Questions On Twinning Doubles

[matt_unique]

...You'll need to get the bands as close to the valves as possible. Tanks towards your butt.

With the lower band at the very bottom of the base of the tank you will be lucky to touch your valves with these tanks. You would have virtually no chance of reaching the valves with the bands raised high on the tank. Add in a neoprene suit and forget it.

Remember it's not a one to one measure of lift vs. land based weight. The same applies when you can lift a huge rock to the surface of the water but not out of the water. My double alum 80's full weigh 96 lbs on a scale. (With manifold/bands of course). I use a 59lb Classic Wing for these, reels, alum 80 deco bottle, etc. Your 45lb wing should float them fine.

I would find a local tech shop and watch them set up your bands/manifold.

-Matt

 

[limeyx]

With the lower band at the very bottom of the base of the tank you will be lucky to touch your valves with these tanks. You would have virtually no chance of reaching the valves with the bands raised high on the tank. Add in a neoprene suit and forget it.

....

-Matt

unless the neck of the tank is really really short (which with those it might be) you ought to be able to reach the valves.

Richard's suggestion is good -- generally (and everyone is different), the shorter the tanks, the more the weight is going be balanced toward your head and push you head down in the sand. Getting the bands as high up on the tank as possible pushes the weight of the tanks toward your feet and helps balance you out.

 

[tangfish]

sorry folks, I've been a bit confused about the band positioning. The way I imagine it (but I'm a newbie) is that the higher the bands are the lower my valves will be and the harder they'll be to reach, which is why I wanted to mount the bands as low as possible. Sounds like there isn't a consensus on this so I'll follow the advice of adjusting as I go. I've also seen an OMS valve extender doodad (looks like a hose with a valve on the end coming from the isolator valve on the manifold), but I've never seen anyone actually use that thing.

thanks for the advice everyone, I'm getting there, slowly but surely.

 

[kidspot]

yes, the manifold will be lower... however my lp72s with the bands at the crown of the tank still put the isolator bar at the base of my skull... they are EASY to reach up this high - it's much higher than my singles sit. In otherwords, don't worry about reaching your valves unless you are very inflexible (and I'm not all that flexible myself, but the valves are still quite easy to reach for me)

You'll probably find it best at this point to just try it and see - don't buy more gear to fix problems you most likely won't have

Aloha, Tim

P.S. http://www.diveriteexpress.com/library/doubles.shtml has a good write up on assembling doubles.

 

[duckster3d]

sorry folks, I've been a bit confused about the band positioning. The way I imagine it (but I'm a newbie) is that the higher the bands are the lower my valves will be and the harder they'll be to reach, which is why I wanted to mount the bands as low as possible. Sounds like there isn't a consensus on this so I'll follow the advice of adjusting as I go. I've also seen an OMS valve extender doodad (looks like a hose with a valve on the end coming from the isolator valve on the manifold), but I've never seen anyone actually use that thing.

thanks for the advice everyone, I'm getting there, slowly but surely.

Your talking about the infamous (SLOB KNOB) for those that can't reach their valve, do to various reasons.

Don't know most of the divers on this board, or how much they have dove doubles, so I can only tell you what I've learned over the past 27 years of diving. The bands need to be as high on the tanks as you can get them. some have already said it, but if you put the bands low thus raising the tanks up higher then you will end up head down and have to fight to keep your head up. you'll expend lots of engery and gas and have a lousy dive.

The 45# wing may float your rig, but as you add estra gear to it it will be close. I would go with the 60# for the added margin of safety. Your drysuit is not to be used for bouyancy. add only enough air to it to take off the squeeze, adding more will complicate your dive as you ascend. You'll end up trying to dump both wing and suit and change gases, and monitoring depth rate of ascent, where your buddy is. etc etc...

 

[rjack321]

With the lower band at the very bottom of the base of the tank you will be lucky to touch your valves with these tanks. You would have virtually no chance of reaching the valves with the bands raised high on the tank. Add in a neoprene suit and forget it.

You must have a very tight suit/undergarment or have shoulder problems.

I don't have these tanks doubled up anymore (too head heavy), but I could easily reach valves on HP80s. All of my other doubles (3 sets - LP85s, HP100s, HP119s) are set up with the bands as high as they can go on the tanks, right below the curve of the crown.

I'm not particularly flexible in the shoulders. But my old neoprene suit and new shells have never been an impediment to reaching valves on doubles. I've never seen anyone mount their bands at the bottom of their tanks? I don't know how you tilt your head to look forward that way?

Reaching your valve on a single tank is another story.

 

[LSDeep]

your 45 should be fine, even if i personally prefer a bit more of "reserve" lift (dpv and stuff you might carry come to mind). i personally use single or double bladder in the 60lbs lift area for most doubles. as for the up and down of the tanks, yes start with tanks as low as poss, do a dive - see how your trim is, adjust to upwards (in really small increments) do a dive see..., adjust......... you get the hang! once you have your trim right start worry about reaching the valve knobs. by the way, all the adjustment "diving" you can do in a pool! so its in play around for a while, out adjust, back in and so on. if you really have trouble to reach your valves ones you have perfect trim, there is the option to use oms (i am sure they are not the only) detachable remote valve knobs. not the best solution in my eyes, but def. better then being not able to operate your valves and isolation manifold.
good luck!

 

[LSDeep]

by the way i guess you could push your tanks all the way up and use ankle weights, it just seems kind of stupid !

 

[tangfish]

Thanks for all the feedback folks, I definitely see a consensus here (i.e., moving the bands up as high as possible on the tanks). This is why I love scubaboard. I'll drop you guys a line and know how it worked out. I just got my manifold so I'll be doubling up soon

 

[tangfish]

Thanks for all the advice, i did my first dive last night 1:10 at around 85-95 feet most of the time. It was great. Very stable and no problems with faceplanting. I think I am the right ht/wt for my rig. Buying HP100's for an alternate setup.