Advice for small doubles

[halocline]

A set of old LP 72s might work out well. They're about 26lbs each empty, and with a slight overfill you can get close to AL80 capacity. Everyone raves about LP85s, but they will be about 10lbs heavier on land, and they're very similarly sized. Plus, 72s are cheap; I spent about $100 each on mine, that includes hydro, vis, a tumble, and a few cans of ZRC galvilite to clean up the galvanizing after removing the paint. If you can find a galvanized set in hydro, that's the way to go. Hammerhead makes good reasonably priced 7" bands, and standard iso manifolds fit fine. Just make sure that the 72s you buy have 3/4" valve fittings. Some of the really old ones use 1/2" tapered valves.

edit: I see you already had started a thread about 72s, so I'm not sure why you're even thinking about the dual bowling balls.

 

[ptyx]

They suck and push everyone head down. It's possible to compensate, but that almost universally results in dropped knees. So while the occasional special person can make them work well, its so rare that I wouldn't waste your money trying.

I have a pair of MP72 which have similar characteristics to the HP80 (without even having the gas). I confirm.

You can compensate the head heaviness with a tail weight, heavy fins, ankle weights, keeping the legs extended, a thick hood and dry gloves.... but is it worth it? Another problem is that they're so short the wing extends way below the tank and requires extra attention not to get pinched when sitting.

That said, I appreciate the (relatively for doubles) light weight for beach dives and I only paid $100 for both tanks. So no regrets.

 

[rjack321]

I have a pair of MP72 which have similar characteristics to the HP80 (without even having the gas). I confirm.

You can compensate the head heaviness with a tail weight, heavy fins, ankle weights, keeping the legs extended, a thick hood and dry gloves.... but is it worth it? Another problem is that they're so short the wing extends way below the tank and requires extra attention not to get pinched when sitting.

That said, I appreciate the (relatively for doubles) light weight for beach dives and I only paid $100 for both tanks. So no regrets.

I don't think I'd use them where you need good trim to come naturally (cave or wreck penetrations). But its worth dealing with some hassles for $50 per tank cheap beach diving

 

[dl348]

My wife uses the Worthington HP 80s doubled up. Took her some time to get used to but she is fine with them now. She is about 5'1".

 

[ptyx]

My wife uses the Worthington HP 80s doubled up. Took her some time to get used to but she is fine with them now. She is about 5'1".

I'm 5'9" myself and curious.

Did she manage a static equilibrium? Or does she needs to constantly adjust?
i.e. if she gets in trim and freeze, will she slowly rotate and end up with her head in the sand? Or stay in trim until she's bored.

To me, that's the difference between the HP100 and the MP72. The only way I could ever manage a stable trim with the 72s was with a tail weight of about half a ton AND ankle weights. (Not worth it for open water - I'll take the dynamic equilibrium).

 

[lowviz]

While my wife has dived taller cylinders she has a set of lp66 doubled up. They are a bit taller than HP80s. Another option is to find a nice set of LP72s.

Agree with the LP72's, worth a try.

I'm 5'9" myself and curious.

Did she manage a static equilibrium? Or does she needs to constantly adjust?
i.e. if she gets in trim and freeze, will she slowly rotate and end up with her head in the sand? Or stay in trim until she's bored.............

See if you can borrow a set of LP72's.

 

[TSandM]

To me, that's the difference between the HP100 and the MP72. The only way I could ever manage a stable trim with the 72s was with a tail weight of about half a ton AND ankle weights. (Not worth it for open water - I'll take the dynamic equilibrium).

We have two sets of LP72s, and I loathe them. Of all the doubles I've dived, they are the ONLY ones I just can't trim out. I even worked with Bob Sherwood (widely regarded as a guru of gear balancing) and his conclusion was, "Yeah, I guess you CAN'T trim those out!" A very heavy tail weight will get them close, but when the LP85s ride like they were made for me, it doesn't motivate me to fight with the smaller tanks. The advantage in total weight just isn't that much. If you can tolerate doubles at all, you can tolerate the LP85s, I think.

 

[lowviz]

We have two sets of LP72s, and I loathe them. Of all the doubles I've dived, they are the ONLY ones I just can't trim out. I even worked with Bob Sherwood (widely regarded as a guru of gear balancing) and his conclusion was, "Yeah, I guess you CAN'T trim those out!" A very heavy tail weight will get them close, but when the LP85s ride like they were made for me, it doesn't motivate me to fight with the smaller tanks. The advantage in total weight just isn't that much. If you can tolerate doubles at all, you can tolerate the LP85s, I think.

Very interesting. I tend to be head-up in trim (with most tanks), 5'11" and large lung volume. Could be why I like them. LP72's may be a bad suggestion in this case.

 

[TSandM]

lowviz, if you are consistently head-up in trim, is it possible that you are head heavy in weight? When you are head-heavy, you rear up to shorten the lever arm that the tanks have to push you downward, which is why almost everybody transitioning into doubles goes head up. If you go completely horizontal and stop moving, which way do you tilt?

 

[lowviz]

lowviz, if you are consistently head-up in trim, is it possible that you are head heavy in weight? When you are head-heavy, you rear up to shorten the lever arm that the tanks have to push you downward, which is why almost everybody transitioning into doubles goes head up. If you go completely horizontal and stop moving, which way do you tilt?

Not completely sure. I seem to be able to compensate with wing/tank bands positions. Probably compensating with body position also. I start with the tanks where I can just hit the isolation valve with my head if I really stretch. Wing goes wherever seems to be best. Double HP100's are the norm, 8 or 4 pound weight belt, depending on sw/fw. Hard to tune in by myself, probably should give trim the attention that it deserves...