? for Suunto Computer Users

[cornfed]

So why is Dive Manager giving you the red triangle symbol at the very beginning of the dive? Or is that the red diamond symbol? Is it telling you it wanted you to extend your surface interval?

RTFM.

 

[miketsp]

I didn't really want to get into this discussion as it can lead off into many others but since I have a little time free....

You must have brought extra gas with you.

No, AL80 single, but I was constantly revising my rock bottom calculation at depth and my buddy and I stick close together. Even in worst case failure at start of ascent we could have done sharing on remainder of either cylinder and still complied with ascent time requirement & deco stops.
In any case there was also an agreement with the boat to suspend an extra cylinder at 5m if I put up an SMB to indicate extended deco requirement.
I checked my log. I started with 218 bar and ended with 108.
My SAC was 12litres/min, my wife's 13.
At this point in the dive rock-bottom was 135 bar made up of 22bar for ascent, 63 for deco and 50 reserve. This would get us both up. Either cylinder at this level would have ended dive.

I'm curious about a couple of things... Since the tables show you should get 15 minutes at 33m I'm making the assumption that this wasn't your first dive of the day.

2nd dive, first was deeper & longer which is why we went into deco so fast. This is one of those dives that would be a waste of time if done within NDL.

So why is Dive Manager giving you the red triangle symbol at the very beginning of the dive? Or is that the red diamond symbol? Is it telling you it wanted you to extend your surface interval?

Dive Attention Mark as described in your User Manual.
There were no deco violations on this dive.

Also, it looks like you spent another 5+ minutes at depth after hitting your deco limit, then about 18 minutes at your safety stop. Is that what the computer told you to do? Did the computer ever give you a FLOOR indicator?

Your interpretation is correct & this deco was done by the computer. This is not always my practice, normally I use tables and would have made stops at 9m and 6m also, but the computer was giving me a higher N2 loading than I had expected from the tables so I reverted to the more conservative requirement. This alternative deco stop also required less air.
Yes, once at the deco stop the computer display changed to the depth range mode.

 

[geraldp]

I didn't really want to get into this discussion as it can lead off into many others but since I have a little time free....

Didn't mean to derail the discussion, but I'm always interested in learning more (which includes RTFM, thank you very much cornfed). :1book:

 

[cornfed]

thank you very much cornfed).

Always glad to help.

 

[vjongene]

I have many dives where Suunto shows more than 100% before starting ascent.
One example attached.

This was not the point. My question was "100% of WHAT"?

The usual definition of N2 saturation is "% of the pN2 where equilibrium is reached between the breathing gas and the tissue", which is dependent on the current depth. By this definition, you cannot reach 100% saturation or more unless your current depth is less than your maximum depth, which roughly translates into "during ascent".

I have done plenty of deco dives with Suunto computers, and have always wondered what their "% saturation" values meant. This is not documented in the manuals. The best I can come up with (and this is by no means certain) is that they have chosen some arbitrary depth (say, 10 m with a saturating pN2 of 1.6 bar), and express saturation values relative to that. This would make sense if you think about deco schedules usually starting around 10 m. Clearly, if you have spent some time at 30 m you will have enough N2 in some of your tissues to exceed 100% saturation at 10 m, thus explaining the >100% values shown by Dive Manager. Also, if you ascend slowly, the gradual lowering of the pN2 in your breathing gas will allow you to offgas enough to avoid mandatory deco stops (also part of the Suunto model).

If anyone knows more, thanks already for your input!

 

[MonkSeal]

This was not the point. My question was "100% of WHAT"?

The usual definition of N2 saturation is "% of the pN2 where equilibrium is reached between the breathing gas and the tissue", which is dependent on the current depth.

The easiest way to understand is to read Baker's Understanding M-Values. You can find it at www.gap-software.com

 

[vjongene]

The easiest way to understand is to read Baker's Understanding M-Values. You can find it at www.gap-software.com

Thanks, MonkSeal. Very interesting paper. Are you sure that Suunto Dive Manager actually represents M-values in its tissue saturation graph? It would be nice if the Dive Manager help or the computer's manual said something informative about this. The only statement I was able to find is "The vertical height of a bar shows the amount of dissolved gas represented in one tissue group of the decompression math model. A decompression ceiling appears if any bar reaches above 100%".

 

[MonkSeal]

Thanks, MonkSeal. Very interesting paper. Are you sure that Suunto Dive Manager actually represents M-values in its tissue saturation graph? It would be nice if the Dive Manager help or the computer's manual said something informative about this. The only statement I was able to find is "The vertical height of a bar shows the amount of dissolved gas represented in one tissue group of the decompression math model. A decompression ceiling appears if any bar reaches above 100%".

Probably yes. However, Suunto's algorithm is not pure dissolved gas model but I believe that graph in Dive Manager has nothing with Suunto's RGBM adaptation (folding to data) of dissolved gas model. The conclusion is that graph represents M-values only. The issue of Suunto's RGBM has been discussed several times on this board. You can easily find it.

 

[rcohn]

This was not the point. My question was "100% of WHAT"?

The usual definition of N2 saturation is "% of the pN2 where equilibrium is reached between the breathing gas and the tissue", which is dependent on the current depth. By this definition, you cannot reach 100% saturation or more unless your current depth is less than your maximum depth, which roughly translates into "during ascent".

I have done plenty of deco dives with Suunto computers, and have always wondered what their "% saturation" values meant. This is not documented in the manuals. The best I can come up with (and this is by no means certain) is that they have chosen some arbitrary depth (say, 10 m with a saturating pN2 of 1.6 bar), and express saturation values relative to that. This would make sense if you think about deco schedules usually starting around 10 m. Clearly, if you have spent some time at 30 m you will have enough N2 in some of your tissues to exceed 100% saturation at 10 m, thus explaining the >100% values shown by Dive Manager. Also, if you ascend slowly, the gradual lowering of the pN2 in your breathing gas will allow you to offgas enough to avoid mandatory deco stops (also part of the Suunto model).

If anyone knows more, thanks already for your input!

Once again , The 100% value represents a N2 loading of 100% of the M-value for direct surfacing for the compartment. It has nothing to do with tissue saturation, unless the 100% M-value just happens to correspond to the compartment saturation at that depth. This might only be possible for the fastest compartments.

Ralph

Ralph

 

[KrisB]

100% could also equate to the maximum level of tissue loading from which it is safe to do a direct ascent (i.e. no deco). So 110% means you've exceeded the NDL in that compartment by 10% at that point.