Learning doubles w/ Twin HP 120s?

[bikefox]

Understood... I'm just not sure investing money in the wrong tanks is his best use of available funds. Tech diving is not an inexpensive hobby. If one can't afford the proper gear, then one should limit their diving to what is appropriate for the gear they have.

I already have the 120's. You are right tech diving is expensive. I plan to buy the right gear for the right situation which is why I'm here asking questions. With the classes being over $1000, the fact I just bought a new BP and wing, I was just asking if I could double up tanks I already own for some practice before the class.

I am 6'1" 205 lbs and I have 2 of the original Sherwood 120's as singles and 2 sets of Asahi 120's doubled up and I love them. I tried a set of OMS/Faber LP95's and thought they were too heavy and too bulky. I do not have any experience with the LP 85's but I have been so happy with my 120's so I don't see a need to change. Good luck the Asahi's hold up very well and the only complaint is that the neck is the non-standard thinner thread so you have fewer option in buying manifolds.

That's good to hear.

I had a set of LP120s that were great for deep diving. My kit weighed 125# with them, but I only used them on a few beach dives. I strongly recommend getting an isolation manifold and backplate with at least 50# lift. I tore up a "tech" BC using the water heaters. I had no trouble handling them in the water.
BTW, I'm 6'4" 220 lbs and my buddy tells everyone that I'm freaklishly strong.

I have a 55 lbs wing and a SS backplate. Should I maybe go with an Al backplate to reduce some weight?

 

[mark99]

Your post caught my eye because I dive double Worthington HP120's and I also have a set of double AL-80s and a set of Faber double LP85's. My 120's are my primary set for tech diving, and in no way are too big or have "too much gas" for typical ocean dives in the 150fsw range. You'll also find them handy for recreational diving where you can get 2-3 rec dives out of a single mix and not have to fill up with non-O2 clean boat gas. There are some arguments from some tech divers to use LP cylinders (and I must say I also love my LP85's) but that mostly has to do with the demands of filling to pressures over 3000 psi and boosting O2 and He if you are doing partial pressure blending. But that isn't really the issue if you already have the 120's.

I would say that I had very little in terms of issues changing from single to doubles, actually the doubles felt more stable right from the beginning. You will find that they have more resistance in the water and you will notice that when swimming them. I use a Halcyon Explorer 55 and I use an AL backplate to reduce weight, and allow a little weight on the belt on the opposite side of stage bottles. (typically I use 5# of wt on the belt). I personally would be a little concerned about the negativity of your brand of HP120s and would try to do a calculation based on what you use with them as singles to see if you will still be negative at 500 psi even with 0 weight and an AL BP. If so that would personally be a deal-breaker for me.

 

[MaxBottomtime]

I have a 55 lbs wing and a SS backplate. Should I maybe go with an Al backplate to reduce some weight?

I used a Halcyon 55# wing and ss backplate with an eleven pound V-weight. I used the same setup for double 95s and double steel 80s. The 120s eventually failed hydro after years of over filling, and since I wasn't making many boat dives, it was a relief.

 

[Colliam7]

I already have the 120's. ... I plan to buy the right gear for the right situation which is why I'm here asking questions. With the classes being over $1000, the fact I just bought a new BP and wing, I was just asking if I could double up tanks I already own for some practice before the class.

Good for you. That is why I doubled up my 120s to begin with - I already had two of them and didn't want to invest even more money in tanks, on top of course fees, regs, etc.

I have a 55 lbs wing and a SS backplate. Should I maybe go with an Al backplate to reduce some weight?

If you want to spend the money, a reasonable consideration. I dive my double 120s (PSTs, which may be just a bit lighter than your Asahis) with a SS BP, and also a Halcyon 55# wing. No problem. (I have an AL BP but haven't gone to the trouble of putting webbing on it for a harness.) In fact, with my drysuit, and that rig, I am actually not overweighted in salt water. I also dive the rig with can light, back-up light, reels, two deco bottles (80 and a 40). Yes, that configuration is heavy in fresh water but again, not a problem. Plenty of people dive double HP120s without difficulty. You have the tanks already. Go for it.

 

[pmetz]

If you do the GUE fundies, they will go over a balanced tech config and how to acheive that. Out here in Hawaii all of us on our Tech Dive Team use Doubled Aluminum 80's, Halcyon 40lb wings on steel backplates. However since it hawaii we dive wetsuits and 80's are great for that. Best bet, talk to your instructor with whomever you choose to do your classes with (GUE, TDI Ect.) and get his thoughts on it before you go out and buy or reconfigure your exsisting gear. Plus I don't know how it is out there, but I know out here the shop I work for has sets of doubles already configured for students to use.