100 or 120cf tanks in Coz?

[inquis]

What is the recommendation for weighting when using steel 120s vs 100s

There are several variants for a given size, but assuming the more recent Faber FX100 and FX120, they are equally buoyant empty. If you know your weighting when using an AL80, drop 5 lbs when switching to either of those two steels.

 

[Lorenzoid]

I've dived with Aldora and used their 120s. I'm pretty good on air so it's almost a comical amount of gas. These are 70 minute dives and I don't think I ever got back on the boat with less than 1200psi and I'd do stuff like swim against the current just to see what progress I could make.

My gas consumption rate is great when I dive Aldora's 120s, much as it is at home when I dive double tanks. I think I suffer from "Aluminum 80 Anxiety Syndrome." If I am concerned throughout the dive whether I will use more gas than planned and end up short, that anxiety shows up in my gas consumption. If I know I have more than enough gas for the dive and hardly need to check my SPG, my gas consumption goes down. With more gas reserves, I feel more relaxed. If I get back on the boat with 1200 psi left, I'm okay with that.

 

[PaulVS]

I think I suffer from "Aluminum 80 Anxiety Syndrome." If I am concerned throughout the dive whether I will use more gas than planned and end up short, that anxiety shows up in my gas consumption.

Wow.... I was just going to say something along those lines. "Aluminum 80 Anxiety Syndrome" is a perfect description. Typically '80s only last me for 30 to 40 minutes, worried that I'm going to go through it faster than an after-dinner mint, and find myself overthinking breathing. I'm much more relaxed when I know I have a 100 on my back, and I'm curious what the psychological effect of having a 120 would have on me.

 

[Carlos Danger]

Wow.... I was just going to say something along those lines. "Aluminum 80 Anxiety Syndrome" is a perfect description. Typically '80s only last me for 30 to 40 minutes, worried that I'm going to go through it faster than an after-dinner mint, and find myself overthinking breathing. I'm much more relaxed when I know I have a 100 on my back, and I'm curious what the psychological effect of having a 120 would have on me.

Rather than focusing on capacity, there may be value in looking at it from the perspective of buoyancy characteristics and increased safety margins. All things equal, steel tanks have a buoyancy profile that is generally more optimal for recreational diving and remain negative throughout the dive vs most aluminum tanks. Personally, I just feel more relaxed diving a steel HP120 in-part because there is no need for extra ballast or having to compensate for a positive buoyancy swing in the second half of my dive. I'm not necessarily looking for longer dives, but always happy to have the option. That said, I get they may not be everyone's cup-of-tea, as the larger ones can feel a little ungainly due to the extra length.

HOW STEEL VS ALUMINUM SCUBA TANKS WILL EFFECT YOUR BUOYANCY?​

 

[boulderjohn]

Personally, I just feel more relaxed diving a steel HP120 in-part because there is no need for extra ballast or having to compensate for a positive buoyancy swing in the second half of my dive.

Aluminum tanks are more buoyant than steel tanks, so a diver will usually need to carry more weight because of that, but that is true throughout the dive, not just in the second half. The difference in buoyancy as the dive progresses depends solely on the amount of air/nitrox the diver expels during the dive. If a diver loses 5 pounds of air during the dive, the diver will be that much more buoyant, whether the tank is aluminum or steel.

 

[halocline]

I would avoid AL100s like the plague. They're super heavy on land and pretty floaty in the water, and a full 3300 PSI in them is not typical, IME. The HP100s (3442PSI) are nice to dive with. I think they are generally more than 5lbs more negative than AL80s in reality, regardless of what the specs say. If you get one, try to do a buoyancy check before the dive if you can; just weight yourself neutral with a full tank and then add 5-6lbs for the air you'll breathe. Then you can fine-tune at the end of the dive if there's a chance.

It is likely that you could improve your air consumption; most of us could! I'm pretty good on air, I'm in very good cardio vascular condition, and I still have dives with guys bigger than I am where I end up turning first. But.....it's also a fact that as a large guy (you didn't list your weight) you will benefit from a bigger tank. The two things are not mutually exclusive.

 

[scubadada]

Hi @PaulVS

Do you know your gas consumption in volume/time? That would help you estimate the amount of gas you would need to execute a dive with known or desired time and average depth. That might take some of the guesswork out of choosing a cylinder to use for your diving. For instance, I know I can reliably get a little over an hour from an AL80 at an average depth of 60 feet.

Average Gas Consumption

There has been extensive discussion lately regarding average gas consumption. A poll may help give us a better idea of what the normal distribution of RMVs is. 1 cu ft = 28.32 liters 1 liter = 0.035 cu ft 28.3 l/min

scubaboard.com

Question - Definitions for SAC and RMV?

This topic comes up over and over. Let's see what you think. Please vote once for SAC and once for RMV or vote for #5 and elaborate in your post or #6 if you don't know what this is all about.

scubaboard.com

 

[PaulVS]

Honestly, I don't look at my dive logs, but that may change now that I'll be doing more diving. Thanks!

Also I can get steel 100's from Aldora & Dive with Martin as well as the in-house dive shop at Secret's Aura. I'll definitely try to go that route.

 

[PaulVS]

Aldora never responded to my email, and Dive with Martin didn't have afternoon dives, so we booked with the on-site dive house at Secrets - Dive Palancar. They didn't have any afternoon dives either, but they only had a three diver minimum so my wife and I just paid for three divers and had the boat to ourselves for two dive trips. They also had no problem getting me 100CF tanks. I definitely recommend dive Palancar if you're staying at Secrets Aura.

 

[ggunn]

I definitely recommend dive Helen car if you're staying at Secrets Aura.

Dive Palancar, maybe?