Replacing my mk5 + balanced adjustable for the new era

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Angelo Farina

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I, my wife and my sons are regularly using MK5+109. Actually none of us is a "tech" diver, simply because when I and my wife started diving, in the seventies, "tech" did mean more than 90 meters with trimix, and everything less than that was considered just "normal" diving.
In fact at our first course we did use twin tanks as the standard equipment. The course was 6 months long and most of the training was done using CC pure oxygen rebreathers, not air tanks.
Our recreational certification was for 50 meters with deco...
No one laughs at our regs (or at my plastic backplate plus wing dating back to eighties), as most divers here know that people using this equipment possess knowledge and expertise.
All that said, if you want to switch to something "modern" for today's tech diving, my suggestion is for two MK10 with Spec booth and silicon-packed (so they are fully environmentally sealed, something impossible with a MK25) with the Din universal conversion kit, and two identical G250V.
 

halocline

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Hello everyone,

I've now clocked 250 dives on my old mk5 + r109's now and have recently started to become more interesting in going the technical diving route. While I had a nice instructor who allowed me to use my 'antique' combo as he called it, for my advanced eanx and all the tech prequisites ( adv rec trimix / + tech lite or however you want to call it) which is basically an IANTD-style fundies,The complaints and funny looks over the 109's have gotten rather tiresome

I have plenty of (older) regs, but am looking for something modern specifically scubapro, just to see what their modern regs are about, since I've been so happy about the r109's / mk5 combo.

I would like to do my full cave this year and was thinking of finally taking the plunge and switching to something more modern.

What you really need is an instructor that is more knowledgeable about regulators. Then I suspect your MK5/109 combo would be fine. In fact, the 109s are almost ideal 2nd stages for full cave dives. I've been using them in caves for years. One nice thing about them is that they tend to have a bit of condensation in the metal case from your exhalation, and this tends to moisten the air a little. I find them very comfortable for 2 hour+ dives. I sometimes will bring one of my D300s on a cave dive, but I usually end up going back to 109s (upgraded to balanced with the s-wing poppet) for both 2nd stages. Another nice thing about them for caves is that they can take a beating; no problem if a tank rolls over on them on the rocks because someone else at the cave entrance isn't too careful (it happens). They're great with stages that you drop on the cave floor. They're just overall bombproof great performing 2nd stages, and dirt simple. For technical diving you can't get better.

For 1st stages, MK5s are great in a cave as long as you can get DIN retainers for them. Again, ultra reliable, very simple, super stable IP, it just doesn't get any better realistically, except in one scenario; for HP tanks, either the MK15/20/25 are probably a bit better due to the bushing system that provides slightly better tolerance around the HP piston shaft. But I use MK5s on HP tanks without problems.

You can use newer regs if you want, most people do. But I can tell you for sure that if I had to choose any of the new regs you listed, I would personally far prefer to stick with the 109s and earlier model balanced piston 1st stages.

DSC4861NWM.jpg


This is with my MK15s and 2 balanced/adjustables. The MK15 has recently been orphaned by SP, and new rebuild kits are not available (or soon won't be). So I'm using mine until I run out of kits, then it's MK5s and MK10s exclusively.
 

elan

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This is one of those questions where you really getting onto the politics of the team that you dive with. There is nothing wrong with mk5 balanced adjustable combo for the tech, assuming you use DIN on it. I never ran them on an HP tank, though I will let the guys to chime in how they handle 3k+ psi pressure but I do have a double set set for a warm water diving. They are mk5 DINs with converted Pilot as the primary and the bal adj as a backup. I even had a rec dive with my former GUE instructor and he was fine doing a rec dive with that but would not do a tech dive (he was referring to the pilot :)). The converted pilot as well as D series regs do present more challenges during the donation as they are low cranking effort regs and tend to free flow easier during the donation - you need to handle them more carefully than a downstream design based stages.

The only inconvenience with the bal adj style regs is the inability to open them underwater which could be an issue if they are on deco/stage bottles and you dive muddy places, like rivers with a current and. But IMHO not a critical one as you can easily feather the valve if the reg starts free flowing due to some garbage getting to it.

Having said that I did have my G250V pinned on my deco bottle during my tech1 checkout dive and th sucker started bubbling. I had to tune the valve so it flowed just enough gas for me to breath. showed it to my instructor so he is aware and we did complete the deco successfully.

I would hesitate to use mk5s for the backgas in a very cold water though. Not that it cannot be done - I tested mine in 42F just fine for fun but I would go with a sealed , say MK17/19 for my primary cold water tech set. I do use pistons in cold water on the stages though - mk5, 15, 20, 25 with no issues.

Speaking of D series I do have one set for my oxygen bottle with MK2 and I love how effortless they breath on a deco stop :)
 

Nemrod

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OP, do your 109 BA seconds have the larger exhaust valve? Most 109s I come across have the small exhaust valve. In which case, there is some merit in going new or at least newer. While all 109s are great regulators, WOB is heavily influenced by exhaust effort, thus the huge exhaust valves found in the newer regulators. But for recreational depths or even well below, you are not gaining much over a good 109, even with the smaller 26mm exhaust valve. My 109 set of BA regulators breaths super easy all around. I do not notice the 26mm exhaust valve unless I were to pop it out of my mouth and stick my AL Titan LX second in and then, yeah, I notice the exhaust effort is somewhat less on the Titan LX.

I used to hate the plastic fantastics. In 1988 I bought at Texas SCUBA a Mares Abyss, it was the first generation plastic I think. On a dive on the Flower Gardens the second stage split at the connection. Then a month later on the Jupiter deep ledge, Hole in the Wall, the other one did the same thing. Both were replaced and I noticed a thicker boss, no more issues after that, but it tainted my view of plastic regulators. Then some years back we bought my wife an AL Legend and despite her efforts to destroy it, the thing just works perfect. And then I got a Titan LX Supreme circa 2008 (the Core now) and it is my favorite all time regulator despite the copious use of plastic and it is tough hombre. The above just as a side bar, but new can be good even for those of us who appreciate classics.

James
 

lowwall

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I used to hate the plastic fantastics. In 1988 I bought at Texas SCUBA a Mares Abyss, it was the first generation plastic I think. On a dive on the Flower Gardens the second stage split at the connection. Then a month later on the Jupiter deep ledge, Hole in the Wall, the other one did the same thing. Both were replaced and I noticed a thicker boss, no more issues after that, but it tainted my view of plastic regulators.
Just a note from your resident Mares reg nerd that the Abyss second has and has always had an all metal body. You probably had the second that came with the MR12 IV or maybe the Beta. I think the Akros/Epos and Axis were introduced a couple of years later.
 

Nemrod

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@lowwal, yes, it was an MR12 set. The second stage was black but had tiny little flecks of red and silver metal flake that gave it a grey-ish appearance. The purge, if I recall, had some red decoration and labelling. They were sort of pretty and breathed fine and after being replaced never cracked again. But I had no confidence in them any longer. I sold them off long, long ago. Sorry for the senior moment.

And, I had from new, a Voit MR12 set, all metal, which I sold off about two years ago in mint condition, bought new by me in the day complete with the plastic bump covers on the seconds. I was not really wanting to sell them but the offer was convincing. They had the roundel red, white and blue purge button and the assist tube.

And I quite like the new Mares Abyss, I wish I could think of an excuse to purchase a set that would be convincing to she who watches over me (that being my little wife person :wink: ). N
 

halocline

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The converted pilot as well as D series regs do present more challenges during the donation as they are low cranking effort regs and tend to free flow easier during the donation - you need to handle them more carefully than a downstream design based stages.

The only inconvenience with the bal adj style regs is the inability to open them underwater which could be an issue if they are on deco/stage bottles and you dive muddy places, like rivers with a current and. But IMHO not a critical one as you can easily feather the valve if the reg starts free flowing due to some garbage getting to it.

I agree with the converted pilot being better for OW dives due to the propensity for free flowing when they're out of your mouth. I love my converted pilots, easily the best breathing 2nd stages I've ever used, but I won't take them in caves. And they all breathe a little wet inverted, so I just avoid the whole issue. I use D300s from time to time and have never had any sort of problem donating them. I had one on my long hose for a couple of years, did many s drills and went through a couple of courses with it.

It's interesting you mention the issue with disassembling 109s underwater, because that was the main reason I used a D300 at first. Those you pull the cover off and you don't even need to put it back on for the reg to work.

But, I have yet to be in a situation or known anyone who has been in a situation where they actually needed to disassemble a 2nd stage in the Mexican cave systems where I dive. Still, I carry a small allen wrench in my pouch and could easily remove and replace the cover if needed. I just don't expect to.
 

elan

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I love my converted pilots, easily the best breathing 2nd stages I've ever used, but I won't take them in caves. And they all breathe a little wet inverted, so I just avoid the whole issue. I use D300s from time to time and have never had any sort of problem donating them. I had one on my long hose for a couple of years, did many s drills and went through a couple of courses with it.

It's interesting you mention the issue with disassembling 109s underwater, because that was the main reason I used a D300 at first. Those you pull the cover off and you don't even need to put it back on for the reg to work.

But, I have yet to be in a situation or known anyone who has been in a situation where they actually needed to disassemble a 2nd stage in the Mexican cave systems where I dive. Still, I carry a small allen wrench in my pouch and could easily remove and replace the cover if needed. I just don't expect to.

Yeah I've built that MK5/pilot set for the same reason - they seem to be the best breathers I have experienced. After breathing it and switching to my G250V for few mins it feels I am pulling last few psis from the tank :D. It's also a good conversation starter as I am yet so see anyone else diving them here.

They also combine great breathing characteristic with the fact being metal they return moisture really well. It is especially noticeable here in cold water.
 
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