Upgrade my MK2...but to what?

[DA Aquamaster]

I test dove a customer's Mk 2 R190 this weekend and while it performed well on the dive (to depths to 120 ft in 45 degree water) inhalation effort was noticeably greater than my personal regs. If you upgraded to a balanced first stage you would notice the difference.

SP has discontinued the Mk 16 and it should potentially be available from SP dealers at clearance prices and could be an extremely good deal. I have gotten great deals in the past from SP dealers on clearence items (regs, BC's and wet suits) as normally the price of clearence items is not controlled by the price restrictions in the SP dealer agreement and some dealers will stock up on clearence items to give them a supply of items to compete with on-line retailers etc.

Given that the Mk 16 is balanced it will offer lower inhalation effort at low tank pressures than an unbalanced Mk 2 with the same second stage. A Mk 16 R290 or R390 would offer great first stage performance with a smaller and lighter second stage. Alternatively a Mk 16 S550 would give you a small sized second stage that was balanced as well. The Mk 16 also is extremely reliable in cold water and I would not hesitate to use one ice diving.

All of the above is also true for the newer Mk 17 (except for the clearence price comment) with the added benefit that the Mk 17 is fully sealed. A Mk 17 R290, S550 or G250 would make an excellent regulator for a rec or tech diver.

In my opinion the Mk 25 is a great first stage and does offer an LP port swivel, but in terms of bang for the buck, it is over priced compared to a Mk 17 and is much less reliable in extremely cold water.

Also I have found I prefer the hose routing with the Mk 16 and Mk 17 compared to the Mk 25 when using doubles as the port arrangement allows all the hoses to be routed straight down. The Mk 17 sports 2 HP ports compared to one on the Mk 16 which increases your hose routing options slightly.

Both the Mk 16 and 17 are also quite compact and, for balanced first stages of brass construction, are relatively light weight.

 

[JKSteger]

Thanks DA Aquamaster!

Your info was exactly what I was looking for. It's good to know that the MK2 worked well but the ease of breathing was not a "good" as your personal regulator.

I'm going to call my LDS and ask if they have the MK16 in stock and what the price is to part with it. If it's a good deal I might get it, if not I will continue to use the MK2 until later and just buy myself some more tanks for now.

Like I stated before, I've never had any problem with the MK2 just didn't know if I was missing out by not moving to a newer regulator.

Thanks,
Jeremy

 

[archman]

hmmm... Mk16's... cheap. I may also look into that. It is more compact than the Mk25.

What's the advantage of the new Mk17 over the Mk16? How great is it to be "sealed"? Does it reduce maintenance significantly? That's what I love about the Mk2.

 

[JKSteger]

One more question...

I found a deal of @215.00 for a Scubapro MK25AF 1st stage without the 2nd stage. Would it make sense for me to get the MK25AF and use my R190 as a 2nd stage until I can come up with more $$$ to buy a new 2nd?

Jeremy

 

[DA Aquamaster]

hmmm... Mk16's... cheap. I may also look into that. It is more compact than the Mk25.

What's the advantage of the new Mk17 over the Mk16? How great is it to be "sealed"? Does it reduce maintenance significantly? That's what I love about the Mk2.

SP has to my knowledge put a few years of effort into the design of the Mk 17 in an effort to create a no compromises balanced diaphragm design.

The Mk 17 is reported to offer higher flow rates than the already great flow rates on the Mk 16. And the sealed ambient chamber on the Mk 17 should make maintenence a little easier as it keeps salt,silt, etc out of the ambient chamber. But that also depends on the seal remaining intact. If the outer diaphragm leaks on a sealed first stage you end up with water trapped in the ambient chamber and corrosion can result as you won't know it is there and can;t rinse it out. (But any damage discovered at annual service would be covered under the SP warranty as long as you get it serviced annually.) On the other hand, the very open ambient chamber on the Mk 16 was very easy to rinse and the exceptional heat transfer made it very reliable in cold water as well, so much of the advantage of the sealed ambient chamber is theoretical rather than practical.

In my particular case the cost difference between the Mk 16 and Mk 17 was relatively small (the local LDS has no plans to stock up on Mk 16's to sell at discounted prices) so going with the Mk 17 made sense.

 

[DA Aquamaster]

One more question...

I found a deal of @215.00 for a Scubapro MK25AF 1st stage without the 2nd stage. Would it make sense for me to get the MK25AF and use my R190 as a 2nd stage until I can come up with more $$$ to buy a new 2nd?

Jeremy

It's a good price for just a Mk 25 first stage and the R190 will work fine with the Mk 25. The balanced design of the Mk 25 will provide a very stable IP for the R190, so you won't get the same increase in inhalation efforts at low tank pressures that you would get with an unbalanced Mk 2.

With an R190 on a Mk 2, the inhalation effort can increase as much as .5" of water between 3000 psi and 300 psi. So even with an R190 well tuned to about 1.2" of water, the inhalation effort near the end of the dive would be 1.6 to 1.7" of water when attached to a Mk 2. On a Mk 25, you would have the same 1.2" cracking effort throughout the dive.

You will still see some qualitative and quantitative improvement when you upgrade to a balanced second stage later, but it would be worth upgrading your first stage now.

Of course to play devil's advocate, you could probably get a Mk 17 first stage for even less money (maybe $50-60 less) and get the same advantages of a balanced first stage but with much better cold water reliability. I guess it also depends on whether you want a swivel turret or not.

 

[Panulirus]

What started me wandering about a new regulator was the other week when I visited a new LDS and they had an Atomic Acquatics Z1 for around $350.00 USD (I thought these were alot higher!) I took a good look at it and thought that maybe it was time to get something newer.

Back to your original post. In case you were'nt aware the Atomic Z1 is being replaced by the Z2. The Z line is Atomic's cheapest model and is recomended with annual service instead of every 2 years. BTW, I am no reg expert. Just passing along some info that I gained recently. I'm looking for another reg myself so have been doing the LDS circuit as well as keeping my eyes open here.

 

[halocline]

Ha ha, I've been pondering the exact same question lately. I also have a well-used Mk2-R190 combo that has performed very well.

My interest in a new reg set comprises only two criteria.
1. smaller second stage
2. 1st stage on a swivel

I've been eyeing the ScubaPro Mk25. I'm fuzzy on second stages. I've even pondered retaining my R190... I wonder if the techies would even let me do that. I really like the rugged outer case on the R190. I'm dropping it constantly on the ground.

I have a MK2 R/190, and I decided to investigate a higher performance SP reg by getting a used MK15 1st stage and an old style G250 2nd; along the way I also bought one of the old metal cases balanced adjustable 2nd stages. Once I got them serviced, I took both regs to Cozumel and alternated them on dives to get a better idea of the performance difference. I did notice a difference in inhalation effort, but only on a comparative basis; i.e, I've never been unhappy with the performance of my MK2/R190.

I would say that the balanced adjustable is at least as good a performer as the G250, and the metal case is REALLY rugged. Because it's heavier, though, you need to have the right mouthpiece for it. Once you get that taken care of, I'd highly recommend it.

Someone like DA aquamaster who services and dives extensively with different regs is going to be very sensitive to differing levels of performance. In this regard his advice is very solid, but remember that what might be a big difference to him could be perceived as slight to one of us who's not as involved with the regulators.

There are lots of people that swear by the old SP MK10/G250 (old style with metal barrel) combination, and these are available very reasonably used.

For Jeremy, the original poster on this thread that dives in cold water mostly, I'd pay special attention to DA's comments, as he dives regularly in very cold water. The MK25 does have a reputation for freezing up when paired with some 2nd stages, although as a warm water wimp, I have no experience with this. (Can't honestly say I want to get that experience at this point!) If money's an issue and you can get the 1st stage alone, you might look for a used balanced adjustable 2nd. I really love having the old metal case reg, and it's a lot better for dry mouth than my R190, or probably any plastic 2nd stage. It's also much less prone to freezing up, or so they say.

Oh yeah, one thing about the swivel, as my MK15 has one. I'm not sure it's such an advantage, as the position of the reg is pretty well set by the LP inflator hose; since that's a short hose and is "fixed" at the other end onto your inflator. This tends to restrict the swiveling; or at least influence it. If your inflator hose is too long, it will really push the swivel on the reg around pushing your primary 2nd stage hose forward. At least that's what I noticed; once I found the right LP hose (a really short one for my wing) the 2nd stage sat more comfortably in my mouth. Without a swivel, you can mount the reg on the tank in a way that "fine tunes" the direction of the hose to the primary 2nd stage and it won't move. In some ways that's more comfortable.

 

[JKSteger]

Thanks,

I got a really good deal at my LDS on a Mk10. I took it out this past weekend and dove with it over several dives. I must say that the Mk10 delivers ALOT more air than the Mk2. In hindsight I don't know If I would have bought the Mk10 over the Mk2 again. I think that I would have just kept diving with the Mk2 and bought a new reg set later. This is not to say I don't like the Mk10. I love it and I think it is alot better than the Mk2...I'm saying that it knowing what I know now I would not have spent anymore than what I did on the Mk10.

My Mk10 has a R190 2nd stage and I might look at the G250 balanced or something a little later on. The R190 attached to the Mk10 breathes fine for now.

On another note, using the Mk10 I was in the "kiddie pool" at the PCB jetties (6' deep) just using up my remaining air in the tank and breathing was fine, alot of air on one breath then on the next there was NOTHING. This was not a problem as I was deliberetly sculling around in 6' water to use up my remaining air to see if it was true about the balanced regs delivering air one breath then the next not having any air to breathe. Everyone is right. My Mk2 does start breating hard once the tank pressure drops under 400psi. The Mk10 breathed fine up until their was no air to breathe!

Anywho, I did enjoy my Mk10 and will use it as my primary and my Mk2 as a backup reg that will travel with me from now on.

Jeremy

 

[halocline]

Thanks,
On another note, using the Mk10 I was in the "kiddie pool" at the PCB jetties (6' deep) just using up my remaining air in the tank and breathing was fine, alot of air on one breath then on the next there was NOTHING. This was not a problem as I was deliberetly sculling around in 6' water to use up my remaining air to see if it was true about the balanced regs delivering air one breath then the next not having any air to breathe. Everyone is right. My Mk2 does start breating hard once the tank pressure drops under 400psi. The Mk10 breathed fine up until their was no air to breathe!

Jeremy

Yep, the increase in breathing resistance as tank pressure drops below 400PSI is something that the MK2 is criticized for, but if your SPG were to fail or you were distracted enough to forget looking at it, it can be a lifesaver, literally! With my well-tuned MK2, (IP at 145) I don't really notice anything until 300 PSI, and then, it's not like you can't get enough air, it's more a gentle reminder that it's time to head up. If yours really starts to breathe hard at 400PSI, maybe getting the IP adjusted up and the 2nd stage tuned to that would help. Anyone that's at enough depth at low enough tank pressure to really have difficulty breathing the MK2 has far bigger problems than reg performance!

Regarding the 2nd stage for a MK10, I'd really suggest finding either the older style G250 with the metal barrel, or the B/A metal case. Then you can them serviced and tuned together, and you'll have a reg that alot of old timers would say rivals the performance of anything currently on the market. The metal barrel and/or metal case really helps with dry mouth; that one I know from experience, and from many posts on the subject, there's a big improvement in cold water reliability due to the heat transfer properties of the metal.