18L Steel Tank - advice needed

[David Novo]

I know you said.you didn't want to discuss your high gas consumption rate but I'm.going to anyway.

According to your profile, you've done less than 100 dives, so the reason your consumption is high is probably because you're not very comfortable, balanced and in trim in the water.

That being the case, about the worst thing you could do is take a huge tank in that will make your trim worse. Twins won't be any better either.

Your consumption will come down the more you dive and the more comfortable you are in the water. That will happen quicker with simpler kit

When I did fundies, my instructor told me that my trim was not an issue at all and that I could afford to sacrifice it a bit to be able to increase general awareness.

Just for the sake of clarity I am not planning to buy ANY tank: just trying to understand the pro's and con's of the options I have to rent on my next liveaboard.

 

[jaseUK666]

When I did fundies, my instructor told me that my trim was not an issue at all and that I could afford to sacrifice it a bit to be able to increase general awareness.

Just for the sake of clarity I am not planning to buy ANY tank: just trying to understand the pro's and con's of the options I have to rent on my next liveaboard.

So why do you think your gas consumption is high?

18s are huge and they weigh a ton. A UK dive shop used to have twin 18s on display and you could barely lift them. Don't think they ever sold them. I've never really found the need for anything bigger than a 12 on average liveaboard diving and I'm not going to win any awards for fitness or slimness. The more stuff you've got on, the harder you're making it

 

[David Novo]

So why do you think your gas consumption is high?

18s are huge and they weigh a ton. A UK dive shop used to have twin 18s on display and you could barely lift them. Don't think they ever sold them. I've never really found the need for anything bigger than a 12 on average liveaboard diving and I'm not going to win any awards for fitness or slimness. The more stuff you've got on, the harder you're making it

I am naturally stressed and tend to have a higher SAC with smaller tanks (due to the notion of higher gas constraints).

 

[Celt]

I am naturally stressed and tend to have a higher SAC with smaller tanks (due to the notion of higher gas constraints).

Are you worried you’ll use to much gas and cut the dive time on your buddy, you need to relax diving is about having fun slow down and stay a little above your buddy you’ll use less.

 

[David Novo]

Are you worried you’ll use to much gas and cut the dive time on your buddy, you need to relax diving is about having fun slow down and stay a little above your buddy you’ll use less.

That complicates diving as a team considerably. Specially for my buddy...

 

[Schwob]

Can’t really help you with your 18l vs. 15l tank question. No first hand experience with an 18l.

People keep saying one should be 1,9m tall before even considering that long a tank. Well I am 1,83 m (6, even), I played a little with HP120s (single and double) and the length of those was fine for me. I think they are about the same length. Not speaking to trim, just to dealing with tank length. I did not like carrying them to refills as I could not leave my arms straight or they would touch the ground, so, bent arms or cradling them (or on the back with doubles). But no issue with them on the back. The point here: The length of your back may matter more than how tall you are (I sit a lot taller than most of my standing height).

Just fix your gas consumption already, will ya!
I hear that a lot too. I still suck a lot of air. Noticeably less when truly relaxed of course, but getting there takes me 1/3 rd of the dive ... or more when feeling responsible for a kid or my wife diving with me. It’s just how it is and in my case trim isn’t to blame or at least not anymore... and I so far neither figured out how to relax faster nor did I come across any advise that would help with it... but still listening... but it sure is amazing how much less my consumption gets later in the dive... wish I knew how to start the dive that way.
The point here: Don’t stress out over your air consumption. Not worth it and just costs more air yet. It will improve when it does and not before then and maybe not as much as some people think it should... Use the volume of gas you need or you can get and enjoy the dive. You know what you need now, so use that for diving now.

Swimming up... you are thinking the right things. You should try (safely) to see what you can trust yourself to swim up. You also have further options other redundancies if need be - you carry a reel and a DSMB or?

 

[runsongas]

@Schwob the 18 liter faber is 150cf and roughly the same size/weight as the e8-149 PST iirc

 

[David Novo]

Can’t really help you with your 18l vs. 15l tank question. No first hand experience with an 18l.

People keep saying one should be 1,9m tall before even considering that long a tank. Well I am 1,83 m (6, even), I played a little with HP120s (single and double) and the length of those was fine for me. I think they are about the same length. Not speaking to trim, just to dealing with tank length. I did not like carrying them to refills as I could not leave my arms straight or they would touch the ground, so, bent arms or cradling them (or on the back with doubles). But no issue with them on the back. The point here: The length of your back may matter more than how tall you are (I sit a lot taller than most of my standing height).

Just fix your gas consumption already, will ya!
I hear that a lot too. I still suck a lot of air. Noticeably less when truly relaxed of course, but getting there takes me 1/3 rd of the dive ... or more when feeling responsible for a kid or my wife diving with me. It’s just how it is and in my case trim isn’t to blame or at least not anymore... and I so far neither figured out how to relax faster nor did I come across any advise that would help with it... but still listening... but it sure is amazing how much less my consumption gets later in the dive... wish I knew how to start the dive that way.
The point here: Don’t stress out over your air consumption. Not worth it and just costs more air yet. It will improve when it does and not before then and maybe not as much as some people think it should... Use the volume of gas you need or you can get and enjoy the dive. You know what you need now, so use that for diving now.

Swimming up... you are thinking the right things. You should try (safely) to see what you can trust yourself to swim up. You also have further options other redundancies if need be - you carry a reel and a DSMB or?

Good that is a liveaboard, so carrying to fills is not an issue

I carry a reel and DSMB that for sure I could use on a wing failure scenario...

 

[Schwob]

@Schwob the 18 liter faber is 150cf and roughly the same size/weight as the e8-149 PST iirc

Yes.
And the length of a 149 cuft HP tank is a mere .2" longer than that of a 120 cuft HP tank (29.53" vs. 29.33") if comparing Faber to Faber, maybe a bit more up to 3/4" or so when comparing more across manufacturers. I tried to point out that in length they are comparable and that playing with HP120 tanks gave me the idea that for my back a HP149 tank (or 18l) would be manageable with it's length. The point was the length of one's back matters more than lhe length of one's legs... That said, I would not buy one myself simply due to it being too long for me to carry dangling on my arm. (Which on an LOB is a moot point)

 

[Doppler]

Yes, I am using the optimal buoyancy calculator spreadsheet that is on a sticky thread somewhere here. I have it calibrated for the configurations I usually use and was testing for the 18L tank.

Regarding trim, that is one of of my worries, hence the post. I will take that into consideration. Thanks

You're welcome. Whereabouts are you going to dive? Wherever have fun and good diving!