Cold water: Does 2.stage matter?

[ams511]

Scubapro has two really good cold water second stages: G260 and A700. Apex second stages hold up quite well in cold water. Poseidon's X-Stream is also a very good for cold water reg. I list these based off of first hand experience or at least diving next to someone with one of regs. I view cold water as anything in the 30's (although I am beginning to feel like anything in mid to low 40s is cold); for ex. winter in mountain valley lakes and diving underneath the ice. Not sure if I agree with the term "extreme cold", unless it is in the high 20's, as in Antarctica.

From what I remember Scubapro had a second stage called the Polar, I am not sure what first stage it was paired to but that was its cold-water regulator. It was later renamed the M-5 or M-50 because divers think you cannot use cold water regulators for warm water. Then it was cancelled. Actually I thought the C series was supposed to be Scubapro's cold water regulators but they seemed to back away from it.

At some point I may add some Poseidon regulators to my collection. I need to learn a bit more about them though.

I agree with you about the definition of cold water. It needs to be more defined.

 

[ams511]

Have to wonder how much difference it actually makes whether the jam nut is plastic or metal.

It could make a lot of difference. I remember reading an article on Antarctic diving. At the time they were using older Sherwood Maximus regulators modified by adding/replacing some parts from the Blizzard regulator and lowering the IP.

Either in that article or another one they talked about when manufacturers update designs the cold water performance could be different even if the internals are the same. At the time the article was written manufacturers were moving to compact second stages that were judged not at cold tolerant. The main punchline of the article was that if an old regular was good, the new and improved model cannot just be substituted. It needs to be thoroughly tested first.

 

[ams511]

From: The United States Navy Experimental Diving Unit: Testing in Antartica

At its inception in 1947 (through the US Naval Support Force Antarctica) through 1967 the USAP diving program issued double-hose regulators to NSF scientific divers. In 1991, double-hose regulators were retired from service and replaced with single-hose, modified Sherwood Maximus SRB3600 regulators. A heat retention plate was fitted over the second-stage exhaust valve and around the air delivery lever and the intermediate pressure detuned from 145 to 125 psi to reduce the probability of free-flow in supercooled sea water at -1.86oC in McMurdo Sound. The decision to investigate replacement regulators was influenced by the age of the 1991 Sherwood models, their less than optimal breathing characteristics, and the lack of continued parts availability in 2008 to avoid potentially catastrophic regulator failure

All the Poseidon regulators and the one Sherwood regulator had a combined free flow incidence of 5%, whereas the others had a combined incidence of 44%. Two of the worst regulators reached an alarming 50% failure rate after only 6 dives each.

 

[JackD342]

I am not all that familiar with the Mares line but I thought the Navy was their top-of-the-line model. Also what is the difference between the Navy II and the Abyss 22?

I would not call it top of the line any more now that the Abyss and the MR22 have been replaced in their line by other newer designs. Navy II is very much the same as the Abyss 22. 1st stage adds an oil filled environmental seal, and the 2nd stage has special (Teflon like) black coating to resist formation of ice crystals. Even the locknut in the service kit has the special coating. It also uses older versions of seats in both stages, as that is what the Navy tested and can’t be changed until/unless they retest.

 

[texspeleo]

From: The United States Navy Experimental Diving Unit: Testing in Antartica

At its inception in 1947 (through the US Naval Support Force Antarctica) through 1967 the USAP diving program issued double-hose regulators to NSF scientific divers. In 1991, double-hose regulators were retired from service and replaced with single-hose, modified Sherwood Maximus SRB3600 regulators. A heat retention plate was fitted over the second-stage exhaust valve and around the air delivery lever and the intermediate pressure detuned from 145 to 125 psi to reduce the probability of free-flow in supercooled sea water at -1.86oC in McMurdo Sound. The decision to investigate replacement regulators was influenced by the age of the 1991 Sherwood models, their less than optimal breathing characteristics, and the lack of continued parts availability in 2008 to avoid potentially catastrophic regulator failure

All the Poseidon regulators and the one Sherwood regulator had a combined free flow incidence of 5%, whereas the others had a combined incidence of 44%. Two of the worst regulators reached an alarming 50% failure rate after only 6 dives each.

I really hope that I can recall my details correctly with this...

I had an extended email conversation back in the early 2000s with a fellow at McMurdo that was the chief diving scientist (I don’t recall the exact job title, but something along those lines), and he provided that very same information to me. I think his name was very close to Brugeman, he was wonderfully generous with information, and helped me build the cold water regs for the fire department’s rescue/recovery team that I worked for in Colorado. I still dive my modified SRB3600s here in northern Montana, and to date haven’t used an equal in very cold water.

 

[ams511]

I really hope that I can recall my details correctly with this...

I had an extended email conversation back in the early 2000s with a fellow at McMurdo that was the chief diving scientist (I don’t recall the exact job title, but something along those lines), and he provided that very same information to me. I think his name was very close to Brugeman, he was wonderfully generous with information, and helped me build the cold water regs for the fire department’s rescue/recovery team that I worked for in Colorado. I still dive my modified SRB3600s here in northern Montana, and to date haven’t used an equal in very cold water.

They are using newer Sherwoods now in Antarctica. There are other articles available about the regulator testing and modifications made. I an not sure why they just didn't use a Blizzard rather than modifying the Maximus unless they wanted to be able to tune down the regulator.

 

[shurite7]

They are using newer Sherwoods now in Antarctica. There are other articles available about the regulator testing and modifications made. I an not sure why they just didn't use a Blizzard rather than modifying the Maximus unless they wanted to be able to tune down the regulator.

A couple of years ago a group from my uni went down there. The conversation I had with the DSO there was informative and insightful for the training of our group. What I did learn was they want to be able to use the reg right out of the box, unmodified. I thought this a bit odd, but didn't push the issue. The station is picky in the sense they would not let anyone use any other reg other than ones they supply. This doesn't mean other regs were suitable, they just didn't want to deal with any possible issues. I can't blame them.

They remind me of the military (ex-navy) - find something that works and stick to it, even if there is something newer and better performing, until it no longer works or no parts available, then up grade.

here in northern Montana, and to date haven’t used an equal in very cold water.

Where in MT are you?

 

[ams511]

They remind me of the military (ex-navy) - find something that works and stick to it, even if there is something newer and better performing, until it no longer works or no parts available, then up grade.

For some reason I want to dive in Antarctica. Don't ask me why, I hate the cold.There were older articles which mentioned that when regulators are updated the newer ones may not perform as well in the cold as the older ones for a variety of reasons. I don't know what is so magical about the Maximus, that it is so freeze resistant. I suspect it may be due to the sealed piston design and the low flow rate of the first stage. I have a couple in my collection.

The best cold water regulator they tested is the Poseidon X-Stream, supposedly there were no free flows recorded.

 

[texspeleo]

They are using newer Sherwoods now in Antarctica. There are other articles available about the regulator testing and modifications made. I an not sure why they just didn't use a Blizzard rather than modifying the Maximus unless they wanted to be able to tune down the regulator.

Precisely. The SRB3600 first has a wide ISP and can be dropped down to 120-125 psi. The heat sink mod to the second stages involved a simple part swap. Otherwise, a great number of the part numbers seem to be common between the service manuals (again, only for the seconds). I’ve used he same 1st stages to drive my Jetstream seconds in a few configurations with great success, with he addition of an OPV on the hose.

 

[texspeleo]

A couple of years ago a group from my uni went down there. The conversation I had with the DSO there was informative and insightful for the training of our group. What I did learn was they want to be able to use the reg right out of the box, unmodified. I thought this a bit odd, but didn't push the issue. The station is picky in the sense they would not let anyone use any other reg other than ones they supply. This doesn't mean other regs were suitable, they just didn't want to deal with any possible issues. I can't blame them.

They remind me of the military (ex-navy) - find something that works and stick to it, even if there is something newer and better performing, until it no longer works or no parts available, then up grade.



Where in MT are you?

C-Falls