First OW class, lots of gear questions!

[tbone1004]

@Aloha Joe glad to help. Steel 72's are the best tank in the world for most types of diving. They have great buoyancy characteristics, they're shorter than AL80's and significantly lighter, you can take 4lbs off of your belt, and they are CHEAP to buy. I have probably a half dozen of them, and they're amazing

@stuartv I have a top load washer with no agitator. I put it in on soak and it stirs it up for me as well as takes care of rinsing, spin dry, and it's a lot less messy ;-)

@jlcnuke depends on how deep and how long you plan on going as well as which part of the islands you are on. The east side of the big island is in the low 70's which is easily 7mm territory depending on duration and depth

 

[stuartv]

@Aloha Joe glad to help. Steel 72's are the best tank in the world for most types of diving.

IF you have a low enough SAC rate. The VAST majority of recreational dives I have done have not been gas-limited. But, MOST of them would have been if I had been diving a single 72. A steel 100 seems to be the sweet size/tank for my SAC rate.

 

[tbone1004]

IF you have a low enough SAC rate. The VAST majority of recreational dives I have done have not been gas-limited. But, MOST of them would have been if I had been diving a single 72. A steel 100 seems to be the sweet size/tank for my SAC rate.

if you're diving with people with AL80's that has not been my experience, though yes most people will need larger tanks to hit their NDL's

 

[stuartv]

if you're diving with people with AL80's that has not been my experience, though yes most people will need larger tanks to hit their NDL's

Just about any woman I have dived with can run an AL80 right up to a liberal NDL with no real problem. I need a 100 for pretty much any deeper (70 - 80 feet or more) dive, if I want to last out an NDL. A 72 would definitely limit me on just about any dive and especially on shallow (less than 60') dives. My RMV runs .6 - .7 (cu-ft/min), which isn't terrible but isn't that great.

 

[Aloha Joe]

I'm sure my SAC is high as a new diver. I've been trying to use my breath to help control buoyancy (exhale and keep less air in my lungs to descend), but whenever I'm challenged by something (learning a new skill) I notice I end up filling my lungs with air, then subsequently floating and having to readjust. That's something I'll work on and get better at, and SAC and NDLs are pretty far from my mind at this point. (That said, I found the computer I want to get when I'm ready to advance )

But I'm not looking to buy one of these tanks, just deciding if I should optimize (and how) for the upcoming ocean dives for OW, or if I should use the opportunity to start balancing my rig for what I expect in the future (Al 80s).

@jlcnuke The 7mm wetsuit is for CA - it's what everyone has suggested - 3 different dive shops in LA and 2 on Catalina, and what I read in forums. I tried to put off buying a wetsuit because I'm not sure what I'll need/want in HI (likely Oahu), or how well I'll tolerate 50 degree water. But for $200 the 7mm I got will quickly earn it's keep - maybe even by the end of next month. When I move I'll be happy to get a new suit!

 

[tbone1004]

@Aloha Joe I'd use the LP72's in the ocean for this go around. It'll be a lot easier on you. You save about 10lbs on total rig weight vs. an al80 on the surface and you won't be needing the gas for your OW dives. Dive those for now and call it a day. If you dive an AL80 in the future, just add 4lbs to your belt and it'll be fine

What computer are you looking at?

 

[Aloha Joe]

That makes sense - esp. since I'm not adding non-ditchable weight to my rig yet.

For now I have a used Oceanic Veo 180 (which hopefully will work! backlight doesn't come on, but the 2 screens I should have access to before diving both seem OK), and I like the Shearwater Perdix AI as an upgrade - when I'm ready. I imagine it'll be awhile before an upgrade is necessary and I'm sure new toys will come out in that time, but I really like everything I've seen in that little computer.

 

[Couv]

I'm not a big guy like Tbone and Stuart, so I'm sure it's a factor. If there is any swimming involved, the extra weight of the tank plus the extra ballast I have to carry with an 80 makes the 72 a better choice as my SAC goes down enough to (almost) compensate for the measly 6 cubic feet. However, if I'm just laying in the sand taking bad pictures, the extra few cubic feet an 80 provides can make a little difference.

 

[tbone1004]

I'm not a big guy like Tbone and Stuart, so I'm sure it's a factor. If there is any swimming involved, the extra weight of the tank plus the extra ballast I have to carry with an 80 makes the 72 a better choice as my SAC goes down enough to (almost) compensate for the measly 6 cubic feet. However, if I'm just laying in the sand taking bad pictures, the extra few cubic feet an 80 provides can make a little difference.

real difference if both are filled to working pressure is only 5cf, so it's not a huge difference. That said, the extra mass of the rig with an AL80 is very real and it is one of the very interesting limitations in tech diving that pushes many of us to dpv's. It gets to a point that despite carrying extra gas, you aren't really making any penetration progress because of the extra effort required to get you in there in the first place.

 

[stuartv]

real difference if both are filled to working pressure is only 5cf, so it's not a huge difference. That said, the extra mass of the rig with an AL80 is very real and it is one of the very interesting limitations in tech diving that pushes many of us to dpv's. It gets to a point that despite carrying extra gas, you aren't really making any penetration progress because of the extra effort required to get you in there in the first place.

I haven't done a full statistical analysis. But, from my anecdotal reviews of my log (where every dive is logged with AI), it seems that the difference in my RMV between diving in a wetsuit and a single tank, compared to drysuit and doubles, is about 0.2 cu-ft/min. I don't even want to think about what my RMV would be if I were diving dry, doubles, carrying multiple deco/stage bottles, and actually having to swim!