Shearwater Petrel vs. xDeep Black

[Father]

I agree with tbone's post and will expand in the significance of the disadvantage of only having 3 gases instead of five. To me that equates to limiting the xdeep to a max practical depth of about 200ft. Yes, I understand that the machine can handle much more pressure. Yes, I understand you can successfully complete 200+ft dives with only 3 gases. BUT 3 OC gases are not optimal for depths beyond 200ft, IMHO. After 200ft I like to add a 4th gas, a trimix deeper deco mix. Thus, as a computer, the xdeep is not optimally suited for dives deeper than 200ft. I would not spend close to $1k on a computer that maxes out at 200ft.

Well, it is... depending on which software you've loaded into the xDeep.
3 mixes, up to 100% O2 each for the Black EANx. ($450+$200) ---> There's your recreational Nitrox dives for 200+ft.
10 breathing gas mixes for the Black TMX ($450+$400) ---> There's your >200ft dives.
Am I missing something?

Wasn't Ahmed Gabr's World Record dive done using an xDeep Black?

So... for pretty much the same price as the Petrel you're going deeper than 200ft.

I haven't done a "Deep Diving" or "Deco Dive" specialty course... what 3 gas mixes are you using to dive up to 200ft?
The MOD for 21% O2 is 187' (@ 1.4 PO2) or 218' (@ 1.6 PO2).
I'm guessing for that kind of dive it would be 21%r to get down to that depth and then two different EANx blends for your ascent/deco stops? What would you need a 4th for? To knock down your hang time?

I'm not doubting Shearwater's customer service. Fortunately, their product has been solid enough for my level of use I haven't had a need for it. To me THAT is the service... making a product I don't need to send in to be fixed.

It sounds like xDeep put together a great product and didn't predict the incredible demand for it. Good for them for making something people want. However, going by what Dr. Lecter stated, it already sounds like they've sacrificed some level of quality in order to increase production.

 

[tbone1004]

depends on how good your budget is, gas mixes for greater than 200 feet would be
travel gas for descent and ascent
bottom gas
50/50 deco mix
02
You could technically do it with three if you wanted to breathe the extra helium, but it's $$ now

The MOD for God's Nitrox is indeed 187, you can't go to PO2 1.6 that deep because you'll run your CNS clock down quite fast, only have 45 minutes on 1.6, vs 150 at 1.4 or 210 at 1.2. The bigger thing there is at 187, you'd be narc'd out of your damn mind. Ideally you want to keep PN2 equivalent to 100FSW or 3.2, so you're ideally on trimix by 100ft although you can obviously stretch that and most people do since HE is so expensive, just depends on how bad you get narc'd.

Ideal gasses to 200ft, I do prefer using standard gases instead of best mixes, but CCR's are definitely the way to go for regular diving below 130ft with HE so expensive now
travel gas-32% to 100ft or 30/30 or 35/25 depending on personal preference, I would lean to 32% since that's what lives in all of my bottles normally for cave diving, PO2 of 1.3 gets you to 100fsw
bottom gas-18/45
deco 1-50%
deco 2-100%
potentially a first deco travel gas. Keeps your PO2 under 1.3 except for 100% deco but the gas breaks here help.

 

[Slamfire]

Well, it is... depending on which software you've loaded into the xDeep.
3 mixes, up to 100% O2 each for the Black EANx. ($450+$200) ---> There's your recreational Nitrox dives for 200+ft.
10 breathing gas mixes for the Black TMX ($450+$400) ---> There's your >200ft dives.
Am I missing something?

I stand corrected now. In your first post you wrote that the xdeep only did 3 gases. I was not aware that there was an upgrade to move it up to 10 gases. I took your post at face value and interpreted that there was three and no more.

I haven't done a "Deep Diving" or "Deco Dive" specialty course... what 3 gas mixes are you using to dive up to 200ft?
The MOD for 21% O2 is 187' (@ 1.4 PO2) or 218' (@ 1.6 PO2).

If I'm diving with the std gases team we'll use 18/45 bottom gas, 50% EAN, and 100%. Otherwise I might go with something like 18/30 or 18/25 for bottom. I'll still use 50% and 100% for deco gas with the non-std bottom gas. Occasionally I might end up with 80% as the last deco gas, which will then prompt me to change the first deco gas to 40%.

I'm guessing for that kind of dive it would be 21%r to get down to that depth and then two different EANx blends for your ascent/deco stops? What would you need a 4th for? To knock down your hang time?

You could but if you can squirt in some helium into the bottom mix you'll be reducing the risk of narcosis and oxtox. Up to you, your risk tolerance, the mission at hand and your available resources. A fourth mix will knock down some time as you come back up. Again, if you squirt in some helium it could also help out reduce the risk of isobaric counterdiffusion hits (see additional reading). Also there is an additional safety factor in having one more independent gas source that you can breath deeper than 50%. If I am at 190ft, coming up from a max depth of 250ft, and something goes wrong with my back gas, I'll feel much more at ease grabbing the 25/25 deep deco reg than going for the 50%EAN reg.

I'm not doubting Shearwater's customer service. Fortunately, their product has been solid enough for my level of use I haven't had a need for it. To me THAT is the service... making a product I don't need to send in to be fixed.

On this dive we had a Shearwater Research employee diving with us. While we were topside discussing the plan this employee noticed some micro cracks around the screws holding the screen crystal (plexi?, acrylic?). I noticed these crack several years ago and didn't think much of it because I never thought it had or would affect performance. Without prompting, the employee took my Predator after the dive and returned it a few days later with a spanking new crystal with no cracks at all along with all the documentation for a warranty repair. I wasn't asking for customer service, yet they noticed something suboptimal and acted proactively.

Additional Reading:
From Isobaric counterdiffusion - Wikipedia, the free encyclopedia

Doolette and Mitchell propose that a switch from a helium-rich mix to a nitrogen-rich mix, as is common in technical diving when switching from trimix to nitrox on ascent, may cause a transient supersaturation of inert gas within the inner ear and result in IEDCS.^[10] A similar hypothesis to explain the incidence of IEDCS when switching from trimix to nitrox was proposed by Steve Burton, who considered the effect of the much greater solubility of nitrogen than helium in producing transient increases in total inert gas pressure, which could lead to DCS under isobaric conditions.​

 

[kprice52001]

Just food for thought, I dive the petrel and I absolutely love it. I purchased the upgraded vbm but think it is a waste of money. I dive it in GF 30/95 and I have great results. My DECO times are excellent and safe. Unlimited gas logging is a great feature as well. Not to mention that the dive computer will never lock you out and it allows you to make changes to system setting while on the dive.

As far as battery life is concerned Panasonic makes a great rechargeable battery called enveloop that provides excellent run time on this computer and their new technology boast that after fully charged the battery will maintain charge on the shelf for years! With charger I picked up mine fir around $30 usd

 

[mirrocraft]

i have a shearwater and a nitec q i dive them both side by side i love my shearwater easy to operate easy to switch gas and easy to set plan and set gas my nitec not a fan of it if i had the money i would get rid of the nitec and get another shearwater

 

[tbone1004]

Picture of slate. Normally a bolt snap lives in the hole on the bottom left of the picture. Pencil lives on top. This is a teaching slate for use in a quarry so you see the map of the quarry there, on the back is the NAUI OW Checklist for new students and some other stuff, but there are a few of these slates with different things on them depending on the dive

 

[Locus]

As far as battery life is concerned Panasonic makes a great rechargeable battery called enveloop that provides excellent run time on this computer and their new technology boast that after fully charged the battery will maintain charge on the shelf for years! With charger I picked up mine fir around $30 usd

Do you mean Eneloop? Love those. I've been using the same handful of AA's and AAA's around the house for thirteen years.

 

[tbone1004]

Amazon Basics rechargeables are eneloops btw. I find that Costco usually has the branded eneloops on sale every few months with charger, but if you just need more batteries, the Amazon Basics are eneloops

 

[Reku]

It was probably said already but once I read rechargeable battery I knew the war was won. Petrel takes any kind of AA so when you are deep in a cave system and it dies you can find an air pocket and raise it out of the water and replace the battery