Going from AL80 to HP100

[hammet]

So taking off 6lbs of weight off the weight belt is about right?

 

[Diver0001]

I would think so. You'll need to do a buoyancy check but roll with that idea.

R..

 

[tbone1004]

So taking off 6lbs of weight off the weight belt is about right?

which HP100?

 

[hammet]

Um, I guess the most common HP100???

Going to a dive in Florida next month again. Last time I did, every one on the boat dove with hp100s I believe. I was doing nitrox with an AL80 but ran out of air too fast to the dismay of my duly assigned buddies. Never dove with steel before so when they asked me what tank I wanted when I signed up, I just assumed everyone was going to use AL.

 

[tbone1004]

Um, I guess the most common HP100???

Going to a dive in Florida next month again. Last time I did, every one on the boat dove with hp100s I believe. I was doing nitrox with an AL80 but ran out of air too fast to the dismay of my duly assigned buddies. Never dove with steel before so when they asked me what tank I wanted when I signed up, I just assumed everyone was going to use AL.

If it's a Worthington you can actually take about 8lbs off of your belt, PST is about 6, but if it's Faber, it's only about 4, so the brand does matter.

 

[Diver0001]

Just make sure you have time to do a buoyancy check. If there is any way you can arrange to make a quick (shore) dive the day before you go out with the group then you'll be able to sort it all out without all the deep sighs and rolling eyes of people who feel inconvenienced by your need to follow proper procedure.

"Real divers" will have all the patience in the world for that but unfortunately tourists who dive from boats often feel that the fact that they paid makes them the most important person on the planet.

R..

 

[hammet]

If you do a pre-dive buoyancy check (full tank) how much to you add to account for the air you use? I believe AL80 is about 5. Is it about the same for a HP100 or maybe a lb or two more?

 

[tbone1004]

If you do a pre-dive buoyancy check (full tank) how much to you add to account for the air you use? I believe AL80 is about 5. Is it about the same for a HP100 or maybe a lb or two more?

roughly .08lbs/cf. At the real high pressures it's not always linear, but like deco calculations, we are measuring with a micrometer, marking with chalk, and cutting with an axe. AL80 is 6lbs, HP100 is 8, HP120 is 10 and that's close enough for government work
AL80=77.4*.08=6.2
HP100=100*.08=8

 

[hammet]

Cool... One more question...Since you're good at scuba math....

How much more air, percentage wise, is a hp100 at 3440psi vs. a 77.4cf AL80 at 3000psi?

 

[uncfnp]

Edit. New question asked while typing