VR3 computer

Divejunkie

Can anyone give me some advice on the VR3 please. I've been using the VR3 and the 4th cell on my inspiration which is going ok.

However I took it for an open circuit dive to see how it differs from tables. I used a table taken from a GUE software plan which I've dived many times before and is very conservative.

During the dive the VR3 instructed me to go back to 25m when I was at the table depth of 20m, because I stuck to the table, the VR3 switched to 'use table mode'.

So I have a couple of questions-

Surely the table is more conservative than the VR3? If not, is the factory default setting very conservative?

If a stop is missed on the VR3, why doesn't it recalculate and penalise me with an additional stop or longer time a shallower depth?

It just doesn't feel right on a 50m dive using a table that a computer tells you to go deeper and stay longer.

To be honest, the VR3 scares the shit out of me more than the Inspiration!

decoweenie

A couple of quick points:

• You mentioned GUE software, so I am guessing it is Decoplanner which uses Gradient Factor algorithm. You didn't mention which GF hi-lo used to generate your deco profile. The deep stops are usually 1-min duration, and spaced out every 3m.
• Your VR-3 uses Buhlmann algorithm with "micro-bubble" feature (i.e. similar to Pyle stop). The deep stops are usually around 2-min duration, and spaced out similarly to Pyle stop.
• Therefore the profiles won't have the same shape.

Also,

• There is usually no 20-m stop in GF profile.
• For a straight squarish profile, tables could be less conservative than computer depending on the settings of both.
• VR-3 profiles are generally more conservative even with ZERO conservative setting.
• If you "missed" a stop per the computer instruction, the VR-3 should still compute the deco profile using "best guess" while telling you to "use table" for reference.

As with all tools, they work well if you know how to use them properly.

Drmike

VR3 is buhlmann which likely has more real man hours of testing than every other deco algo put together

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abowie

What happened is that you missed a VR3 deep stop.

You get 30 seconds to go back down and do it or it says "use tables". It does however still compute deco for you. I bet everyone who owns a VR3 has done that at least once.

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Andrew Bowie

Rebreather-friendly Buddy

Depth-junkie

Yep, mine has a habit of counting down even when at the exact stop depth. last weekend on a stop at 18m, and i was at exactly 18m and it was giving me the big arrow and 30 seconds to get deeper. Had to go to 18.9m to get it to stop counting. Sometimes i dont bother and just let it revert to use tables the stops are the same so long as you dont miss the stop, if you do it will recalculate for you.

As for consevatism i find the VR3 set a 0%, gives close RT as V-planner VPMB set on Consv 3, the only differnce is the VPMB stops are longer midwater and shorter shallow wheres the VR3 is short midwater and longer at 6m. But the RT are with in 5min of each other. So the VR3 is conservative even set at 0%.

ATB
Gareth

Divejunkie

Thanks gents very enlightening!

Andy Del

As a Virgo I had this problem as well, until I started following the little man on the rope. This changed my ascents to a slow, gradual one, rather than 'wham-bam' every three metres. It also got me to see how I was probably moving much too fast from one stop to another. Now I tend to move much more cautiously from each stop depth to the next.

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Heinz

Yes I have found the same issue, "following the little man on the rope" does reduce the problems of error "use tables"

GuyW

It does depend on what kind of dive you have done. As computers multi-level, whereas a dive table assumes square profile, computers often appear to be less conservative. However the algorithms are often more conservative. If you do a square profile dive the VR3 will usually be more conservative than a (sensible) table.
Because it would be a BIG GUESS. The Vr3 just gives you Buhlmann and lets you add the big guesses yourself.
The VR3 will usually give deeper deep stops than gradient factors so it is not suprising. Set your deco program to GF 5-80 and see what that looks like.
Then you don't full understand your Inspiration.

Downtime

Andrew,

My VR3 gives me a 60 second timer to get down below the stop level if you trav el above it. In fact my one real and only criticism with the VR3 is that if it asks me for an (e.g.) 18M stop, and I stop somewhere above ~18.6M, it will ask me to descend below 18, and give me the timer. In my books 18.6M is below 18???

Are the new ones 30 seconds?

Cheers,
Michael

PS. I know this sounds like nagging, but when's the next Surface Interval coming out?