BTW, unless something changed, no way the REC wing is 18# while the TEC is 50#. If anything, REC might be 18kg.
My bad. Their website says "13kg/28#". In my mind, I guess I dropped a couple of digits out of the middle.
Katana is fine with 2x steels and 3x al80's in a drysuit in cave country, though I wouldn't recommend trying to bob at the surface with it. That is not really a balanced rig though. In a drysuit assuming you are balanced, which in cold water you are, with 2x cave filled steel 121's and 2x al80's the wing has to compensate for 26lbs of lift. Gives you 9lbs to deal with keeping your head out of water and you can get some advantage from your drysuit. 35lbs is enough. It can't float your rig, but in sidemount you can't really take it off without removing the tanks first.
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For Mexico with just AL80's I'd use the DECO rig that Oxycheq sells. Just under $300, just add a bungee mechanism of your choice and you're good.
DECO - Dive Equipment Company - Sidemount - BCD's
I looked at Oxycheq's website and I only see their Recon I and Recon II SM rigs. Those don't look anything like the harnesses I saw on DECO's website. And the wing itself definitely has nothing to do with the one and only wing DECO has. Am I missing something?
Anyway, the bigger question I have is about lift requirements. I have seen you recommend to someone in the past a 35# wing for single tank back mount (steel tank, cold water, drysuit). I don't understand how 35# of lift can be way too little in BM and enough in SM for an otherwise identical config (e.g. double steels, 2 x AL80s, drysuit, cold water undies).
I haven't found anywhere in my reading on SM where it explicitly discusses calculating lift requirements. I would have thought the basic requirements are the same for SM as for BM. I.e. You need enough lift to match your max negative buoyancy, accounting for suit compression or dry suit catastrophic failure, and you need enough to float your rig. Whichever number is greater.
If I were using 2 x HP100 + 2 X AL80, then I reckon that would mean starting the dive 28 # negative (the sum of all the gas I'm carrying). If I'm in a drysuit with cold water undies, I might be wearing (for the sake of argument) 14# of lead. If my suit has a total loss of bouyancy, that potentially leaves me 42# negative at the bottom, at the start of a dive. Is the lower lift requirement because in SM I can just ditch 3 of the 4 tanks, if I had to? If it's the start of the dive (in this hypothetical scenario), I won't yet have much of a deco obligation (if any), so 1 tank of bottom gas should be plenty to get me to the surface, right?
That still means starting at 28# negative. That only leaves 7 # of lift to keep my head out of the water - and that's if I am perfectly weighted. If I decide to use my HP120s, then I'm more like 31# negative at the start and 35# of lift really starts sounding like not enough.
Then the other requirement to evaluate is floating my rig. You dismissed that by saying I would have to remove tanks first. Really? HAVE to? I have not tried SM yet, so I could just be totally not getting it. But, it looks like you could shuck your whole rig without unclipping tanks, if you wanted to. I read a post in another thread where someone was talking about getting back to a boat and unclipping tanks to clip them to a line before he got out. With steel tanks being negative, there would be the risk of dropping one and losing it. The guy said his buddy asked him, "why didn't you just take off your whole rig and clip that to the line?" He seemed to think that was a good idea. Also, when I did Rescue training, at least one of the exercises involved taking off my complete rig on the surface while also towing a non-responsive diver and giving rescue breaths. Would I not do the same thing even if I were wearing a SM rig? In which case, wouldn't I want my rig to be able to float itself, so I don't just lose my steel tanks?
To float the whole rig, if tanks are full, the steels would be around 11# negative and the AL80s would be about 3#s, right? That's counting attached regs. If the harness has 14# of lead on it, then the total rig would be over 42# (again) negative.
So, again, my lack of understanding about SM brings me to the conclusion that 2 x steels plus 2 x AL80s plus a drysuit and cold water undies would yield a need for more than 35# of lift.
Please tell me what I'm missing! Part of why I've been reading so much on SM lately has been because of this specific question and trying to work out the answer on my own.
I have a buddy who just got a Sump Uk wing and some miscellaneous pieces from Andrew Goring at Sump UK on Facebook. I am impressed and probably about to get me an H harness setup with his wing. It is very reasonable and shipping to the States wasn't bad at all.
I was looking at his stuff. It does look really cool. But, I could only see where he has one wing and I wasn't sure if it would have enough lift for me, either.
the new Katana has changed my opinion on the need for 2 different rigs for AL80 vs steel tank diving btw. It is the first rig that I've dove that handles both gracefully so long as you are diving somewhat close to a balanced rig. I.e. it can't treally handle cave filled PST104's no matter what you do
That's down to the increased weight of the gas you're carrying in a pumped-up 104, right?
I'm talking about using HP tanks versus LP. Does the increased overall weight of an HP tank (e.g. HP100 or HP120) change your feelings regarding 35# of lift being enough for 2 steels plus 2 AL80s, drysuit, etc..?
Stealth tec works just fine for that imo.
Butt dump is a non-issue, that only someone that hasn't understood how to use it will point out. If you can wipe your ass, you can dump air of a stealth.
The Tec is often used with stages (which are dropped in the cave) and left with 2 tanks, so it's not a problem. Quite some pictures on the facebook group (Stealth 2.0 sidemount).
P.S: I wouldn't consider Neto to be the reference about Xdeep or anything that looks like it. I'd more have a look at what Sidemount Silesia or Steve Martin do...
Thanks! I had a good look at Steve Martin's website the other day. When I do eventually decide to ante up and actually start learning to dive SM, I will probably also ante up for his videos. It was something like $175 for all his stuff, which doesn't sound too bad, to me, for what it looks like you get.