Coldwater diver with some basic BM tec training, looking to enter world of SM, need BC advice

[Wibble]

The course actually just has you using air as back gas, and two AL40 deco bottles - a 50% O2 and a 100% O2.

Surprised at that as you've got to be using far more strict switching protocols, especially with O2 around.

 

[Scuba Shibe]

Must say that sidemount with two cylinders isn't nice in my experience.

If going to normoxic depths (~60m/200'), those deco cylinders need to be ali80s so that you've enough reserves to cover one failure. Sidemount with 4 full-sized cylinders (2 sidemount, 2 deco) is horrid (IMHO). Steve Martin makes it look oh so easy, but they're utter bs'tards to handle. Steve also uses sliding bottom clips to tighten them into the body. If you don't do that, they dangle horribly.

If you're only using a second deco stage as a backup for shallower depths, circa 40m/130', then you can use ali7s or even ali40s if they're similar gasses. These are easier to handle but again dangle unless you tighten everything up.

Personally, backmount is far nicer for normoxic depths.

I must say I am a bit confused by your post and I'm sure it's just due to my own ignorance.

If you are saying sidemount with 4 full-sized cylinders is not ideal and that backmount is far nicer for deeper depths, in your opinion, when is sidemount better than BM in an OW setting?

 

[Scuba Shibe]

Surprised at that as you've got to be using far more strict switching protocols, especially with O2 around.

Sorry but could you explain more? Like, as opposed to what? I am hoping my phrasing does not come off as rude.

 

[Wibble]

I must say I am a bit confused by your post and I'm sure it's just due to my own ignorance.

If you are saying sidemount with 4 full-sized cylinders is not ideal and that backmount is far nicer for deeper depths, in your opinion, when is sidemount better than BM in an OW setting?

Just that handling the stage cylinders in backmount is easier. OK, if it's warm water then everything's easier.

Diving in cold waters with two sidemount cylinders and two stages is a lot harder than diving backmount with two stages.

Sorry but could you explain more? Like, as opposed to what? I am hoping my phrasing does not come off as rude.

Not at all. I'm probably being a little to 'strident'!

From my experience with TDI the difference between the first deco + helitrox course and the "normoxic" course was very much the single stage vs. two stages. And more planning.

I'd look up the standards for the PADI Tec45 but I know it'll upset me to go to the awful PADI site to check the standards....

Edit: Just been to dreadful PADI site:

The PADI Tec 45 course is the second part of the full PADI Tec Deep Diver program. You'll extend your depth limit to 45 metres/145 feet and learn to plan and execute repetitive decompression dives using a single stage/decompression cylinder. It puts you in a complete tec diving rig, which can be either backmount or sidemount. You'll also make accelerated decompression dives using EANx or pure oxygen.

A single stage with up to 100% to a max of 45m.

Would expect the limit to be planned to have that cylinder fail, so whatever you can get out of Dodge on with backgas alone. That's pretty much the same as the TDI and no doubt the others.

Looked up Tec50..

Develop competency & have the skills to dive to a max of 50 metres/165 ft. Learn how to extend & accelerate decompression stops using up to 2 gases.

That's the subsequent one with two stages but limited to only 50m.


Then of course there's their Tec65... Oh, that's not being done any more.

Going to TDI, IANTD and others with Tec45 would probably qualify you to go straight into the Normoxic course which gives you 60-ish metres/200 feet-ish with a normoxic mix (above 18% oxygen, with as much helium you can afford).

 

[wetb4igetinthewater]

I am hoping my phrasing does not come off as rude.

You are obviously new here. It is important to be as rude and condescending as much as possible on ScubaBoard! You just have to toe the line with the ToS, so being subtle, yet not so subtle is the way to go for insulting those who disagree with you, but with an overwhelming amount of rudeness. Think "would I get punched in the mouth if I said this to this person directly?" If you answered no, then you need to up your game.

 

[Scuba Shibe]

Just that handling the stage cylinders in backmount is easier. OK, if it's warm water then everything's easier.

Diving in cold waters with two sidemount cylinders and two stages is a lot harder than diving backmount with two stages.

Hm, maybe I should rethink this before buying a SM BC. Seems like in the end it will just make my life more difficult, not the other way around.

 

[wetb4igetinthewater]

Hm, maybe I should rethink this before buying a SM BC. Seems like in the end it will just make my life more difficult, not the other way around.

there are pros and cons with SM. Just as a heads up, SB overall is very anti-sidemount overall. You are better off getting information from various FB groups. Lots of useful help there without all the drama.

 

[Wibble]

there are pros and cons with SM. Just as a heads up, SB overall is very anti-sidemount overall. You are better off getting information from various FB groups. Lots of useful help there without all the drama.

Hope I'm not coming over all anti sidemount!

I love sidemount. Just want to call out when it's great and when it's a pain. Wreck diving on sidemount's great, but, in my experience, only with a single deco stage, therefore not deep. Backmount's a lot easier as you can put the two stages left and that tends to stop them flapping around.

There's nothing quite like diving sidemount for the sheer comfort of it. How the trim is perfect; streamlining's wonderful; everything's kept out of the way; you don't clout things with your back; it works in any position: up, down, sideways; it's fully redundant; valves are in front of you.... It really is great.

Backmount's great for flat, but is a right pain at other angles as that massive weight above your centre of gravity rolls you over. Backmount, of course, has space in front and to the side for stage cylinders.

They're both a compromise.

I would take sidemount every day of the week for a beach dive over backmount. OK, I'd take my rebreather...


One other sidemount advantage: you carry one cylinder at a time. If you're climbing over a hill to get to a mine (UK people will know Dinas Chert Mine in south Wales) for a killer climb with a twinset is just that. With sidemount, you carry one tin at a time. Same with the beach, one tin, go back for the other as you climb the shingle mountain. (And before you start, I don't dive a single as there's no backup gas; a pony's just taking the piss where sidemount comes out on top).

 

[rjack321]

Hm, maybe I should rethink this before buying a SM BC. Seems like in the end it will just make my life more difficult, not the other way around.

As a 20+ year Puget Sound diver with something like 7-800 deco dives on OC and CCR, I'll say that SM is not the panacea it's made out to be.

As far as your current cert goes... I would be very very careful doing 2 deco gas dives in the 90-150ft range (at all). The first question is why do you need more than one loaded gun on you? Especially when you're on air and narced. A single al80 of 50% minimizes your rock bottom, can cover your deco, and has a reserve for your buddy if there's a lost deco gas.

 

[Scuba Shibe]

As a 20+ year Puget Sound diver with something like 7-800 deco dives on OC and CCR, I'll say that SM is not the panacea it's made out to be.

As far as your current cert goes... I would be very very careful doing 2 deco gas dives in the 90-150ft range (at all). The first question is why do you need more than one loaded gun on you? Especially when you're on air and narced. A single al80 of 50% minimizes your rock bottom, can cover your deco, and has a reserve for your buddy if there's a lost deco gas.

What you're saying doesn't not make sense but what training agency teaches this way? Since you mention "rock bottom" should I assume UTD?

The other thing I guess I'd ask is when you dive this way, does your buddy also carry one 50%? Only then would I say it makes sense since you theoretically deco together if you're using the same GF, etc etc. I mention this because the guys I do my tec dives with are all very willy nilly. Everyone's using different equipment set ups, different GF, different mixes, it makes no sense to me but they don't seem to mind. And since I'm either the student or the newbie, I'm not really in a place to speak up. But at the same time, I don't have anyone else to tec dive with.