Teric not Accepted as Primary Dive Computer?

[Esprise Me]

Perhaps folks should consider hearing his reasoning before calling it stupid and jumping straight to tar and feathering...

Your winky face isn't lost on me, but calling something stupid doesn't mean people are angry about it, or that they think this person must be stopped somehow. It's perfectly possible to hold the opinion that a course requirement is stupid, "rubbish," "nonsense," or any of the other words that have been used, while also acknowledging the instructor has every right to enforce that requirement. Personally, I'm interested in his reasons, and the reasons any instructor in this thread may have for their seemingly arbitrary requirements, because I want to learn from them. I'm considering buying a Shearwater Teric or Perdix in the near future, and if this guy has a solid reason for preferring the latter, maybe that's what I'll get. If I don't agree with his reasoning but really want to take his class, I'll at least rent one for class but maybe go back to whatever I prefer after. This discussion has been helpful for me.

 

[wetb4igetinthewater]

2. The larger screen size of the Perdix and Petrel allow you to see more data on the screen without having to scroll screens to see other data elements.

Any idea of what the elements that must be seen? (and which ones don't quite make it on the Teric?)

 

[wetb4igetinthewater]

Yes, Ratio uses Buhlmann ZH-L16b, but JC is mandating a very specific brand and a model of dive computers not an algorithm. He even goes as far as not accepting another model from the same mfg with the same algorithm.

I susp

Start writing a curriculum for a distinctive specialty.

While supported by SDI, I'm generally not a fan. I prefer to take advantage of SDI supporting/encouraging instructors to exceed minimal standards of the specialties that I do teach. Hmmm, how can I use tar and feathers in a way that is appropriate for adding value to courses? That word appropriate is kind of an obstacle.....

 

[Jay]

It's informative to hear JC's reasoning and thanks @loosenit2 for cutting through the noise nicely.

Paraphrased JC's said:

Via email:
1. The Teric does not allow you to change GF High while diving, while the Perdix and Petrel do. <-- historically correct and probably still is, but if someone can check if it's still correct post recent FW updates (or await SW's reply via LoosenIt2)
2. The larger screen size of the Perdix and Petrel allow you to see more data on the screen without having to scroll screens to see other data elements. <-- You can also configure the Teric to show "other elements" (including programmed GF) without having to scroll, and all three of the screens seems to have the same overall data capacity. Sounds like it he might be stretching it on this one. I say "might", as of lot of us have jumped on this thread quickly and not thought about 1/ .. and the tar and feathers sure got blown back! (regardless of the pros/cons/'not using new features' aspects of it).

and from the website;
3/ Shearwater - because it in class we'll download and dissect. <-- his class, his call. But ... depending on what software he's using, it's a bit marginal. But, it's his call. (does he really turn away an EON Core diver??)
4/  The Teric's okay for backup, but not acceptable as a Primary as it does not give you all the dive data of the Perdix/Petrel <-- that's not an accurate statement by itself, but probably no more than a sloppy way to say 1/ and perhaps 2/ as per his email clarification.

Websites tend not to be often updated, but given his email response it appears either he doesn't know about SurfGF and how to use it, OR wants to keep doing things the way he did, OR for some other reason he wants to be able to change GF during a dive? (cue tar & feathers round 3).

So, can anyone whose done his class let us know what these "other data elements" are and/or why he needs to change SurfGF on the fly?

 

[Colliam7]

if someone uses AI then they will need to add an SPG to their rig. If they don't want to do that, they can go elsewhere.

FWIW, I have the same requirement. I do not have sufficient confidence in AI to permit that to be the ONLY source of gas information in my courses. If someone objects, they are absolutely free (and encouraged) to train with someone else. As I said before, that would mean I won't be offended by their decision (to train elsewhere) and they won't be inconvenienced by my requirements. Oh, and for the record - my opinion may change in the future, IF I perceive that the reliability of AI has reached the point where I am comfortable with it as the sole source of gas supply information..

It DOES NOT matter if I, or Jim, are somehow 'wrong'. It is a matter of what I, and Jim, are comfortable taking responsibility for, as Instructors.

 

[ScubaWithTurk]

I think JC is showing, yet again, his way of doing things that many of us do not agree with. As I stated in the thread with the video of him teaching, I wanted to take a course from him because he is JC and I am a massive wreck fan. But I will no longer do so because of what I see and read.

Changing GF high during a dive is ridiculous when you have SurfaceGF and GF99. It just is not needed but that is my opinion.

Having said that, he is the instructor and can set whatever stipulations he wants for you to take the course. You can choose to abide by them or you can choose to find another instructor. I have no issues with that whatsoever. When I teach Sidemount I teach a certain configuration only. We will talk about other configs but I do not and will not teach them as I teach what I feel is best. Many instructors have specific things they require from students and I can't fault JC for it.

 

[doctormike]

Changing GF high during a dive is ridiculous when you have SurfaceGF and GF99. It just is not needed but that is my opinion.

If you are on your last stop and you decide that you want to surface at 85% instead of 70%, then yes, you don't need to change your GFHi, you just watch your SurfGF and surface when it hits 85%, so it's the same thing.

But if you are deep and decide that you need to accept surfacing at a higher GF as a tradeoff between operational concerns and DCS risk, then you want to change the GFHi itself. That way, the computer generates a new ceiling line (between GFLo and GFHi) with a greater slope, and a different plan with different stops. Theoretically you could do that yourself by interpolating that line in your head, ascending for each stop until GF99 was approximately where you thought it should be along that line (somewhere between GFLo and GFHi for each stop), and then just watching SurfGF on your shallow stop. But much easier to just change GFHi and let the computer figure out your new ascent plan.

 

[jgttrey]

That's all true but, in practice, pointless, particularly given the fact that preferred GFLo values are creeping up these days anyway.

If you need to expedite your exit, just ride the GF99 up at whatever GF you feel is appropriate. If you have the luxury of padding the last stop or two, great.

Drilling down to change GFHi to tweak your profile so you can retain some little bit of slope on your GF line in that situation just doesn't make my list of necessary features. It isn't wrong or bad, just nearly irrelevant.

 

[doctormike]

That's all true but, in practice, pointless, particularly given the fact that preferred GFLo values are creeping up these days anyway.

Separate discussion. You made a plan based on whatever you chose as your GFs, but you aren't going to reassess that plan based on a review of decompression physiology literature on the fly during a dive. So whatever you planned is whatever you planned.

If you need to expedite your exit, just ride the GF99 up at whatever GF you feel is appropriate.

Yes, but as you pointed out, the way that GFs work is that you generate a line with a slope determined by the two end points, and then at any point at your ascent your permissible overpressure is based on that line, so the actual overpressure limit changes linearly during the ascent.

I guess you could just dive by watching your current overpressure and pausing for a stop whenever you thought it felt "inappropriate" for that particular point in the ascent, but most of us use dive computers to make those calculations in real time.

Drilling down to change GFHi to tweak your profile so you can retain some little bit of slope on your GF line in that situation just doesn't make my list of necessary features. It isn't wrong or bad, just nearly irrelevant.

OK, so don't make that a requirement for your course. Totally reasonable. JC apparently feels differently. That's OK too.

 

[tursiops]

Theoretically you could do that yourself by interpolating that line in your head, ascending for each stop until GF99 was approximately where you thought it should be along that line (somewhere between GFLo and GFHi for each stop), and then just watching SurfGF on your shallow stop.

"Ratio GF"?