Dive computers... SO many choices!

[KenGordon]

Shearwater and Dive Rite implementation appears pretty clear, what more do you want?

How they chose the depth that the GF value starts to be interpolated between GF lo and GF hi. When they assume a lower ascent rate. How they decide if any stop is due at all, since they ignore short stops when calculating NDL.

 

[stuartv]

How they chose the depth that the GF value starts to be interpolated between GF lo and GF hi. When they assume a lower ascent rate. How they decide if any stop is due at all, since they ignore short stops when calculating NDL.

I think the only choice that is going to satisfy your desires is an OSTC 3 or 4. And, to be honest, I strongly covet an OSTC 4 myself. I would love to have an open source dive computer!

 

[KenGordon]

I think the only choice that is going to satisfy your desires is an OSTC 3 or 4. And, to be honest, I strongly covet an OSTC 4 myself. I would love to have an open source dive computer!

Until you read the code...

 

[dmaziuk]

I think a dive computer is a software product. They ought to be able to do it.

Until you read the code...

It needs to have downloads that work, sometime uploads.
...
Whatever, if they want to claim that the computer implements ZHL16C+GF it would be nice if they made clear what that means.

Yes, they should have downloads and possibly a way to change the settings easier than one button and a tiny screen. A cute GUI that plots a dive profile with ceilings and photos and GPS coordinates attached: no.

Yes they should make it clear exactly how they implemented their algorithm so that people writing dive planned software can match it. It doesn't have to be open source, it's enough to spell it out someplace in words and numbers.

 

[atdotde]

I am pretty certain that MultiDeco uses the Baker method of assuming an instantaneous ascent. My own software can do either but agrees with MultiDeco when doing it that way rather than allowing for the projected off gassing. Looking at the SubSurface code, and I think confirmed by the author, it anchors at the first projected stop. At first glance it looks like it uses the projected ceiling for GF but the instantaneous one for VPM.

Almost: Subsurface uses the maximal instantaneous ceiling to determine the anchor for GFlow (as otherwise it would get too complex with depth dependent ascend speeds etc), but when it comes to decide if we are ready to leave a stop or stay for another minute, we take into account off gassing during the ascent to the next stop for Bühlmann since I think this is the sensible thing to do but for VPM-B we don't since that is what the original Baker implementation does to which we wanted to be identical in outcome.

That said, the difference is minimal and very likely much smaller than any systematic uncertainties in decompression modeling.

There are many places where a model that is only described in words can be interpreted in different ways. Another is for example: everybody wants to do deco stops in full minutes. But how do you count? Full minutes of total runtime or since lea bing the previous stop or since arriving at thus stop (the difference typically is 20s which can change the minute counts of some stops).

Without specifying all this fine print, there is no such thing as the Bühlmann model.

 

[Jason]

Thanks @LandonL

I agree with @stuartv, running the same GF presets as Shearwater Rec is easily the best choice for their 1st computer and beats a proprietary RGBM hands down.

Not to mention that it'll help make the Deep 6 computer the go to backup computer for all existing Sheatwater users.

 

[ls1dreams]

@LandonL How often is depth sampled during a dive? (Not for logging purposes, but for actual recalculation of the NDL/stops and ascent rate).

I'm curious how it compares to others. One gripe I've heard about the Suunto is that it can be slow to do this.