HP130 for lobster diving and spear fishing

[FloridaMan]

So I am at a bit of an impasse. I am just under 6 feet and 215 lbs. I am relatively fit, and the Army made me accustom to carrying a bunch of weight on my back . I will be doing boat and shore dives. One of the main reasons I got into diving was spearfishing, lobstering, and maybe some salvage. I have some interest in maybe doing deeper tech stuff, but I do not see that here in the immediate future. Also I am nitrox trained and any tank I get will likely be for Nitrox and be run on DIN. I do have a dive shop very close and can get AL80 nitrox rentals for $16. While renting for me is easy, I am thinking about getting my own tanks so I can stay down longer.

Originally I was trying to decide between steel HP100 and HP120's. I was thinking I would get two for any boat dives. I can say that I think I have ruled out HP120s, as I think they maybe a bit too long. I find myself occasionally hitting the back of my thighs on an AL80, so I am pretty sure an HP120 would be worse. So I was debating pulling the trigger on two HP 100's, but I had a few apprehensions about doing so. First, I do not think that on a charter running across people with similar air capacity would be common. Usually, on a charter and with AL80's, my dive buddy and I consume at the same rate or they consume a little faster than I do. If I cant stay down longer on a charter due to a buddy not being able to match me on air, maybe two HP100's would not be beneficial in this circumstance. Second, I worry that the HP100's would give me less than desirable gas for the more physically active tasks of spearfishing and lobstering. So my thought was use the rental AL80's on the boat charters and get a big HP130 to use when I spearfish and lobster (I would just get 1 HP130 for this).

The only concern I have with the big HP130 is trim. Part of me would like to get the HP100's and have my trim, buoyancy, and gear squared away, having one setup that doesn't need to be adjusted between different types of diving (this may not maximize my kit for certain niche dives though). Switching between AL80's on the boat and a HP130 for hunting would mean 2 different weight profiles and swapping things around with my gear between different activities. Also, how bad is the tendency to roll with the big HP130's?

Another random idea would be to just dive two smaller doubles, or maybe even two AL80's. I have the HOG system with soft plate. I could swap to a hard plate and run doubles. Though this maybe an additional cost for the plate and the whole setup, it could feasibly be cheaper if I got AL80's or even some older used steel 72's (I may have the hookup on some free 72's that need to be hydro). I guess I even could run double HP100's for hunting, but the additional kit for this maybe cost prohibitive and I would defiantly have switching around that wound need to be done.

What are your thoughts? It seems like an HP130 would be the simplest for giving me more air while diving for lobster and hunting. Any input would be much appreciated.

 

[Eric Sedletzky]

If you get the 130 close to your back they aren’t that bad for roll. I would borrow or rent one first though to see how you like it before buying one.
Twin aluminums sounds like a nightmare.
Twin 72’s would be ok. You would need to manifold them (extra cost) otherwise you would have to run them independently (another reg)
You could run a manifolded set of doubles on one reg if you didn’t care about two regs for redundancy.
Otherwise with a twin setup run with regs on each post and an isolator you’d have built in redundancy and balance might be better than one big tank.
It also depends on how agile you want to be lobstering spearfishing etc. doubles will be a little more of a backfull to swing around and chase after stuff. In Southern California the lobster divers all use the biggest steel tanks they can find and don’t use BC’s, and that’s with 7 mm wetsuits!
Gallery of California Backpack Divers : 1999-2001

 

[BoltSnap]

Doubles, steel, is always better. I use the bigger tanks, 18L, for diving from boats and use 15L for diving from shore since they are more manageable than 18L when diving from shore and having to swim 300 meters on surface and walking down the sand/rocks to get into the water. I haven't used AL tanks since the late 80's myself and no looking back at all. Even if your buddy has less air and you come up with lots of air, that is still good, it never hurts to have more air than what you need than the other way around.

If I were you, I'd consider smaller doubles or, definitely, use the 130cuft.

 

[scubadada]

Hi @FloridaMan

If you're OK with a fatty, have you also considered the 117? Nearly 5 lbs. lighter and almost 3" shorter.

 

[FloridaMan]

I had thought about them a little, but I was thinking focusing more on maximum air, i.e. the 130. I guess picking up two 117s could be a decent compromise between the two main options (having two HP100s in single mount for everything or dive AL80's on the boats and use the HP130 for lobstering). I am trying to think how much bottom time a 117 would give up over a 130. I know sac and depth are biggest factors, but just thinking average time at about 60 feet.

 

[scubadada]

I had thought about them a little, but I was thinking focusing more on maximum air, i.e. the 130. I guess picking up two 117s could be a decent compromise between the two main options (having two HP100s in single mount for everything or dive AL80's on the boats and use the HP130 for lobstering). I am trying to think how much bottom time a 117 would give up over a 130. I know sac and depth are biggest factors, but just thinking average time at about 60 feet.

I was going to ask the depth you'd be diving and your RMV.

With a Buhlmann GF high of 95, for a 1st clean dive, the NDL at 60 feet is 86 min with 32% and 116 min with 36%

If your RMV is 0.5 cu ft/min (about avg), you'd have about 85 min of bottom time with a 133 and about 74 min of bottom time with a 117. These would be leaving you with a "normal" reserve of 13 cu ft. You can do the calculation with your own RMV

 

[Soloist]

The vast majority of the lobstering/spearfishing boats in South Florida have a sixty minute dive limit, so the HP130’s may be more trouble than they are worth depending on your objectives. Some boats may have difficulty accommodating the larger diameter tanks too. If AL80’s are hitting your thighs it’s possible your tank is setup too low or there is an issue with your BC. I’m roughly your height and have never had an issue diving HP120’s. Cheers!

 

[LiteWeight]

As Soloist said, one concern is the tank racks on the boat. Most boats will have tank racks for Al 80's, 7-1/4" diam. Depending on the boat, E7-100's are too short. And you can't fit the 8" cylinders in there (HP 117, 130). Not a problem if they let you lay it down somewhere.

My air consumption is good, so for a while I would bring 1 HP 120 on the boat and use it for both dives. Then HP100's that I laid down, sometimes using one HP100 for 2 dives if second one much shallower.

Gave up on all that and now just use Al80's.

 

[FloridaMan]

So I just found out my AOW instructor has his own personal HP130 that I can use on one of our dives. It will give me a chance to try before I buy something, though I am leaning toward the 130.

 

[Angelo Farina]

Most people here in the Mediterranean Sea use a 15 liters steel at 232 bars. Mostly made by Faber. Typically with double valve with double posts, so you can use two independent regs.
If my math is correct, this means 122.89 cuft: I find that these tanks are the correct size, not too tall, not too heavy, and perfect trim. In the past I did use a couple of times a 18 liters steel at 200 bar, with is 127 cuft, but these are too long and too bulky for me.
I did also use a compact twin (2x9 liters, aluminium) and they are very streamlined and very light. But they are very buoyant, requiring a lot of additional weight...
So in the end a single 15 liters steel is still the best for me.