Question What mix to use for 200ft (60m)

[rx7diver]

Hey there. First off this post is ...

@Dann-Oh,

You might take a look at post #51 in my thread from last year Question - Question for Experienced O2ptima CM Divers.

If the rebreather diving you're anticipating eventually doing doesn't preclude a chestmount rebreather, then there is a lot of good information in that thread, I think. (Ignore the noise and bluster, though, as usual.)

If I were starting off today, and if a chestmount rebreater would suit my needs, I likely would begin by purchasing LP manifolded doubles (e.g., Faber LP 50's) and getting proficient diving them with a couple of small deco cylinders (e.g., Luxfer Al 40's), before incorporating a Choptima eCCR or Triton mCCR. Seems a neat solution if it will work for the type of diving you intend to do. Don't know how well this will work, though, if your plan is to dive with a housed, full-frame, DSLR, for example.

FWIW,

rx7diver

P.S.: Caveat emptor. (I am NOT a rebreather diver.)

 

[Jared0425]

I agree. But it’s cheap.

It seems that @Dann-Oh is especially sensitive to price. As a recovering cheapskate myself, I understand the concept. As a technical diver with a few years experience now, I now find it much more effective to focus on figuring out the proper plan first based on the dive environment and requirements, and only *then* start to optimize on price. The plan does not have to be the absolute optimal plan (‘perfect is the enemy of good enough‘), and price may play a role in selecting between a couple of highly-effective solutions. But picking fundamental strategy based primarily on price… in the end this often provides substantially less actual *value*.

Fortunately, @Dann-Oh is some time away from this decision. I hope he ends up with something that delivers more than minimal value. And maybe my armchair psychological analysis is completely wrong. In the end, as long as it is *safe*, what solution he uses is up to him.

My dive buddy once asked me "are you going to skimp on your life support system and therefore your life?

We purchased an ROV last year for when the time comes for helium diving.

 

[Wibble]

I have ZERO issue spending the money on the right tool. I do know that I REALLY REALLY enjoy Sidemount OC Rec diving, I listen to Speaking Sidemount with Steve Davis podcast, he does a lot of wreck diving and comes from an Sidemount OC Tech background. It just seems that it would make sense to get a sidemount rebreather if I like OC Sidemount.

With any rebreather you’ll be diving sidemount for the bailouts (unless you want sticky-up bailouts that jam in a wreck or cave).

Backmount CCR isn’t anything like backmount OC doubles. You want minimum weight on CCR as being overweight is a nightmare. CCR with sidemounted bailouts almost feels as stable as sidemount OC.

Would also suggest that you don’t dismiss backmount CCR for your first rebreather. There’s a lot to learn.

 

[J-Vo]

Not disagreeing with those that say starting with a back mount unit is the best way to go, but it does depend on your history.

Personally I had 500 + side mount dives and only ~50 back mount dives and none with doubles when I went down the CCR path. I'm sure getting something that let me maintain my configuration made a huge difference as to how quickly I learned.

 

[berndo]

I'm sure getting something that let me maintain my configuration made a huge difference as to how quickly I learned.

I bought a BM ccr after diving SM for 12 years or so. I don't know why it would have been easier to learn on a SW. Unless you doing cave dives where you actually need a SM unit, the SW seems to be a poor choice with only downsides.
The thing doesn't even have a water trap and people dive it without a HUD.

 

[Wibble]

From what I’ve seen and experienced, the few Sidewinder divers I’ve dived with look incredibly sorted in the water. Certainly in comparison with the majority of backmount CCR divers who frequently look a mess, be that out of trim or vertical stages.

Sidemount divers definitely have the edge on backmount divers for trim and efficiency. Once the Sidewinder unit and rig is sorted— as with any sidemount diving — it’s no worse than any backmount unit and a heck of a lot better for streamlining

N.B. Very few if not all people on a Sidewinder would ever dive it without a HUD or Nerd.

There’s also the Sidewinder clone, the Fathom Gemini, which adds some refinements to the Sidewinder design (single injection block, removable scrubbers)

 

[rddvet]

From what I’ve seen and experienced, the few Sidewinder divers I’ve dived with look incredibly sorted in the water. Certainly in comparison with the majority of backmount CCR divers who frequently look a mess, be that out of trim or vertical stages.

Sidemount divers definitely have the edge on backmount divers for trim and efficiency. Once the Sidewinder unit and rig is sorted— as with any sidemount diving — it’s no worse than any backmount unit and a heck of a lot better for streamlining

N.B. Very few if not all people on a Sidewinder would ever dive it without a HUD or Nerd.

There’s also the Sidewinder clone, the Fathom Gemini, which adds some refinements to the Sidewinder design (single injection block, removable scrubbers)

I have given my negative opinion of the sw here many times, so I won't bore you again. As I always have I will concede that the sw has one very huge advantage. It is easy to dive in trim and look great in the water with. Even with multiple sm rigs, the sw just puts everybody in a great trim position. The issue is the downsides to the unit that I've already stated. It just isn't a great 1st unit imo. Of course on the internet they're the world's greatest unit, but if you delve further many of the hard core pro-sw divers have never dove another unit to have anything to compare to.
I love my fathom and am very biased. My fathom is a dream to dive. Its likely a big reason I hate the sw. I can flood the hell out of my fathom without issue. The sw, not even close. I have not dove or even seen the gemini in person. Only have heard from other fathom divers who love theirs and feel it is a huge upgrade from the sw. I would love to dive one, but I haven't been diving enough the past 2 years to make it a worthwhile investment. Hopefully as life calms down in 2024 I will be diving more and have a chance to try one. I've got to swing by fathom in a few weeks to pickup some stuff I sent in for service, and am hoping to put my grubby fingers on a gemini and have Charlie or his right hand man (can't remember his name right now) run me through one.

 

[J-Vo]

The thing doesn't even have a water trap and people dive it without a HUD.

People can decide to dive any unit without a hud. I'm not one of them.

 

[J-Vo]

...I don't know why it would have been easier to learn on a SW. ...

I didn't say SW, I said a unit that let me maintain my configuration. The SW is not the only option.