Wow...okay. Well first READ THE MANUAL....TWICE and leave the computer in the box!!!! Delta used to have a really crappy manual but with the latest revision of the software they have done a pretty fair job of producing something that makes sense. Then read the manual and play with the computer as you go along.
IMHO the reason people have issues with the VR3 is that it simply allows you so much latitude in adjustment of settings that initially, it is rather daunting. I have been using one for years...so I guess I am just used to it. I am assuming if your experience level is accurate that your upcoming dives will be no decompression and no gas switching? If that is the case, pay particular attention to setting up your gas profile and making sure you have the right breathing gas turned on and any others turned off. Also be sure you have the PO2 levels set correctly, certainly not over 1.6. The VR3 calculates MOD from how you have the PO2 level set. Generally I will set my bottom mix to 1.4 and my stage mix(s) to 1.6. This is what generates the gas switching prompts.
The computer will allow you to have 3 separate gas profiles, with 9 different gases in each stored. Be sure you have the right profile called up for your dive and again, that the right gas mixes are on and the non-used ones are turned off. This can be changed during the dive...but burns up dive time if you are adjusting during a dive. Not to mention that the computer is calculating your dive based on you having and using the gases that are switched on. It does recalc should you make a mistake and have to turn something off.
If worse comes to worse and you set a bottom mix gas and a stage gas, but were diving only 1 gas, the computer will still figure correct NDL and deco...it just burns time slower because you couldn't/didn't switch. On the other hand...if you do a gas switch in the computer and actually don't have a gas it would be bad...very very bad. One vital thing here....as with any computer...but ESPECIALLY with this or any computer that allows gas switching...THE COMPUTER DOES NOT KNOW WHAT YOU HAVE DONE....IT ONLY KNOWS WHAT YOU TELL IT YOU HAVE DONE.
So...as an example....if you were diving EAN26...did a dive to 140 and took a stage bottle of EAN 50 for deco. As you come up from 140, you are going to get a prompt from the VR3 to switch gases at 70 feet (EAN50 MOD @ PO2 of 1.6). If you start breathing the stage bottle and don't signal the computer you switched, it will assume you are still on bottom mix and calculate your deco accordingly...so you error on the safe side. Needless to say if you have EAN50 switched on....and tell the computer you are using it...when in fact you aren't....well you can figure out the potential problem there. Do not tell the computer you have switched gases until you have physically put the regulator in your mouth and started breathing the next gas! When you signal the computer you have switched gases...leave the switches alone for 20 seconds...the VR3 is a great computer (my opinion) but it isn't exactly the processing monster of something like an X1...so it needs that time to check and recalculate your deco profile...and if you play with the switches right after a gas switch...it will have to wait until you are done and then will recalc.
Be sure you have your CNS warning set where you want it. The VR3 will actually allow you to set the warning past 100%...do not do this! I routinely keep mine set at 80% so that I get an air break warning when I am at 80% of the NOAA max ox. exposure level. The VR3 only tracks CNS...you will have to monitor OTU manually.
Before a dive I do one thing religously...turn on the computer and check from the main menu screen the "gas profile". This will list the current gases that are switched on...so you can confirm what the computer thinks you are diving and what you are really carrying are the same. Then let the computer turn itself off....which also allows the computer to sense and calculate ambient pressure. It is mentioned in the manual, but be sure to turn on the computer and let it turn itself off (like 20 seconds) before you dive. There have been problems when a user changes dive sites and there is a difference in altitude and they hit the water without the computer being allowed to "calibrate" prior to the dive.
The only real annoyance I have with the VR3 is if you depend on the automatic turn on. If you are doing a rapid descent it can sometimes be a bit "tardy" turning itself on. To avoid that, I will turn it back on again when I am ready to actually hit the water...go to the dive screen and do a short push on both switches <dive now> and it keeps the computer on for 5 minutes of inactivity. Once it senses pressure it will remain on for the duration.
One other little note. The VR3 can be used with regular old AA 1.5volt batteries. I do that only when I don't have the 3.6 volts. The backlight (which has 4 different modes ranging from always on to always off) really will eat through a 1.5 volt battery if you leave the backlight on continually. You can get 3.6 volt batteries from Dive Rite separately or in trays of 10. I have heard that the ones that radio shack sells have issues, so I haven't bothered even trying them. I also bought a couple of extra battery caps. The reason is, as you know, this is not an inexpensive computer, and you only have about a half minute or so to change the battery before the memory is dumped. So when it comes time for a change, I pull an extra battery cap, make sure the o-rings are good and have a VERY LIGHT coat of silicone grease on them, and then change. If you pulled your battery and found you had one of the o-rings going bad, you probably will not be able to replace it and get the thing back together in a minute. It doesn't ruin anything other than dumping your gas profiles and possibily losing your dive records in the computer. But if you change batteries between dives and have a memory dump...it is going to forget your dive information and surface interval...not good. Best thing is check the battery before you dive and replace if need be. The start up screen will give you a voltage readout.
As you get into deeper deco type diving...be sure you learn how to use the dive planning feature and cut a set of tables that you put down on an underwater notebook and take with you. I have never had my computer crap out...but I don't personally want to find myself in a deco situation and have to ad-hoc fashion a profile sitting under the water if for some reason the computer failed. It can be done...but why put yourself in a situation like that.
I could go on and on...but since it is new...I would suggest your first few dives be conservative until you REALLY are comfortable with the thing. Personally I love mine, but I will be honest and say I will probably switch over to the X1 if they ever get to the point where they have a user replaceable battery versus the rechargeable thing they have now. Just personal preference, but I really don't want something I can't change batteries in.
Good luck and have fun
