My new toy, Advice please!! 4th Cell?

[Dive_gimp]

Hi Guys just got me hands on a second hand Inspiration. It does not come with a harness though, was wandering what advice you guys could give me on harness choices? I was thinking about putting my Halcyon twin set up with back plate on to it, however I am not sure how the breakless harness would be in getting the unit on and off.

Also te unit comes with a 4th cell cable, I am very keen on the idea of the 4th cell. However I get mixed reports on it. Lets through that out to the wind then!

4th cell good or bad and why?

Cheers guys

[jknights]

4th cell good if you have a VR3 to connect to.
If I was starting again and I didn't have the VR3 I would probably just go for the Vision electronics as they seem to have sorted out the timer problems.

DeltaP mode of licensing teh VR3 codes really pisses me off as I keep having to pay £50 for every little step. I expecially object to having to pay £50 for the Big Graphics option which is a safety feature that should be free. Not everybody can see the finer graphics so it is a safety feature to have the output readable.

[nigelH]

Originally Posted by Dive_gimp

Also te unit comes with a 4th cell cable, I am very keen on the idea of the 4th cell. However I get mixed reports on it. Lets through that out to the wind then!

4th cell good or bad and why?

I, personally, don't believe it would add anything to my VR3 setup.

So why not?
Nothing makes the fourth cell magically right when the others go wrong. In fact when people had the early cells with the thermal compensation on the PCB they always read wrong as the thermistor was at water temperature while the cell was virtually at loop heat. So once you've been diving for a while you get to see the voting logic in action. You can work out in your head which cell is being ignored, it might be high or low, but you have three and you're getting the best fix on the setpoint. Am I really going to base all my decompression calculations on a fourth cell with no safety checks other than me watching that it doesn't drift too far from the others? Well not me. I know I am the weakest link in the chain and I'd far rather set the computer to what the loop is supposed to be and trust the three cell team rather than the solo cell.

Three is cross-checking - four is confusion. I might stick an oxy-gauge or something like that on it if I had one but I haven't.

[Dive_gimp]

Cheers for te input guys. I just quite like the idea of having another cell to fall back on. However I see what you guys are saying about the entire deco being calculated on that one cell. It will actually add another thing to calibrate. What would u say is the safest way to dive with the unit? Some guys around here hate the VR3 where as I quite like the device, computers make life much easier really. As long as u have the back up tables with you of course. My instructor for the inspiration loves his 4th cell, thats what made me like the idea. Actually bought his old unit off him. I would love a vision, just can't afford one. Poor scuba instructor wages!!

Cheers

[MAD]

I'm kinda with Nigel on this one.

Before I had my Vision, I originally dived with a 4th cell, but once you start thinking about it... it actually adds very little.

Here's the other point... I've seen more dives cancelled because of a dodgy 4th cell on the VR3 but actually I've never seen one saved by one. (Now some might say that's a good thing, but I'm not so certain)

Oh and calibrating the VR3 can be a real pain in the ar*e, if you're not careful then it can be easy to get it wrong. (Setting the wrong cal gas etc...) and you NEED to calibrate iti before every dive.

Personally I'd use the VR3 without the 4th cell, just don't forget to switch the thing for low to high setpoint... I've seen that done more than once!!! (& don't forget your backup tables!!!)

Cheers,

Mark

[Manxdiver]

I agree with the points above.

Only thing extra I'd add is that I've only ever had problems with my Insp holding neg pressure or flooding when I had something 'non-standard' in the loop - such as the 4th cell holder. Personally, I'd steer well clear of it.

[Digger]

Well, they've covered the 4th cell thing. Now, on to the harness:

I found with the inspo lungs that a one liece harness is a pain in the arse. You need a break on one side, preferably both, to make it easy to get into and out of. Depending how you are goign to attatch the lungs you might find this easier or harder, but for me I needed a break to get out of it easily, and also from a rescue point of view it's slightly more complicated and I wanted to make it easy for someone having to strip my kit off.

Digs.

[Dive_gimp]

I will try my breakless harness out, but after that last post not gonna hold out any hope for it at all. So what would you guys recommend? What works for you?

With the 4th cell, if it fails can you tell the VR3 to ignore it and calculate deco using the loop PPO2 as it should be?

Any body got anything good to say about the 4th cell? Lets here both sides of the argument

[Angleseyskipper]

ya deffo need a break in the harness as it'll be a nightmare to get in and out of,its bad enough with a standard set.
As for the 4th cell thing i take out loads of inspo divers some with em some without and have not hear one good thing about em.
seems to be another optional extra ya can take or leave.
If your newly qualified on CCr my suggestion is forget modification and add ons and just go diving to gain some experince the rest will follow with time.
ATB elfyn