Big guy... big tanks?

[prunefoot]

Some dive operators, including live-aboards, may have a few 100 cf tanks around; websites won't always mention it and they may be 1st come, 1st serve, so ask well in advance.

But maybe you'd like destinations that offer big tanks routinely? For 120 cf steel tanks?

1.) Cozumel - Aldora, Living Underwater, Liquid Blue Divers.

2.) Jupiter, Florida - Jupiter Dive Center.

3.) Morehead City, North Carolina - Olympus Dive Center.

Jupiter and off-shore NC diving are pretty deep, with much of the dive spent deep and nitrox is advised. Here are a couple of trip reports - Jupiter, Morehead City. There are likely others; I'm just posting ones I know about.

Richard.

Great info! I will check out the trip reports.

 

[prunefoot]

When I first started diving, my gas consumption was terrible. I was turned on to sidemount (SM) and absolutely loved it. Not only does it give you double the gas but also redundancy. As others have mentioned, in some parts of the world you will be limited to one size cylinder (ie. Al 80) so a larger single cylinder may not always be an option.

I enjoy not having to rely on a buddy, especially when paired up with a complete stranger. This gives me freedom underwater as well as I don't have to worry about staying close to my redundant gas (buddy) as it is always within arms reach.

The extra gas may also relieve the stress of trying to control your high gas consumption. My best advice is to not concentrate so much on your breathing but to try to relax and stay calm while diving. Improved consumption will come with experience.

I only dive SM now, including open water. It was great to have on my recent Raja Ampat liveaboard. While the rest of the single backmounters ran low on gas and had to go up, I got to stay down and play with the mantas for an extra half hour. If you're interested, there are many agencies that offer a recreational SM course.

Many of the responses recommend side mount. I'm definitely going to look into it. thanks!

 

[prunefoot]

Prunefoot. You don't need as big of tank as you may imagine. the 115 is a good recommendation.
the al80's have actually 77 cuft in them. so at 500 psi they have round 16 cuft so you have 60- cuft to use on the dive. So to get a tankand subtract about 15-17 cuft should give you tha amount of usable air on the dive and still come up soth around 4-500 psi. Given that a 130 will give you twice the dive air than the al80 a 108 would give you an extra 50%. Look at the huron tank specs at weight. the al80's are about 35# the al100 about 45# the lp108 about 41 the lp120 45#. And yes many will over fill if you ask them to. a 3k fill on a lp tank is normal to find. that would make a lp108 hold in the 120's. That little bit of over fill is about 13% more air (2640-3000)

Here is a link Scuba Cylinder Specification Chart from Huron Scuba, Ann Arbor Michigan

look at the oms 121 and 135. the oms 121 is actually 125 and the list says the 135 is actually a 131. Even at an normal fill the 121 is right at twice the air of a al 80. I have 3 oms121's among others. Dive in shallow lakes all day with them. One place I go to fills are 8$ whether it is a 30 of a 150 tank. Buoyancy's all all negative -1>-10 to start with. Since the -1 is all that counts you can off load perhaps 4# from using al80's. If you go to a BPW you wont need much lead at all.

I normally use lp95's a bit short but I am 6' and 260# there is a drastic difference In the amount of air In a lp95 filled to 3k. (108) AND A AL80 AT 77.
I suspect carrying another al40 is not the thing for you to do at your experience level.

One other thing ..... Do you know what your sac is. If it is bad it should improve in time and ease the problem.

Thanks! Great info. I do not know what my SAC is. I need to test it on my next dive. That is a great chart, thanks for the link.

 

[prunefoot]

Something else to think about. Most people use al80's because they are the most available tank there is. when you dive at home in FW you know before you board that plane how much weight you are going to need when you get to coz. its 1# for every 30-40# of you fully rigged. Start changing tanks and set suits and it gets more difficult to get the weighting close to get the max for you diving buck. Here is an example. I dive with a lp95 in fw with a shorty and I need no weights. I goto coz wit no suit and I need 16# and 21 if I wear the shorty with their al80 tank. scaled out rigged I am about 330# that should take 8-11# with my same gear. now a al tank 4# more buoyant and no suit should be a wash but it takes 14-16# of lead.With my same FW gear on a boat in coz like waters I put on 8# and I am good. That works out to 1# for every 40 for me.

More great info... i can see altering weights and buoyancy being a pain. On my first dive... the "try scuba dive" I did at Chankanaab on Cozumel. Holy bouncy batman! It was myself an a group of people from Texas that came in on a cruise ship, were were staying at the Cozumel Palace. The guys running the dive ran out of weight and wound up stuffing rocks in the BCD I was using. But it got me hooked!

 

[The Chairman]

Side mounting on a boat can be a PITA for the crew having to carry four tanks on the boat instead of two. I've done it on liveaboards with great success, but I doubt I would do that at a resort.

 

[tbone1004]

big dude as well, 6'4" 280, mostly solid.
I don't mind 130's, but they're a touch short for me if I had to choose. I have a short inseam at 32" so take that with a grain of salt if you're normally proportioned

So, pros and cons. If said shop in PCB will fill low pressure tanks to 3500-3600 psi, call and ask, then you're golden, get PST 104's, and call it a day. You'll find plenty of them around. They sink like bricks as well so you'll be able to take 8lbs off of your weight belt vs an al80. Hows that for efficiency? Combine that with a SS bp/w and you'll have 0 lead, 2x the gas if they fill them up completely, and essentially identical in weight on land to a jacket bc with al80 and a weight belt. How about them apples?

Realistically though, 104's are not the best balance for capacity/weight, and they're obnoxiously heavy. My favorite "tall person" tanks are the PST HP120's which are tall and skinny, give you a roughly 6lb buoyancy advantage over an AL80, but are 7lbs lighter than a 104. Part of this is also going to be a balance of cost/fill along with efficiency of use. If you have your SAC rate vs. that of your wife/daughter, you'll want to balance that ratio to your tank selection. If you don't have that specifically, if you had to turn the dive and you got on the boat with 500 psi, and they came up with 1500psi, then to balance that you need a tank that's ~1.6x as large to balance out. That's going to be roughly a 120cf tank. Any bigger and you're probably wasting money on fills if they charge by the fill instead of the cubic foot, and you're probably also carrying around more weight than necessary, especially since you had to go to an 8" diameter tank instead of 7.25". The extra two downsides to that are the boats may have their racks set up to only fit 7.25" diameter tanks, in which case the 8" won't fit, as well as the extra factor of having to readjust your cam bands if you want to dive AL80's. Not a huge deal, but I find it annoying enough to not want to deal with it

When you are looking for tanks, I'd highly recommend hunting around for used tanks as you'll save quite a bit of money, and look specifically for either PST or Worthingtons since it sounds like most of your diving is going to be in the ocean, and in my experience, they hold up quite a bit better than Fabers with salt water.

I will echo @NetDoc 's comment on sidemount probably not being appropriate for this. Going to a larger steel tank will be easier/more appropriate for this kind of issue than switching to a completely new style of diving

 

[AJ]

Big tank will help, sure. But a better way is to get your sac down. It's not because you're a big guy you use a lot of air. It's because you inhale a lot of air When I started diving I inhaled deep and fast. Now I inhale slow and shallow because I'am really comfortable under water. I'am even able to keep up with some women while being a tall guy.

My advice: relax and enjoy your dive. Don't focus on breathing, don't try to keep your breath or even try to breathe shallow. It will get better in time as you relax.

 

[Caveeagle]

...get PST 104's, and call it a day. You'll find plenty of them around. They sink like bricks as well so you'll be able to take 8lbs off of your weight belt vs an al80.

I have a set of the PST 104s and 100% agree with tbone on this. I am 'only' 6'2" and ~270, but do tend to use up some gas.. In salt water, I can dive a 104 with a steel backplate & 3mm suite and just 2# of weight so I am not floaty at the end..

For Fresh water.. I have found my PST 95s and 104s to be over-heavy with a steel plate and have switched to an alum plate (wetsuit).

Now recently, I have started diving Faber LP108s (doubled) in fresh water and really like these. Not as heavy as PST tanks and with a 3mm or 5mm and alum plate, they are just about perfect.

For the OP.. I suggest trying out a couple combinations before you buy. If you get too heavy.. the extra air in your bc will become a pita.. and your buoyancy could suffer.

 

[bamafan]

I like the lp 120's and really like my lp 131's for single tank spearfishing. I can easily do 2 dives in the 120 - 130' range with no problem. It helps on a boat to be able to carry fewer tanks.

I agree with Aj in that working on your sac rate will help but a big person will never be able to keep up with an equally skilled small person. I had an old time cave diver tell me to just not breathe as much. There are things you can do that will probably get you close to your wife but if she tried the same as you it won't even be close. I have heard that we only use about 25% of the O2 in each breath so it just stands to reason that the bigger your lungs are the greater the waste factor.

 

[bamafan]

Overfilled... interesting. So far, all of my experience has been with Pat's shop (PCDiving) and it has been great. He has a great crew with great instructors. I'll give a shout out to Chris, who was my OW, AOW, and Nitrox instructor, and Travis, who instructed my wife and daughter for their OW cert. He had a hard time with my wife stressing out, but he was patient and got her through it. We dove with them all week. Attached is a pic of the boat crew, a spearfisher named Ken, and our 3 person group.

Edit: which shop is Rob's?

Rob is Chipola Divers and Edd is Cave Adventurers. They are in the Marianna area and cater to the cave diving crowd but either are ow friendly. They are about 1.5 hours north of PCB. You could stop on the way down or the way back.