First set of Doubles

[leviathan]

i would get one more 120 and put them together. Make sure you get the valve opposite if your going to use a manifold.its nice to have the extra air .a lot of times i do 2 dives off 1 set of doubles

 

[wb416]

MASS-Diver once bubbled...
Well although I've enjoyed diving with my 120hp and 40cu stage, I think I'm ready for doubles and I plan on devoting a chunk of my tax refund toward them. Any advice on all aspects of doubles would be much appreciated.

Thanks for any feedback.

I chose to keep my LP120 a single tank for future "recreational use" and instead got the 104's. I wouldn't worry as much about your back as your knees. In particular, stepping down and leaving all the pressure on one knee. Step deliberately and with purpose.

If you are interested in my first dive with doubles a couple of years ago, it can be read at the following link.
First Dive in Doubles

Enjoy... the balance is nice....

 

[MCL00]

I have been diving doubles for two years now and must say you have definitely made the right decision to dive twins.

First off, having tried a few sets of doubles and a couple of bc's, your diving goals play a significant role in your choice. R u going full on tech, or still a recreational diver going down with plenty of air???

I myself am not a small guy (smaller than I was when I started) and let me tell you gettin on a rockin boat with twins can be a challenge. I started out with LP 72's and have now switched to HP80's by Genesis. 120's are WAY TOO BIG. In my shop we have a set of 95's and 120's...no way would I dive with those, too big and heavy. Actually a buddy of mine just got a set of OMS (Faber tanks) 66's. These are nice twins. Compact, light (compared to many) and still plenty of air (132cf), these tanks will give you plenty of bottom time and still leave you with a back when you are 60+.

AS for a bc, I see no other bc as fit for twins as on OMS IQ pack with 100lb bladder, or if you really want, go with the 100lb redundant bladder set up. The bc's are comfortable, they have 17 D rings positioned all over, and they are high quality. Go to OMS-Dive.com to find a local shop selling OMS.

Best of luck with you new adventure....but watch that bottom time, you can easily get distracted and get into trouble.

 

[roakey]

Bigmike00 once bubbled...
AS for a bc, I see no other bc as fit for twins as on OMS IQ pack with 100lb bladder, or if you really want, go with the 100lb redundant bladder set up.

Why did you choose 100 pounds of lift?

Roak

 

[wb416]

roakey once bubbled...

Why did you choose 100 pounds of lift?

Roak

Salvage Ops and "Righting Artificial Reefs" like the Speigal Grove.

 

[MCL00]

I chose 100lbs for a very simple reason.. SAFETY. As a DM for a local boat, I have seen to many instances where divers have a bc with insufficient lift. In my case, the tanks weight over 30lbs each, the manifold is approx 2lbs, the bands are almost 2 lb, I wear 6 lbs of lead....I have a huge camera set up, and sometimes take down 2 cameras, I also get scallops on the same dive...and if a student or dive buddy drops a weight belt, I know that with all this crap on me, I can still remain positively buoyant at the surface. Most diving accidents involve weight situations such as forgetting (or unable) to establish positive buoyancy. With a large amount of lift, this problem is eliminated. Plus if you look at many of the manufacturers, the price difference between lift capacity is not very significant. OMS and Deep Outdoors both offer large lift capacities which are only slightly more than the lower lift capacity bladder, but offer much more lift. (i.e. OMS 60 or 100, D.O. 55 or 85??)

 

[wb416]

Bigmike00 once bubbled...
I chose 100lbs for a very simple reason.. SAFETY. As a DM for a local boat, I have seen to many instances where divers have a bc with insufficient lift. In my case, the tanks weight over 30lbs each, the manifold is approx 2lbs, the bands are almost 2 lb, I wear 6 lbs of lead....I have a huge camera set up, and sometimes take down 2 cameras, I also get scallops on the same dive...and if a student or dive buddy drops a weight belt, I know that with all this crap on me, I can still remain positively buoyant at the surface. Most diving accidents involve weight situations such as forgetting (or unable) to establish positive buoyancy. With a large amount of lift, this problem is eliminated. Plus if you look at many of the manufacturers, the price difference between lift capacity is not very significant. OMS and Deep Outdoors both offer large lift capacities which are only slightly more than the lower lift capacity bladder, but offer much more lift. (i.e. OMS 60 or 100, D.O. 55 or 85??)

Are you saying that you try to hang on to the weight belt that your buddy or student has dropped? If so, that sounds to me like you're trying to use your BC as a lift bag. What would happen to you if you dropped their weight belt while holding on to the other stuff your carrying?

Also, don't confuse the weight of your tanks on land with the negative buoyancy of your tanks underwater. While weighing almost 30# each on land, your tanks are approx -9# bouyant each when full.

By comparison, 104's are -12# each UW, yet my 65# wing is plenty of lift for twin 104's, manifold, SS backplate, and stage(s). My buddy dives an identical rig with a 55# wing.

Remember that your wing should be sized for your max negative weight at the beginning of the dive (you get lighter as you go).

Do you carry a lift bag / surface marker? Also, are you diving wet or dry?

Don't be tempted to buy bigger just because the price differential is minimal... get the right tool for the job. Too many people choose to "Biggie Size It" unnecessarily.

wb

 

[roakey]

Bigmike00 once bubbled...
I chose 100lbs for a very simple reason.. SAFETY. As a DM for a local boat, I have seen to many instances where divers have a bc with insufficient lift. In my case, the tanks weight over 30lbs each, the manifold is approx 2lbs, the bands are almost 2 lb, I wear 6 lbs of lead....I have a huge camera set up, and sometimes take down 2 cameras, I also get scallops on the same dive...and if a student or dive buddy drops a weight belt, I know that with all this crap on me, I can still remain positively buoyant at the surface. Most diving accidents involve weight situations such as forgetting (or unable) to establish positive buoyancy. With a large amount of lift, this problem is eliminated. Plus if you look at many of the manufacturers, the price difference between lift capacity is not very significant. OMS and Deep Outdoors both offer large lift capacities which are only slightly more than the lower lift capacity bladder, but offer much more lift. (i.e. OMS 60 or 100, D.O. 55 or 85??)

Ok folks, pay attention.

Here we have the classic mistake of adding up "in air" weight and thinking we need to base our lift requirements on "in air" weight. This is what I was afraid of when I read the post and why I asked the question.

We do not worry about "air weight.". We base lift requirements on "in water" weight (or buoyancy if you prefer). Folks like OMS prey on folks like this that were probably taught by so-called "knowledgable" instructors who don't understand the concept either. This problem is widespread in the industry and getting worse fast-track instructor by fast-track instructor.

There's plenty of posts on this topic in the file already, searches on "lift" and "buoyancy" will probably produce them. Bottom line: When discussing buoyancy and lift requirements, if you ever hear someone talking about how much something weighs out of the water, stop listening to them.

Double 104s swing a measly 16 pounds from full to empty. With an AL backplate, 45 pounds of lift is more than enough. You could probably get by with 30.

100 pounds of lift in the name of safety is quite the opposite. Many accident reports read along the lines of "during the rescue the divers became seperated and one sank and the other surfaced." This is an understatement. If one diver is using their OMS super-duper 200 pound lift double BWOD to drag someone up to the surface (versus using the other diver's buoyancy device for that diver's buoyancy) and they get "seperated" one's a Polaris missle and the other is a lead brick. THIS is what's happening when you read about divers "getting seperated" during a rescue and this broken concept of having tons of lift to be able to drag other divers to the surface is to blame for the tragic outcome of many of these failed rescues.

Roak

 

[MASS-Diver]

roakey


Good point, it makes sense and everyone should understand it, bit, nonetheless, you will hear uneducated divers tallying up how much their gear weighs OUT-OF-WATER and then deciding well, with my doubles, camera, a couple lobsters in the bag I need a BC with 275lbs of lift............

 

[VTernovski]

Roak, excellent post. I just ran acorss it, and thout it is worth posting in this thread to refresh the subject. I am plannon gon getting doubles, my eyes are already set on the Oxycheq #50 wing. If I understand correctly, this should be fine with the paired PST E8-130 tanks? I hear some poeple say that 55# wing would be better, but Oxycheq only has 50 and 70 lift wings, and 70, in my opinion, is way to much for what I am going to do, so the answer is 50.

-VT

roakey once bubbled...

Ok folks, pay attention.

Here we have the classic mistake of adding up "in air" weight and thinking we need to base our lift requirements on "in air" weight. This is what I was afraid of when I read the post and why I asked the question.

We do not worry about "air weight.". We base lift requirements on "in water" weight (or buoyancy if you prefer). Folks like OMS prey on folks like this that were probably taught by so-called "knowledgable" instructors who don't understand the concept either. This problem is widespread in the industry and getting worse fast-track instructor by fast-track instructor.

There's plenty of posts on this topic in the file already, searches on "lift" and "buoyancy" will probably produce them. Bottom line: When discussing buoyancy and lift requirements, if you ever hear someone talking about how much something weighs out of the water, stop listening to them.

Double 104s swing a measly 16 pounds from full to empty. With an AL backplate, 45 pounds of lift is more than enough. You could probably get by with 30.

100 pounds of lift in the name of safety is quite the opposite. Many accident reports read along the lines of "during the rescue the divers became seperated and one sank and the other surfaced." This is an understatement. If one diver is using their OMS super-duper 200 pound lift double BWOD to drag someone up to the surface (versus using the other diver's buoyancy device for that diver's buoyancy) and they get "seperated" one's a Polaris missle and the other is a lead brick. THIS is what's happening when you read about divers "getting seperated" during a rescue and this broken concept of having tons of lift to be able to drag other divers to the surface is to blame for the tragic outcome of many of these failed rescues.

Roak