Tank Advice - First Time Buying

[ScubaSpicher]

I am looking to buy a set of tanks. I dive primarily in the NE and definitely want steel tanks, but cannot settle on a size. Here is a little about me...

Just switched to a BP/W setup and plan on getting into tech (primarily deep/wreck) diving in future. Until I am ready... have the equipment and experience... I want to use the tanks separate, probably for at least a year or so. Therefore, I will probably be doubling the tanks in the future. I am not really concerned much about the weight of the tanks as I am 6'3" and a relatively fit 235lbs.

So finally to the point... what tanks would you recommend for me and why? Thanks!

 

[Puffer Fish]

A lot depends on the type of diving you do, your sac rate and who you are diving with.

I own 100's, 117's and 149's...all HP....I use them for the following types of diving:

1. Boat dive with insta-buddy... they usually pair me with a newer diver, so I know I don't need a large tank (we will be diving their profile), so 100's it is. Lighter and slightly smaller than Al80, they are easy to handle.

2. Shore diving.. with a long walk.. 100's again.

3. Boat diving with people with silly low sac rates... I use the 117's (I would suggest that for you, the better one would be the 120 in the 7.25 diameter tank). I know several woman that I will never be as low as.

4. Diving with others using large tanks... the 149's (120 thru 149 will all work)...you have to worry about deco.. but long nitro dives are easy to do.

In the keys this year, on each boat trip, I used one 149 for both dives...because getting fills quickly is difficult there, and I was diving both morning and afternoon...one tank in the morning, one in the afternoon...

If I were planning on making doubles out of the tanks later, the really big ones can sort of become silly, pretty fast (300 cubic ft of gas with two 149's is a lot of weight change).

What to buy first? I would evaluate the type of diving I was expecting to do... and how I expected to use air compared to others and pick a size... I would bet it would be between 100 and 120 in the 7.25 tanks.. then find the best deal...

 

[littlejohn]

I would say go with the HP 100's
They are a great size and trim out great.
200 cf is a nice setup for tec diving

 

[stairman]

I agree with Little John on the hp100's.You can have a lot more gas with bigger lp's but some shops wont overfill them.The hp's are stamped 3400 psi.

 

[ScubaSpicher]

Thanks for the replies everyone! So a couple more comments / questions. I'll assume for now, since most of my diving is done helping classes, that for the single tanks I use do not have to be very large since most people will have higher SAC rates. On the other hand as I begin to switch over to tech I believe most people that I dive with... in the beginning will have lower rates, so I would want slightly larger tanks.

Anyway... have you ever experienced shops that are not able to fill a HP tank to stated pressure? I have heard arguments that it happens, but do not think any shops I have seen would have that issue.

Also, is there a reason you are all suggesting tanks with 7.25in diameter and not the larger 8in diameter tanks?

Lastly, have any of you dove with the 120's that are 7in in diameter? I would not want a tank that hits my legs or head, but being 6'3" would they be too long?

Thanks again!

 

[dcs917]

Another vote for the HP 100's. I have 2 Worthington 3447 psi steel 100's and really like them. The bouyancy characterictics are great, but if you plan on doubling them it is a lot of weight.

 

[Steve_Dives]

A friend let me dive her double HP100's. (They weigh almost as much as she does.) It was a dive easily done on a single AL80 (like the one my buddy wore). They felt pretty comfortable on my 6'0" semi fit frame. I don't have any experience with other doubles, so please don't rush out and buy anything on my advice!

 

[spectrum]

Anyway... have you ever experienced shops that are not able to fill a HP tank to stated pressure? I have heard arguments that it happens, but do not think any shops I have seen would have that issue.

There are some shops and notably boats that cannot deliver pressures to fill the 3442 psuedo HP cylinders. So far I have not run into one and I dive almost exclusively 3442 & 3500 cylinders but they surely do exist.

Secondly HP steels get beat up for cooling losses. This will vary with the fill operators skills and methods. If you are getting an on the spot fill it's almost impossible to avoid having a few hundred PSI of loss when things cool to 70F after 4 hours. Some shops will fill them to a slightly higher warm pressure so they cool down close to spec.

From what I see HP steels get a bum rap on this one since I regularly have buddies with AL80s show up with 2700-2800 in their 3000 PSI cylinders. It is certainly true that a LP steel cylinder will be less at the mercy of Charles Law but even they see some shrink.

In any event with the HP100 being smaller, lighter and with better buoyancy properties than an AL80 being short a few 100 PSI is no big deal.

If you can leave they cylinder at a shop most will do a top-off when they cool and provide perfect fills.

Also, is there a reason you are all suggesting tanks with 7.25in diameter and not the larger 8in diameter tanks?

Generally length is your friend when it comes to trim so the stouter 8" cylinder is not always favorable. It also raises your center of gravity and needs to punch a bigger hole in the water. Finding used twin hardware is probably harder too.

If you are stout the 8" starts to make sense.

Pete

 

[Lightning Fish]

I am looking to buy a set of tanks....

My biased suggestion would be HP 130s. I'm 6'2" and I trim out beautifully in my single 130. And getting out after a 60 min dive with 1000 or more psi still in the tank, again, beautiful. There is nothing wrong with having an excess amount of gas.

Almost forgot to add, 8" or 7.25", who cares. It's a hassle having to adjust my bands when I switch between my HP130 and a rental Al80. But who cares. If you're buying two, then you won't have that problem.

Cheers,
Bill.

 

[rcpilot44]

I second the 130s. I used to be the first out of the water. Now I am one of the last out of the water. I dove last week off the coast of Morehead City NC and even with 30% I was running out of bottom time and not having to surface do to low nitrox.