2 Tank Dive, Nitrox for Both?

[ChuckP]

I guess I really should have asked this first - who did you dive with before, how long were your dives and what tank were you using?

if you’re new and on a big cattle boat staying with the group and doing 45 minute or less dives then maybe air is kosher otherwise

Your dives will more than likely be 80-100 for the first and 60-80 for the second. You absolutely can blow your ndl even with an average sac rate on the first dive using air.

Your computer uses Buhlmann so it’s not as harsh on you for second dives but I’d still use nitrox for both dives - 32 first dive and 36 second. Cozumel diving is just a little bit more aggressive with depths - add some safety.

Who are you diving with?

 

[Brett Hatch]

In the space of "money spent on scuba," consider whether diving nitrox for a week vs air is going to make a big impact. For fifteen bucks a day, you'll be increasing your safety and/or dive times (most likely both). I'd say do it.

 

[kmarks]

I started diving nitrox when I was right around the same experience point as you. It was my third trip to Cozumel and in previous trips I was getting single digit NDLs a little later in the week because your computer will give you progressively shorter NDLs as the week goes on because it takes more than overnight to get rid of all that residual nitrogen. I did my first two days (two dives each) on air, then switched to 36% for the rest of the week. I did Palancar Bricks and Punta Delila one day and Santa Rosa wall and Paradise the next, all on 36%, not exceeding the MOD for 1.4, which is ~95 feet. I didn't feel limited, but if I hadn't been on 36% I would probably have gone deeper at Santa Rosa.

If I'm looking to save a couple of bucks, I stick to that formula of using air for the first day, then going to nitrox and I request 32% or 36% depending on where we plan to go that day (dive with a smaller op - even better, a friend - and you get more say in the planning). If you are going to be diving for several days in a row - you really should consider taking a full day off after about 4 or 5 days - you'll need to be on Nitrox after probably day 3 or 4 or your NDLs are going to catch up to your air time, even if your SAC isn't super great yet. I carry two Suunto computers, which tend to be a little conservative, but I've found that lately, if I'm on air still on day 2, I'm NDL limited.

I would use the same percent on both dives. That makes it harder to forget to change your computer to the right gas blend in between dives.

 

[1967Goat]

I guess I really should have asked this first - who did you dive with before, how long were your dives and what tank were you using?

Who are you diving with?

Hi Chuck-
When we stay in Playa I dive with Marcos (owner) of Dive Balam. He's a small operation out of the Royal Haciendas resort. The dives were 4 - 6 people max per DM (Cristian, Esteban), and no more than 8 people I think were ever on the boat. The first 3 years I only dove sites in and around Playa. It's really a "valet" dive operation...which is great for someone like me who had just started out.

For this trip I am staying down South at Sunscape Sabor and using Dive Palancar. We're staying there because my wife doesn't dive and prefers all inclusive. I am also taking my 8 & 9 year old so we needed a place with a decent sized pool. Initially I was going to go to Hotel Cozumel (which would be fine with me), but my wife didn't feel it was "fancy" enough for her.

In retrospect, I think my question was a bit of a stoopid one. Nitrox is available for $8 each tank. I'll just go Nitorx with all dives. I really don't know where we'll be going. <looks silly now>.

 

[1967Goat]

If you are going to be diving for several days in a row - you really should consider taking a full day off after about 4 or 5 days - you'll need to be on Nitrox after probably day 3 or 4 or your NDLs are going to catch up to your air time, even if your SAC isn't super great yet. I carry two Suunto computers, which tend to be a little conservative, but I've found that lately, if I'm on air still on day 2, I'm NDL limited.

I would use the same percent on both dives. That makes it harder to forget to change your computer to the right gas blend in between dives.

Thank you for this. I was thinking of taking a day or 2 off, but hadn't thought about the timing (my inexperience).

 

[rongoodman]

Thank you for this. I was thinking of taking a day or 2 off, but hadn't thought about the timing (my inexperience).

It's pretty common on liveaboards to do 5 dives daily for the week so I don't see any particular reason to need time off with only 2 dives per day, unless you just want to do something else. I would just do them all on 32% and not worry about it.

(If you're switching your computer from nitrox to air and back daily and happen to forget one day, you might well end up with it locking you out. Not worth the hassle.)

 

[SandyRobinson]

with those I'd be tempted for nitrox on dive 1, but certainly not on dive 2..

Ditto.

 

[ChuckP]

Hi Chuck-
When we stay in Playa I dive with Marcos (owner) of Dive Balam. He's a small operation out of the Royal Haciendas resort. The dives were 4 - 6 people max per DM (Cristian, Esteban), and no more than 8 people I think were ever on the boat. The first 3 years I only dove sites in and around Playa. It's really a "valet" dive operation...which is great for someone like me who had just started out.

For this trip I am staying down South at Sunscape Sabor and using Dive Palancar. We're staying there because my wife doesn't dive and prefers all inclusive. I am also taking my 8 & 9 year old so we needed a place with a decent sized pool. Initially I was going to go to Hotel Cozumel (which would be fine with me), but my wife didn't feel it was "fancy" enough for her.

In retrospect, I think my question was a bit of a stoopid one. Nitrox is available for $8 each tank. I'll just go Nitorx with all dives. I really don't know where we'll be going. <looks silly now>.

Your family will really like Sunscape, it's a nice place. Keep them happy and find different things for them to do while you're out relaxing and oh yeah, just pay for the rental car and stay far away from the folks selling time shares LOL.

Dive Palancar is a bigger boat place so don't be shy in weaseling your way into the group that more fits your diving abilities - they might be diving two groups and one may have shorter bottom times than the other, you never know until you see the group your with. Most places use 32 for first dive and 36 for the second - just reset your computer between dives, that's a plenty good gas plan for two a day dives.

The day off in the middle isn't a bad idea, diving seven days straight wears you out - relax and enjoy your vacation.

 

[scubadada]

I nearly always dive nitrox, perhaps all but the shallowest dives. I have a good RMV and would like my dives not to be NDL limited unless necessary. Some SIs are limited, and I would like to have a longer 2nd dive.

 

[BRT]

I'm heading to Coz on Thursday for 9 days. While there I am going to complete my AOW (I have about 35 dives total so far). I was Nitrox certified last November. Dive shop asked if I want to use Nitrox for this trip.

For this example, let's assume for each 2 tank dive the first will be deep (max 90') and the second will be shallow (25' - 40' or so). The Nitrox has the advantage of allowing longer bottom times at deep depths. Shallow, not so much (run our of air first).

Nitrox is an additional $8 per tank. Not a huge price difference, but money is money!

Do folks use Nitrox on the first dive, then switch to air for the shallow dive? Is it better to just use Nitrox for both, even if there's a not a benefit for shallow dives? I plan on diving 6 - 7 days.

I realize I would have to change the setting on my brand new Deep6 Excursion I received over the weekend. Maybe @cerich or @LandonL have an opinion on how swapping mixture settings between dives effects the Excursion? (Can't wait to get it wet!!!)

Our experience doesn't usually have the second dive that shallow. If it is, use air for it.