First thing diving should be fun and an escape from daily life.

Second you should be asking yourself is why you need doubles to begin with? What dives are you doing that you need that capacity? What dives are you doing that wouldn't be solved with a single back mount and a pony? Or just a single larger back mount; 100?  Are you pushing yourself or is your shop steering you?

I’m pushing myself. Want to do tech in a couple of years. Deeper wrecks and more bottom time. This is in prep for tech. I’ve got a 27 year long passion for Great Lakes wrecks that is behind all the diving I do.

For my deeper  wreck dives next year I will be going with HP100 and my 30cft pony.

I have a hard time reaching my bungees and basically bungeed the tank loops to one of my chest d-rings with smaller shock cord. It eliminates the "can't find them" and "can't get ahold of them" issues, but wouldn't solve the issue with placing them over the tank valves I don't think. Made a world of difference in the time it takes me to set up in the water, though.

I've been diving for over 45 years and in that time have had exactly zero situations where having doubles would have been a benefit, except for extreme deep diving to 200'+. The extreme deep diving was done with twins set-up as separate cylinders, complete with individual regs, for a truly redundant set-up; 1 tank was used for descent/ascent to the stage bottles, the other for the bottom.

Wreck penetrations with back-mount AL80 twins- for me- was an epic pain in my ass. I kept bumping into stuff with one or the other tank, but an old diving buddy used conjoined twin AL63's because he was an air hog and at the time, 100+ cu.ft. tanks were vaporware.

If I were to use a twin system again, it would be side-mount, even though I waddle like a ruptured duck using them and would have to get a whole new rig.

I too like the DR ring bungee system,

I want to do deco dives. So that means doubles or sidemount. Since I’m having such issues with sidemount, I’m giving doubles a try.

Decom dives are best done with staged bottles and regs, NOT with the air on your back (or sides as it may be). With the advent of high volume cylinders, twins are mostly unneeded.

Besides that, your narc depth is going to limit how deep you can go, so now if you want to do decom, you have to exceed your bottom time and again, twins aren't really needed there either.

With all that said, I encourage you to try it, but don't buy all the gear until you decide you like it.

The only things I needed to start doubles with are a manifold, different wing, and tank bands. My tanks already had left/right modular valves from SM. I’m being given a manifold and a wing. I’m getting used tank bands for $40. I just have to switch some hoses around on SM regs to make them work for doubles. I’ll take the SPG and hose off my single tank regs and try it on my doubles set.

So essentially I’ll only be into doubles for $40 (bands) and whatever my shop charges me to assemble everything. I’m not going to try it myself for the first time. I’ll have them show me.

Got wing and manifold today.

Doubles wing didn't hold air overnight, about 6 hours. Reinflated and put it in the bathtub to check for leaks. Lots of bubbles coming from power inflator head mouthpiece, plus from underneath elbow. Plus, it was used in salt water and metal around buttons on power inflator is green.

I can fix this easily myself. I'm ordering the parts from DGX. Less than $50.

My goal is to take AN/DP towards the end of the 2020 season. Add in helitrox as part of AN/DP or separately. Just want that bit of helium to take the edge of the dark narc you get in the colder, darker Great Lakes.

Here the standard kit is doubles plus a 40cft deco bottle. SM is used by a sizable minority. This is for dives up to 150ft or so. Divers here are generally not dropping stages, at least not that I know of. Maybe on much deeper dives? Not sure.

Anything deeper than 150' and you almost have to stage bottles because of the time you have to spend decom in water.

I realize that mixed gas reduces the amount of time, but you still have your individual breathing rate to deal with.

Back in the day when I was doing regular extreme deep diving (200+), we would spend up to 2 hours or more decompressing in water (we used Navy dive tables for air decompression).

We would carry rigs to the bottom (or wear twins, each single-rigged), change out in place, do our shell searching and change back to the descent rig to ascend to the first decom stop, which usually began at 70-90'. On some of the dives I made, we had a surface supply rig for decom that made life easy, as it was good down to 90'.

Twins with a 40 pony sounds like its gonna be heavy as hell. Good luck with it!

That’s why I’m working my arse off this winter. Recumbent bike at the gym every other day and weight/core work at home the other days. Found out my knees can tolerate dumbbell squats. Better for building leg strength. Did 12.5 miles on the bike in 50 min today. I was dripping sweat when I was done. Feels good.

It may be as simple as cleaning everything up and replacing a few O-rings and the exhaust valve seals. Unless of course you want to be super cautious then you can just replace the whole power inflator. I don't think those things run more than 15-20 bucks.

Just take Helitrox (or what ever it's equivalency is). It's basically the same as AN/DP except that you get to run a little Helium to take the edge off of narcosis. Otherwise you learn the same gas planning, deco, and in water skills as the AN/DP course. Plus if you're going to dive at a depth where you might incur a deco obligation but not necessarily a narcosis issue you can just run Nitrox.

I regret just taking AN/DP and not going Helitrox. There are a few systems that are a little on the deeper side that cutting my mix with a little Helium would certainly help with.

Don't get wrapped up with fancy deco planning software. Your Shearwater actually has a pretty good planning app that is more than acceptable for AN/DP level dives. It's what I basically use then I just write down the plan and my contingencies on my wet notes and go on about my dive.

I’m just going to replace power inflator head, elbow, nut, and OPV. Corrugated hose is still good. Wing is 10-12 years old and has been sitting unused for a while, so I’ll just go ahead and get everything replaced at once. Plus it puts me just over the amount to get free shipping.

ETA: the AN/DP instructors I’ve talked to make sure you can do the math and then use either software or dive computer. I’ve not yet played around with tech settings on my Perdix.

The math isn't that hard. I still do all the planning manually simply because I enjoy the process and I come away with a better understanding of what to expect on the dive.

Generally speaking there are two approaches to actually executing the dive. The first of which is to write down your plan, follow it, and use your bottom timer as a source of information for depth and time; your computer becomes a back up to the depth timer. You then follow what you've written in your wet-notes. You'll generally plan several time contingencies and maybe a depth contingency or two. You'll only resort to using your computer as a means to deco if you've blown all of your contingencies and you're then going to use that as your absolute measure of last resort.

The second option still involves you planning your dive, best gas selection, gas management, writing everything down, contingencies, etc.... However, instead of using a bottom timer as your primary and a computer as your back up you're simply going to use your computer since you now have two and one can serve as a back up in case of a failure. Now when it comes to planned decompression you just follow the computer.

Since I only have one computer I follow the first option.

I hate math. I am not a science person either. I managed to get through most of Deco for Divers last month. Very interesting and helpful.

I’ll definitely end up getting another Shearwater as a backup.

I have all the TDI course books and the math definitely looks intimidating. Hopefully it’s less so when explained.

@jerrwhy01

So just planning ahead... if AN/DP instructor allowed my HP80s (either SM or BM), I’m assuming the only other “big” purchase would be an AL40 and an O2 deco reg, correct?

Basically yes. You might need a DSMB and a reel/spool and some other doodads and a 2nd means of buoyancy but you've already got the covered with a dry suit. There is a case to be made for a 2nd AL40 and another deco reg filled with 50% Nitrox.

There are pretty much 2 standard deco mixes 50% and 100%. A 50% deco bottle would allow you to hit a 1.6 PPO2 at around 70 feet and allow you to start off gassing sooner. In all honesty though something like that can wait until you're more experienced and start doing more demanding dives.

Ideally tank selection comes down to the best tank that's required for the gas requirements for the dive. In reality you're going to do what the rest of us do and use what's lying around.

Personally I wouldn't go out and get a bunch of different size tanks so that you have a selection to choose from that best fits the dive. If you end up doing the occasional dive deeper than AN/DP level dives just rent what you need or add a stage. On the other hand if you find yourself doing a lot of dives deeper than AN/DP level dive it's probably time to invest in a rebreather.

I’ve got 4 HP80s (2 others are being sold to dive buddy). I was considering getting a pair of HP100 to use for single tank deeper dives (down to 130’) I’ll be doing next summer.  I can rent them from my shop but that adds up quickly.

I haven't been in this thread in a while. There has been some awful advice given but I'll just stay in my lane. haha You will need a AL40 or two for sure. Most companies "o2" regs breath pretty bad. They are cheap though but not recommended for use below 20'. For your beginning tech dives to 150' or less you can stick with 50% or 100%. You can get on the 50% quicker (ie 70' vs 20') but do your own planning and see what the dive calls for. On the longer and/or deeper dives you will want both of them. Its all about gas planning and management.

What do you guys think two full sets of 7.25" tank bands are worth?

Anywhere from $75-$100 from what I see in other postings online. Depends on if you include bolts.  New is around $140.

Wing parts should arrive tomorrow.

I sold both sets for $100 + shipping. No point in waiting for an extra few bucks when I had someone interested right away, especially when she offered to pay shipping costs. lol

Also found a guy wanting to trade me two PST LP80's for my Worthington X7-100's tomorrow afternoon, which is cool cause that will net me an extra 10 cubic feet of gas over the set of 100's when they're cave filled... and I can actually swim them up when they get down below 2000psi. I tried swimming the banded 100's up when I first got them with zero air in my wing and that wasn't happening. Hoping I can find someone that wants my Dive Rite can light and two batteries cause I don't see me using it anymore now that I have the LX20. If I get a different light it will probably be a Big Blue handheld 4800 lumen.

I'm really fighting the urge to build a minimalist sidemount harness for when I dive open water and maybe some light cavern diving or checking out holes in the ground, with a DECO company 22lb air bladder and mirrored AL80's. I've already got lead of varying weight to thread on to the spine strap, enough webbing for a crotch strap, and all the D-rings/slides I'd need. Only have to buy the remainder of the webbing, a wing/bladder, and the lumbar/thoracic plates to thread the webbing into.

Box from DGX arrived today at work from the post office ripped up and stuff missing. Went down to the shop tonight to take one pair of my HP80s to get doubled up. Manifold I was given doesn't fit my valves. Threading is different. Shop had one that fit and gave me a good deal on it. I'm selling the one I was given.

Got the parts I needed from the shop. I was going to switch them out myself, but the one guy came out of the back with my wing and everything replaced! Turns out it didn't need a new elbow. It just needed to be tightened just so (I hadn't touched it when I first got it).

Going to redo my regs this weekend.

I've got one of those. They're pretty sweet for a minimalist/travel rig. I ended up dumping the bladder and replacing it with an Xdeep bladder for use with LP-50's.

I finally ordered the wing and plates on Tuesday night. The rest of the stuff I needed I got from Dive Gear Express when I was down in Deerfield Beach yesterday.

Now the waiting game for how long OxyCheq will take to ship it... since it’s coming from Marianna, I assume it will be here in two days with Priority.

It's a nice basic rig no frills rig. Hopefully it'll serve you well. Let me know how it works out for you when you get it set up.

I will, if they ever ship it out. LOL

I ordered it Tuesday night, page still shows processing and my card hasn't been charged. I was hoping it would ship within the 24-48 hour time frame they quote for "most orders" on their site.

OxyCheq is in Marianna, though, so I'm wondering if they might have had some storm damage.

Just dropped my SM regs off to get 5th port installed.

Swivel?

And I sent DECO an email to cancel my order because I just sent a guy in Jax $475 for:

- XDeep Stealth 2.0 Tec system
- XDeep large expandable pouch
- SumpUK sliding d-rings (2)
- Trilobyte line cutters (2)
- XDeep large 4 pocket spine weight system

Couldn't pass that up lol. It was purchased in April, set up by Joseph Seda, and only used a few times.

No, 5th port comes out of the bottom of the first stage. Makes for nicer hose routing. My SM regs are Apex XTX50 and there is a kit for it if regs didn’t come with it.

Good deal you got there!

Thanks! I've posted my Nomad XT dual bladder for sale on CaveDiverForum, ScubaBoard, and a few other places, hopefully I can get it sold pretty quickly to make up for what I spent on that.

If not, my buddy wants the wing for sure and I'll just sell the rest of it as a TransPac.

I'm thinking about selling my SM rig. I really doubt I'm going to go back to it. Thinking about selling my 5mm wetsuit, too. The 7mm would work if something happened to my drysuit and the 3mm is good for pool work in the winter

I hate having too much stuff!

I don't recall if you've done any backmount doubles diving yet, but I'd hold off on selling anything until you're 100% sure you can make doubles work for you.

Personally I'm going the other direction and selling off all of my backmount stuff (entirely, even the single tank setups are gone now) because the simplicity and ease of packing sidemount gear is too much to be ignored. If I was going to the Keys to do shallow single-tank (or even double tank) reef diving with AL80s, I can pack a small wing and a webbing harness and be done. Cave diving, the Stealth will work just fine although without a drysuit I'd like some sort of redundant wing. Guaranteed I could pack my whole dive setup in a backpack at this point and carry the tanks in my hands at this point if I was rec diving.

If I ever get to a point with tech diving where I need back mounted tanks because I've run out of space for stages/deco bottles in a sidemount configuration, I'm betting it will be YEARS in the future and I'll be able to better afford backmount stuff in addition to my current gear.

I had several people tell me SM wasn’t ideal for boat diving, but I had to experience it myself. Now that I’ve discovered I can do dumbbell squats without my knees hurting, I’m all in for a twinset. I’m working my ass off to be able to handle the weight for when the season opens here in April.

I love my BP. Easy on/easy off. I know where everything is. One BP and I can just switch wings for single tank or doubles. I love simple. SM was just too freaking complicated and my frustration was through the roof. F’ing bungees. I’ve not tried doubles yet, but I’m done with SM.

Just posted SM rig for sale on SB and two FB sale groups. When I get my new yellow transmitter back from Shearwater after the recall, I’ll sell that, too.

If it works for you, it works for you! I'm sure you'll be able to handle the weight of the system if you're exercising the problem joints/limbs and getting them more physically fit. I know I have way less soreness in my back trying to stay in trim after I started squatting 200+ pounds three days a week. My core strength is way better than it used to be and it's translated well to a lot of areas in "real life" outside of the gym.

I've found with sidemount that it greatly depends who is instructing you and how much they know regarding the various SM systems, the intended style of diving of the end user, their experience with actually diving sidemount frequently with that system or in that environment, so on and so forth. I got lucky and have 3-4 people I can bounce ideas off of, and it's changed my way of thinking about diving and equipment setup. Kind of ironically, the guy that first got me into cave diving now is coming to ME for ideas on trim/rigging rather than the other way around.

My cave instructor sized me up with a Nomad, got me the correct setup and had me in the water and trimmed out perfectly in less than 30 minutes from the time we pulled into the parking lot at Ginnie. A friend of mine (who has taken sidemount cave instruction from another guy in a different part of the state, as well as done the Steve Martin sidemount courses online and had prior experience tech diving for a few years of his own) made a few minor suggestions that made the don/doff process for gearing up and putting the bottles on effortless compared to always needing help from a bystander to reach my bungees and stuff. A mutual buddy with some of the same experience showed me a few ways that I'd never seen or thought of to switch regulators one-handed, mount canister lights, secure wings better so they don't beach ball or become uncomfortable and hold air unevenly, etc.

Point being, all of that made me more comfortable and capable in that system and it works best for me because of the environment I'm diving in and my physical build. If backmount works better for you, I won't be one of the ones trying to convince you to avoid it, I just remember you posting a lot about your lower body strength/ability in the early parts of this thread.

My SM instructor dives the same rig. My extreme frustration has everything to do with the complete fuckety-fuck gearing up is. I love simple. SM is not simple for me. It makes me want to bang my head against a wall. Fuck that. Fuck the bungees. I’m done.

I’ve discovered I can do dumbbell squats without hurting my knees. I’ve been doing them for a few weeks and my knees already feel better and I’m already stronger. Things like climbing stairs are easier. I’m working my ass off to get it into shape.

Posted an unused pair of fins on a FB sale group. Sold those for $90 (includes shipping). Posted my 5mm wetsuit as I’m no longer using it. Still have 3mm and 7mm

Shearwater has a recall on the yellow transmitters. I’ll get a new one sometime in January. I’ll then sell that one, too. Won’t need it with giving up SM.

Selling two of my HP80s (the galvanized ones I bought used) to regular dive buddy for $185 each later in the winter. These were the two I liked least. He had borrowed them for a dive and loved them, actually asked to buy them from me.

It’s nice clearing out the extra bits.

Amen. Between gun stuff and dive gear I've made something like $1100 in the last month selling extra random stuff I don't use.

Downside: I only have like $50 of it left.... thanks a lot groceries and bills.

I’m putting it in the savings account I call the “scuba fund.” I’ve got my SM regs at shop getting 5th port installed and annual inspection/service. That will run a bit over $200. So that will come from scuba fund. Also tanks getting VIP and doubled up.

I really want to switch to regs that I can buy service kits for and have a shop/tech teach me how to do them myself.

F U, ScubaPro... I have two of their first stages, and four of their second stages. That bill will suck

I have no desire to learn how to service my own regs. Mine are AL and Apeks.

You will when you have a failure when you're on the boat with no backup. You may not want to learn to do a full service but you should know how it works and how to fix simple failures.

Sell them and pick up some Deep6 regs. You can probably sell your SP's and be into the Deep6 for almost nothing.

I only do, because I don't want a simple failure to cause me to miss a day of diving when I have to travel 2-3 hours away to do any cave dives (and I'm not going into the overhead with malfunctioning equipment without fixing it).

Plus I'm getting to the point in life where I want to do preventative maintenance every 6-12 months depending on amount of diving vs. waiting for something to break or paying to service them.

And the Deep Six regs are smaller than my MK25's lol

I've been doing my own equipment work since 1983 when I went to a Sherwood repair tech class.

Regulators and tank valves aren't intricate pieces of equipment that require a delicate touch. If you can unscrew the lid off a ketchup bottle, you can do most field repairs on a regulator or valve and having a spare parts kit for your gear is just good planning.

A flow bench or intermediate pressure gauge is really handy, but for doing work on my own gear, I go by what feels and breathes right for me.