First time with doubles tomorrow, help with weight

[USNMARS]

Well I was basically given a set of aluminum 80's the other day and am itching to get out and play. My current setup I use a stainless BP with 60lb oms wing. I dive a single steel 100, and when I dive my 3mm with my setup I normally have 15lb on my belt, yeah I'm fluffy and float like a cork. So my question is what should be a general idea to set my weight to for my first time with double aluminum 80's versus my steel 100. There are no pools around that I can go play in and test so a friend and I are hitting the local river and doing a 20ft dive just to get wet and try them out, but I'd like to have my setup somewhat close when we go.

Thanks in advance,
Eric

 

[Fishpie]

Once you factor in the added weight of manifold, bands and additional 1st stage and take that away from the the additional buoyancy of the 80's you'll probably end up with a very similar amount of weight.
Remember you are weighting for empty tanks at 10ft.

 

[rongoodman]

If you can, have a way to attach some weight low on the tanks, a tail weight or pouch, weight belt, or a couple of weights you can at least attach to the bottom of the plate with zip ties. Doubles often tend to put divers head down in the water, to which the natural response is to swim head up, which is very confusing because it makes you think you need more weight up high rather than down low. TSandM talks about "shortening the lever arm". Making the issue worse is that Al80s are notorious for getting butt light as they empty. As I recall, she uses a 7 lb tail weight with her aluminum doubles, and she's a small woman. I hang 4 lb off the bottom of my LP85s.

(That's a big wing for a small set of doubles--watch out for air getting trapped above the tanks.)

 

[divad]

I hang 4 lb off the bottom of my LP85s.

How?....................

 

[rongoodman]

An 8 lb V-weight cut in half. Unfortunately, I don't think anyone is making them any more. I've also used a soft weight in one the of the XS Scuba tail weight pouches, but it's a pretty snug fit between the tanks.

 

[Tug]

An 8 lb V-weight cut in half. Unfortunately, I don't think anyone is making them any more. I've also used a soft weight in one the of the XS Scuba tail weight pouches, but it's a pretty snug fit between the tanks.

I believe North East Scuba Supply sells v-weights


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---------- Post added August 1st, 2013 at 10:59 AM ----------

Yup, here is the link http://www.northeastscubasupply.com/v-weights/


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[rongoodman]

Good to know, thanks.

 

[TSandM]

Yes, I use a 7 lb v-weight hung off the bottom bolt with Al80's in Mexico. As I recall, I used 4 2kg weights in the Red Sea with the same setup. That's in water where most people would dive a 3 mil. But I can't tell you how that compares with what I use with a single HP100, because I don't dive that tank in warm water.

 

[pickens_46929]

I'll 2nd what rongoodman says above... AL80 doubles are tricky... you think because they are doubles you have extra weight but in reality you end up with two large empty floatation buoys on your back.

Compared with diving a small set of double LP85 steel tanks, I ended up having to add about 6# v-weight with double AL80's.

 

[USNMARS]

Well everything went extremely well, I ended up with a total of 10lbs of weight. I am now a double diving addict and am already setting up to put together another set. I am fortunate enough to live within an hour and a half of Northeast Scuba Supply and got a nice set of used bands and a new manifold cheap. I am in love with these things, They actually trimmed nice and were easy to manage in the water. I use OTS guardian mask so having 160 cu ft is very nice because my SAC is a little high. During my dives I did a few valve drills until I felt like I mastered them and could do them blindfolded. My one dive buddy is an instructor and I we had it planned that he would shut off a valve during our deco stop to simulate a problem and I would isolate and switch to my octo. So that was a bit fun, but I feel confident that during an emergency I could handle myself safely.