Differences Between UTD and GUE

[PfcAJ]

Range of the gases, ease of mixing, good to excellent deco properties, knowledge of what to expect deco wise, simplified marking, etc etc. All the normal reasons for diving a standard gas.

I make tables one time at Kinko's for a wide range of times and depths, and its done. I still discuss deco strategies with my buddies, and everyone is on the same page, but there is a defined baseline for the tables (ie 30/85, S-shaped stops).

If I used "best mix" on every dive, I'd need a portfolio of tables and wonky bottle markings.

Don't get me wrong, I think ratio deco is a neat trick, but I also think its over emphasized.

 

[LiteHedded]

it's a good trick for the unexpected.
but for everything else tables work fine

 

[Rainer]

it's a good trick for the unexpected.
but for everything else tables work fine

Um, it's a great tool for the unexpected *and* the expected (which is why I prefer it over stuffing a bunch of tables in my pocket, all of which I can generate on the fly anyway, so can't see why I'd want to bother). If you're dependent on tables, you aren't going to be fun to have along for those unexpected profiles.

Personally, I prefer a dynamic in-water decompression option given limits determined prior to splashing.

 

[Blackwood]

it's a good trick for the unexpected.
but for everything else tables work fine

I don't even like reading tables *on the surface* (at least not those with a wide array of data). In the drink with crappy viz and heavy current, it's even easier to jump off the row or column and arrive at the wrong answer. That's why we dive in teams, but I prefer using simple math to hard-format references.

Don't get me wrong, I think ratio deco is a neat trick, but I also think its over emphasized.

To be fair, it's all I've ever used since I started doing decompression diving. In my deco courses (IANTD and TDI), we ran numbers through V-Planner, DecoPlanner, GAP, etc. so that we had a warm fuzzy feeling that what we were being taught (ratio) was at least in the ballpark of other more rigorous algorithms. That may explain why I'm somewhat partial to it.

 

[rjack321]

Why bother with the tables? Seriously I can generate a working deco schedule for any depth/time combo on boat and most I can do on the fly UW if I choose to.

Average depth ain't what we expected? poof new schedule
Contingency deco with a lost gas? poof new schedule
Suit flood, bailing really early? poof new schedule

Having to rifle through your wetnotes for tables seems so rudimentary. Besides what do you do when you: lose a deco gas, bring the wrong tables or they don't cover the depth/time your actually did by accident, or even drop your wetnotes? Do you actually use a straight decoplanner shape? What rules do you use to add deep stops? Do you need the same deep stops if you have to modify the table or not? If you modify the deep stops on the fly (e.g. low on gas) do you modify the tables afterwards to compensate?

If RD is good enough for those (stressful) times, its good enough for every dive. You either know the principles & patterns or you really don't/won't when the poo's in the fan.

 

[PfcAJ]

I don't believe math underwater is optimal, its one of the reasons we don't use o2% as a primary identifier for gas switches.

My tables have everything listed on them that I need, to include deep stops, a modified (s curve) ascent schedule, and lost deco gas is real simple. 1.5x the stop time sharing. I feel that this level of math (which is few and far between) is within reason. If I drop my wetnotes, my buddy has tables as well, no biggie. If we were going to do a dive together at Alachua, I'd simply make you a copy of the same table I have. Its about 2 bucks. Think of it as a present.

Each standard gas covers roughly 50ft or so, and deco times are limited by the amount of deco gas you gave. Thats one or two sheet's worth. Hardly stuffing a myriad of notes into my little clear pocket.

When something goes wrong on a dive, its never a poo hits the fan situation. I just deal with it because I know I have enough resources to get out just fine.

 

[Blackwood]

I don't believe math underwater is optimal

Personally, in the conditions I generally dive, I prefer to avoid reading and writing as much as possible.

A couple of weekends ago when Rainer's 50% regulator took a crap in heavy current and poor viz with dense fog on the surface and our boat sitting in close proximity to the major shipping hub for the western united states, we were primarily concerned with keeping the upline in sight (it was a 'few seconds off the trigger and it's gone' situation) and keeping the team together. I'm glad we didn't have to pull out any tables. Re-figuring our ascent schedule (gas share) was the one of the the easiest parts of that dive.

Given how simple it is (multiply by a small number, and add or subtract even intervals of 5), I have a hard time seeing it as obtrusive or less desirable than hard formats.

 

[AndyNZ]

BTW, as far as I can tell, GUE does not have clear guidance on how to apply RD to shallower O2 only deco dives. They didn't when I took GUE Tech1 and they still don't seem to. In fact its gotten a bit more confusing since the MOD for 30/30 moved up to 100ft.

It was covered in my (recent) Tech 1 class... I think it was a ratio of 1:2 (not 2:1!), but I will have to go and dig through my notes.

Personally, in the conditions I generally dive, I prefer to avoid reading and writing as much as possible.

A couple of weekends ago when Rainer's 50% regulator took a crap in heavy current and poor viz with dense fog on the surface and our boat sitting in close proximity to the major shipping hub for the western united states, we were primarily concerned with keeping the upline in sight (it was a 'few seconds off the trigger and it's gone' situation) and keeping the team together. I'm glad we didn't have to pull out any tables. Re-figuring our ascent schedule (gas share) was the one of the the easiest parts of that dive.

This seems to me the real power of Ratio Deco - it is interesting (to me) looking at the people who are obviously diving using RD all the time, and they know it works for them.

Personally, being relatively new to RD, I'm still in the "pragmatic deco" camp - run the profiles on Decoplanner then adjust it to suit convenience and preference. Then use RD as a means to adjust on the fly if required.

 

[liuk3]

Funny. I think that all you guys are really just arguing about doing the same thing. Ratio Deco is based off of Deco Planner or computer generated models. Most people trained in the system just use RD and figure it out in their head. He just happens to have printed out whatever variations he needs and chucks it in his wetnotes. I've done both the modifying deco on the fly, as well as whipping out the wetnotes and writing out the profiles in wetnotes underwater for the team. Either way, they have been non-issues for the team. In referring to the wetnotes and having a board meeting underwater, the time for the process only took a minute and usually your first stop is much longer than this. I think that the key is agreement in the team on the procedures. I've also had lost deco bottle occur on a dive last year and totally forgot about it until just now because it also was a complete non-issue since my teammate had been similarly trained, and we executed no issues. Again, this was due to the integrity of the team.

Whether you're writing your tables out or using Ratio Deco in your head, they're all just based on Deco Planner or some computer program. I can see pro and con of both. Some may not be comfortable with the mental math underwater and just want things written underwater to confirm. I've also been on dives where people calculated the profiles incorrectly, and I had to correct. But, that's what the team is for.

Anyway, I was taught that there's also nothing wrong with playing with a decompression software program and coming up with your own methodologies based on observed patterns and relationships spit out by the program combined with your own experience once you have enough of it. That's how those guys game up with Ratio Deco in the first place.

 

[lamont]

BTW, as far as I can tell, GUE does not have clear guidance on how to apply RD to shallower O2 only deco dives. They didn't when I took GUE Tech1 and they still don't seem to. In fact its gotten a bit more confusing since the MOD for 30/30 moved up to 100ft.

MOD for 30/30 is 100 ft +/- 10 ft.

A 110-120ft dive for GUE would use 21/35 and EAN50 for deco. Personally, I have done 21/35 dives in the 115ft range with EAN50 & 15-20mins of deco and I felt awful. I prefer O2 deco for these slightly lengthened MDL-ish dives.

GUE doesn't have an issue using O2 there.

There may not be an explicitly taught RD there, but you should have the tools from the Tech1 course to figure it out for yourself.