"Sidemounting With Benefits" - Lessons from a newbie Sidemount Diver

[Cdncoldwater]

Unfortunately, some (all?) of the gas compressibility math isn’t covered in any TDI/IANTD/SSI/Paditec tech instructor manuals that I know of domestically. It’s much more a problem with high helium mixes or once you push past 200ish bar.

Very likely and I'm definitely not any type of authority, I'm just a rec diver with PADI and SDI. I'm surprised that the instructor manuals in those International dive organizations aren't the same at least within the specific organization such as TDI for example. I don't consider PADI tec at the same level as TDI or IANTD. Fortunately the instructor I have has a lot experience in this area. We talked a bit about z-factor and actual capacities the other day after looking at your points and my take away was at the rec level it is less critical vs tec with deco obligations, team air responsibilities (OOA, equipment failure etc). I was surprised that the tanks I'm discussing are stamped 2400 PSI but the literature lists working pressure with the + 10% to get "50". Very good information for me and I am adjusting my spreadsheet regarding cf and psi. Subconsciously I was already using a basic form of the z-factor as I do a "surface plan" but check for the psi (capacity) change once my tanks have been in the water to get my true capacity for that dive and adjust my plan accordingly. I regulate all my diving by psi not cf while diving through my SPG. I know that SPGs are not 100% accurate however I'm diving thirds, and am comfortable with the level of accuracy in the information they provide. I think the OP would be in the same situation as me at this point.

 

[J-Vo]

Using ideal gas laws adds a layer of conservatism that I'm not ready to get rid of for an extra minute of dive time. Not to mention simplifying the gas planning.

To the OP:. The best thing I did for side mounting off boats was learn to stand up and attach tanks without assistance. Put your harness on and figure it out while watching TV or something. Practice regularly to keep up strength. I can do it with cave filled LP 108s.

 

[grantctobin]

Using ideal gas laws adds a layer of conservatism that I'm not ready to get rid of for an extra minute of dive time. Not to mention simplifying the gas planning.

Your other posts would indicate you know this, but for anyone reading this and thinks it’s “a minute, why would I care?”, it’s 15% for a helium rich gas at 3600psi. E.g an LP85 is not 116cuft, it’s 100. Nitrox 32 is ~5%.

 

[SlugLife]

As Marie13 says and even better with just a piece of rope and double enders you can remove when not necessary.
If you are small or tall enough, on a rocking boat, having to walk to the exit, you just attach.the top of the tanks to the dring waist, put the 1m reg in your mouth, and jump and do the setup in the water

Quick Update:

I just tried this and holy crap it's awesome! You need much less cord than I first anticipated, about 20cm / 8inches if using a large bolt-snap. I can easily clip the tanks from sitting, kneeling, and bent-knees. Then when I'm ready to stand, I can get into an almost-standing position, without bearing any tank-weight, then straighten the knees, and both tanks are off the ground by about 5-inches with almost no effort. If I clipped to lower-chest-d-rings (instead of ring-bungies), they'd probably be a little higher off the ground. It should also be really secure, given it's double 425 paracord (I tied a loop).

With this system, I don't think ring-bungies provide any benefit to the type of diving I do. So I'll probably switch back to loop-bungies.

I'll post up pictures later.

I also tried clipping directly to the waist-d-rings (on land, without regs). That seems to work better than what I was doing before. But not quite as nice as the cord+clip system above. My only other concern is that I probably wouldn't have much excess regulator-hose-slack, and risk that getting yanked out when jumping in the water.

 

[SlugLife]

Another Quick Update:

I will soon be vacationing in San Diego CA, and bringing my scuba-equipment with me. This isn't really a scuba-vacation, because I'm visiting family and not really controlling the schedule. I'll probably mostly be doing shore-dives when I can sneak in the time. This will be an interesting opportunity to test out my general kit for things like: Does my kit travel well? What about the ocean and salt-water? What about the don/doff, including setting up tank-rigging on rental tanks? My kit isn't optimized for travel, but I usually pack light. That means I have two checked-bags worth of space for equipment. I'm bringing my complete sidemount setup, wetsuit, fins/mask/accessories, pony-bottle, extensive save-a-dive kit, etc. The only major thing I'm really leaving behind is my full-sized tanks.

This has caused me to take a slight break from diving, as I want to make sure my equipment is all packed up properly, dry, and ready to go. So I haven't tested the clip-on-a-cord (see previous post) yet during an actual dive, but am getting somewhat close.

Sidemount & Regulator Testing

Another interesting side note is that sidemount has been useful for testing out some custom Spec Boots. I don't think anything is likely to go wrong, but in the 0.1% chance it did, I'd have redundant air. If anything did go wrong, it would be my own incompetence rebuilding 1st stages. Which I've rebuilt 1st stages about 5-6 times so far.

 

[DogDiver]

Your other posts would indicate you know this, but for anyone reading this and thinks it’s “a minute, why would I care?”, it’s 15% for a helium rich gas at 3600psi. E.g an LP85 is not 116cuft, it’s 100. Nitrox 32 is ~5%.

 

[SlugLife]

Side-Note:

I didn't know where else to share this, but I just bought two sets of Scubapro MK25 + S600 + Oceanic Transmitter for a fantastic price! Maybe not a deal-of-the-century, but a hell-of-a-deal. I could potentially even sell the transmitters and get back a decent chunk of what I spent.

Since I'm basically about to hop on a plane & haven't tested them fully yet, they're sadly going to sit on the shelf for about 1.5 weeks. However, when I get back, they'll be perfect for sidemount, and I can't wait to try them.

I also got a couple oceanic-computers really cheap, that I'll probably sell. They seem like decent computers, and in great shape, but I just don't need them and already have equal-or-better computer already.

 

[grantctobin]

That ignores gas compressibility. It is not linear as you approach those higher pressures. The chart doesn’t even tell you whether it’s air, 32%, 21/35, 10/70, etc, all of which are slightly different.

 

[SlugLife]

Quick Links:

• Part 1 - "First SM dive! Fumbling, but Fun!"
• Part 1b - "On-land practice & equipment changes."
• Part 2 - "Not Completely Incompetent!"
• Part 3 - "Weekend Madness"
• Part 4 - Ponymount (80 & 19cu)
• Part 5 - A-B Testing
• Part 6 - Thralls of Steel

(check latest posts for updated table-of-contents)

[Part 6] Thralls of Steel

Quick-Clip: Experiments with the "quick-clip" are going great! The "quick clip" is basically a large-bolt-snap on about 8in or 20cm of cord (or less), near the neck of the tank. See previous posts for more comments/details. The goal being to make it easier to clip from almost any position, stand, and jump in with tank secure. Then complete donning in the water. I even tried it with a (rented) steel-100 tank, and it worked fine on that too.

The one down-side is it's not fun carrying a single tank on land that way relatively-long distances, with 20-lbs of lead (I was diving salt-water). It works fine, but I'm fairly sure carrying the tank separately, on my shoulder, or just back-mount would have been easier. As mentioned earlier, the main goal for me is "quick clip" and jumping in soon after & not hauling tanks on land.

Single Steel 100: Speaking of steel, I (intentionally) tried monkey-mount with a 1x Steel 100 & 1x AL6 pony. It was about a 35-40 degree tilt to the left, and a strong tilt, enough that I eventually decide I might as well stop fighting and "enjoy" it. I'm sure counter-weights (on the right) would have worked. This is basically the exact result I expected, but I wanted to see first hand.

Dive Charter: I did my first dive-charter (and ocean-dives), on an actual "dive boat." I dove with a single AL80 side-mount for those dives (and 6AL pony).

Slow SM? Was I the "slow SM-diver?" Somewhat. Out of a group of 7, I was the 6th person in the water on both dives, and my dive-partner didn't have to wait that long. I'm honestly super-happy with those results, given I'm still a newbie sidemount diver & still getting faster each time. Also, having a bench to don equipment was such a massive upgrade from what I'm used to; I didn't need the quick-clip here. On the bright-side, the SM (and colors) made it easy for my dive-partner to distinguish me from the other divers using BM and mostly black equipment.

P.S. One diver sat out the 2nd dive, so okay I was last the 2nd dive, but right behind diver-5.

RIP Ring Bungies: I've decided to ditch the ring bungies, and plan to switch back to loop-bungies this week. For carrying tanks, quick-entries, etc, the "quick-clip" works much better. For keeping tanks snug, the loop-bungies work better, and take only a few seconds to add/remove. I acknowledge the possibility ring-bungies may work better for some people, or be incompatible with my harness, or I may be doing something wrong .... but it's not for me (for now). The hardware is reusable, so zero loss trying it.

 

[SlugLife]

I might as well throw out a 1-year update!

1) Sidemount is going great! Still haven't taken any classes, except online sidemounting.com materials.
2) I'm not as fast getting in the water as my friend who has been diving 22-years, but probably fairly average compared to most backmount divers. Jale's idea (scroll up a few posts) for putting bolt-snaps on a cord has been a massive game-changer for donning equipment quickly.
3) I still often dive with an AL80 + AL19, although occasionally 2x AL80s. The offset sizes don't bother me at all. That said, I don't expect the AL19 will work with #4 below

@SlugMug

Surely you have other stuff you could sell to fund some 40s or 50s. Like ammo. If you’ve got extra, people will fight for it.

4) I just bought a matching pair of Steel 100s! As a bonus, I didn't have to sell any ammo to buy them. Killer deal: $100/each, 2019 hydro, 2004 birthdate, full 3500PSI. I haven't taken them into the water yet, but may post and update once I do. (I don't expect to be doing Steel 100 left + AL19 right, I already tried that once and it sucked. Unless I add weights to the AL19).
5) I still suck at and need to work on frog-kick.