Another question about Suunto RGBM

[Chopper]

I posted this yesterday, but probably in wrong forum. No response. Judging by some of the discussion here about the Suunto Vyper, perhaps here the place. I'm new to the site, so just getting used to it!! My question related to one posted last month.

I have read with much interest all the discussion about the Suunto RGBM and it has answered many of my questions. I came along looking for answers as to the following: I noticed when using my Suunto Vyper for deco dives that it was bringing me up very shallow to deco, ie. typically giving me 3m ceiling for anything in the 30-40m range. This seems to be contrary to my understanding, in that RGBMs should introduce deep stops to smooth out the deco profile. I now learn that this ‘recreational’ RGBM is not the full implementation and it’s mainly for divers who avoid necessary deco. I’m not happy with such a shallow ceiling, and generally ascend slowly and stop deeper than the computer says. Funnily, enough, buried in the small print in the Vyper instruction booklet, it recommends deco-ing at below 4m!! Well, I thought, no matter. I’ll follow the decompression ‘floor’ which should allow me to off-gas more slowly whilst staying a bit deeper. According to the instructions, the ‘floor’ is represented by the upward pointing arrow (ie. the lower half of the ‘hourglass’ icon), which disappears when you enter the deco zone. The deco zone should start when the leading tissue reaches a sufficiently low ambient pressure to begin off-gassing. Well following the Vyper, this doesn’t seem to be the case, since the ‘floor’ seems to be not much below the ‘ceiling’ ie. about 6m. This is very misleading as it represents the most efficient deco zone and not the real ‘floor’ at all. In fact, when I analysed some dive profiles using the desktop software, it seems that the leading fast tissues start off-gassing and the slow tissues stop on-gassing about where you’d expect them to, ie. about where you would put in the first deep stop, which is half the maximum depth minus the first stop ( about 15m for a 35m dive). Presumably this is at or close to the real ‘floor’. OK, so the Suunto RGBM is not the full implementation, as it doesn’t put in the deep stops. It seems that for the most part the modifiers affect what happens on the surface and for following dives in a series rather than actually modifying the dive profile itself. That’s fine, I still thing RGBMs are the way forward, but can anyone tell me what would happen if, using the Vyper in normal air/nitrox mode I put in the deep stops ? Would it penalise me unduly ? or is a foolhardy thing to do given the way it works ? Should I use it in Gauge mode for serious dives and use dissolved gas tables with gradient factors or go out and buy a new one with the full RGBM ??

Grateful for any suggestions,

Cheers,

Chopper.

 

[BlueDevil]

As you have discovered the Suunto RGBM implementation is not the "full" RGBM with deep stops. And personally if I had bought one of these computers without realising there were no deep stops I would not be particularly happy. Mares have recently released an RGBM computer which does incorporate deep stops, but from what I can gather in a fairly "reduced" form. Their web site gives an example of a 50m dive with the first stop being 1 min at 22m, but it then looks like the next stops are quite shallow (ie it appears to only give one deep stop). This would be an improvement over the Suunto no deep stop RGBM, but probably not as full on as most would want. However, I believe that Suunto will be releasing an RGBM version in a few months that incorporates deep stops, but I don't know whether it will be similar to the Mares limited deep stops version, or whether it may be a more complete RGBM with a full set of deep stops.

I am not sure how the current Suunto RGBM will react to you including your own deep stops. But even if it does penalize you somewhat deep stops are of significant importance and you should do them anyway. Ideally deco dives should be preplanned on deco software rather than relying on a computer, and i would encourage you to take this approach. Personally I would use it as bottom timer and workout a deco schedule using VPlanner, or similar. However on odd occasions I may do a deco dive where there is significant opportunity to multi-level and get a time advantage. On these dives a full RGBM computer would be good, and there are such computers available (but expect to pay a lot more than the average recreational computer).

Hopefully someone else with greater knowledge of the Suunto RGBM may give you further advice.

Cheers, BD

 

[Spectre]

There are a number of threads where this has been answered.

Try right here: http://www.scubaboard.com/showthread.php?p=530671#post530671

But so as to not confuse you with all that noise.

A computer is not a decompression profiler. It is a simple tool used to record your time underwater and give you constant feedback to your time.

Your computer doesn't tell you how to dive, it tells you only what you can NOT do. When your computer says you have a 10' ceiling, and you have a 10 minute deco obligation; it's telling you -just that-. You can NOT get out of the water for another 10 minutes, and you can NOT ascend higher than 10 feet.

If you had a non RGBM, and you ascended slowly or did deep stops, you would see that decompression obligation increase as you slowly ascended. The Suunto takes those profiles into account.

However... once again..,. your computer does not, and -should not-, design your profile for you. Talk about the ultimate micromanager.... jeez

 

[Chopper]

Guys,

thanks for your comments-much appreciated. Pretty much as I suspected. I will be changing my approach to deep diving and not relaying too much on the thing strapped to my wrist. I think it's probably better to plan deep dives with intentional deco obligation on tables such as D-plan with GFs for the deep stops to better control the ascent and microbubble generation. It may also be OK to sit out the shallow stops at the end of the dive until the computer clears so that it can be used for subsequent dives in a series which may have little or no planned deco or shallower and using nitrox. After all, it's pretty OK as a dive logger!!

thanks again and happy diving,

Rich (Chopper)

 

[String]

The vyper will start to rattle off a deco obligation fairly deep - on a lot of dives you notice by the time you get to the planned stop depth its already cleared.

I love the vyper but slightly irritating feature is its <5m for the 3 min optional stop. The tables here use 6m as a stop depth (and 9m for some profiles as well). At 6m the vyper never clears its optional safety stop so i find myself trying to hold 5.9 or whatever.

Shallower stops than that arent fun in rough seas hanging onto a DSMB and line.

Other than that i love my vyper

 

[Lead_carrier]

I have used the Vyper and now use the Cobra and Vytec. The safety stops that mine give are between 15-20 ft(5.5-7.3 metres). I don't understand what you mean by clearing its optimal safety stop. The safety stop timer should count down just fine at 6m.

 

[ShoalDiverSA]

String is correct. Set to metric, my Cobra only begins counting down the safety stop once you have ascended above 6m. You have to stay in the zone between 6m and 3m for the countdown to continue. Any deviations (say to 6.1m) will result in the countdown being paused.

I second his comment about rough seas. When you have 2m swells passing overhead, keeping your computer in a 3m high zone can be fun

Seems like the Imperial setting may give more leeway? (Small correction: 15ft=4.6m, 20ft=6.1m).

Cheers,

Andrew

 

[Albion]

As blue devil mentioned the new Suunto deepstops is supopsoed to be in the pipeline, does anyone know if it is possible to get existing computers upgraded or ifd it is a completly new model?

I use a stinger and have had two different sitautions not sure how it works yet, both were on same site. Last weekend, i got to the point where my no deco counted down to Zero then started deco (ascend to below 4m etc), i decided to do my planned slow ascent and then do whatever stop it decided i needed to do, this was at 28m, i was going up slowly and at 24m it reverted back to showing no deco times. A little while ago my GF stinger went deco and we were going for the same plan of a slow ascent, but hers just kept building up the deco time during the deep phase, she had gone further into deco before the ascent though. Any ideas???

 

[svidlano]

....
Ideally deco dives should be preplanned on deco software rather than relying on a computer ....

And deco software runs on what?????

It's just one computer instead of the other. SAL instead of HAL.

First you have to realize that every dive is a deco dive, but on some of them you can omit deco stops and surface without being seriously hurt

You have to understand underlying principles and use that "computer between your ears".

The key to safe diving lies in diver, not in computer.


And yes, computers are great tools and they can lead to safer diving.

 

[String]

Should be noted here im complaining only about the optional safety stop NOT the mandatory deco that does this. The mandatory stuff as i said seems to start at depth provided you're above a pre-defined floor (even if it is outside the optimum). Its the optional 3 mins the Suunto winds onto every dive that will not clear at 6.0m or below (countdown pauses and resumes when you get back into window). Its not a major issue - you dont HAVE to do this stop and the computer will not punish you if you dont but it would be nice to be able to use my backup tables stop depths and a little deeper. Im sure 3-4m is nice on a calm sea but clinging onto a drifting DSMB/line, a few meters more makes it a lot more comfortable.
As pointed out though - it could be a metric > imperial conversion rounding artifact.

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As for upgrades i doubt any will be upgradable, physical issues aside its also business sense - they want to sell you a shiny new computer.

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Computers are merely another way of presenting tables. Theyre nothing to be afraid of provided you arent 100% reliant on ONE of them.