Mares Carbon 42 or Scubapro A700/MK17 for back up reg

[hg frogman]

1) Depending on how they are designed, some so-called "over-balanced" diaphragm first stages are more prone to free-flow at depth. That often comes from a specific "dry chamber" (or "environmental seal") design, which makes the IP increase with depth, thus making breathing easier (nice) but free-flow more likely (not so nice). These dry chambers that use an external diaphragm plus a piston to put the pressure on the actual diaphragm may (design depending) slightly "deform" the ambient pressure curve applied on the actual diaphragm (in other words, they don't behave completely linearly for transmitting the ambient pressure).

That is not the case of the Scubapro Mk 25 (ie, maybe it's advertised as "over-balanced", but it can go at extreme depths) nor of the Mares 22 or 42 (without a dry chamber ; I don't know with one). I don't know about the Mk17. But that may be the case with the Legend, which for sure needs balanced seconds (also for the octopus) because of its "over-balancing" that boosts the IP at depth (balanced seconds stand much more variation of the IP than unbalanced ones).

But normally this free-flow happens deeper than 60 meters/200 feet, ie rather in the 80 to 120 meters range (see an article about extreme depth regs in Mark Ellyatt's website) so maybe in your case it's also a matter of tuning ?

2) I own (or owned) both Mk17/G250V and Mares MR22 Abyss, and I prefer the Mares. It's much simpler, yet amazing at depth, and I find it a better breather (more flow) than the Mk17. I went to this Mares reg two years ago because of its ease of servicing + its metal second (more robust and less dry mouth) and I have not been disappointed by the breathing of the MR22 Abyss, nor by the durability of the Mares seats. To be fair, a Mares Abyss needs a bit more "tinkering" than a G250V to stay perfectly tuned after 100 dives or more (unlike the G250V, the Abyss has no external device to harden the reg, to do so you have to remove the Abyss second stage from the hose and use an Allen key, for example) but this adjusting is very easily and quickly done, especially by someone who services his regs himself. On the other hand, it's easier to adjust the IP on the first stage of the Mares (no dry chamber) than on the Mk17.

3) Having a metal second feels so comfortable that it would make me choose the A700 instead of the G250V.

 

[Speardoggin]

i definitely notice the dry mouth with legend compared to the Abyss I owned and the A700 i currently own. What cracking effort do you set your Abyss at and the octo?

Jeff

 

[hg frogman]

i definitely notice the dry mouth with legend compared to the Abyss I owned and the A700 i currently own. What cracking effort do you set your Abyss at and the octo?

I am often in quite remote locations where I can use only a very limited set of tools and no magnehelic gauge. That's part of the beauty of the Abyss, few tools are needed and most are standard ones. I set the cracking pressure so "it feels good" to me, that gives around 2 to 4 centimeters (no very accurate measurement) when measured in a bucket of water. I set the octo a bit harder. I correct if needed after one or two dives ; then after 50 dives I often have to tune it again, especially for the octopus (wear of the second's seat and hence slight free-flow) then it's OK for a long time. I slightly unscrew the seconds' seats connectors when I don't use the regs for some time, so as to not engrave these seats (that's, at least theoretically, more a concern on an Abyss than on a balanced second).

Its massive flow (also at depth) is the main asset of the MR22 Abyss, its cracking pressure is good (or very good if very carefully tuned) without being exceptional and that's normal. By the way, I noticed that my MR22 Abyss breathes even better at 50 meters than at 6 meters.

 

[Stu S.]

We have a local Mares Dealer who says the carbon regulator is just too expensive. He doesn't stock it. He is pleased to sell the Abyss.

 

[Speardoggin]

I am often in quite remote locations where I can use only a very limited set of tools and no magnehelic gauge. That's part of the beauty of the Abyss, few tools are needed and most are standard ones. I set the cracking pressure so "it feels good" to me, that gives around 2 to 4 centimeters (no very accurate measurement) when measured in a bucket of water. I set the octo a bit harder. I correct if needed after one or two dives ; then after 50 dives I often have to tune it again, especially for the octopus (wear of the second's seat and hence slight free-flow) then it's OK for a long time. I slightly unscrew the seconds' seats connectors when I don't use the regs for some time, so as to not engrave these seats (that's, at least theoretically, more a concern on an Abyss than on a balanced second).

Its massive flow (also at depth) is the main asset of the MR22 Abyss, its cracking pressure is good (or very good if very carefully tuned) without being exceptional and that's normal. By the way, I noticed that my MR22 Abyss breathes even better at 50 meters than at 6 meters.

I have heard the MR22 first stage breathes better than the MR42, but I cannot comment since i have only dove the 42. Do you think it is noticeably better with the MR22

 

[scubafanatic]

We have a local Mares Dealer who says the carbon regulator is just too expensive. He doesn't stock it. He is pleased to sell the Abyss.

...especially in this economy, the Carbon couldn't have come at a worse time...I'm bettin' Mares drops this reg from their lineup...it really is for people with $ to burn, and there are a lot fewer of those people around these days.

 

[Speardoggin]

I can get the Carbon cheaper than the A700/MK17, that is why I am considering it.

Jeff

 

[scubafanatic]

I can get the Carbon cheaper than the A700/MK17, that is why I am considering it.

Jeff

....I'm familiar with the attraction of the 'bling' factor, and do own some 'high bling' factor regs too.....my very 1st 'bling' reg was a Mares RUBY ( I still own it, it's still a fine reg, and just this spring I had it upgraded to the new tri-material HP seat/dry seal cold-water kit). Adjusted for inflation, it was just as expensive as the 'Carbon' is today....it sounded 'sexy'/cool, plus I bought it barely used off E-Bay for a tremendous discount, which is the only way I'll buy a very high bling factor reg. My biggest 'issue' with any Mares is the non-adjustable 2nd stages, it just annoys me to not have control over that in the field, on the fly as I'm diving, hence all my Mares regs are in my reserve fleet, but I'd place a bet that my approx 10 yr old RUBY performs just as well as the new Carbon....reg technology is VERY mature with very little real progress in pure performance....maybe modern regs are a bit smaller/lighter on average, but air-flow stats are pretty much the same. If you compare the 1st-stage of my 'old' Ruby to a modern Mares 1st-stage, the newer Mares 1st-stages are smaller/lighter (they trimmed off some of the excess metal/weight) and maybe slightly changed the location/orientation of the HP/LP ports....but I highly doubt you could tell any difference in terms of pure performance/air flow.

 

[hg frogman]

I have heard the MR22 first stage breathes better than the MR42, but I cannot comment since i have only dove the 42. Do you think it is noticeably better with the MR22

I don't know. The MR22, being bigger, may have a bigger flow, but I am not sure. The MR22 has one bigger hose for the primary second stage (more flow then, but it may be marginal unless at extreme depths) and three other regular hoses, while the MR42 has four regular hoses (that can also be an advantage for routing) if I am not wrong.

I prefer the Abyss than the Carbon (price, plus brass seems more resilient to me ; also weight in the water is a non-issue : no problem with the Abyss, provided one changes the original floppy Mares mouthpiece).

But frankly, given that you already have a Mk25/A700, why not buy another Mk25/A700 in order to standardize your equipment (spare reg, spare parts etc). From what I have read that was written by competent divers, it's an excellent reg. And it offers more routing options than the Mares for diving a twinset or an H-valve as you seem to do.

 

[hg frogman]

modern regs are a bit smaller/lighter on average, but air-flow stats are pretty much the same. If you compare the 1st-stage of my 'old' Ruby to a modern Mares 1st-stage, the newer Mares 1st-stages are smaller/lighter (they trimmed off some of the excess metal/weight) and maybe slightly changed the location/orientation of the HP/LP ports....but I highly doubt you could tell any difference in terms of pure performance/air flow.

You are right. I am told by my LDS/Mares dealer that the inners of the Ruby and of the new "trimmed" MR22 are pretty much the same (eg same kit for servicing). Why change what works ?