Dive with martin or aldoras

[ggunn]

I assume a reputable dive shop won't take a rusty/new diver to a place with strong currents. I will be doing a reef dive in cancun and 6 cenote dives before hit cozumel

While it is true that dive ops try to arrange dives to fit the experience of the divers, around Cozumel there is usually current on most every dive and it can change during a dive. It's usually not that big of a deal.

 

[ggunn]

An AL 80 is actually an AL 77.4. I don't disagree about the AL 100s, I'll dive with your steel 120s

Taking your and Dave's numbers as accurate, 92/77.4 = 1.19. An AL100 gives you about 20% more air than an AL80.

Using the trade numbers, 100/80 = 1.25. Not that different.

 

[cicopo]

There is shore diving both north of town & along the southern section of town between roughly the Park Royal area down to a bit south of the vehicle ferry pier & then again starting a bit north of that pier up to just past the Palace area. Hotel Cozumel & Scuba Club are at roughly the center of that last section I mentioned & this album is a collection of the photos taken at the start of each trip when I use a shore dive to check my gear & weights.

https://flic.kr/s/aHskG82Mm6

 

[scubadada]

Taking your and Dave's numbers as accurate, 92/77.4 = 1.19. An AL100 gives you about 20% more air than an AL80.

Using the trade numbers, 100/80 = 1.25. Not that different.

The AL 100 is 8" in diameter rather than 7.25", may or may not be a hassle for you. The buoyancy characteristics of an AL 100 are undesirable. A HP steel 120 is 7.25" in diameter, will allow you to remove about 4 lbs of weight, and gives you about 55% more gas than an AL 80

 

[Dogbowl]

I assume a reputable dive shop won't take a rusty/new diver to a place with strong currents. I will be doing a reef dive in cancun and 6 cenote dives before hit cozumel

I don’t mean to offend in any way, but you might want to reconsider those 6 cenote dives until you can resolve your air issue. Don’t get me wrong, I did cenote dives as a beginner too and there’s a lot going on in caverns that you need to be able to deal with (up and down and up and down, equalizing in those conditions, mask fogging in darkness, etc.) If you add “air hog” to all that, there just might be too much task loading involved. Just my thought. Hope you take it as a friendly concern.

 

[MargaritaMike]

Factoid:

An aluminum "100" filled to 3000 psi is actually a 92 cf tank, gaining you 12 cf over the aluminum 80. Buoyancy, in my opinion sucks and you better add 4 or more lbs.

Dave Dillehay

An AL 80 filled to 3000 psi is actually an AL 77.4. I don't disagree about the AL 100s but they should be filled to 3300psi. I'll dive with your steel 120s, they should be filled to 3442 psi

So the 100 (92 cf) minus the 80 (77.4 cf) - both at 3000psi - is 14.6 cf more of air. 14.6/80=18.25% more air in a 100 than in an 80. I KNOW that I am wrong, but I still think that at the same temperature and pressure the proportional values of volume of air should be the same. BWDIK

I rarely see tanks filled to over 3000 psi - generally 29nn psi.

Cheers - M²

 

[ReefHound]

Shore diving? Thought reefs were pretty deep in cozumel

you won't be diving the reefs from shore which is why I said to also do your daily boat trip. The shore dives are right by the shore in 20-25' where you will find small fish, critters around rubble and isolated soft corals. They can be fun and interesting dives but the real point of my recommendation is they would offer you plenty of bottom time to just play and practice skills without having to keep with a group.

 

[ggunn]

So the 100 (92 cf) minus the 80 (77.4 cf) - both at 3000psi - is 14.6 cf more of air. 14.6/80=18.25% more air in a 100 than in an 80. I KNOW that I am wrong, but I still think that at the same temperature and pressure the proportional values of volume of air should be the same.

You aren't wrong; I did the math a little differently and came up with 18.86%. That's pretty close to 18.25%.

 

[deepsea21]

Well, I think we've loaded this thread with enough feedback and commentary to freak the OP'ster out (myself included with blood pressure commentary). I know I'd be freaked out if I read through all this as a new diver heading to Mexico for first dive trip and my BP would be through the roof.

Cutting through all of this, the OP stated he was going to do a reef dive on the mainland followed by several cenote dives. I agree with a prior post that stated cenote dives may not be the best UW environment for a new diver. I would recommend this diver pay the few extra bucks for a dedicated dive master for his initial reef dives on the mainland and further recommend that he consider doing more reef dives on the mainland until he is comfortable with his buoyancy and has listened to the advise of a DM who can give some instruction on how to minimize air consumption UW. A few cenote dives could then follow if he is totally comfortable and either sticks close to the DM or again hires a private DM for initial cenote dives. Vacation is supposed to be stress-free and I say if one is stressed about a dive, spend the $ and hire a personal DM, relax, and enjoy yourself. Skip a few dinners out when you return from the trip to save the $ you spent on the personal DM.

Once on the island of Cozumel, I'd recommend a private DM again for the first day as this will be new drift diving. A private DM on the island runs about $50 bucks for a 2-tank dive and there is nothing better than having your own DM who not only can provide instruction and watches out for you but can take you on a tour and point out critters 99% of us pass by never knowing they were there. Again, after becoming comfortable (and it usually won't take but a day of diving with a DM) the diver is comfortable and ready to dive the rest of their trip.

 

[MargaritaMike]

You aren't wrong; I did the math a little differently and came up with 18.86%. That's pretty close to 18.25%.

I'm really curious. How did you do the math. Have they changed math while I wasn't looking. I've been away for a while, but I thought that numbers are pretty stable.

Cheers - M²