Question for steel tank aficionados

[Brent Bowman]

I have been using HP 100 steel tanks for awhile and think they are the greatest thing ever. I have been thinking about adding another steel tank to the fleet and was thinking maybe a HP 117 ? So what's it like to swap back and forth between a HP 100 and a HP 117 just based on personal experience? Am I going to have to change my weighting much to swap back and forth between the 100 and the 117? I use about 6 lbs of weight now because we mostly shore dive and I like to be able to swim back in to the beach underwater with not much air left.

Thanks for input on using a HP 117 steel tank.

Thanks again,
Brent Bowman

 

[tmassey]

When my 120 empties out I think it’s lighter than the 100 in the water. Same wall thickness but bigger air space.

That’s the part everyone forgets/doesn’t understand. Dry weight is irrelevant — except schlepping the tanks around to the water. Full buoyancy is irrelevant — except making sure your BCD has enough lift to hold your head up in the beginning. *Empty* buoyancy is the only thing that matters for weighting: you need enough lead to hold you down on your safety stop with empty tanks (and fully-fluffed exposure suit).

And usually the empty buoyancy difference between *any* two tanks is measured in low-single-digits.

So anyone who says “I could drop 8 pounds when I moved to steel!” is just bragging about being previously-overweighted…

Just make sure you understand what the manufacturer means when they say “buoyancy empty”: sometimes it includes the valve and sometimes it doesn’t. But even that only makes ounces worth of difference.

 

[gmerick]

117 Tank is 3.5 lbs heavier, it holds 2lb more air, and when empty is 1 lb more buoyant than the 100. Add 1 llb to your rig when changing tanks. the buoyance center hardly changes, so you may be able to compensate with no weight change.
Schlepping: 6 lbs more weight to carry.
I regularly switch between 2 HP117's and 2 AL80's. That's where notes come in handy. Center of buoyancy as well as total weight carried changes a bunch. (I add 6 lbs of lead with the AL80s, I switch BC's, because the HP1117's require more lift than my tropical rig can supply.)

 

[Eric Sedletzky]

Cam bands seriously, I used to be scared of cam bands, you can't get them properly tight, without removal from the last two slots anyway for a good pull and feed you should learn them backwards

Would be a legit padi course

Cam band torquing specialty.
$199 and a test. Would you have to do a dive too?

 

[InWay2Deep]

I would suggest another HP100, I agree, they are awesome tanks, then you have 2 which you could later turn into a set of doubles.

 

[-JD-]

Cam band torquing specialty.
$199 and a test. Would you have to do a dive too?

Yes. 10m/30'

For PADI This is part of the Rec-Tec tier of classes ...
You need to remove your 7-1/4" AL80 tank from the BC, adjust the Cam Band(s) and replace it with a racked 8" Heiser-190 tank and return the AL80 tank to the fill-rack. Proper procedure is to always verify that the exchange tank has a suitable valve prior to the switch and you should always maintain proper buoyancy control.

In the equivalent GUE twinset wingnut spinning class, it is a team exercise where the twinsets have to be exchanged simultaneously in a clockwise fashion among team members without exceeding a 20-degree trim or 0.5m depth variance. For the Tech-Pass, tools to disassemble and reassemble the twinset shall be carried in the wetnotes. It should go without saying that DIN tanks will be required, but gas mixtures must confirmed by the team prior to reassembly of the twinsets and reinstallation of the regulators.

 

[Bob DBF]

Cam band torquing specialty.
$199 and a test. Would you have to do a dive too?

Two dives with different diameter tanks. If either tank slides out you have to pay double and do the class over.

 

[NW Dive Dawg]

I have a steel 100 and a steel 120.
I swap no problem without having to add or subtract lead. The 7-1/4” diameter for both is nice.
I don’t personally care for 8” tanks.

This is exactly what my answer would have been!!

And the part about adjusting cam bands....... i just don't get at all....other than it could be a PADI specialty course.

PS...... 8 in tanks with a boot don't fit in my boats tank rack!

 

[34109411]

I have been using HP 100 steel tanks for awhile and think they are the greatest thing ever. I have been thinking about adding another steel tank to the fleet and was thinking maybe a HP 117 ? So what's it like to swap back and forth between a HP 100 and a HP 117 just based on personal experience? Am I going to have to change my weighting much to swap back and forth between the 100 and the 117? I use about 6 lbs of weight now because we mostly shore dive and I like to be able to swim back in to the beach underwater with not much air left.

Thanks for input on using a HP 117 steel tank.

Thanks again,
Brent Bowman

sometimes i use 119 with 4 pound of led. i might i could have 0 led at all and sunk like a wreck. if you go with the 117 drop two pounds.

cheers

 

[MidOH]

If you already have 100's, get a pair of 133's.

You can use an STA, and get another STA and cam bands for what? $60?

One STA for skinny tanks, one for fattys.

 

[chrisjur]

The biggest pain is not the weighting difference but rethreading your cam bands with each change. HP 117s are 8” diameter tanks and HP 100s are 7.25”. Doesn’t seem bad but believe me, it becomes a PITA. Stick with one diameter tank. You’ll be much happier.

I think it all depends on what your setup is. I use a Scubapro Super Cinch tank bank and move pretty effortlessly from AL80s to HP100s to HP117s. I've never even thought of this as being a potential issue. However, I guess it can be given your specific setup.