My DC died at 108 ft. Now what do I replace it with?

[Hoag]

No. I've been running it in Rec mode on the liveaboard trips, with medium conservatism(40/85) on 32%, and doing 5 dives daily. Since I travel by myself I usually follow the DM in the water. Over the course of the week the slower compartments show a little loading, but I've only occasionally come close to the NDL on some of the deeper sections.

Thanks.

Anybody else use it on a LOB?

 

[stuartv]

I see advantages for both. I only get diving about once a year or so, and when I do, I tend to do Live Aboards and dive 4-5 dives a day for a week or so. The advantages of the DSAT algorithm on the Oceanic dive computers can be exploited on this type of diving. I am a little concerned that the Shearwater products, being developed primarily for tech diving do not view deco as a big deal, and are therefore running a conservative algorithm which would result in a deco stop when doing repetitive dives particularly over several days.

@scubadada has been racking up experience comparing DSAT and Buhlmann w/GF. I think I recall him posting that in situations of multiple days of repetitive diving that Buhlmann w/GF was actually giving longer NDLs on the later dives. But, I could be misremembering that. Perhaps scubadada will chime in and clarify.

 

[scubadada]

Hi @Hoag

I've been diving DSAT since 2002, about 1400 dives, am very familiar with it. Most of my diving is rec, about 5% light deco, less than 15 minutes, average much less. I dived a Geo 2 backup to my primary VT 3 for about 5 years, 650 dives. I think the Geo 2 is a fine computer and keep it as a backup for anyone in my family who might need it. I switched my backup to a Nitek Q about a year and a half ago to learn about Buhlmann ZH-L16C with GF, and have about 250 dives on it.

The relationship between DSAT and Buhlmann is not entirely simple with a perfect association. I generally dive a GF hi of 95 to about 80 feet and often a GF hi of 100 below that. If I were to pick a single setting from Shearwater rec mode it would probably be 45/95, low conservatism. Keep in mind that DSAT is among the most liberal of rec decompression algorithms and is not the best choice for everyone. For example, @rongoodman dives 40/85 very successfully. I often dive 4 dives per day from my home in Florida and have done a couple of liveaboards with 4-5 dives per day with the Nitek Q. I have not done a systematic review of the influence of repetitive dives with DSAT vs. Buhlmann, but have noticed no significant difference between the two. They both handle my occasional short deco similarly also.

This is only my experience and what is working for me, your choices may or should be different.

Good diving, Craig

 

[scbaNE2179]

Thanks.

Anybody else use it on a LOB?

Same here! Prior to Shearwater releasing rec mode on the Petrel, I was using the default "tec mode" but ever since they released Rec mode, that's the mode it stays in. As for conservatism, I too just leave it the default settings-I'm not knowledgeable enough with GF to mess with these settings.

 

[scubadada]

Same here! Prior to Shearwater releasing rec mode on the Petrel, I was using the default "tec mode" but ever since they released Rec mode, that's the mode it stays in. As for conservatism, I too just leave it the default settings-I'm not knowledgeable enough with GF to mess with these settings.

Tec default is 30/70, extremely conservative for rec diving. I'm not sure what the rec default setting is, 40/85, medium?

 

[MargaritaMike]

I have been using the default medium conservatism of 40/85 on my Perdix, but after doing some heavy reading on some of the factors causing DCS, I want to be somewhat more conservative. I'm not sure the High Consevatism setting on OC Rec is conservative enough. I'm thinking that the 30/70 of the OC Tech has you coming up at the right time, but to be honest I don't know the difference between the 70 and 75 and if it's significant.
Some of the factors that I possess are that I'm over 65, overweight by 25 or more pounds (it was 55), but it's coming down, I've had 7 spinal surgeries, a plate put in my forearm, and I'm shrinking, which makes lowering my BMI a real task.
The bottom line is that I think I'm going to use OC Tech 30/75. It's a bit more manual but does the same thing as OC Rec High Conservatism with a little extra margin. UNLESS someone (and I'm sure there is at least ONE someone) can point out the error of my ways.

Cheers - M²

Edit: I aoologize. This post belongs on another thread. It has nothing to do with DC death at 108 feet. Mea culpa. Mea culpa.

 

[outofofficebrb]

I am a little concerned that the Shearwater products, being developed primarily for tech diving do not view deco as a big deal, and are therefore running a conservative algorithm which would result in a deco stop when doing repetitive dives particularly over several days.

@rongoodman you mentioned that you had used a Shearwater on several LOBs. Did you find that the Buhlman deco algorithm that is used by Shearwater limited you or forced you into deco when doing multiple dives over consecutive days?

I really want a computer that will not put me into deco when I am diving lots of (relatively shallow) dives for several days in a row. I know that the "conservatism" can be altered on the Perdix, but is that feature available only in Tech Mode, or is it available in Rec Mode as well and if so, how much difference does it make?

Thanks again for your advice.

Suuntos are famous on Scubaboard for being super conservative. Surely, it can’t be worse than them, right? I actually dive a Suunto Vyper Air with AI (plus an analog SPG but that is for another thread!) and have a Suunto Zoop as a backup. I dive locally once in a while but I rack up most of my dives on vacation in warmer water on back to back days, usually on a liveaboard for a week diving 4 or 5 dives a day. I usually dive nitrox and have not had issues as you would expect with conservatism. The closest I have come to NDLs were actually on land-based dayboat photography muck dives where I was getting 75-80 minute dives with a max depth of 80-90 feet on the 3rd dive of the day with relatively short surface intervals in between and diving the days before. I think I got down to about 4 minutes to NDL as we were ascending from 80-90 feet. Obviously, as we came up, that number was no longer an issue.

I, too, have heard such great things about Shearwater. User replaceable batteries are awesome - each battery kit+service and pressure test adds up! The digital compass on the Perdix is also quite something. I’d probably go that way myself if my Suuntos died on me.

 

[Hoag]

Well, today ("Black Friday") I came up with a short term fix. I am still waiting to hear what the "verdict" is on my ProPlus 3. Enough people have said to get the Perdix (with or without AI) that if my PP3 is toast, I think that a Perdix will be my long term fix.

Having said that, I was at my LDS today, and he "made me an offer I couldn't refuse" on his last Geo2 that he had in stock. This gives me a functioning Dive Computer in the short term which will serve as a back up to either my refurbished PP3 or a new Perdix in the long term.

Ya gotta love Black Friday clearances.

 

[MargaritaMike]

Good for you. I have avoided the deals because my "want" list adds up to about 2 G's or more, while my need list is MUCH less. Black Friday may put retailers in the Black, but it puts M² in the RED!
Cheers - M²

 

[Marie13]

Well, today ("Black Friday") I came up with a short term fix. I am still waiting to hear what the "verdict" is on my ProPlus 3. Enough people have said to get the Perdix (with or without AI) that if my PP3 is toast, I think that a Perdix will be my long term fix.

Having said that, I was at my LDS today, and he "made me an offer I couldn't refuse" on his last Geo2 that he had in stock. This gives me a functioning Dive Computer in the short term which will serve as a back up to either my refurbished PP3 or a new Perdix in the long term.

Ya gotta love Black Friday clearances.

I love my Geo 2.0. However, the interface could be better, although I'm more used to it now after 100 dives. I'm going to a Perdix over the winter and the Geo will be my backup.