Which Deco Computer Plan to use on Deco runs.

[exposure]

For each dive, we plan the dive with V-Planner and then decide whether it will be our main plan to follow or a back-up by using a computer. We always compute some table as back-up, like few meter/ft deeper and few minutes longer. Using the plan on slate guarantee the team to be all together at all the time, which is a critical element in tec diving in my view. By deciding to choose the computer as main plan and the slate as back-up, you have to accept to be delayed within the team during the deco. We never follow one computer for the team, that is against all safety rules. Personnally, I prefer to follow the slate but for some dives I did the other way around. In the two choices, you'll have to follow the plan for the bottom part, otherwise your back-up won't work on the deco part.

Choosing between VPM or ZHL16 doesn't really matter as far as you understand what will happens during the dive and the deco part and take that into account in the preparation within the team.

 

[decompression]

This has the suggestion for "ratio deco" all over it.

 

[boulderjohn]

Last year I joined a group of divers who were using V-Planner. I agreed to follow their plan and put it in my wet notes. I inputted the gases and plan into my Shearwater Predator on Buhlmann to see what it would do, and as you said, the plan was significantly different. It wanted me shallower must fast, and it had a shorter deco plan overall. I followed their plan and had the Predator as a backup. The Predator adjusted constantly throughout the dive to what I was doing while following the V-Planner schedule, and it had me done at almost exactly the same time the V-Planner schedule was over.

 

[Peter69_56]

Yes soon as I get home from this dive trip I am going to put all my dives into various algorithms and see the results. I am still leaning towards VPM with a +3 setting.

Not familiar with ratio decompression but on reading up it seems an interesting concept. Will look into it further, thanks.

I agree with your understanding of Buhlmann on a dive compared to V-Planner VPM. I suppose its what one feels is best to use rather than either one or the other.

 

[RiverRat]

Last year I joined a group of divers who were using V-Planner. I agreed to follow their plan and put it in my wet notes. I inputted the gases and plan into my Shearwater Predator on Buhlmann to see what it would do, and as you said, the plan was significantly different. It wanted me shallower must fast, and it had a shorter deco plan overall. I followed their plan and had the Predator as a backup. The Predator adjusted constantly throughout the dive to what I was doing while following the V-Planner schedule, and it had me done at almost exactly the same time the V-Planner schedule was over.

Interesting
I plan most of my dives using Vplanner +2. I'm always trying to get the point across to just "plan the dive, dive the plan" to some of my dive buddies. Many "dive the computer" and use tables for backup. I could see doing that for a dive that had many variables, many depth changes etc. Then yeah maybe dive the same computers and plan a backup together. But I see many issues on the dives with switching gasses, different ascent profiles etc. etc. I find that despite all of that we're typically back on the boat usually within the same time frame (unless different teams dropping in at different times or doing different bottom times). To me less is more. I like to do most of the planning before I get in the water. On square profile dives the computer isn't really going to buy me anything. I've even planned multi-level trimix dives with vplanner. Same deal. I find ratio deco interesting but I found it had to many restrictions (can only use certain mixes etc.) for me. So far I like vplanner.

 

[GrimSleeper]

Try tweaking the Gradient Factors on the Buhlmann computer. Reducing the GF-Lo (the first number) will make it ask for stops deeper, and raising the GF-Hi will make it require less time shallower. You ought to be able to get it closer to the schedule VPM is giving you. Looks a little scary, though, when you start telling your computer to surface you at close to the maximum allowable tissue-gradient... If you believe in the assumptions of the bubble models, though, the deeper stops will have you off-gassing more cleanly when you're shallow, so you won't need as much time as the dissolved-gas Buhlmann model would have you do.

Or make your buddy buy a computer that'll run VPM?

 

[Peter69_56]

Well sold my Liquivision and now we both have Shearwater Petrels so both on the same plane. I have bought the unlock codes for both PC so we can both use VPM. We usually plan with V-planner (now Multideco) and then use that bottom time as the max time with the minimum deco being computer (but normally more like the V-Plan). Given to date our dives have always been multi level above our plan depth, we have a fair bit of margin built in.