Deco Options on the Megalodon CCR

[Jill Heinerth]

Rebreather Pro Eric Stadtmueller shares his thoughts about Shearwater Pursuit, Liquivision X1 and V-Planner/V-Planner Live

While I've been following patiently the development of the Apecs 3.0 electronics as a replacement upgrade for my Apecs 2.00, I've also been
keeping my eye on a few other developments. I currently run a
non-integrated VR3 with hard tables cut from V-Planner as backup. I also carry a 21/30? IANTD deco table in my Wet Notes just in case. The problem that many rebreather divers seem to have is the ability to make their planning software and their dive hardware match up with any consistency. Click here to read the rest of the article.
Then come back to ScubaBoard and let's discuss it. You can click the ScubaBoard icon on my website to return. --Jill

 

[alyafi]

The topic of the article is really well chosen. I plan to do my Mod 1 CCR on a Meg this summer and I am still undecided about what electronics I will be using. The article directly addresses this quandary I am facing. Below are the options I am considering. Forum user feedback on any misperceptions I may have would be greatly appreciated:

All the options I am considering will include cutting custom tables and contingency plan tables from an offline planner like V-Planner before the dives. Options I have considered are a) Apecs 2.5 and a normal dive computer in Guage Mode (no computerized Decompression requirement and Oxygen Toxicity monitoring systems), b) Apecs 2.5 and out of the loop computer (VR3 or the new Diverite computer when it becomes available) c) Apecs 2.5 and integrated computer (VR3 or Diverite) connected to the 3 sensors (not a fourth cell solution). d) Wait for Apecs 3.0 when it becomes available and proves itself in the market.

I am not considering Megalodon Copis, Shearwater, Hammermeg or fourth cell solutions.

Before reading this article I was unaware of the Liquivision X1 and V-Planner Live options.

Have I left an out option out?

I still don’t know all the details of the solutions mentioned above. That's part of what I hope to learn about through the course this summer.

I look forward to reading discussion of this article by the experienced Meg Divers in the forum.

 

[Gill Envy]

I wouldn't hold your breathe on the Apex 3 coming out... things seem to be going in a different direction. I won't spread any rumors, but I hear an exciting twist may be in the works.

Nice article Jill.

After much deliberation, I decided against the stock eCCR electronics on the Meg... the next best thing was to get the Copis and add my favored brand of in line deco and with the problems i've seen with solenoids, I was happy to go manual. I've been very happy with the Shearwater piggy backed to all 3 cells along with the HUD and love the "at one with the breather" feel of manual injection. I use the HUD as my primary since it's real time po2 on all three cells, with periodic glances to the hand set to track deco. I started out with a GF and now using a Pursuit with the HUD. I love the gradient factor, it just jives the best with what I've studied about avoiding decompression illness over the years. I've been easing my way into deeper dives, mostly on reefs and from shore where I can work off the deco without having to hang and Freeze. when diving in the north west US I am seeing how the cold is going to be more of a limiting factor for me than anything else, even in a good dry suite. Long hang times in this cold water are going to be a challenge for me if I get into wreck diving here.

My wife is taking a break from diving as we are thinking about having little ones so I am adding her Pursuit for back up as i'm getting into deco dives. I have always had quite an aversion to tables particularly in this mind numbing cold water and haven't really needed back up since I've stuck mostly with no deco until recently. I certainly see the need for two (preferably the same) computers with the exact same algorithms for long deco diving. I assumed I'd never have the appetite for significant decompression stops, so now that that is changing it's time for me to go back and sharpen the mental calculator and get more training.

 

[Hyper-limits]

I wouldn't hold your breathe on the Apex 3 coming out... things seem to be going in a different direction. I won't spread any rumors, but I hear an exciting twist may be in the works.

Insteresting, we need rumours. Are we taking about Shearwater and ISC working together again.

Al

 

[almity1]

Insteresting, we need rumours. Are we taking about Shearwater and ISC working together again.

Al

Oh Could be!!!!!!!

 

[Mr.X]

I wouldn't hold your breathe on the Apex 3 coming out... things seem to be going in a different direction. I won't spread any rumors, but I hear an exciting twist may be in the works.

Nice article Jill.

A I love the gradient factor, it just jives the best with what I've studied about avoiding decompression illness over the years. I've been easing my way into deeper dives, mostly on reefs and from shore where I can work off the deco without having to hang and Freeze. when diving in the north west US I am seeing how the cold is going to be more of a limiting factor for me than anything else, even in a good dry suite. Long hang times in this cold water are going to be a challenge for me if I get into wreck diving here.

My wife is taking a break from diving as we are thinking about having little ones so I am adding her Pursuit for back up as i'm getting into deco dives. I have always had quite an aversion to tables particularly in this mind numbing cold water and haven't really needed back up since I've stuck mostly with no deco until recently. I certainly see the need for two (preferably the same) computers with the exact same algorithms for long deco diving. I assumed I'd never have the appetite for significant decompression stops, so now that that is changing it's time for me to go back and sharpen the mental calculator and get more training.

Suggestions for long, cold deco. - Hot chocolate served after the dive by a lovely lass.

Argon - might help, but I've never noticed the difference

CCR - you have that already

Dry gloves that don't leak. Other than that I have suffered through many, many long dives in very cold water and without something like electric heating (which you can port into your drysuit), or commercial systems you tend to eat it on those longer dives. Last ones were in 36-37F. On one dive the dry gloves leaked and I had to shoot video. The hands were fixed into a gorilla-grip after the dive and two weeks later tons of skin started sloughing off my hands. Not pretty.

X

 

[PacketSniffer]

My opinion is...

Initially, I was waiting for APECS 3.0 as well (couple YEARS ago..lol). But, I'm glad that I didn't wait. And now, I'm even more sold on the idea that the deco algorithm and the RB electronics should not be integrated into the same box......at this time. We need plenty more maturity and QA/QC before the two should be in the same box.

I have chosen the Liquivision X1 (see my reviews on TDS, RBW, or Zendiving) running VPlanner Live for my deco algorithm and have about 50 dives on it; some fairly deep, some very long. It's holding up very well and I like everything about the unit. The OLED screen is worth its weight in gold especially while cave diving. I don't see any downside to the X1. Some complain about the potted battery design but that was brought about to ensure quality assurance when you need it; during the dive! Just like the Meg, the X1 has been a strong performer right out of the box for me and gets better as Ross provides new enhancements on a regular basis. The two devices make a happy marriage.

Using a separate deco computer, I have the benefit of using it for OC, CCR, or when switching to another CCR whether underwater or on the surface. I still get to use the SAME deco computer that I am very familiar with no matter what I do. That adds a lot of comfort during the dive. Comfort = Less Stress.

Backup tables? I can use the Dive Simulator right on the X1 to build my backup table (a very accurate bailout plan at that). I can also use the VPlanner Desktop version since they are runing the same algorithm.

I don't believe there is anything that comes close to the performance of the X1.

 

[ScubaDadMiami]

And now, I'm even more sold on the idea that the deco algorithm and the RB electronics should not be integrated into the same box......at this time. We need plenty more maturity and QA/QC before the two should be in the same box.

The X1 is a great computer. I especially love its display and size. So, nothing against it from me. However, I prefer a computer that provides information based upon cells in the loop. Especially if you fly manually, this will provide the diver will real time information based upon what is actually going on during the dive.

I enjoy having the Juergensen Hammerhead integrated into my Optima CCR. I have two fully redundant computers and monitors (plus the HUD) that provide information to me based upon actual diving conditions because both handsets monitor all three oxygen sensors in my Optima. Juergensen builds computers for military rebreathers. So, they are a mature company. Quality is mostly good though there have been growing pains during changes in models and versions. The Hammerheads can be added to the Meg, creating what many affectionately call the "HammerMeg."

Again, the X1 is a great package. However, there are other alternatives that also provide great options.

 

[Gill Envy]

The X1 is a great computer. I especially love its display and size. So, nothing against it from me. However, I prefer a computer that provides information based upon cells in the loop. Especially if you fly manually, this will provide the diver will real time information based upon what is actually going on during the dive.

I too have a preference for in line deco, for the reason's Howard states, particularly since I fly manually. but I also understand Packet sniffers sentiment about having a primary that tracks po2 only. the style of HUD I use is a separate computer with it's own battery, all in a separate box, which gives me continuous po2 on all three cells, so that is how I achieved both, having an independent po2 primary and in in line secondary po2/deco integration. They do share the cells, which is an issue for purists, but everything else is truly redundant.

As for back up deco, I don't mind having a computer that is on a set point and not integrated with the cells. Until seeing how little difference in deco calculations the integration actually makes, I felt more strongly about it. I was worried that manual injection would lead to peaks and valleys in my po2 maintenance having a big effect on deco. As keeping steady po2 has become second nature it seems to not be an issue that amounts to much.

Putting on quite a few hours over the last two years with a Prism diver who uses a non-integrated deco computer exclusively, I have had it confirmed how surprisingly little a difference it tends to make by how similar our obligations are even on long dives with nearly the exact same profilles. Having a set point controller, his calculations are pretty tight even without the integration.

Certainly as a back up, non-integrated deco computers give you a much better chance at accuracy than tables alone...though I certainly understand the sentiment for having something with "fewer points of failure".

I have not taken much notice of the Liquivision... would love to check one out some time if I get the chance. Looks very nice and compact.

 

[Mr.X]

The X1 is a great computer. I especially love its display and size. So, nothing against it from me. However, I prefer a computer that provides information based upon cells in the loop. Especially if you fly manually, this will provide the diver will real time information based upon what is actually going on during the dive.

I enjoy having the Juergensen Hammerhead integrated into my Optima CCR. I have two fully redundant computers and monitors (plus the HUD) that provide information to me based upon actual diving conditions because both handsets monitor all three oxygen sensors in my Optima. Juergensen builds computers for military rebreathers. So, they are a mature company. Quality is mostly good though there have been growing pains during changes in models and versions. The Hammerheads can be added to the Meg, creating what many affectionately call the "HammerMeg."

Again, the X1 is a great package. However, there are other alternatives that also provide great options.

The Hammerhead electronics is a nice package. That being said I have had several colleagues who have had them go funny on many, many an important dive. In fact, the latest (black plastic Hammer) went out on a colleague last year after hauling his stuff across two continents. Expensive to say the least when they go funny. On one expedition three Hammerheads (acrylic) went out. I was using an Inspiration and tables - no problems there That being said, I also have an original Meg Shearwater which hasn't died yet. It will though...soon.

My preference is diving tables, with computer as a backup. The biggest headache with the wetnote tables is reading them in a current on the deco. line. That being said, I find them a reliable way to dive. As noted, my profile is very close to the computer. Of course, there are many, many pages of "what if" tables which I've generated and inserted into the book.

In short, I don't trust computers to work reliably.

X