Well, I notice you have gone several days without any replies, and guess I am uniquely qualified to comment on this question, so…
Both the Cobalt and PPX have TFT displays, and battery life is comparable. The PPX has a slightly larger display, but the same resolution. The PPX was pretty clearly intended as a response to the Atomic Cobalt when it was announced several years ago, the striking similarity in appearance is no accident. Now as it turns out now both are being sold by Huish Outdoors, since they purchased the Oceanic brand. The Oceanic computers are still being made by Pelagic (Aqua Lung), Atomic manufactures the Cobalt itself.
Apart from bluetooth, the biggest differences are in the firmware. I will highlight a few below.
The Cobalt contains a full featured onboard
dive planning and simulation application that allows dive planning without changing the actual dive computer settings, including multi-gas and multiple dive sequences. PPX gives no-stop limits in a list format only. Cobalt also has a no-stop time calculator, to allow you to predict what no-stop times would be after additional surface interval and/or with a different mix.
PPX reverts
gas mixes to defaults after 24 hours, Cobalt keeps entered mixes- and tank sizes, which are needed to give SCF/M or L/M breathing rate data- saved until they are changed by the user.
Cobalt is generally more sophisticated in
UX design regarding
how dive events are handled. Starting dives, for instance, is determined by an algorithm that looks at depth, time and descent rate, so you don’t start a dive when you drop a few feet just adjusting gear. PPX starts a dive when it sees 5 feet. Or determining violations when away from a deco stop- Cobalt has another algorithm that looks at % of distance to surface, distance away from a stop, and time away to determine if a violation has taken place or if a deco count can be resumed, vs. a simple 5 minute timer on the PPX. Cobalt in general uses algorithms much more to determine diver intent in instances like these.
The PPX has a
lock out mode and will switch to gauge mode if some kinds of deco violations take place, the Cobalt will issue a warning if there is a violation, but will never go to lock out or gauge mode, either during a dive or after a violation. It does not have a gauge mode, or an "apnea" mode, if those are something you want.
Both contain dual algorithms, in the PPX it's a user selection between a Buhlmann implementation and DSAT, in the Cobalt it's a "folded" RGBM implementation that is middle of the road for conservatism, this automatically switches to a fully iterative RGBM model when a dive exceeds 150' in depth.
re. the compass question, there are philosophical differences in how the dive display is handled- neither better or worse, just different choices. The
dive screen on the Cobalt stays consistent with our without the compass- the compass just appears and moves things around a bit, but leaves all dive data visible and is more or less the same spot. Once you turn the compass on it stays visible and active until you turn it off. The PPX has a separate compass screen that displays only the most important data, and this allows for a bigger compass. The screen times out and reverts to the main dive screen after a minute. Cobalt has more bearing options, for reciprocal, 90°, and 120° markers, if that matters to you. But the PPX compass display is much bigger.
PPX has both
bluetooth and
USB for downloading dives, Cobalt has USB only. That means the PPX can connect to phones and other devices that don’t have a USB connector. The PPX can also adjust some settings from a phone interface. Both come with the cables and connectors you need.
Dive log capacity for PPX is given as 99 dives, for the Cobalt it’s approximately 1200 hours of diving at the default 30 second sample storage rate. Cobalt generally provides a good deal more information in its onboard log, including actual SCF/M gas consumption. Cobalt gives a viewable graphic profile of the dive that the user can step through, looking at each data point. They can see exactly when events or violations occurred, what the NDT and gas mix was at each point, where schedules were created and when stops were completed- essentially what one would see on a desktop computer dive log, but on a small screen.
There is a difference in the look and feel of the interfaces. I’d characterize the PPX as more slick and "designed" in graphic appearance, the Cobalt is more straightforward utilitarian with an emphasis on ease of use and clarity. If you are considering them it shouldn’t be too hard to find a dealer where you can try setting up various functions and see which style you prefer.
Hope this helps to provide some more info- as with many things it comes down to taste and what is important to the individual.
Ron
