Tank Size?

[spoolin01]

i tried an hp100 it was just to heavy for me it made me back heavy causing me to roll and in the end i really didn't need that much gas. if you have a good sac rate an 80 is plenty i can dive an 80 to 100fsw to the ndl the accend and continue the dive and still have plenty of back gas left. but my avg sac is low .31 to .35

You must have tried a DOT 3AA tank - those are anvils. There are lighter HP100s that are pretty much like AL80s in weight.

I found I needed a bigger tank to go shallow, below 60 ft I can't use more than the 80 offers.

 

[halocline]

On the opposite end, an AL80 really isn't "enough" gas for 90ft dives.

Really? I guess all those caribbean 90-100 ft dives on AL80s don't actually happen, huh?

 

[halocline]

You must have tried a DOT 3AA tank - those are anvils. There are lighter HP100s that are pretty much like AL80s in weight.

Well, about 5-7 lbs different depending on the brand in terms of buoyancy. That's certainly enough for me to notice a big difference.

But, one of the SP (3442) 100 cft tanks is probably about as good as you can get for a compromise between size, dry weight, buoyancy, and capacity. That is, unless you live in N FL and can get serious overfills.

 

[PfcAJ]

Really? I guess all those caribbean 90-100 ft dives on AL80s don't actually happen, huh?

Be back with 500psi!

 

[Dr Wu]

Does this mean that with the right training I should be able to take two HP100's down to 200 feet?

With the right training you should be able to take two 19cf tanks down to 200 feet.

 

[The Kraken]

By the depth, time and mix which you wish to dive.

That being said, the HP100 is an allround excellent choice of tanks.

the K

 

[scubadiver888]

Really? I guess all those caribbean 90-100 ft dives on AL80s don't actually happen, huh?

I guess you didn't notice the quotes around "enough" in rjack321's post. If you are using rule of thirds you should be back on the boat with 1000 PSI (unless something went wrong). If you are using Rock Bottom Gas Management you probably need to keep even more in reserve. Most people doing 100 foot dives on an AL80 come back to the boat with 500 PSI or less.

 

[scubafanatic]

...also, if you plan to travel (fly) to dive, won't hurt to buy a tank of the capacity/material you're most likely to find available 'on-site' at your typical dive resort/liveaboard, that way you gain experience handling the bouyancy/trim/dive profile-times you can reasonably expect to encounter on your trips. Why get used to a nice, juicy HP 120 steel tank that you'll never encounter out there in the real world.......might as well get lots of practice with the 'standard' AL 80.... 90% of the time that's what you'll have to use anyway.

 

[laguna230diver]

As for being back with 500 PSI, with a little experience it is NO trouble to back on the boat with 500 PSI even on dives to 120ft. A local instructor here uses a HP100 and gets 2 dives at 110ft out of it. Aluminum 80s have the best mix of all features and that is why they are so popular with charters. You should really only need big steels if you are a bigger person, are going very deep, or need more negative buoyancy. If your tank determination is based solely on a bad SAC rate then i would suggest getting an al80 and working that SAC rate down with a little bit more diving.

 

[PfcAJ]

Ya, there is more to gas management than that.

Al80s are popular because they are cheap, light, low(ish) fill pressure, and easy to get ahold of.