Do I NEED an adjustable 2nd stage for 95 ft diving?

[AfterDark]

The easiest breathing regulator ever made the Scubapro pilot was non-adjustable. The Navy tested it at well over 100fsw and found no difference, it was just too complicated and expensive as well as a little temperamental. So no but, as someone mentioned you may want to get yours serviced and ask the tech to max out the IP adjustment.

 

[DivemasterDennis]

No NEED for an adjustable reg, but I sure like mine. Aqualung legend.
DivemasterDennis

 

[EdTeach]

I have found an adjustable 2nd stage useful in two circumstances, 1) when on or near the surface or 2) when swimming into a current. Logically, the same could be inferred for scooter diving. The control is used to de-tune the regulator and prevent free flow. If you expect strong currents on the ledges, an adjustable 2nd stage could be useful.

The Scubapro Pilot, along with all the other Scubapro vertical demand valve designs, actually does have a provision for adjustment of the cracking effort in the form of a Dive / Pre Dive switch. The switch actuates a lever which impinges on the diaphragm. I have only used the Pre-Dive setting on my Pilots, Air 1's and D-Series regulators on the surface or in shallow water to prevent free flow.

Honestly, they breathe so easily that it is easy to forget to put them into dive mode. I have only encountered one occasion when I used cracking effort control in a current, and that was with a Scubapro 109. I was glad to have the capability. BTW, the Navy tested the Pilots to 1800 FSW and gave Scubapro a plaque that still hangs in their corporate headquarter, I believe.

 

[John C. Ratliff]

My easiest-breathing regulator is a Scubapro A.I.R. I, which has the "Dive/Pre-Dive" switch. However, this is not an adjustmentable second stage. Those were developed in response to complaints that the regulator would free-flow in a current; especially in caves this was a problem. Because of the location of the demand diaphragm behind the regulator on the Scubapro A.I.R. I, Pilot and two other regulators, those don't respond to current in the same way as regulators (Scubapro 109 and others) with the diaphragm pointed into the current. Hence the Adjustable second stage. This has nothing to do with performance at depth (although any use will increase inhalation resistance), but de-sensitizes the demand valve for diving in a current.

SeaRat

PS--AfterDark, that was 1,000 feet that the U.S. Navy tested the Scubapro Pilot to, not 100 feet of sea water.

 

[Garth]

I enjoy a counterlung as opposed to a regulator. The moist air and silence is IMO way better...


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[EdTeach]

I agree with John C. Ratliff's observation that the Scubapro vertical demand valve regulators are nearly impervious to the effects of current because of the reversed diaphragm design. The regulator case shields the diaphragm from the front and the diver's body shields it from behind. The Pilot and Air 1 can be vulnerable from the side.

Since the diaphragm serves as the exhaust valve on the Pilot and Air 1, it must be allowed to unseat when exhaling. Strong side currents can also unseat it, causing damp breaths. I've experienced this a couple of times. The D-Series are not vulnerable in this respect, since the exhaust valve is centered on the diaphragm and is well-shielded.

I gladly trade this minor inconvenience of the Pilot and Air 1 for their superior ease of breathing. If there is an easier breathing 2nd stage than the Pilot, I would love to try it. The Air 1 is a close second and the D-Series regulators aren't far behind.

I do consider the Dive / Pre-Dive switch on these regulators to be an adjustment. They certainly increase cracking effort. That is what they are designed to do. The only reason I can see for doing this is to prevent free flow.

I'm possibly missing the point about performance at depth because my references are the Pilot / Air 1 / D-Series. They are all known to be superior regulators at depth. Why would anyone adjust their regulator to breathe harder, other than to prevent free flow?

 

[John C. Ratliff]

EdTeach,

Thanks for your comments above. I've really enjoyed my AIR I, and have picked up a second AIR I second stage. Concerning the wet breathing, this happens when in an inverted position, and it can be annoying. The reason, I think, is that the diaphragm/exhaust valve (both the some) is held on at the bottom of the regulator. Most of the sealing surface that is potentially vulnerable to currents for the diaphragm are high up, and really away from the opening. I have had this regulator in high river currents without it affecting the exhaust at all. Because the diaphragm is held at the bottom, though, there is a few drops of water that are hard to expell totally from the regulator, and they manifest themselves when the diver is inverted (head down) and the water flows into the LP chamber, where it is pushed into the diver's mouth/throat on the next inhalation. These can be expelled by a sideways exhalation, but they will reappear because of breath condensation, if nothing else. So in the inverted position, it breaths wet. But it also breaths so easily, and smoothly!

The Dive/Predive switch does add about an inch of inhalation resistance, but my feeling is that this is mainly for snorkeling with the regulator out of the mouth, and it does prevent free flows. It can also be used as a safe second, with this switch in the Predive position, and it will not free flow.

Finally, the Pilot and the AIR I are the only regulators that I know of that accept two LP lines, one on each side. This maximized the pool of LP air at the regulator for really deep or strenuous dives. It can also be used as a safety feature by providing for independent doubles which are hooked into a single second stage. The photos show a setup I made using the AIR I with Scubapro and Dacor Oylmpic first stages feeding it.

SeaRat

 

[EdTeach]

I will have to try the dual first stage set up some day, John. You and I are of the same mind on the Air 1. It is a superior regulator. That's why I have a lifetime supply! I lucked into the Pilots, but I will never part with my Air 1's.

 

[DownDiver]

Agree with DivemasterDennis, not needed but my wife and I dive AL Legends and love them; exceptionally decent breathing at rec depths.

 

[Steve_C]

Have dove the meg ledges. My advice is avoid exertion. Take your time. Move slowly. Dig slowly. You are at 100 ft and have all the air consumption/CO2 issues that come with exertion. Check your air frequently, it is easy to catch "tooth fever" and not pay attention. Dive a larger tank if you are used to AL80s. Most divers on the ledges have 100s or larger. I dive HP 100s at 30% with pony back up. I am NDL limited and not air limited.

Many teeth are found close to where the anchor is. You descend along the anchor line. So you are starting at the bottom. Your will stay within a couple feet of the bottom most of the time If there is current go slowly into it along the bottom and work your way back. You want to return up the anchor line unless in an emergency situation. The reels are good for finding your way back once the bottom is stirred up a bit and you are slightly narced.