Question Shearwater Teric (GF40/85) goes into DECO on first dive (max depth 25.9m, avg depth 17.6, duration 48mins)

[Belzelbub]

Could you be so kind to share briefly or post a link on some explanation on how to interpret the tissue graph on the teric and which is the chart for slower tissue?

I managed to find 1 sample tissue chart but it doesn’t explain much.

The individual horizontal lines are the tissue compartments. Fast ones at the top, slow ones at the bottom.

The vertical line in the green represents saturation at the surface. Before a dive all are on the line as you are at surface pressure, and the tissues are saturated at surface pressure.

The next image is after initial descent. You are breathing at a higher pressure, but you N2 loading is still at the surface, so the bars drop way into the green.

The next few images show various stages of the dive.

Basically, to keep it simple, you want them to stay out of the red line before you surface. As they’ll change during the dive in relation to depth, I usually only look at the graph on the surface. I use SurfGF to tell me where I am.

SurfGF takes the value of whichever is the controlling compartment at that point in the dive and were suddenly at the surface. Not ascending now, just instantly at surface pressure. Many use it to adjust safety or deco stops for a bit of extra buffer. This is independent of the conservatism settings. For me personally, I set my computers on low conservatism, then just watch SurfGF during the dive and ascent. I’ll on occasion lengthen the safety stop, or shorten if needed.

 

[Saboteur]

Understood, from my next dive onwards, I won’t just follow the dive guide and listen to my dive computer.

As for the tissue loading graph, the data have been cleared due to me updating the the firmware of the teric at the end of the day (as I assume the teric was malfunctioning and further assumed that updating the firmware will resolve any bug - not knowing that by updating the firmware would clear the tissue loading).

Could you be so kind to share briefly or post a link on some explanation on how to interpret the tissue graph on the teric and which is the chart for slower tissue?

I managed to find 1 sample tissue chart but it doesn’t explain much.

Thank you so much in advance.

Somewhat dated but still applicable…

 

[mrtechbench]

... So you missed a deco obligation. Yes maybe you do not feel any effects. Safety wise I would say take a day off and then be certain you are clear. Others may look at your log and say yes if your next dive you had say an 18 hour surface interval you are fine to dive again.

I would err on the side of caution especially since after missing your deco obligation you reset the tissues by upgrading firmware.

 

[Blackcrusader]

I would err on the side of caution especially since after missing your deco obligation you reset the tissues by upgrading firmware.

You replied to me but you meant the OP.

 

[Sascha314]

All these tissue calculations are still models, lots of unknowns, and limits are empirical and statistical.

I prefer to be more on the conservative side, and take 5min Deco, which mostly clears on ascend anyway, if you are not ascending directly on a rope. Of course only max 5min, because of gas management and so on. I believe its more dangerous just to avoid deco by ascending a bit. In that sense you are loading different tissues to the max, which is to mympersonal view a bit more uncertain, especially as most of the data are based on rectangular dives.

But I get that deco is a nono with guides and in vacation destinations. Take a second aggressive computer with you to show the guide and dive with the conservative one.

 

[mrtechbench]

You replied to me but you meant the OP.

Yes, I meant the OP and didn't make it clear. Wanted to build on to that part of your quote I agreed with much of what was said and mention additional risk by resetting tissues.

 

[Nemrod]

Y'all can do as you wish but here are things you do not do with computers IMO and I have observed this many times including nearly everyone I have encountered on my current and ongoing trip.

1. Following a dive guide as if he/she is your computer. Especially routinely, you are dropping below the DMs depth.
2. Diving with no computer or air only computer on Nitrox, and see number 1.
3. Tricking yourself by setting your computer to air or diving an air only computer with 32% Nitrox and then the computer locks out because you blew deco following the the DM, see number 1, see number 4.
4. Continuing to dive with a locked out computer, following the guide, see number 1, because he/she is now your computer since yours is locked out.
5. Borrowing a computer for dive number 2 because your computer locked out because you set air when on Nitrox.
6. Trying to stay down as long as another diver yet going deeper and thus incurring deco (air or Nitrox) because he stayed shallow and did not incur that deco and could thus run a long dive.
7. Not following your computer no matter what you think or thinking it is defective. It is not defective, you are defective and the computer is only as good as the data you input, if you put in the wrong gas mix, you could be seriously bent.
8. Not knowing how to set, read, use, apply your computer and not following it during a dive.

Note that I know two people who have seriously been bent, one is in a wheel chair and the other has permanent nerve damage. I prefer to keep my spinal nerves and brain intact for a while longer.

9. If you set air in your computer or have an air only computer as a "safety" measure using Nitrox you are playing a dangerous guessing game if you do not follow the computer, especially on deeper dive profiles. You cannot safely dive Nitrox on multiple dives setting an air profile and then ignoring the required deco or bottom time and depth (MOD) limits. Even if the computer does not lock out or you clear it out.

Here is what you do and if your computer cannot do these things then you need a new computer that can.

1. Analyze your gas mix and set your computer to that mix.
2. Set the conservative factor or gf settings to suit your safety requirements.
3. Follow your computer, not the DM, not your buddies computer, not the visiting sharks computer, your computer only and do what it says. Do not exceed the MOD.
4. It is nice to have a buddy team running the same model or brand of computer with the same settings.
5. Have and use two similar algorithm computers because two is one and one is none.

Note, there are captains who will not let you back in the water if they know you dismissed deco and locked your computer out regardless of trickery or incorrect settings or trying to use air settings as a safety pad with Nitrox. How the heck would they know what you did if you set incorrect gas mix and then did not follow the computer, no more diving for you!

 

[td275]

Because 50min at 18m (60ft) on air has you with a surface gf of like 90% and a direct ascent to the surface at 30ft/min won’t off gas enough to below 85%.

I didn’t do the math, as you may have. I was just going off my dives last weekend of 65 FSW, run time over 1 hour. Course I run 50/80 on my GF. No DECO on my rec dive. Plenty of NDL left over as we came up from depth.

 

[Blackcrusader]

Hi all, my Shearwater Teric goes into DECO on first dive (max depth 25.9m, avg depth 17.6, duration 48mins). Isit acting normal?

Hopefully now you have learned a few things from this post. You made a mistake assuming your DC was in error when it was user error.

Also you have Teric and you need to learn about the settings and functions available. Yes a firmware upgrade resets the DC and starts you with a new surface interval time. I went to Bali in January but my previous dives were several months before. I know some dive ops ask when did you last dive and some like to offer a "refresher" dive. So a new firmware was out I loaded it a few days before diving in Bali so when asked about my dive I showed them my screen saying surface interval 3 days etc. Naughty but not what you did which was not good.

So please search the forums on Gradient Factors. When I bought my Perdix in 2018 I spent many hours reading the USER MANUAL and reading posts on SB. So now I am very familiar with my settings. I use OC TEC mode as I get even more information.

When you have time sit with your Teric and learn how to use the dive planner. Do you know what your sac rate is to use with the dive planner? If not set a sac rate of 20 and plan dives on that. Then plan same dive with a sac rate of 15. You can see how many liters of gas you will use.

Enjoy your dives. be more independent and do not just follow a guide. In fact if with your wife, dive to your or her NDL which ever is the lowest then ascend to avoid going into deco. Manage yourselves. You can dive as a pair and just let the guide take you to see things. Just monitor your own NDL and air. I like to take photos and video. Before doing that I check my NDL and air. Then when finished taking video or photo I look again. I make it a habit to do that. When I am taking photo and video it's very easy to have several minutes go by and you can lose situational awareness focusing photography.

I love using my Perdix as it does things I cannot in real time.

 

[inquis]

When you have time sit with your Teric and learn how to use the dive planner. Do you know what your sac rate is to use with the dive planner? If not set a sac rate of 20 and plan dives on that. Then plan same dive with a sac rate of 15. You can see how many liters of gas you will use.

OP, the 20 & 15 values are surface consumption rates in liters per minute. If your computer is set to use feet, the equivalent is 0.7 and 0.5 cubic ft per min. The NDL planner doesn't use these, but the deco planner does. As such, the deco planner is useful for specific NDL dives, in spite of the name.