Looking for input on 2nd stage + octo to pair with MK17 for ~45F water

[lexvil]

Did the barrel design and configuration in the S600 cause any known issue in the regulator? I never heard or known that there is any issue with the S600 for the many years I have used it. It is as trouble free as a regulator can be especially with the metal barrel.

No, which is why I said it’s been a proven performer, I assume it originated to the idea of making the S600 as light as possible, I don’t see anything short of the reg getting crushed causing any issue with the two parts coming out of lock up. With similar tuning, not to much fine line super hot but good tune the 260 may feel a little better but one thing it has that I like is the button lock seat saver which I like along with the Atomic and Zeagle F8 auto seat saver, it makes a difference when you have to many regs to dive them all regularly. Changing a seat and reliving either one is a 15 minute job with the alignment of the plastic cover lock being the hardest part.

The S600 uses a very thin very flexible diaphragm to make it respond better, a rubber cover with the hard outer cover is a little reminiscent of the 109.

 

[stuartv]

I dive in the Pacific Northwest where the water temperature can get into the low 40s. I am leaning towards a Scubapro MK17 Evo first stage, but I am suffering analysis paralysis on the second stages. I need to pick a primary (S600? G260??) and then something else which can be cheaper and less performant for a backup. Cost is not my first concern, but I also can't say price is no object.

If it matters, I do use a long hose setup with the backup under my chin, and I will take the setup to the tropics once in a while--no plans to maintain a second set of vacation gear. I'm used to the funny looks I got with my old Dive Rite cold water gear on cattle boats.

I dive air normally and nitrox on vacation. Typical recreational stuff, nothing exciting.

I guess I don't have to stick with Scubapro for everything, but after chatting with my tech it certainly sounds like a safe bet. Open to any ideas you may have.

1) You can buy the service kits for Dive Rite regs from Dive Gear Express. So, perhaps you could just order some service kits and then one of your local folks would do the service for you (with you giving them the regs and the kits)? Keep some spare kits on hand for emergencies, so you never have to worry about long down times?

2) For the diving you described, I would prefer the ScubaPro Mk 25 EVO over the Mk 17. SP says the Mk 25 EVO gives just as good cold-water performance as the Mk 17 EVO and I believe it. I prefer the Mk 25 because it has a bottom port. I like to route my long hose off that bottom port in a single tank setup. I like that better than having it stick straight out the side of the 1st stage and then have to bend down to go under my arm.

3) For SP 2nd stages, I have owned the G260 and the S620Ti. SP says the S620Ti is their lowest Work Of Breathing 2nd stage ever. Comparing them back to back, I and other people I know all agree that the G260 breathes just a little bit nicer. Bonus that the G260 is less expensive. The S620Ti is also a lot noisier breathing in the water. Personally, I would use a G260 as primary and a 2nd one as alternate. But, if you really want to save some bucks, I would go with an R195 for the octo. When tuned right, it still breathes extremely well.

4) I like my ScubaPro gear. But, I recently changed my single set to an Atomic Z2 and I would recommend it for your consideration for the same reasons I changed. It is less expensive than any of the ScubaPro options you are talking about (I believe). The 1st stage can be purchased as a sealed 1st stage (where the SP Mk 25 cannot be sealed). The Z2 has a bottom port, so it affords the same hose routing advantages (for a single tank config) as the Mk 25. The Z2 breathes just the same as every other Atomic, including the stupid-expensive T3. The Z2 only lacks a swivel turret (its turret is fixed) and the more expensive materials of the other Atomic regs. Presuming you can get Atomic serviced locally, I think it is an option well worth considering. An unsealed Z2 set (1st and 2nd together) is only $440 list price! I think the sealed version is $480 or $490.

 

[davehicks]

Hi Matt,

I'm a fellow Puget Sound / PNW diver out of Seattle and have been active diving here since 2001. I applaud your thoughtful approach to getting gear that is going to suit your needs. I think you are on the right track of getting a consistent set of regulators (or other equipment) that you can get serviced conveniently and locally. Probably the biggest mistakes that I have made were in buying a fairly random set of gear from multiple manufactures over time. With both myself and wife diving, I have a lot of gear that needs servicing and attention over time. Going with ScubaPro regs all around will make this a LOT easier as everyone will service it, no problems.

The voluminous and ongoing debates about with model of which reg are better for this or that are much less important. Pretty much any model of SP reg you get is going to be a winner in the PNW for year round use. The sealed vs unsealed arguments are just not that important for diving in this area. Buy some quality gear up front and maintaining it will give you the best results for years to come. If you want to see some real hard hitting arguments start asking about DrySuit and Undergarment brands!

Feel free to reach out if you want to meet more divers. I'm really active with the NWDiveClub.com and MarkerBouy clubs, both of which are great local communities to meet and join lots of planned or ad-hoc diving adventures.

Cheers,
dave

 

[halocline]

The S600 uses a very thin very flexible diaphragm to make it respond better, a rubber cover with the hard outer cover is a little reminiscent of the 109.

All SP 2nd stages use silicone diaphragms that are, to my knowledge, the same thickness and flexibility, going back decades. I guess you could find an extremely old 2nd stage with a thicker, less flexible diaphragm, but it's nothing to replace it with a current one. The old 109s are easily retrofitted with G250 diaphragms.

But, speaking of diaphragms, the larger 2nd stages (like the G250) have a bit more mechanical advantage over the smaller ones like the S600. I would be skeptical if it made any noticeable difference in breathing response. What does make a difference, to me anyhow, is the volume of air contained in the 2nd stage body. More ambient pressure air volume means that air moves a little more slowly through the body of the regulator, allowing the expanding air coming out of the valve to warm up a bit and maybe moisten up a little before it goes into your mouth. This is one of the reasons I like the old metal 2nd stages so much.

 

[lexvil]

Just a quick look inside the s600 ti core

The 600 diaphragm taller and more flexible, noticeable difference in resistance to folding them over.

Heading out for a few days, when I get back I want to try filling each 600, 250 and 260 water to see what difference in volume there may be, just for fun.

 

[halocline]

I'm not sure that just folding the diaphragms is an accurate indication of how much resistance they offer in use, there are just so many variables. Still, it's good to know. I like your idea of measuring volume, and I would suggest that you try to include the case volume as well if you can. I would be very curious to know the actual volume of air that sits in a G250 vs a S600.

 

[lexvil]

I'm not sure that just folding the diaphragms is an accurate indication of how much resistance they offer in use, there are just so many variables. Still, it's good to know. I like your idea of measuring volume, and I would suggest that you try to include the case volume as well if you can. I would be very curious to know the actual volume of air that sits in a G250 vs a S600.

Totally unscientific but I had the ti core 600 and g250 graphite sitting on my bench and as I’m heading out until Sunday I quickly filled the 600 with water, poured it into a container and filled the 250 with the same water, it hit just about the same point on the mouthpiece neck before the exhaust valve opened, to do it right I will need to block the exhaust valve (unless someone else would like do do this in the next few days) they seem to have the same volume for this quick test. The g260 is packed away so I can’t check it until next week.

 

[Matt S.]

Thanks for all the thoughtful replies, guys. This is a lot to think about... analysis paralysis!

@stuartv, great detailed post, thanks.

I guess I could get kits for the Dive Rites, but then I have to find a tech that is willing to do it that way... and if other parts were needed during service, then the hassles multiply. If I LOVED the regs it might be worth the effort, but while they have been reliable, it's not a love affair. In fact I always felt like they weren't the best breathers, though my exposure to other regs is very limited. I think the last time I used someone else's regs was... my OW pool session.

With regard to the MK25, it is a possibility, I am just gun-shy about an unsealed reg as I have only ever used a sealed diaphragm style. All I know for sure is that my DiveRite sealed first stage never gave me any trouble. As to the Atomic z2, I will take a closer look. I like that you can get a sealed version, but I also read that increases the maintenance costs substantially ($50 of Christolube to repack?) and so eliminates some benefit of the 2 year service interval. I'll see what my tech says about the maintenance issue.

@davehicks, I am already on NWDC, just haven't been active in forever. I am looking forward to doing club dives again, but we have to get our reg situation sorted out, and then do a lot of easy practice dives and drills!

 

[stuartv]

@Matt S. I don't know for sure, but I am skeptical that it adds $50 to the cost of the service. Definitely something to ask the tech you'd be taking it to.

 

[lexvil]

Still not scientific but I just checked an S600, G260 and G250 by holding them the exhaust valve flat at the highest point, filled the 600 first (unscientific because I haven’t and cylinders with precise graduations) and it took about 1/4 cup of water, I poured that water into a measuring cup and poured that water into the other two regs, one at a time and they all seem to hold exactly the same amount despite the larger external size of the G’s 250 and 260.