Best first regulator, DIY service

[buddhasummer]

I'll disagree with @buddhasummer on the second HP port requirement for AI. If you are doing recreational diving especially, and are doing it with a quality computer, i.e. Perdix AI, then I see 0 reason to have redundant pressure monitoring. Even in a cave, I wouldn't bother with it unless the dive was 100% critical to complete. If the transmitter fails, the dive gets turned. Once turned, you either have enough to get out or you don't, SPG's don't matter after you've called the dive. In OW, if the SPG fails, depending on how good you are, you can either ballpark it and continue the time to your planned time limit *which should have been set based on a combination of gas limits and NDL's, basically whichever comes first*, and should have an adequate buffer. Keep a SPG on the boat in your save a dive kit to swap out at the surface, but no need to bring it on every dive

I don't disagree, I actually dive this way unless travel diving. I was trying to keep it simple. Thabks for adding the additional info.

 

[tbone1004]

I don't disagree, I actually dive this way unless travel diving. I was trying to keep it simple. Thabks for adding the additional info.

even travel diving, after 100 or so dives, you should have a really good grasp on your SAC rate and have the ability to look at your SPG and know within about 200psi where it's going to be.

If I'm planning an easy NDL reef dive, call it 66ft/20m/3ata for easy math, and I'm diving a standard 11l/al80. I know my rock bottom pressure is 1000psi, and I have 2000psi to play with.
Call my sac rate .66 for easy math, so I know I'll be consuming 2cfm at the bottom. Easy math again assuming my max depth is my average depth.
My NDL per NAUI is 45 minutes.
I took a 26cf out of my tank, and have 52cf left to use. I know that I'm pulling 2cfm, so my planned bottom time is 26 minutes.
I know that I planned conservatively because I used rock bottom with a psi buffer, I am calling my max depth my average depth, and I will round my SAC rate up to the nearest tenth for a bit of extra buffer. If I'm diving with wireless AI, as long as my computer and or watch is still functioning, if my SPG fails at 5 minutes into the dive, I'm going to continue the dive until I hit the time limit and call it a day. Assuming nothing goes wrong with my buddies air supply, I should get back on the boat with somewhere around 1500psi in the tank. If I can't get the AI to work at the surface, then I'll take 2 minutes and swap it for an analog SPG and continue on with my day.

Literally 0 need for redundant pressure gauges in recreational diving as long as your dive planning is at least relatively solid.

 

[buddhasummer]

If I'm liveaboard travel diving, in expensive unknown waters in unknown conditions with unknown "buddies"and unknown guides I feel more comfortable having an SPG. I'm new to AI and have only 18 dives on mine. I had a DS4, which I know can be routed upside down, but I asked SW if having transmitter on left with computer on the right would cause issues, they replied saying they did not recommend this configuration. I did it anyway using a 6" hose, no signal issue at all. I've never in almost 20 years of diving had an SPG fail on me. I'm still learning to trust AI. You are a very experienced and knowledgeable diver, most are not, the OP has 15 dives. At my local dive site which I know better than the back of my hand I've been diving sans SPG, so far so good.

 

[tbone1004]

If I'm liveaboard travel diving, in expensive unknown waters in unknown conditions with unknown "buddies"and unknown guides I feel more comfortable having an SPG. I'm new to AI and have only 18 dives on mine. I had a DS4, which I know can be routed upside down, but I asked SW if having transmitter on left with computer on the right would cause issues, they replied saying they did not recommend this configuration. I did it anyway using a 6" hose, no signal issue at all. I've never in almost 20 years of diving had an SPG fail on me. I'm still learning to trust AI. You are a very experienced and knowledgeable diver, most are not, the OP has 15 dives. At my local dive site which I know better than the back of my hand I've been diving sans SPG, so far so good.

I have essentially no experience with AI though outside of a working knowledge of the technology. I'd personally run a DS4 upside-down in that scenario, though ironically if given the choice, I would run it upside-down anyway since it will have less of a chance to whack your head. I wouldn't put the transmitter on a short hose either unless you had "valet" service for your gear. I really don't like other people touching my gear, so I'd just try to avoid that to begin with, but that's just me.

Even at 15 logged dives though, you can set limits that mitigate the need for a backup SPG. Set the limit of, if it fails, and doesn't reconnect after say 3 minutes, then call the dive. Set two time limits, one based on a conservative sac rate and max depth=average depth, like the example above, and then have another one which is a pressure based limit.

In that scenario as an instructor going over dive planning with a student with AI, I'd do the following.
We require our students to calculate SAC rate for every dive during training and encourage them to do it on every dive thereafter. I tend to be a bit lazy about it because it is quite complicated when dealing with gas switching and decompression, but I do enough OW dives every year to keep track of it.
When setting the limits for that same 66ft dive, using NAUI tables with a 45min NDL because it's the first dive of the trip, we will go through the following.
Limits that you need are depth, time, and pressure.
Depth limit is 66ft, because that's your limit.

Time:
NDL=45 minutes, so you are limited by NDL to 45 minutes for this dive.
Gas:
Diving an AL80, at 66ft, and you recorded your SAC rate at 0.66cfm. Assuming that you stay at 66ft the whole time because it is a true square profile dive, you will be consuming 2cfm at depth. We know that your tank is 77.4cf, but we also know that regulators really need a 200psi buffer to function properly and 5 minute safety stop is what I like to plan for. 66+1.5+5=5cf=> 200psi+200psi for the regulators=>10cf. This gives us 67cf to use, divided by 2cfm yields your real time limit of 33 minutes. That gets you back on the boat with somewhere around 300-500psi give or take.
Gas trumps NDL in this case, so your time limit is 33 minutes.

Pressure: This is what normally turns most peoples first dives, and is a proper limit that can't be violated.
I believe in rock bottom calculations, and doing it with "Excited" sac rates, I'm not entirely a fan of the way that rock bottom is normally calculated. I do 3 minutes of conflict resolution at depth, 1cfm sac rates, and a 3 minute safety stop at 15 ft. 2cfm*3ata*3 minute=18cf for conflict resolution, 2cfm*1.5ata*3=9cf for safety stop, and I typically will leave the ascent blank because there is buffers built in there. 27cfm total=1050psi, plus 200psi for the regulator, and they have an ascent pressure of 1300psi. For al80's, my "rule" is 400psi/ata for down and dirty math. It's easy, and prevents having to calculate anything. That's my rule, and students have to calculate it.

Time round 2: If using AI especially, you have to estimate a time turnaround based on safety if you want to continue your dive in the event of failed pressure gauge.
We know that we are allowed to use 1700psi out of this AL80 based on the pressure limits above, and that 1700psi=44cf. From our previous SAC calculations, we can estimate that we will use 2cfm when at depth, and it should take us roughly 22 minutes to consume that amount of gas. We know that there is a real time limit of 33 minutes based on full gas consumption. To give us a bit of a buffer for safety, if we have an AI failure, as long as your bottom timer/computer/watch/buddy is functioning properly, then you have a contingency time limit of 20 minutes. No reason to stop the dive early so long as your watch works.


Aside from the AI bit, this is the type of planning that we teach at the basic open water level and is not beyond the abilities of someone with 15 dives. The difference is that at that level of their diving career, the limits are going to be exceptionally conservative because they haven't had enough time to really get a handle on their SAC rates and know what they are going to stabilize to. You are also adding a lot of conservatism by assuming your average depth=your max depth, but until you have the experience to know to change that, you have to use the conservative numbers.

If I am diving in a new cave for the first time, I use the max depth as my average depth for my time and decompression limits. One of my recent dives in Jackson Blue was 200 minutes with an average depth of 65 ft, but the max is 96. That's including deco, so for gas planning it's really an average of about 80ft. If I'm not familiar with that cave to know what the average depths are going to be, I have to assume it's flat at the bottom and stays that way forever. That means I'm probably planning a very long time with a lot of extra deco gas, as well as cutting myself short on the penetration limit that I set.
If I plan that dive, the planner says I have 51 minutes of planned deco. In reality, I had 39 minutes when I got to the bottom of the chimney. That means we planned well, had extra gas with us, and on the next time, we can either chose to adjust the gas plan to be a bit more accurate, or we can continue to plan a bit on the conservative side and have less to worry about on the way out.

I'm a lot more cavalier with my gas planning in OW, but the surface is accessible which makes all the difference in the world to me

 

[buddhasummer]

You know your stuff, respect. For me my main reason is not wanting to have to cancel any dives I've paid big money for and a lot of effort to do. After a year of AI diving I'll evaluate my position. Cheers.

 

[tbone1004]

You know your stuff, respect.

I try, and I apologize for the narrative, but it is a bit of a pet peeve of mine when I hear experienced divers and even instructors say that "oh they only have a dozen dives, they can't properly plan". The planning bit isn't rocket science as long as you are OK with marking with a can of spray paint and cutting with an axe. Too many divers, especially technical divers try to plan with a micrometer and cut with an exacto, but for things like dive planning, you can only work with rough numbers and orders of magnitude and get "close enough". No, you are not going to maximize your dive time by planning like that, but by God no one ever died from having too much gas.

 

[Polomelo]

Your knowledge is impressive and I am grateful for your willingness to share it with new divers like me, even though I feel a bit lost at this point. If you don't mind answering them, I still have a few questions:

A jacket is mostly "plug and play". Is a BP/W very easy to set up (harness, D-rings, etc.) ? How about getting used to it underwater ? I've never tried a back-inflate system. I assume that you almost feel naked in comparison with standard jackets.

What is the average lifespan of a quality reg that is rinsed and maintained properly ?

What is your criteria when choosing an SPG ? Where should it be attached on the harness ?

Most dive shops sell yellow octo regs that seem to be inferior second stages. Is it a problem to have the exact same black second stage as an octopus ? Where do you attach your octopus ? My instructors are mostly "octo donors" but I don't feel comfortable with it as I feel it's not how things usually happen in emergency situations.

 

[KeithG]

Average lifespan of a quality regulator that is taken care of?

It will most likely out live you.

Our ordinary sherwood regs are approaching 30 years old. No issues. All salt water dives except for our cert dives.

 

[tbone1004]

@Polomelo feel free to send any questions on the planning in private message, i have 0 problems helping you through that.

bp/w is very easy to set up. Adjusting is a bit more complicated to get perfect, but it's fairly simple if you have a second person to basically hold the backplate against your back. Plenty of videos and how-to's on line.
Getting used to it in the water is basically non-existent. No getting used to to happen, it just is.
You do feel almost naked compared to standard jackets, it's immensely liberating

lifespan of the backplates is longer than you will be alive. Exceptions to this are aluminum plates used with doubles. The bolt holes get rounded out over time, but that's still like 15-20 years of normal use. Kydex plates can wear over time if you abuse them, particularly with UV, but I would expect nothing less than several decades there. Soft backplates are probably 15-30 years depending on conditions. Lots of UV and Chlorine will kill them in 10-15 years, but still a long time.

Regulators will last as long as the plastic is maintained. I have some metal regulators from the 50's/60's that are just peachy, and I have some plastic bodied Poseidon Jetstreams that are from the early 80's with no issues at all. UV and chlorine is the biggest killer of plastic, so keep them out of the sun and the pool if at all possible

For backmount, it's brass and glass, in whatever size you want. Most all are made by the same company in Italy called Termo, so I go for whatever is cheap/comes with used regulators that I buy. As far as attachment, it should have a bolt snap tied to it and depending on what you like, it will be left hip *DIR/GUE*, left shoulder *one of my preferences*, or tied along the corrugated hose. Left shoulder is probably the easiest of the lot. If using a console, it should cross clip to your right shoulder, but if you have a computer, a console is unnecessary.

I prefer matching second stages. On single hose open circuit I will not under any circumstances dive a secondary donate or secondary take regulator configuration *on CCR or double hose it's a bit different since you can't donate the loop*. It is a ridiculous regulator configuration, not streamlined by any stretch of imagination, and not safe IMHO. Primary second stage goes on either a 36" hose, a 40" hose with an elbow/swivel, or a 7' hose for me. Secondary second stage/octo is on a 22" hose and bungeed around my neck.

 

[KeithG]

Yellow is the new orange?

Way back when we bought the rage was to have an orange face plate on your octo. Then someone (in sales & marketing) decided that yellow was the best colour.

I prefer my octo to be the same as my primary reg. I do not care about the color. I have never had anyone complain about my 2 black second stages on black hoses.