Thinking of doubling up my HP80s

[Marie13]

Tanks dropped off at shop tonight for VIP/doubles assy. Manifold I was given did not fit my valves. Threading was different. I'll sell that one. The one I bought wasn't too bad. I'm still way ahead with being given the wing - current model of the Dive Rite Rec wing retails for $329.

 

[rjack321]

hp80s are super short so unless your back length is also short they are hard to trim out. Most divers end up "popping a wheelie" in them. This is where you drop your knees and rear back your torso because there's too much mass up high. You end up looking head light but its just overcompensating for being head heavy.

 

[Marie13]

hp80s are super short so unless your back length is also short they are hard to trim out. Most divers end up "popping a wheelie" in them. This is where you drop your knees and rear back your torso because there's too much mass up high. You end up looking head light but its just overcompensating for being head heavy.

Yes, that has been repeated ad nauseam. As I have also repeatedly posted, I am 5’5”. I also tend towards being feet heavy so something that may put my head down is not a bad thing.

I used the same tanks for SM. People here swore up and down that I’d never get them to trim out. However, they trimmed out pretty decently.

These are the tanks I have. Some SB folks do not seem to understand the concept of making do with what you already have.

 

[Marie13]

OK, maybe this is a stupid question, but I can't find the answer...

All the analog SPG I have seen, even the "tech" ones, only go up to 5000 psi. I have 3442 psi service pressure tanks, so when I double them up, obviously I'm going to have over 6000 psi. I'm going to have both analog SPG *and* a Shearwater transmitter, on different posts (I *love* my AI and I seen no point in going without it). Will my Perdix register more than 5000 psi?

 

[KenGordon]

Yes, that has been repeated ad nauseam. As I have also repeatedly posted, I am 5’5”. I also tend towards being feet heavy so something that may put my head down is not a bad thing.

I used the same tanks for SM. People here swore up and down that I’d never get them to trim out. However, they trimmed out pretty decently.

These are the tanks I have. Some SB folks do not seem to understand the concept of making do with what you already have.

I suspect that these will work out pretty well, assuming an HP80 is essentially the same as a Faber 232 bar (3500psi) 10 litre cylinder. My other half dived a set of those in Scapa, one of our club regulars always dives them, another regular usually dives independent 10s.

You know that if you want to properly annoy the snobs you should dive them inverted

 

[RyanT]

All the analog SPG I have seen, even the "tech" ones, only go up to 5000 psi. I have 3442 psi service pressure tanks, so when I double them up, obviously I'm going to have over 6000 psi. I'm going to have both analog SPG *and* a Shearwater transmitter, on different posts (I *love* my AI and I seen no point in going without it). Will my Perdix register more than 5000 psi?

Marie: you'll be doubling volume, not pressure. When your isolator is open, together they'll still read 3442 (or whatever they're actually filled to) when full.

 

[Marie13]

Marie: you'll be doubling volume, not pressure. When your isolator is open on both tanks, together they'll still read 3442 (or whatever they're actually filled to) when full.

OK, thank you! I was coming at this from doing SM, which is probably why I was questioning it.

 

[Jack Hammer]

OK, maybe this is a stupid question, but I can't find the answer...

All the analog SPG I have seen, even the "tech" ones, only go up to 5000 psi. I have 3442 psi service pressure tanks, so when I double them up, obviously I'm going to have over 6000 psi. I'm going to have both analog SPG *and* a Shearwater transmitter, on different posts (I *love* my AI and I seen no point in going without it). Will my Perdix register more than 5000 psi?

Just to reconfirm, pairing tanks doubles the volume, not the pressure.

If you do find the HP80s difficult to trim or are just curious it should be fairly easy to find hp100s/lp85s locally to try out and see how they work for you. Those tanks are a little longer and only weigh a few pounds more.

 

[Jack Hammer]

OK, another question:

Is there anything special I need to do my first time in the pool?

Keep your waist belt tight, it's ok to have some slack in the shoulders. When first diving doubles occasionally some people experience a shift in weight pulling them to the side and some folks go full turtle, laying upside down on their backs on the bottom. Others are too head heavy and find themselves in heads down position like having feet full of air in a drysuit. Be mentally prepared, just in case.

Shifting is either your harness isn't adjusted properly or your doubles aren't securely attached to the plate. Stop and remedy this before continuing, it will only get worse if not addressed.

 

[guruboy]

OK, maybe this is a stupid question, but I can't find the answer...

All the analog SPG I have seen, even the "tech" ones, only go up to 5000 psi. I have 3442 psi service pressure tanks, so when I double them up, obviously I'm going to have over 6000 psi. I'm going to have both analog SPG *and* a Shearwater transmitter, on different posts (I *love* my AI and I seen no point in going without it). Will my Perdix register more than 5000 psi?

OK, thank you! I was coming at this from doing SM, which is probably why I was questioning it.

Even with sidemount you don’t combine psi. You have two tanks at X psi giving Y volume of air each.

During your dive, one tank might have 2500psi and one might have 3000psi. That is not the same as having 5500psi.

If for some reason you have one tank at 100psi and one at 2900psi and you signal to your buddy that you have 3000psi, someone is going to be very disappointed if you have to share air.