not a shearwater fan ?

[dmaziuk]

However it (Suunto) works this out using your "instantaneous" consumption rate from its last sample rather than the average consumption over the whole dive.

It's bad either way. What you really want is a well-calibrated crystal ball that will know exactly what your gas consumption is going to be all the way to the surface. Without that, you can argue relative merits of one over the other but either's pretty much a shot in the dark. Same goes for computed NDLs: they are merely projections based on the current reading of the pressure sensor, and in many cases: also on the ascent rate that you'll stick to on the way up. At least the tank pressure reading is not affected by you moving your arm a few inches up...

 

[Colliam7]

Yeah, I thought the Eon Steel was a trim weight with a screen. If you don't need each and every bell and whistle, go with the Eon Core. It's pretty.

To continue this, what are the bells and whistles you give up with the Core, compared to the Steel?

It appears, from Diving Dubai's post, that firmwear updates may be one.

 

[scubadada]

Lots of people like Shearwater so I'm sure it's a fine computer, but I went with Scubapro G2. One thing I value from air integration is the Air Time Remaining and this is where Shearwater is deficient. If you happen to go into deco the Perdix stops displaying its Air Time (correct me if I'm wrong) whereas the G2 and other computers, such as Oceanics and I believe the new Suuntos, continue to include the deco stops and display the correct Air Time.
Other features I like about my G2 is the profile dependent deep stops which tell me when I'm starting to offgass the leading compartment and the heart rate monitor. The dependable rechargeable battery is icing on the cake as I don't have to worry about opening the battery compartment and the O ring issue.
Adam

Oceanics use the average gas consumption over the last 90 seconds in the air time remaining calculation and includes all stops, safety or deco, in the ascent calculation. If gas consumption was to increase significantly, as in filling a lift bag, the ATR calculation would revert back to normal after 90 seconds of normal breathing.

 

[pauldw]

To continue this, what are the bells and whistles you give up with the Core, compared to the Steel?

It appears, from Diving Dubai's post, that firmwear updates may be one.

I don't think there are very many of them to give up: Compare Products

 

[Jay]

The Suuntos (at least) do do this. Your Gas time remaining (or Time to Die clock as I call it) does indeed take into account all your obligation when calculating your remaining gas time.

Does this mean that it computes to the number down to OoG/A (assuming you're breathing at a constant rate)? [EDIT; thought I was being a bit lazy so I checked the Steel's manual and it seems to be that it's displays zero at 35bar or a one set [reserve] limit)

FYI SW compute it down to your Gas Reserve setting (whilst not including any known SS, and if in Deco it's not displayed as @Hatul mentions).

 

[Graeme Fraser]

To continue this, what are the bells and whistles you give up with the Core, compared to the Steel?

It appears, from Diving Dubai's post, that firmwear updates may be one.

Suunto are in the process of bringing out a Bulhmann option. Could be wrong, but I believe this will only be available on the the steel.

 

[Diving Dubai]

To continue this, what are the bells and whistles you give up with the Core, compared to the Steel?

It appears, from Diving Dubai's post, that firmwear updates may be one.

As far as I know: Currently the only differences at the moment are

Case construction and depth rating (Core 80m vs Steel 150m)

Battery capacity (Core 20hrs vs Steel 40 hrs Depending on settings and environment)

All the firmware is currently the same on both

The Steel only is getting Buhlmann - which I believe is to give a greater separation between the models. Realistically at teh moment there's little reason to buy the Steel because the differences between them are so little

 

[Diving Dubai]

Does this mean that it computes to the number down to OoG/A (assuming you're breathing at a constant rate)? [EDIT; though I was being a bit lazy so check the Steel's manual and it seems to be that it's displays zero at 35bar or a one set [reserve] limit)

FYI SW compute it down to your Gas Reserve setting (whilst not including any known SS, and if in Deco it's not displayed as @Hatul mentions).

So on Suunto the gas reserves are either default 50 bar then 35bar your settings (if you make your settings greater than default)
At 50 bar your contents display turns orange and at 35 bar it goes red

It will then compute down to zero

Gas time - yes you are correct, it's computing remaining time to reach the surface whilst meeting your reserve obligation - at default 35 bar

In my experience when I've looked at that data out of interest, it's been a very cautious estimate by the computer.

As I say, I don't use it because on normal dives I'm carrying more than enough gas - I'll be on the surface after 1 hr with 90-100 bar or more. But that headroom give me options either to spend time deep and be able to carry out some backgas deco - or deal with mother nature which can mean I'm on the surface after only 35 mins with 40bar because we've been given "a slapping" underwater.

That's why I have my rule of thumb "turn pressures" which are applicable to me

 

[Diving Dubai]

It's bad either way. What you really want is a well-calibrated crystal ball that will know exactly what your gas consumption is going to be all the way to the surface. Without that, you can argue relative merits of one over the other but either's pretty much a shot in the dark. Same goes for computed NDLs: they are merely projections based on the current reading of the pressure sensor, and in many cases: also on the ascent rate that you'll stick to on the way up. At least the tank pressure reading is not affected by you moving your arm a few inches up...

That's why I teach and urge people to work out their gas minimums. As I've written above mine conveniently (using some rounding up) mean that I need the same amount of Bar as my depth is in metres to mince to the surface and make a stop

Because I've rounded up to a nice 1 bar/min SAC I can make educated decisions on the fly regarding how much time to stay deep - how much deco I'm prepared to take etc etc to keep to the planned dive time and my personal reserve pressures

 

[Hatul]

That of course is fair enough, that's what the function is for

I do it differently which might be of interest.

I know my SAC very precisely but I use a rounded up number that's easy to calculate - in my case 15l/min on a 15/tank equals 1 bar/min at the surface

But I might dive Al 80 (11.7l which I round down to 11)

Doing the maths and with a bit of rounding up - on a AL 80 amy rule of thumb to leave and depth, make a 5 min Safety my gas requirements work out at needing the same number of Bar as I am at metres depth.

So at 40 m I need 40 bar and 30 metres, 30bar etc

On a 15l cylinder it's half of that (40 metres = 20 bar and so on)

So a cursory look at my gas contents and my depth and I know at what pressure to start to ascend to honour my reserve on the surface.

I deliberately rounded up my calcs so they make nice round numbers which are easy to remember. They also have some "fat" in the numbers so I'm not required to make a 10m/min ascent.

Of course experience comes into it too so that I instinctively know anyway - but if I need a quick reference that's it

That's similar to a rule of thumb I use for imperial units (with a 100 HP tank non deco dive):
at any depth I should have psi > 500 + 10*(depth in feet)
That actually roughly allows for an air-sharing ascent (so called Rock Bottom tank pressure).

Other rules of thumb I follow for non deco dive:
solo diving must have RBT (Remaining Bottom Time on my G2) greater than 0 minutes. I set my tank reserve at 550 psi

Buddy diving to account for air sharing ascent:
- set tank reserve at 550 psi
-time to surface is depth in feet divided by 30 (tank reserve allows for safety stop)
-always have Remaining Bottom Time in minutes (the G2 Air Time) > than (depth in feet)/30 + 1

Adam