My dive computer is too conservative, what can I do ?

[Gandalf-the-Diver]

Ya know, someone has to be the 1st to bring it up. There can be only ONE. Shearwater is the answer you are seeking. How much you want to spend on a new computer will determine the model.

 

[arkstorm]

I hear anecdotally that Suuntos are notoriously conservative with regards to NDL's, especially on repetitive dives. But how penalizing are they if you go into deco? Since RGBM is a "bubble model" do they mandate a deep first stop and then relatively shorter shallow stops?

What would your TTS be on a Suunto that just barely crossed into deco vs. a computer running a ZHL-16c algorithm with a 5-minute safety stop?

EDIT:
So just for fun I installed Suunto DSM on my computer and compared the Suunto dive planner to my Shearwater (running gf 50/85) and I am surprised that the NDL for a 100' dive is exactly the same for both planners at 13 minutes.

So to answer my own question, above, if the Suunto crosses into deco by one minute, the net difference between the NDL dive and the deco dive is one minute which is equal to the extra minute spent at depth. Suunto is not more conservative for a single dive to 100'. For both the NDL dive and the deco dive, Suunto advises a deep stop at 50' for 1 minute. For the NDL dive the second stop is at 10' for 2.5 minutes, for the deco dive it is 10' for 3 minutes.

What this tells me is that while the Suunto will go into deco, the deco time is so slight that it barely changes the dive profile.

If we treat safety stops as mandatory, there is no effective difference between the Suunto algorithm and ZHL-16c (gf 50/85), only that Suunto will throw in that deep stop. Assuming a 5-minute safety stop for a 100' dive to within 1 minute of NDL, the Suunto diver and the Buhlmann diver will ascend together, the Suunto diver sill stop at 50' for 1 minute while the Buhlmann diver continues the ascnet to the 15' safety stop, the Suunto diver will pass his buddy at the safety stop and stop at 10', both divers will reach the surface at the same time especially if they are watching their SurfGF and waiting for it to fall to a very safe level before hitting the surface.

Oh wait, only one of those computers has SurfGF... Conclusion: get a Shearwater.

 

[tridacna]

 

[MB NZ]

My issue with the original Suunto RGBM algorithm (Gekko; Vyper) was not the NDL conservatism (no doubt they are conservative though), but the fact that they would rack up decompression time during the ascent right up to the decompression stop window.

I have used a Suunto HelO2 for many years. It runs the Suunto "Technical RGBM algorithm", just a name, but it's been great. No help to the OP though.

Buying a dive computer which matches your buddies or a programmable diving computer would seem like the safest, most sensible solution. From what I have been advised, a Shearwater is the obvious choice. Note this is armchair advice. I haven't taken the plunge while my last remaining HelO2 hangs on to life.

 

[MB NZ]

I hear anecdotally that Suuntos are notoriously conservative with regards to NDL's, especially on repetitive dives. But how penalizing are they if you go into deco?

With the basic RGBM algorithm, penalising with extreme prejudice! No deep stops with the basic algorithm. With their "Technical" model, there are deep stops, but curiously they can be ignored without penalty.

 

[rongoodman]

The problem is that you have no idea what the propriety algorithm is doing. It’s probably safe to assume that your Zoop doesn’t have the computational power to actually run RGBM, so maybe a dissolved gas model with some RGBMish tweaks? In any event, you’re playing a guessing game with high stakes.

 

[Saboteur]

It has an adjustment for conservatism, yes, it tends to be more conservative, but can be adjusted to match other algorithms. I have since moved on from my Vyper Novo, but I was able to adjust it to match (roughly) buddy's computer.

If it is already on P0, that is as “liberal” it can be. All you can do is make it more conservstive.

 

[Dan]

I started up with Suunto D4 and now use Shearwater Teric.

The big hiccup for my D4 was when I compared it with Teric (D4 on my left wrist & Teric on my right wrist). D4 went crazy conservative after a short surface interval (< 1 hour). If I have surface interval > 2 hours, the RGBM matches reasonably well with Teric’s conservatism 40/85.

So the D4 is now in my dive bag as a back up, when my Teric breaks during a week long liveaboard diving in the middle of no where.

 

[inquis]

If we treat safety stops as mandatory, there is no effective difference between the Suunto algorithm and ZHL-16c (gf 50/85)

I would caution you against drawing conclusions based on a single, clean profile. Suunto's conservative reputation is earned on repetitive dives.

 

[Centrals]

Hello hello,

Here's my problem. I've just bought a Suunto Zoop Novo, but I realise that the algorithm used is on average significantly more conservative than that of the dive computers of the people I dive with (for example Aqualung). I'm not at all in favour of excessive risk-taking, but I'm thinking more and more that Suunto's conservatism isn't really justified, since other computers allow longer NDLs at the same depth (again, I'm thinking in particular of Aqualung), and yet they're widely used by dive clubs all over the world, without causing a significantly higher number of accidents (tell me if I'm wrong on this point). I realise the same thing when I compare the NDL given by my Suunto with the PADI dive tables, which are also more liberal.

I'd also like to stick with my dive computer as I like everything else so much.

I was thinking of a solution that would allow me to slightly reduce the conservatism of my computer: set it to an O2 level slightly higher than the one I actually use (Nitrox 25% if I dive with air, for example), so as to obtain results close to the PADI dive table when I plan my dives with the computer.

Is this taking a risk? What could be dangerous?

Thx a lot for your responses !

I had heard diver set the computer to AIR mode while diving with Nitrox but never the other way around.
RGBM is conservative and very critical to certain factors:
1. no reverse profile.
2. long surface interval,
3. no violation of ndl, it will punish you on the following dive by reducing the ndl significantly.
4. Slow and control ascend.

You should notice dm on guided dive does not spend too much time at depth. Multi-level is the way to go. Reef is most beautiful at shallow depth.

Set the computer to gauge mode and use PADI table.