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tonka97
08-20-2007, 15:02
Are double HP steel 100s suitable for cave diving, or will they create a head down diving position, versus horizontal trim?

I have read where they are excellent for shorter divers, but wonder about cave diving.

cummings66
08-20-2007, 18:54
It really depends on the person more than anything else. Get your trim right and it won't matter, you can always shift things around. Well, maybe some people would have troubles. It's almost one of those try it and see what happens things.

CompuDude
08-20-2007, 19:36
Are double HP steel 100s suitable for cave diving, or will they create a head down diving position, versus horizontal trim?

I have read where they are excellent for shorter divers, but wonder about cave diving.
I think you're thinking of HP80s. Those are hard to trim out for anyone not shorter. HP100s make excellent doubles for nearly every application, and the vast majority of divers can trim them out no problem.

As to whether they are "suitable", well, every dive has different parameters. Eventually you may want or need more to do deeper penetrations, but I guarantee if you're just starting out it will be quite some time before you outgrow a pair of HP100s.

tonka97
08-20-2007, 20:53
Are double HP steel 100s suitable for cave diving, or will they create a head down diving position, versus horizontal trim?

I have read where they are excellent for shorter divers, but wonder about cave diving.
I think you're thinking of HP80s. Those are hard to trim out for anyone not shorter. HP100s make excellent doubles for nearly every application, and the vast majority of divers can trim them out no problem.

As to whether they are "suitable", well, every dive has different parameters. Eventually you may want or need more to do deeper penetrations, but I guarantee if you're just starting out it will be quite some time before you outgrow a pair of HP100s.

Thanks for all replies. I purchased HP100s (Worthington X7-100s from Scubatoys...note: each HP100 steel tank is only 1.3 pounds heavier than AL80) and am awaiting delivery of drysuit.

tonka97
08-21-2007, 07:46
The discussion that led to my posted query:

"Double steel HP100s position too much weight on the upper part of your body, and you will be struggling to maintain horizontal trim during cave diving, as compared to double LP85s. These (LP85s) are lighter, and can be overfilled 10%, providing nearly the same amount of gas as the HP100s. The LP85s are longer (avoiding excessive weight toward the divers head) thereby enabling the cave diver to better maintain the necessary horizontal trim. Skilled cave divers who use double steel HP100s are essentially non-existent".

BTW: I have just learned that the older steel HP100s weighed 36.4 lbs empty, compared to the newer manufactured tanks that weigh only 33 lbs empty. Perhaps that 3.4 x 2 = 6.8 lbs difference for doubles contributed to the initial criticism of steel HP 100s.

By contrast the empty weight of the OMS LP85 is listed at 31 lbs.

Old Double steel HP 100s: 72.8 lbs.
Newer Double steel HP 100s: 66 lbs
Double steel LP 85s: 62 lbs

CompuDude
08-21-2007, 10:22
The discussion that led to my posted query:

"Double steel HP100s position too much weight on the upper part of your body, and you will be struggling to maintain horizontal trim during cave diving, as compared to double LP85s. These (LP85s) are lighter, and can be overfilled 10%, providing nearly the same amount of gas as the HP100s. The LP85s are longer (avoiding excessive weight toward the divers head) thereby enabling the cave diver to better maintain the necessary horizontal trim. Skilled cave divers who use double steel HP100s are essentially non-existent".

BTW: I have just learned that the older steel HP100s weighed 36.4 lbs empty, compared to the newer manufactured tanks that weigh only 33 lbs empty. Perhaps that 3.4 x 2 = 6.8 lbs difference for doubles contributed to the initial criticism of steel HP 100s.

By contrast the empty weight of the OMS LP85 is listed at 31 lbs.

Old Double steel HP 100s: 72.8 lbs.
Newer Double steel HP 100s: 66 lbs
Double steel LP 85s: 62 lbs
Perhaps that's it.

The quote is really amusing especially since AG has been quoted as saying "HP100s make the perfect doubles".

hydro
08-21-2007, 14:18
There are always other things you can do help trim out, even in HP100s that some might say traditionally incline a head-down position; wear more negative fins (jets), get some trim weight on a weight belt, move your wing up (towards your head) a bit, etc.

Enjoy your new tanks!

tonka97
08-21-2007, 14:54
There are always other things you can do help trim out, even in HP100s that some might say traditionally incline a head-down position; wear more negative fins (jets), get some trim weight on a weight belt, move your wing up (towards your head) a bit, etc.

Enjoy your new tanks!

Thanks for the replies!

I am enjoying this forum. Thanks Scubatoys!

ScaredSilly
08-21-2007, 15:53
Also check the bouyancy specs - some are also very negative. Faber has two versions of HP cylinders, Worthington only one.

tonka97
08-21-2007, 17:19
Also check the bouyancy specs - some are also very negative. Faber has two versions of HP cylinders, Worthington only one.

Worthington HP X7-100 : Buoyancy: Full -10 Empty -2.5
Doubles: Full -20 Empty -5 lbs

OMS Steel LP 85: Full -6.7 Empty 0.0
Doubles: Full -13.4 Empty 0.0

Faber Steel HP 100: Full N/A Empty 7.26
Doubles N/A Empty 14.5 lbs

Big difference in the Faber and Worthington Doubles Steel HP 100s: 9.5 lbs!

ScaredSilly
08-22-2007, 09:51
Go here for Faber specs:
www.bluesteelllc.com

Here for Worthington:
www.xsscuba.com

WaterRat
08-23-2007, 17:30
Tech Diving Limited has a sexy spec page. They list a ton of tanks.

http://www.techdivinglimited.com/pub/tanks.html

Ron

ScaredSilly
08-24-2007, 09:46
It is a nice page but some of the specs are not correct/current.

in_cavediver
08-24-2007, 12:04
I know several somewhat accomplished cave divers who dive the old PST HP100's. My wife has 85's and dives caves. I've dove the HP100's in a cave without problems as well. Any tank will work, if you get can trim them out for your body. Tanks are merely a tool to dive.

Now, the question is can you get good trim in HP100's?
Play with them and find out. My guess is that you can.

willardj
08-24-2007, 12:16
Any double's will work fine as long as yur body type trims out well. I like my lp95's myself.. more than enough gas. exp. with a good cave fill.

CompuDude
08-24-2007, 14:16
Any double's will work fine as long as yur body type trims out well. I like my lp95's myself.. more than enough gas. exp. with a good cave fill.
Just about any doubles will work, period, some just present more a challenge to trim out than others.

The only exception I've heard about is the HP80s... they're so extremely short that taller divers, even experienced ones, sometimes have problems trimming out with them.

Any other size tank is going to be roughly the same height within a few inches, so pretty much all other tanks will work fine for anyone not on an extreme end of the height spectrum.

caroln
08-28-2007, 17:20
So Compudude, would those HP 80's be a good choice for a shorter diver since they are typically too short for a taller diver?

CompuDude
08-28-2007, 19:36
So Compudude, would those HP 80's be a good choice for a shorter diver since they are typically too short for a taller diver?

Everyone is different, and there are no hard and fast rules.

That said: Most likely yes. They are very popular with shorter divers for that very reason... and unpopular with taller divers for the same reason.

tonka97
08-28-2007, 20:41
So Compudude, would those HP 80's be a good choice for a shorter diver since they are typically too short for a taller diver?

Everyone is different, and there are no hard and fast rules.

That said: Most likely yes. They are very popular with shorter divers for that very reason... and unpopular with taller divers for the same reason.

Thanks CompuDude!

This has been a fruitful thread.

:smiley20:

caroln
08-30-2007, 12:02
How much shorter are HP 80's then HP 100's?

CompuDude
08-30-2007, 16:24
How much shorter are HP 80's then HP 100's?
About 4.5", which doesn't seem like much until you see the two side by side. Just under 20" is darned short for a tank.

Specs for all of the tanks were linked above, btw.

caroln
08-31-2007, 08:51
About 4.5", which doesn't seem like much until you see the two side by side. Just under 20" is darned short for a tank.

Specs for all of the tanks were linked above, btw.

Thank you! And sorry I missed the stats first time around. I'm not ready for doubles yet, but I'm buying my first tank this week, and I want to get something that I can eventually double up when I get to that point, so this is very valuable info. I'm also 5'3, also 4.5 inches is quite a lot to me.