Suunto Vytec and USN Tables compared

[DiveRite-SW]

My point exactly, Wreckwriter.

How does one decide which model or table is right for them? How does one decide which is conservative/liberal enough to suit their kind of diving? I'm not sure I'm smart enough to arbitrarily decide that "I spend too much time on a hang" and therefore I need a more liberal model/table.

My point is that every author of every table/deco-model made a conscious decision as to how they were going to categorize their results (even if it was with a buncha lawyers breathing over their shoulder), and if we want to flaunt our immortality then we should go for it. Just because one computer/table is more liberal than another one doesn't mean that it's better, it only means that it is more liberal. And I don't think that's a slam for or against any product out there. To criticize a particular model for its conservativity (is that a word?) isn't giving it a fair shake.

 

[WreckWriter]

Originally posted by ronbo
Just because one computer/table is more liberal than another one doesn't mean that it's better, it only means that it is more liberal.

It can also mean, as was put forth in this thread, that one is better than another for a particular application/use. That's what was said here and I agree 100%.

Does that make it "better"? Better for me, yes. Better for you? Probably, but that's your call. You may change your mind if you ever get into deco with it.

Tom

 

[MuddyFox]

I'm simply looking for a computer that can handle the Bikini dive schedule, not one that is a "get you home and keep you there naughty naughty you shouldn't have been doing deco in the first place" type computer.

I suspect that the Vytec is a movement toward the more serious type deco computer as it features gas switching at depth as well as adjustable RGBM. However I'd like to see more sims before I buy one.

I really like the concept of the Vytec, it's a nice computer. However it has to be able to perform comparably to the Status II I've been using. The Status II has had much success there.

I suppose I should just drop the extra cash for the VR3 or Nitek3. Or just rent the Nitek3 there.

 

[halcyondiver]

Originally posted by ronbo
My point exactly, Wreckwriter.

How does one decide which model or table is right for them? How does one decide which is conservative/liberal enough to suit their kind of diving? I'm not sure I'm smart enough to arbitrarily decide that "I spend too much time on a hang" and therefore I need a more liberal model/table.

Ok, you all surely take computers and whether they are conservative or not to the extreme. For gods sake it is pretty black and white. Either a computer is designed for advanced diving, where it can calculate properly for deeper off gasing stops or it can't. Frankly 99.9% of all the computers on the market are not designed to complete advanced deco diving. They don't have the right models in them.

They are programmed to the mass market... recreational divers. Very few have decided to go for it in the tec world. VR3, Nitek and now the Suunto Vytec (possibly, still trying to determine this). That is why I am having Brian check it out in the real world. DEEP and on Deep dives with repetitive Planned Deco Diving. We are talking about dives that consist of 30 minutes at depth thereby requiring deco times sometimes in excess of 60 minutes.

I agree with Brian. You have to be trained for this kind of diving, and during the training you use Tables, Computer based dive planning software and actual dive computers.

Dive computers are only a single tool among the mix of these tools to determine what is safe and what is not. However if you use a computer that is not designed for consistent repetitive deco diving, you will lock it out or you will have to leave it on the anchor line so that you can use it next dive.... but that brings up another question totally altogether. If you switch gases and your computer doesn't take into account for that, and you have to leave the computer behind while you surface... Why the heck are you using the darn thing in first place!!!!

You should be using a computer designed for deco diving.

Hopefully after this weekend we will have some comparable data on a VR3 vs Vytec. If anyone has a Nitek that they want to send to us, we can use it along side the others as well. This way we will have common data to compare, and will be able to see how they stack up to each other.

If you are interested in sending one down for testing, please post a reply or drop me an email - gsmith21@austin.rr.com

 

[mdutra]

No one has mentioned changing the RGBM model to 50% on the Vytec. If the computer is too conservative for you at 100% move it down a notch and try it out. I would be interested in the sim at 50% RGBM for the dive mentioned at the beginning of this thread myself.

 

[TexasMike]

Per mdutra's request, I ran the sim on the 170fsw/20min dive with the RGMB setting = 50% and recorded the ascent profile.

(NOTE: The information presented here reprepsents a dive that involves mandatory decompression. DO NOT engage in these types of dives unless you have received the appropriate training. Always observe and respect your No Decompression limits (NDL's) and personal limits. Always dive within these limits.)

Settings on the Vytec were Altitude = 0 (sea level) and Personal adjustment = 0 (fit diver and perfect diving conditions), Model = Air, RGBM = 50%

Dive was performed by holding down the button for descent until I reached the planned bottom (170 ft). This was reached within 3 minutes of sim'ed dive time and computer showed I had 3 minutes of NDL time left. Then I "stayed" at 170 ft until 20 minutes elapsed on the clock and pumped the ascent button as fast as possible without getting any "SLOW" alarms until I reached the first ceiling shown on the computer.

The entire simulated run resulted in the following stops and remaining ascent times. I should point out that I would only ascend to the next stop (eg from 40 to 30 feet) when the computer said it was okay to be at that new shallower depth.

• 
  Ceiling depth -- ASC TIME remaining
  ===========================
  35 fsw................40 min (recorded while at 170 fsw & starting ascent)
  43 fsw................46 min (having reached 43 fsw)
  30 fsw................43 min
  20 fsw................39 min
  10 fsw................30 min

One interesting observation that I didn't see the first time (wasn't looking for it) was that once the ASC TIME had run down to 3 minutes, the mandatory ceiling disappeared and the remaining time "acted" like a no-deco safety stop.

Now so you won't have to scroll all the way up to the top of the thread, here are the sim results from my original second run at this dive profile..

• 
  Ceiling depth -- ASC TIME remaining
  ===========================
  43 fsw................48 min (recorded while at 170 fsw & starting ascent)
  45 fsw................48 min (the ceiling dropped during my fast ascent)
  48 fsw................48 min (it dropped again while at 45 fsw...probably due to fast ascent)
  40 fsw................47 min
  30 fsw................43 min
  20 fsw................40 min
  10 fsw................31 min

A quick comparison of the ascent profiles does not show much difference from 30 feet upward between RGBM = 100% and = 50%.

So from the sim, I would call the experiment inconclusive. Probably the only way to know how much the 50% setting affects the calculations will be on real repeatitive planned decompression dives.

I'll run some of the other sims when I get the chance.

 

[TexasMike]

I think I have figured out how to sim repetitive dives on my Vytec. I'm working through some "shallow" ones right now to test my method.

Shortly I'll try sim-ing the 170 foot dive multiple times and see what happens.

So I know what to look for, when we've discussed a computer "locking out" what does the display show?

 

[BFaure]

170 foot dive for 20 minutes on air with decoplanner:

170' 20"
80' 1"
70' 1"
60' 1"
50' 3"
40' 3"
30' 6"
20' 37"

So the two are off alot...what I really what to see is a deco dive like that with the vytec but switching gases 50% at 70' and 100% at 20'....should see a big difference it time.

But from just looking at the air dive the vytec does....try some deep stops like what decoplanner is doing....you should see a change it deco stops if the RGBM is being used correctly.

 

[WreckWriter]

Originally posted by TexasMike
So I know what to look for, when we've discussed a computer "locking out" what does the display show?

Er

 

[TexasMike]

Or at least a beer!

Deep stops are on my list....will try following your profile as well as the one Tom posted earlier in the thread.

Also plan on doing one at 150 ft. on the best mix of Nitrox, 50% at 70 ft, and 100% at 20 ft. and record what happens....


And I found out what happens when your ascent time is more than 99 minutes....

The ASC TIME part of the display is only two digits, so if if the Vytec computes your total time to the surface to be more than 99 minutes, then " - - " is what is displayed until the time drops back to 99 minutes.