Teric NDL Plan

[mcpowell]

This weekend after diving to 105 feet, with an average depth of 48 feet for 27 minutes, I checked the Teric’s NDL dive plan. If I were to immediately start another dive, I could stay at 110’ for 13 minutes. This is no different than when I check the NDL plan now, 54 hours later.

This makes me think the NDL plan on the Teric either doesn’t account for previous dives, or I hadn’t accumulated enough tissue saturation to make a difference with the 27 minute dive. I checked the manual, but couldn’t find any details.

Anyone know what’s going on?

BTW, I love the Teric. Easy to read and a great user interface.

 

[mcpowell]

Additionally, if I check the NDL plan now I can dive 12 minutes at 110feet. But, if I set it to estimate the NDL plan 1 day from now, I could dive 110’ for 14 minutes. Not much difference, but I think something is slightly amiss.

 

[lamby66]

This all sounds odd to me. I hope you get a good answer, as Shearwater has always been great for dive planning. I would hate if that was screwed up.

 

[lamby66]

Just since I am nosey, I checked my two computers (teric and a perdix) both on medium gf with only air.. (been 61 days since i dove last, but the teric was updated 34 days ago)

Perdix says 110' for 12min (now and tomorrow)
Teric says 110' for 12 min (now and tomorrow.

The last time i checked after a dive the NDL was right on (with the perdix only).

Not sure if any of this helps

 

[broncobowsher]

Are you setting this for air or some other gas?
What other settings do you have dialed in (GF, etc.)? There is so much adjustability in the Shearwater products.

It does appear odd what you are getting. Did you go to the tissue loading chart and see what it showed for loading?

 

[DawgFan]

I did a class on Saturday with my Teric. Max depth 15 feet and surface interval 54 hours. Tissues graphs look clear. On air and medium 40/85 rec mode at 110 feet Teric is showing 11 minutes NDL now and same 11 minutes one day from now.

I will say a few of the depths do show a 1 minute difference now vs one day from now.

 

[mcpowell]

Are you setting this for air or some other gas?
What other settings do you have dialed in (GF, etc.)? There is so much adjustability in the Shearwater products.

It does appear odd what you are getting. Did you go to the tissue loading chart and see what it showed for loading?

Yep...good questions:
1) Gas is 21% oxygen
2) GF factor is set to medium 40/85
3) Tissue loading chart showed some fast tissue loading just after the 105' dive (as you would expect the tissue loading tapered to nothing for the slow tissues).
4) Tissue loading after 54 hours showed none.
5) Safety stop is set to "adaptive".

 

[Shearwater]

BTW, I love the Teric.

First of all, thanks for the kind words, @mcpowell .

This makes me think the NDL plan on the Teric either doesn’t account for previous dives...

The code that runs the planner is the same code that runs live underwater calculations. It does take current state of tissues into account.

or I hadn’t accumulated enough tissue saturation to make a difference with the 27 minute dive.

That could be the case. It depends on the shape of your profile and on the time that elapsed between you surfacing and running the NDL plan. Without having your exact profile we did a simulation trying to come with a scenario similar to yours -- 105fsw, avg depth 50fsw, for 27 minutes. At 12 mins after surfacing our NDL for 110ft was reading 11 mins. After 30 mins on the surface we were back to the full 13 mins at 110fsw. I would suggest to run some scenarios on your next dive paying attention to the time elapsed between surfacing and running the plan.

I hope this clarifies things.

Cheers.

 

[mcpowell]

@Shearwater ,
Thanks for the quick follow up. I'm glad to know the NDL planner does account for the current state of tissue saturation. I assumed it would, but didn't realize it would return to normal quite that quickly. I guess now I need to go dive more, and longer....hmmmm.

The user interface is wonderfully easy to understand and navigate, and the display is world's better than the LCD display on my other computer.

Thanks for a great product!

 

[KenGordon]

NDL is a terrible indicatior.

For a bounce dive your limit will very likely be the fastest tissue. So you do the dive and come up. Very soon that fastest tissue (half time of 4 minutes) will be pretty much clear. If you were to jump in again AND DO A SQUARE DIVE then there is a good chance your limit will again be the fastest tissue. Since it would be back to normal very soon after you got out (and possibly sooner depending on the shape of the first dive) it isn’t going to limit your second dive much more than the first.

Keep doing this and eventually the slower tissues will build up saturation and become the limit.

Was the first dive a direct descent followed by a reasonably fast ascent and some time shallow?

The NDL is for a (likely fictional) square dive. A longer NDL for a square dive doesn’t simply map to a longer multilevel dive depending on the state of other tissue groups.