Hollis tx1 computer

[stuartv]

I did many test dives with the TX1 and it will do the job... but you may find the Petrel worth the investment especially if you believe you may do more "tech" later on... also, there are several information screens on the Petrel that are useful during your dive. I particularly like the tissue loading graphics in Bulhmann mode.

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Also like the fact that the display is bright enough to exit a cave with no other lights on! LOL

I'm just curious: Do you actually use any of those bars other than longest one for anything? Or is just kind of "a neat feature".

To be more clear: Most "regular" computers will show a 1 bar TLBG. Presumably, what those show corresponds to whichever bar is longest, on the Petrel display. So, for NDL diving (as one example), you would be aiming to get out before that 1 bar (or longest bar) gets to the red. So, with all those different bars shown on the Petrel, do you ever base a dive decision on any of the bars but the longest?

I'm only basic OW certified. No decompression training yet, but I think I understand the basics of what a normal TLBG is telling you, so I'm curious about the actual functional usefulness of the graph showing multiple bars.

 

[tbone1004]

he actually does, but for normal decompression you don't use the tissue loading bars, it is important to see them as approximations if you have to cut a deco stop for whatever reason, either entirely or cut short.

Realistically though unless you have to have AI, just spend the extra $100 for the Petrel, there isn't anything above it that makes it "just another $100", and it includes CCR features if you need that later, or options for multiple algorithms.

 

[Lorenzoid]

. . . So, with all those different bars shown on the Petrel, do you ever base a dive decision on any of the bars but the longest?

For the no-stop diver, maybe it's fun to watch the bars during your surface interval.

Seems to me the Petrel is an engineer's wet dream.

 

[victorzamora]

I'm just curious: Do you actually use any of those bars other than longest one for anything? Or is just kind of "a neat feature".

To be more clear: Most "regular" computers will show a 1 bar TLBG. Presumably, what those show corresponds to whichever bar is longest, on the Petrel display. So, for NDL diving (as one example), you would be aiming to get out before that 1 bar (or longest bar) gets to the red. So, with all those different bars shown on the Petrel, do you ever base a dive decision on any of the bars but the longest?

I'm only basic OW certified. No decompression training yet, but I think I understand the basics of what a normal TLBG is telling you, so I'm curious about the actual functional usefulness of the graph showing multiple bars.

The Petrel tissue loading bar graph does a drastically different job than on recreational computers. On rec computers, they don't quite translate to anything mathematically other than consumed portions of NDLs and the graphs don't change with depth. On the Petrel, they represent the current state between m values of your 16 tissue compartments, fastest to slowest being top to bottom. This changes with your depth and isn't quite so useful for NDL diving.

As for what the other bars are for, there really important. They tell me what my SI should be. They tell me if I need a dry day or to skip a dive. Within NDLs is no big deal, but during tech dives you can pretty quickly accumulate nitrogen in your slow tissues. Once you start really digging into deco theory (or if, I should say) you'll see that heavily loaded slow tissues might mean extra long deco or a skipped dive.

If you watch the Shearwater video about how to read their bar graphs, they do a spectacular job running you through it. Watch it a few times and then start asking questions. I've seen it like 4 times and need to watch it a few more to be 100% confident. One of the most interesting things I've ever heard regarding deco procedure is in that video, and it took 3 watch throughs to catch it.

---------- Post added February 9th, 2015 at 03:55 PM ----------

Seems to me the Petrel is an engineer's wet dream.

As an engineer, I can safely say: "Yup!!"

 

[Doppler]

I'm just curious: Do you actually use any of those bars other than longest one for anything? Or is just kind of "a neat feature"...

Much more than just a "neat feature."

Don't have time to explain fully what gradient factors are. Pity you cannot attend this seminar tomorrow night! LOL https://www.facebook.com/events/750527605042052/

But there is an excellent set of videos on the Shearwater YouTube Channel...

 

[tbone1004]

shame you can't video the lecture and post it later Steve....

 

[Doppler]

shame you can't video the lecture and post it later Steve....

I am

hoping to record it... and link the voice over with the slides... but it will be a long presentation... and a lot of work

 

[stuartv]

Much more than just a "neat feature."

Don't have time to explain fully what gradient factors are. Pity you cannot attend this seminar tomorrow night! LOL https://www.facebook.com/events/750527605042052/

But there is an excellent set of videos on the Shearwater YouTube Channel...

I have read enough about GF to think I do already understand the very basics of what they are and how they are used in a computer like the Petrel.

But, I will look for the Shearwater video that Victor referenced before I make any more ignorant statements.

 

[Octopusprime]

Would you take the petral in a tropical warm water non deco dive? I almost would feel it is too much computer?

 

[tbone1004]

there is no reason not to. My opinion is if you are going to have two computers, you get something like an Oceanic Geo 2.0 which can be worn as a watch while on vacation and be run in gauge mode, and then a Petrel for technical diving, but with the recreational mode on the Petrel you really can't beat it as your only computer if you're only going to have one and are planning on doing lots of decompression dives down the road