"neutrally buoyant" 80's as doubles?

[Flightlead]

I'm looking at putting together a set of double AL 80's. Are the slightly heavier "neutrally buoyant" AL 80s a good choice? worth the extra $100 for the pair? As a side benefit, looks like the working pressure is 3300 lbs (according to scuba toys web site) does this mean its 80 cu ft at 3300 or at 3000?

 

[DIR-Atlanta]

I'm looking at putting together a set of double AL 80's. Are the slightly heavier "neutrally buoyant" AL 80s a good choice? worth the extra $100 for the pair? As a side benefit, looks like the working pressure is 3300 lbs (according to scuba toys web site) does this mean its 80 cu ft at 3300 or at 3000?

Stick with the regular AL80s - they are more versatile (can also be used as stage/deco bottles), and provide a better safety margin for diving in a wetsuit (do a SB search on "balanced rig" for more details on this). If you want to make them more negative, you can always add a V-weight, which will run you less than the extra $100 you will spend on the NB80s.

 

[mfalco]

Most shops will fill them to 3000psi anyway.

I think I read somewhere that the neutral 80 have weight added to them, so it should be a lot cheaper to just add the weight to your belt.

 

[Flightlead]

Stick with the regular AL80s - they are more versatile (can also be used as stage/deco bottles), and provide a better safety margin for diving in a wetsuit (do a SB search on "balanced rig" for more details on this). If you want to make them more negative, you can always add a V-weight, which will run you less than the extra $100 you will spend on the NB80s.

why couldn't I use a "neutrally buoyant" 80 as a stage/deco?

by "margin for safety" I assume you mean that I could ditch weight to become positively buoyant? I'm actually working the other direction on my steel doubles rig - thinking that being OOA/air sharing and accidentally ditching weights when I have a deco obligation would be worse than the alternative - being a few lbs heavier than neutral due to carrying extra gas and having a torn wing.

v-weight costs me nothing - I operated a lead foundry this weekend - melted down about 70 odd lbs of wheel weights in my driveway - I wonder what the neighbors thought

 

[Flightlead]

Most shops will fill them to 3000psi anyway.

I think I read somewhere that the neutral 80 have weight added to them, so it should be a lot cheaper to just add the weight to your belt.

supposedly they have a thicker wall which also accounts for the higher pressure

 

[DA Aquamaster]

I have never understood the neutral 80 doubles argument from anything other than the perspective of having tanks similar in weight to your other steel doubles - and then it makes more sense to get more steel doubles as the cost differential is slight.

For stage use, the regular AL 80 is nice as it is not overly negative when full and it trails along nicely behind you when empty and is more or less neutral when empty when you inlcude the reg and the stage strap.

If you go the neutral 80 route, it is possible you could remove some lead weight, but then removing or handing off the stage to an OOA buddy would leave you positive at the deco stop so it actually limits your options. Most tech divers with steel doubles are not in need of adding lead weight anyway, unless the water is very cold with a comensurate increase in insulation, and in that case adding a V weight makes more sense than using heavier stages.

I tried a steel 72 as a stage once - only once - as even though it is essentailly neutral when empty, like a neutral 80, in practice that is a 3-4 pounds negative when fully rigged and empty and 8-9 pounds negative when full so it just does not handle as well underwater.

 

[WD8CDH]

The N80 is only about 1/4" shorter and weighs about 3 or 4 pounds more. If you add 3 or 4 pounds to each regular 80, then they will weigh the same and have the same buoyancy and you will be $100 less poor. I wouldn't buy an N80 unless it was the same price or cheaper than a regular 80.

 

[Bismark]

On a recent project in Truk lagoon our team had to use neutral al 80's and they suck. As doubles, they didn't trim out worth a damn and by the time you got trim weight to where you wanted, they were too negative. We also tried them as a stage bottle and that was stupid too. They hung down when empty and swung back and forth like pendulums. We finally went through all the al 80's the shop had and cobbled together enough gear for our trimix dives. If I never see another one of those bottles it will still be too soon....... Once we we went to send our stages up the upline and even practically empty, they just hung on the up line and bounced....

 

[The Kraken]

I'd just put in a little extra dough and get two HP 100's.

Extra gas and they'd fit Bugtiff quite nicely as singles and then, when you really did NEED to dive doubles, you could double them up.

the K