First Rebreather Questions

[inquis]

My issue is still on the DSV/BOV

You'll have to wade past the hypoxic aspects given where you are now and some silliness about connecting it to an onboard 3L, but a really good thread on this topic is linked below, especially from post 20 onward. Another site has a nice summary of the BOV pros by Mark Chase.

Current Views on Hypoxic bailout/BOV Configurations

Starting MOD3 soon and looking for opinions on how everyone else handles hypoxic bailouts with a BOV. Or if nothing's changed in the past 10+ years and everyone does what they want anyway, lol Kiss classic, stiffer spring/orifiace. Onboard o2/dil with drysuit bottle.

scubaboard.com

 

[PEDiver]

i use a bov and always have, to me it would feel like i was sacrificing some safety margin switching to a dsv. i heard from one person who had to bail to a necklace reg from a dsv during a co2 hit, said they almost drowned doing it.

I have a similar anecdote. Someone I know was about 1000 ft. back in the cave when he had a bad CO2 hit and almost died trying to switch from his DSV to his necklace regulator. He's only alive because his buddy saw it happen in real time and swam over and shoved the second stage in his mouth. Even if a BOV isn't always ideal, I would rather have OC gas at the quick switch of a lever AND also have a necklace regulator I can bailout to.

 

[lermontov]

Funny how more experience affects one’s preferences

Hmm lets just break this down a bit -
are you saying that because of your experiences of having a Co2 hit youve deduced a BOV is no advantage because you where able to switch in a timely manner?
or are you saying because your experience of not having a co2 hit -then its probably ok to not have BOV because it unlikely to happen?

if its the latter- it sounds like a classic case of normalcy of deviation

 

[broncobowsher]

When I got my rebreather a BOV was not a factory option. No big deal, I can add it later. Ordered end 2017, got the start of 2018. Several options exist, easy change. Now, 2024, I have done other upgrades (transmitters, had a custom stand made) but still never did the BOV. Learned to dive with the DSV and have been happy with it. The idea I needed a BOV on my pre-rebreather ownership research has changed after actually owning a rebreather without one.

 

[Wibble]

Hmm lets just break this down a bit -
are you saying that because of your experiences of having a Co2 hit youve deduced a BOV is no advantage because you where able to switch in a timely manner?
or are you saying because your experience of not having a co2 hit -then its probably ok to not have BOV because it unlikely to happen?

if its the latter- it sounds like a classic case of normalcy of deviation

CO2 hits do happen; fortunately extremely rarely.

Seems to be either mis-packing the scrubber (incorrect, poorly stored, old or used lime; breakthrough from incorrect tamping; missing the O-ring (Inspo et al); missing the scrubber altogether; plus myriad other packing related fails) or pushing the scrubber too far/long. And there’s the overbreathing the scrubber especially at depth.

If one follows the instructions/rules that shouldn’t happen. Virtually all rebreather divers will never have a CO2 hit in their entire lives.

On the many hundreds of boat dives I’ve done (600+) I’ve never heard of a rebreather diver with a CO2 hit. Some floods, caustic cocktails (me included), many units failing before the dive, but no CO2 hits.


Bailing out…. With a correctly configured BOV it’s so easy; flick the switch and you’re done. Hopefully you’re using a proper bailout and not the diluent, ‘cos that won’t last long and you’ll loose your buoyancy and diluent…

A standard bailout configuration would be either a bungeed standard reg on the bailout which you reach round and pull out, or a necklaced regulator under your chin which you’ve breathed from of course during your pre jump check. Switching is quick: just grab the reg, hold down the purge button, shut the DSV with one hand whilst throwing it upwards (sod having the bloody two handed Inspo bollox), then shove the purging reg in your mouth and gasp away.

Obviously every rebreather diver does this bailout check on every dive, right? This is a well practiced manoeuvre so very quick.

 

[rjack321]

I’m


Im for sure going with the HUD.

My issue is still on the DSV/BOV. I am now reading the thread on the 'Gag Straps' and am leaning more toward a BOV and gag.

Honestly I know this sounds rather expensive but you probably should try both DSV/necklace and BOV. People have various preferences for their own varied reasons both work.

The gag strap should be required in either case though and its a shame they arent a standard thing.

 

[PEDiver]

The gag strap should be required in either case though and its a shame they arent a standard thing.

I've been on the fence about buying a gag strap. Seems like it's still a debated topic even after the data from RF4. I have a BOV and offboard it to my bailout so I don't see many reasons to not have the gag strap with that configuration outside of having to get used to a new piece of equipment. Are there any downsides to utilizing a gag strap in your opinion?

 

[rjack321]

I've been on the fence about buying a gag strap. Seems like it's still a debated topic even after the data from RF4. I have a BOV and offboard it to my bailout so I don't see many reasons to not have the gag strap with that configuration outside of having to get used to a new piece of equipment. Are there any downsides to utilizing a gag strap in your opinion?

Yeah it can really mess with your mask strap if you aren't careful. And with dry gloves on its hard to get everything "even" and coherent and flat behind your head. It can be a little challenging to get the strap tension to your liking - at least on the Drager version.

I've had the Drager gag strap for years on both my BOVs on two different units. I'm a fan although it took some getting used to the thickness of the mouthpiece wings.

 

[piranhaman00]

Honestly I know this sounds rather expensive but you probably should try both DSV/necklace and BOV. People have various preferences for their own varied reasons both work.

The gag strap should be required in either case though and its a shame they arent a standard thing.

Actually, the plan is to order with DSV and by a Divesoft BOV as 'aftermarket'. I do want to learn on the BOV + gag strap.

Yeah it can really mess with your mask strap if you aren't careful. And with dry gloves on its hard to get everything "even" and coherent and flat behind your head. It can be a little challenging to get the strap tension to your liking - at least on the Drager version.

I've had the Drager gag strap for years on both my BOVs on two different units. I'm a fan although it took some getting used to the thickness of the mouthpiece wings.

The other issue I have read about is the caustic cocktail and removing the BOV from mouth. In addition you cant easily use a necklace second stage. Any opinions there?

 

[rjack321]

The other issue I have read about is the caustic cocktail and removing the BOV from mouth. In addition you cant easily use a necklace second stage. Any opinions there?

You definitely do not want a necklaced reg and a BOV at the same time. Totally no way. It's one or the other.

The Spirit is not a "water tolerant" CCR and caustics are a very really concern honestly. I have it's sidewinder cousin and it's a big fear of mine. I still use a BOV with a gag strap. It's not hard at all to yank the BOV down and out of your mouth even with the strap.