Back up computers

[gripper]

This is purley hyperthetical so no going into rant mode please.
From what I can gather the VR3 is basically a buhlman computer and the vytec a rgbm (think thats the right way round) For air and nitrox diving only is it possible to use the the VR3 as your primary computer and run the vytec at the same time as a back up.
Would they be so different that you spend prolonged time in the water just to clear one or the other in order not to bend it. Also should the VR3 fail and you have to switch to the vytec are you inviting trouble.
I have done some simulated calcs with the vytec against proplanner and they do seem very similar as long as you set microbubble on proplanner to zero.
Like I said this is purely hyperthetical as I dont even have a VR3 but I would be interested to hear from anyone that has used both either together or seperatley for comparrison sake.

[Tricky]

In Scapa a couple of months ago I dived my Vytec and my buddy (nickb) dived his VR3. Despite having the same gas, and approximately similar profiles, Nick's VR3 cleared some 5-7 minutes quicker than mine. This may have been partly related to the fact that the Vytec penalises you for taking your final stop below the ceiling depth.

Another benefit that he had over me was that the VR3 calculates deco including the gas switch (if you have one). The Vytec doesn't, so when leaving the bottom, it was showing me more deco than I actually needed to do.

[finbar.taylor]

If I'm air / nitrox diving thats pretty much what I do.

The last instance I can think of I was diving 50m for 3 days and the results worked well. 40-50 mins bottom time and then follow the assent profile of the most conservative computer. this typically was the VR3 up to 12/9m because of the deeper stops and then once the vr3 cleared at 6m I would have about 7-12 minutes stil to clear at three on the vytec. This allowed for a 2 minute a meter assent to 3 followed by a short stop at three and then a 2 minute a meter assent to the surface. Probably over conservative but I was wide awake for the drive home and feeling good that evening.

If somthing was to go horribly wrong on the dive such as a dry suit flood I would opt to take the shortest route out this would probably be the vr3 which lists a TTS which is more acccurate than the Vytec as this will not incorporate the gas switch benefit until you have made the switch.


Just my thoughts


Fin

(this following view must be taken with a pinch of salt and could kill you!)

Or if you have a real emergency such as forgetting to conect the P valve, you can clip the vytec off at 3 m on the SMB once the VR3 is clear and leave it to clear for a while ;-)


(just realised 150th post and it's verging on constructive(but undoubtedly full of spellign mistakes))

[Mark Chase]

I tried to run my Vytec with my VR3 and it worked OK on square profile dives on air or Nitrox but it was miles out on multi level dives. On one memorable ocasion giving me about 30mins more deco than the VR3

I gave up and just ran worst case scinario tables and the Vytec in gauge mode.

Then I baught a second VR3

Now I run two VR3s and my Vytec in Gauge mode. If both VR3s crap out i will get home with the gauge and a little mental gymnastics.

ATB

Mark Chase

[troc]

Originally Posted by finbar.taylor

The last instance I can think of I was diving 50m for 3 days

Wow, what was your deco time? Did you have a pee valve? Does Domino's deliver?

heh

T.

[vid]

if you compare an "old" vytec (which doesn't recognise deep stops as benefitting the off-gassing process) with a vr3 - then as others have said, you'll spend more time in the water until the vytec clears - but this is probably a thing of the past now, given that Suunto have brought out a new Vytec (just have to spend more £s)

vid

[vid]

Originally Posted by Mark Chase

Then I baught a second VR3

Now I run two VR3s and my Vytec in Gauge mode. If both VR3s crap out i will get home with the gauge and a little mental gymnastics.

isn't that the worst of all worlds?

shouldn't you buy a third VR3 and trust the two that show the same

vid

[onthetrain]

Originally Posted by gripper

This is purley hyperthetical so no going into rant mode please.
From what I can gather the VR3 is basically a buhlman computer and the vytec a rgbm (think thats the right way round) For air and nitrox diving only is it possible to use the the VR3 as your primary computer and run the vytec at the same time as a back up.
Would they be so different that you spend prolonged time in the water just to clear one or the other in order not to bend it. Also should the VR3 fail and you have to switch to the vytec are you inviting trouble.
I have done some simulated calcs with the vytec against proplanner and they do seem very similar as long as you set microbubble on proplanner to zero.
Like I said this is purely hyperthetical as I dont even have a VR3 but I would be interested to hear from anyone that has used both either together or seperatley for comparrison sake.

I've done this. By the time I got to 6M My Suunto have me over 30mins more stops that the VR3 on a 45 M dive with a 40 min bottom time and it kicked the crap out of me for the deep stops (it runs up additional deco whilst the VR3 is offgassing).

Why not run the Suunto in guage mode as a bottom timer and cut some tables. The VR3 plan function does this for you, it takes about 30 secs to run a couple of plans, one for the gas you are actually carrying, one for a loss of deco gas.. Stick it on a slate and your bail out is in place.

Of course the vr3 allows you to adjust for loss of deco gas etc whilst under water.

Hope that helps

Alan

[Mark Chase]

Originally Posted by vid

isn't that the worst of all worlds?

shouldn't you buy a third VR3 and trust the two that show the same

vid

Now theres an idea

ATB

Mark Chase

[BJ]

Originally Posted by troc

Wow, what was your deco time? Did you have a pee valve? Does Domino's deliver?

heh

T.

One of the first dives I did with a pre-production Inspiration at Rasdoo in the Maldives (with MP) was carefully planned 50m for 20min with back-up alternatives.
However as all experienced divers know the plan goes out of the window once you are surrounded by schooling hammerheads. I did 55m for 25 mins as I recall.
My air computer (we did not have Closed Circuit computers in those days so we used a nitrox computer set for the mix breathed at the deepest planned depth) said I had a time-to-surface of 188 mins.
I abandoned this plan with 55 mins still to go when the dhoni came by above me and MP lowered down (on a rope) his Aladin with SOS displayed. He might have lowered down some breakfast! Thank goodness there was plenty to look at in the shallows in the Maldives in those days.