I dive almost exclusively with Shearwater computers (https://www.shearwater.com/). I believe that they are best computers for diving and have been tested on more deep, decompression dives than any other computer (by far). Many (most?) rebreathers use Shearwater computers today.
That said, I have assembled a list below of some of the features I’d like to see them add. This is based on my experience diving with their product in many real-life situations.
1. Deco Plan Display
Shearwater computers display the Time to Surface (TTS) including ascent time & decompression stops and show the next decompression stop depth and time, but don’t display the “deco profile.” It would be nice to see a display of all stop depths and times, similar to:
- 40 feet – 1 minute
- 30 feet – 2 minutes
- 20 feet – 4 minutes
- 10 feet – 10 minutes
Update: This feature is now implemented. I’m not sure if it was there all along and just not clear in the manual or whether it was added at some point.
2. Change Last Stop Depth (During Dive)
Since most of my diving is in the ocean, it can get rough at the surface so I generally conduct my last decompression stop at 20 feet. However, I set my computer last stop to 10 feet in case I want complete my deco obligation quicker. Because my last stop is actually deeper than what the computer is predicting, my Time To Surface isn’t accurate.
I’d like to set my last stop at 20 feet on the computer and then be able to change it mid-dive depending upon conditions and how I’m feeling.
I can set it at 20 feet and “violate” the 20 foot stop by checking that the actual ceiling is less and ascend to the ceiling, but then I have a deco stop violation and I just don’t like those. 🙂
It would also allow you to see the decrease in TTS by switching from 20 feet to 10 feet during a dive.
3. Copy Settings via Bluetooth
I often have three Shearwater computers when I dive with my rEvo rebreather. Two are “on-board” and have external O2 sensors (a Petrel controller and a NERD2) and a third (Teric) has an internal setpoint and is the “oh shit” computer in case my other computers die.
I’d like to be able to setup the gasses (CC/OC) and GF, etc on the Petrel and then “transfer” the settings to the other two computers for a given dive and then override some settings.
This would save time, but more importantly, cut down on possible error configuring gasses.
4. Bailout TTS
I thought about this one during some (deep-ish) wall diving in Grand Cayman. In rebreather diving, you always bring “bailout” tanks with open-circuit scuba regulators in case your rebreather completely fails. In fact, most dives on a rebreather are limited by how much bailout gas you bring and not the rebreather scrubber or gas on-board. It would be nice to know “if I bail out right now, what is my revised Time To Surface.”
This would allow you to extend your dive knowing what the TTS would be if you were required to bailout and you could estimate if your bailout gas was enough.
5. Manually “vote out” an O2 cell
I have my rEvo setup with a NERD2 computer monitoring two independent cells. Twice in the past year, I’ve had one of the two cells “go wonky” during a dive.
As I found out the first time, when this happens, the NERD2 cannot figure out which cell is correct and which is bad. Therefore, it bases your deco profile on the lowest cell reading and your CNS clock on the highest cell reading. This is smart and the most conservative approach.
If you don’t want your deco / TTS to be artificially high, during a dive you can change the PO2 setting from “external” to an “internal” set point that matches what you are using in your controller or manually setting. This is what I did the second time this happend.
However, I would really like the ability to manually “vote out” a cell. Since I have three other cells connected to my Petrel controller, I KNOW absolutely which cell of the two on the NERD2 is faulty. Therefore, I’d like the ability to manually vote out the bad cell but continue to monitor the good cell for deco, CNS, etc.
6. Rotate NDL Field
The “NDL” field is customizable to show a number of different parameters once you enter into decompression. In the words of the Petrel manual “Once NDL reaches 0, the NDL display is just wasting space. To address this, a few different values can be set to replace the NDL.”
On my Petrel2 controller, I have it set to @+5 which indicates the TTS if you stay an additional five minutes on the current depth. On my NERD2, I have it set to SurfGF.
I often find myself pushing the right button to get to the screen that shows the other values.
It would be nice to have the ability for the NDL display on the main screen to rotate through the possibly values with 1-2 seconds on each value before moving on. If you are on a deco stop, it would rotate SurfGF -> @+5 -> Delta+5 -> CEIL -> GF99 -> SurfGF, etc.
7. Keep SurfGF after Deco Cleared
As mentioned above, my NERD2 has the SurfGF displayed in the NDL field once I enter mandatory deco. I definitely like this datapoint both during the bottom portion of the dive and during my deco stops.
I often perform some extra decompression after my deco clears and like to look at my SurfGF during that time. The problem is that once deco clears, that display field reverts back to NDL=99 and you have to keep pressing the right button to see the GF and then it reverts back to the main screen after a few seconds.
If the NDL Display field is set to either SurfGF or GF99, it would be nice to keep that data on the main screen on any dive that has required decompression stops instead of reverting back to NDL once deco clears.