100 size tanks?

[tursiops]

No, I want it centered. Not above, not below, not next to me.
I prefer less lead tugging in one direction as buoyancy is going in the other.

So put 4 of the pounds of lead you are carrying on the cam bands, right up against your back.
Where are you carrying your lead now?

 

[Blackcrusader]

I can’t understand why someone would want to use an aluminium 80 cuft. On land they weigh more than a 100 cuft steel. More dead weight and less air. The only reason I can think of is people who hire them don’t have to paint them.

They are the standard tank used across SEA Australia Japan Taiwan where I dive. Some dive centers may have larger tanks available on request but not all. As many places limit dive times an AL 80 is fine. More weight in the tank just means less weights in your inserts or weight belt.

 

[cvchief]

Wow. What a fight. It's argumentative and pointless all at the same time. I love it!

The wife dives a 80 nitrox. She can run about anyone out of air.

I used to dive 100 nitrox to keep up, but they are annoying as they go empty.

So now I dive 117 steel tanks. Why? BECAUSE I CAN. Could I probably stay pretty close to her on an 80 nowdays? Probably.

I am never air limited. EVER. I love the trim and can stay until Susan decides she is cold and has had enough. Oh and I got a pony. Why? See above. (BECAUSE I CAN). And I want to be cool like @DandyDon

If I OWNED a shop, I would probably want to run 80's because I was either limiting the dive time or I just want to turn the boat faster. I would run 80AL because they don't rust and are more durable in that regard.

OR I would get all 120 steels like Aldora and build my own fill station as no other filler will properly fill a tank larger than an 80, and then sell a better, LONGER dive experience. Wait, I would almost def do that since it seems to work really well for them.... Many the time I have wanted to sneak out there by casa mission with my steel tanks and see if I could buy a REAL fill with that sweet, sweet Aldora nitrox.... (Isnt the owner a 'native'?)

 

[BRT]

Sure, the swing is larger with larger tanks. Duh.
But the typical statement is "AL's are terrible because you go positive at the end of the dive" is total BS. It's not the fault of the tank, it is the fault of the weighting at the beginning of the dive. That's what I was responding to.

And you are correct in that.

 

[scubadada]

A factually based thread is not bad 100 size tanks?

 

[Blackcrusader]

Seems it is common for folks on this sight to need larger tanks, is 80 not enough?

This on an AL 80 started this 93 minute dive with 210 bar 3045 psi finished dive with 50 bar 720 psi.
Max depth 34m 111 feet average depth 14.22m or 46.6 feet. Sac rate shown on the dive log.
Not many divers have a sac rate below 10l/min let alone below 8l/min. Many have sac rates of 12l/min or more

 

[tursiops]

This on an AL 80 started this 93 minute dive with 210 bar 3045 psi finished dive with 50 bar 720 psi.
Max depth 34m 111 feet average depth 14.22m or 46.6 feet. Sac rate shown on the dive log.
Not many divers have a sac rate below 10l/min let alone below 8l/min. Many have sac rates of 12l/min or more


View attachment 710530

The OP felt that new divers and photographers had high SACs...so could not get by with an 80. So your post shows that at least one photographer has a low SAC. I do too (not as low as yours!), and I'm old. But the OP isn't going to be convinced that he is wrong (noting that he is probably correct about new divers) by a bunch of folks coming on and posting how low their SACs are.
I use less gas when I have my camera with me -- even though I have a lot more drag -- because I am not swimming very much. I also use less gas when I am relaxed...which it is hard for new divers to do.

 

[Blackcrusader]

The OP felt that new divers and photographers had high SACs...so could not get by with an 80. So your post shows that at least one photographer has a low SAC. I do too (not as low as yours!), and I'm old. But the OP isn't going to be convinced that he is wrong (noting that he is probably correct about new divers) by a bunch of folks coming on and posting how low their SACs are.
I use less gas when I have my camera with me -- even though I have a lot more drag -- because I am not swimming very much. I also use less gas when I am relaxed...which it is hard for new divers to do.

I go diving to relax. I feel more relaxed when diving than being out of the water. My brain cells can relax and not think about anything. So my heart rate slows, my breathing slows, I dive slowly and drift with the currents where I can. I love being neutrally buoyant in the water. That is one of my better dives where sac was below 8L/min. I was a bit surprised really as the dive was planned to visit a wreck then slowly come back to a reef wall and follow that along at about 14m depth where it meets the sea bed. Plan was to end the dive at 50 bar and not be time constrained. The DM I was with has a lightly better sac rate than I do. He dives for a living and is a lot smaller than I am.

Also a lot of divers chase everything instead of just floating along slowly being near motionless. IF you want to see things you want to go very slowly so many people rush and critters hide or they didn't see that tiny animal inside a soft round tube or inside a cavity. They wonder why photographers saw things they didn't on the same dive.

I spent a lot of time on that dive taking video's and photos and a lot I have posted on SB already. I'm only 62 this year so not too old to stop diving yet lol. Also I am a wee sized chap 6 foot 1 and weigh 300 pounds... did the op think large people need to use a lot of air as well?

 

[tursiops]

did the op think large people need to use a lot of air as well?

Maybe he thought it, but he didn't say it.

 

[Blackcrusader]

I have figured out who needs the bigger tanks. Appreciate the responses, I understand.

I understand I have never figured out who needs what size tank. I have seen small women from Korea go on a vacation dive with me and finish the dive with 40 bar while I still have 120 bar or more.

Once I went on a dive in Thailand. I rented their gear as I was only doing the one dive. They looked at my size and sniggered about the 30 minute dive time I would do. On the boat the dive briefing was done. The DM clearly stated that you had to be back at the boat doing your safety stop once you got to 50 bar. I asked was there any time limit and he said no. I asked again just to make sure.

So I was the last diver back on the boat. The DM was out of the water on the boat banging away for me to surface. When I eventually got on the boat the guide was upset. I'm like what are you upset about? He said I stayed down too long and must have had a near empty tank. I asked the other divers didn't he say no time limit and we could dive to 50 bar? They said yes that was what the dive briefing was. I told the DM I was following his dive briefing. I showed my SPG still had far more than 50 bar and should I get back in the water to finish his dive plan briefing. The other divers by this time were having a good laugh as well. On the way back the DM had calmed down and felt the levity as well. He simply realized he had screwed up. He admitted he thought I would be one of the first divers back on the boat.

Silly DM had figured out who needs a bigger tank and their dive times based on appearance. Shocking really to assume to know who needs what size tank. Lucky he hadn't given me a larger tank to dive with.