Scubapro Uwatec 2G: Is PDIS mode any good?

[MrSpock]

I just picked up Scubapro/Uwatec 2G from my LDS, which is an upgrade from my aging Mares M2. 2G is a newer model, replacing Tec 2G. One of the added features is something called PDIC. Here is what official site says:

PDIS (Profile Dependent Intermediate Stops) optimizes your dive by calculating an intermediate stop based on how much nitrogen uptake your body has endured, taking into account your current dive, previous dives and breathing mixes. PDIS is a unique scientific application for safer technical and recreational diving.

Has anybody actually used this feature? It looks OK on the paper, but any practical experience? I will certainly try it, but would like to hear any comments on it.

Oh, and for some reason PDIC is turned off by default.

[jpdunc]

I use it as an additional safety feature and it has had minor impacts on my dive profiles. As the name implies, the computer recommends an intermediate safety stop depending on the depth and length of time at that depth.

The stop at the recommended depth is 3 minutes and the computer automatically starts a countdown when you move up to the recommended depth.

Unlike failure to clear a decompression stop, failure to observe the PDIS will NOT lock up the computer.

Once you turn the PDIS feature on, I believe it remains on and automatically recommends the intermediate stop until you turn the feature off.

Hope that helps somewhat.

[MrSpock]

JPDunc, thank you, it helps somewhat. What kind of impact on my profile should I look for? Would it give me longer bottom time upfront or it will extend my time after I completed the PDIS stop? The former would be rather unsafe...

[Jax]

There is a lot of discussion on 'mid' stops, deep stops, intermediate stops. What I have found on the boards is a general belief or agreement that it is better to have intermediate stops, and not just a safety stop. Because it is computer-generated, it is hard to say it would 'take away' from your bottom time, but all time is accounted for as 'bottom time'.

The Uwatec models offer PDIS and conservative levels L0 - L5. The levels have more to do with micro-bubble theory.

PDIS will always give you an intermediate stop. The "L-evel > 0" setting will give you 1 or more additional stops, but you can skip the safety stop. Some people will boil me in oil for saying you can skip the safety stop.

I recommend Mark Powell's Deco for Divers book.

[jpdunc]

I really don't think it affects your overall dive time or dive profile. It is just an additional method of reducing the nitrogen build up from the dive. I am a "senior" diver so I just use it as an additional safety precaution.

It may possibly extend your no decompression time or shorten you surface interval because you are slightly reducing the amount of nitrogen. However, that is well above my knowledge base and pay grade so I certainly don't know the true impacts.