to modify where the stops begin and how long the shallow stops take then hange the deco model to Gradient Factors.

Take a look at this thread, google the theme or reade a book before starting to manipulate it.

http://www.ccrexplorers.com/showthread.php?t=13576

BTw. Have you considered that with your other pc you HAVE to do a 3min at 5m stop? Which doesn't come into play when using G/F's



D

[Smiler1968]

Thanks for the reply. I'm trying to get my head around decompression theory (the basics anyway) and I'm part way through Mark Powell's book. I guess I'm just a bit shocked at the difference. I never expected them to match but it does seem like a big gap. I suppose I just want to make sure my unit is reading correctly and I don't know anyone locally who I can speak to and/or compare readings. Just as a matter of interest, does your unit give 13 minutes at 30m on 21% on 30/90?

Regards

Jerry

[dmainou]

Smiler1968 Wrote:
-------------------------------------------------------
> Thanks for the reply. I'm trying to get my head
> around decompression theory (the basics anyway)
> and I'm part way through Mark Powell's book. I
> guess I'm just a bit shocked at the difference. I
> never expected them to match but it does seem like
> a big gap. I suppose I just want to make sure my
> unit is reading correctly and I don't know anyone
> locally who I can speak to and/or compare
> readings. Just as a matter of interest, does your
> unit give 13 minutes at 30m on 21% on 30/90?
>
> Regards
>
> Jerry


Well I was going to recommend you to read it anyway!

Happy to run a profile for you but you need to give me the bottom time as well.

Why do you have your last stop at 4m?

Leave it at 3m (remember that one of the settings is an offset of 1m from the stop i.e. your deco calc already assumes you'll do it at 4m)

D

[Smiler1968]

dmainou Wrote:
-------------------------------------------------------
> Smiler1968 Wrote:
> --------------------------------------------------
> -----
> > Thanks for the reply. I'm trying to get my head
> > around decompression theory (the basics anyway)
> > and I'm part way through Mark Powell's book. I
> > guess I'm just a bit shocked at the difference.
> I
> > never expected them to match but it does seem
> like
> > a big gap. I suppose I just want to make sure
> my
> > unit is reading correctly and I don't know
> anyone
> > locally who I can speak to and/or compare
> > readings. Just as a matter of interest, does
> your
> > unit give 13 minutes at 30m on 21% on 30/90?
> >
> > Regards
> >
> > Jerry
>
>
> Well I was going to recommend you to read it
> anyway!
>
> Happy to run a profile for you but you need to
> give me the bottom time as well.
>
> Why do you have your last stop at 4m?
>
> Leave it at 3m (remember that one of the settings
> is an offset of 1m from the stop i.e. your deco
> calc already assumes you'll do it at 4m)
>
> D

That's a very good point, I forgot about the offset for the stop. As for the bottom time, I am actually running it as a dive, so just taking the unit down to 30m and reading the NDL from the screen. Hope that makes sense.

Regards

Jerry

[dmainou]

Sounds about right.

Try calculating the deco for 30 meters and 29 minutes on a 30/85 and shoot a copy of the plan. much easier

[Smiler1968]

Ok that gives me
15 - 1
12 - 1
9 - 2
6 - 4
3 - 10

Are you getting similar?

Jerry

[dmainou]

Smiler1968 Wrote:
-------------------------------------------------------
> Ok that gives me
> 15 - 1
> 12 - 1
> 9 - 2
> 6 - 4
> 3 - 10
>
> Are you getting similar?
>
> Jerry


I got 1,1,2,5,10 but its pouring here in Sydney so the small variation is understandable.

Deco planner gives me 1,1,2,5,9 with the safety factor ON (which differs from the 1m ofset but its somewhat close).

Now this may be too conservative for that depth. Plain buhlman (as per the default OSTC settings) gives 11m at 3m.

Also consider that you may clear a number of these stops as you ascend as you are unlikely to have an immediate descent and perfect square profile.

[Smiler1968]

Very helpful, thanks very much. I'm happy now.

Jerry

[Touchwood]

Jerry, my comp is at home, I am at work, however using HW's Deco Planner, and with the deco offset set to 1m, I am getting the same times as you listed i.e.

29:02 30.0m Deco:
3 m : 10 ' 42 '
6 m : 4 ' 45 '
9 m : 2 ' 47 '
12 m : 1 ' 48 '
15 m : 1 ' 49 '
0 m : --- ' 51 '

[Smiler1968]

Thanks for the reply, clearly mine is working just fine. Can't wait to get it wet now. HW deco planner? Where's that then?

Jerry

Ignore the above. Ive just found the Deco Planner. Hours of fun there.