Question about twin tanks

[al249v]

Hello out there, Al Webber from the Central Valley of California here, a new DH diver with a freshened up (but not yet Phoenixed) D.A.A.M. and a couple of tank questions.

I have a single steel 72 with a J valve set up with a USD KamPack that I really like using, it fits me well and is comfortable. The tanks I'm having a little trouble with are the twin 72s (with J valve) that I just got. They came with a 3-piece manifold and simple, narrow (1") webbing that is attached directly to the tank bands without any sort of backpack. I'm thinking that I'd prefer some sort of a backpack between the tanks and my back but have not run across anything like a "twin KamPack". What do you guys like to use for twin tanks? Also, the 3-piece manifold deal worries me a little, leaks at the joints and such (no actual leaks, just me worrying)- is this a real worry such that I should look for a 1-piece manifold or should I forget about it?

I'm also thinking about when I take both the single 72 and the twins into the ocean (I've been limiting myself to local lakes until I get used to this "new" stuff)- I think I'd prefer a B.C. in the ocean, especially as I'll be diving with my girlfriend who will be using a modern singlehose on a B.C.- I want to have the same basic operational layout as she's pretty new to scuba in general. Is anyone here using Bryan's Ultimate BCD SetUp with twin tanks? How are you attaching the tanks to the BC? Any other suggestions for a newby?

Thanks for your thoughts-

[Nemrod]

Most people use exactly what you have, a vintage Navy/military style harness, no plate is needed. For a BC a horse collar such as still (?) made by SeaTec is suitable. You will find a modern W type bent tech plate unsuitable for use with a double hose regulator because the center channel area interferes with proper positioning of the regulator keeping it way to high.

I suspect that several people have already adapted the new VDH plate to doubles use, perhaps some will speak up as to how they did it. I would use stainless tee nuts pressed into the plate and stainless bolts to fix the bands. I would use modern bands such as typically used with the aforementioned bent W tech plate.

Yes, three piece manifolds can leak if not assembled and maintained correctly. Otherwise, they are fine and completely suitable for diving, past, present and future.

Nem

[swimjim]

You will not find a better doubles set up then the one you have. The one inch straps directly to the bands with a crotch strap keeps everything in place. In the water, it a very comfortable set up. You just need to make sure you run your webbing so it's a one pull and your out deal. Check out the right way in Basic Scuba by Fred Roberts. There are undoubtedly threads that cover the way to run the straps too just a search away.
The manifold can be a PITA, but once set up correctly you will really like it.

Jim

[swimjim]

In this video, https://vimeo.com/51971914 , you will see me learning how to use a Hydroglove dry suit using the same doubles system you have.

Jim

[luis]

I had a thread that got lost (server crash) of my technical diving kit with a Phoenix on doubles 72. Here is parallel thread from SB:
http://www.scubaboard.com/forums/vintag ... oenix.html

If you look in the thread you will see my doubles.

With doubles I prefer not to use any type of back pack or back plate. I prefer the tanks as close to my back as possible and with the doubles the space in the middle is nice because nothing is pressing on your backbone. Having the tanks as close as possible to your back makes it easier to carry the weight. For some of my shore diving I have a long walk.

I have several sets of small doubles and a set of double 72. I use a basic (Navy style) harness directly on the tank bands on all my doubles. I find this to be the most comfortable set up with doubles.

For a BC I like using a Zeagle wing. It is a simple horseshoe style (U shape) that is open in the middle and it is very easy to just strap directly to the tanks. Allan made me four Velcro straps so that I can easily move the wing from one set of doubles to another.

Here is the bladder that I used:
http://www.scubatoys.com/store/detail.a ... enaBladder
For a set of double with a basic harness I think this wing is the best.

I have a slightly smaller one (24 Lb) that I use with my VDH plate for my singles kit.


Here are some pictures from 2008:

[Drado]

After I got my Sherwood manifold, I banded 2 of my lp72s to use with my dh's. First off, let me say I have every bit of confidence in its 3 piece construction. In fact comparing it to the more contemporary isolation manifold beside it on the al80s, I dare say it would be slightly more robust.


As for attaching the tanks, I modified an aluminum backplate in two ways to make it more dh-friendly: I stepped on it several times to make it flatter, and I put a cut-out in the middle to accomodate proper positioning of the regulator.


As for the bc, I tried 2 methods: one was more traditional with a horse collar bc, while the other utilized my current doubles wing. One thing I eventually found out with the horse collar is that due to the position of the air bubble behind the head, looking straight forward while maitaining trim was difficult. I needed to pitch up a tad if I wanted to see where I was going. Granted though my time in the water with a horse collar is somewhat limited so take these experiences with a grain of salt. I felt more comfortable with my wing but one major obstacle is that some doubles wings like mine have a centrally mounted inflator hose, and this gets in the way of the reg.

[luis]

As for the bc, I tried 2 methods: one was more traditional with a horse collar bc, while the other utilized my current doubles wing. One thing I eventually found out with the horse collar is that due to the position of the air bubble behind the head, looking straight forward while maintaining trim was difficult. I needed to pitch up a tad if I wanted to see where I was going.

I used horse collars for several decades and IMO, they are fine as long as you don’t need to put any air in them and used for surface flotation only. IMO, as a buoyancy compensator they are terrible. Any volume of air pushes your head down and they ruin your trim by adding buoyancy right behind your head.

Your center of gravity is down by the middle of your body and adding buoyancy at the extreme end (by your head) just screws up trying to keep a somewhat horizontal position.

Also, since I have been using a wing I really like not having anything cluttering my chest. With a wing I can actually forget that I have a BC since it is totally out of the way.


Ed,
It looks like your doubles should move down your back about 4 or 5 inches. I am just guessing by using the diameter of the tank as a scale. But it looks like the regulator is behind your neck, not behind your shoulders. If you slide the tanks down your back about 4 to 5 inches you will see the regulator lower in the water column about 1 to 2 inches. That will make it breathe that much better.

Your trim is what I consider perfect for swimming. That slight amount of slope allows you to look forward (comfortable human neck flexure is only about 45 degrees), and with a double hose in the right position (lower on your back) it places the regulator even with your inner ears.

[Drado]

Now that you mention it, it does look a bit high... Will drop it down a bit, but even then, with a Phoenix HPR, the diff in WOB was unnoticeable

[USdiver]

Hi Al,

Welcome to our madness. I prefer to dive my twin 72s with just the harness set up, although I use a single piece manifold rather than the one you describe. It's much stronger and as I don't have a backplate, I prefer having a single piece manifold to provide more stability to the bands.

[Nemrod]

Now that you mention it, it does look a bit high... Will drop it down a bit, but even then, with a Phoenix HPR, the diff in WOB was unnoticeable

Actually, it is more than a little too high. You have run into the problem I did several years ago, the upper band will fall off the shoulder of the tank when it is properly positioned for a double hose regulator. You will have to reposition that top band some way or other. Or settle for a less than ideal position. While I am not into having the bottom of the tank hitting my heels like some, your tank is definitely too high.

James

[al249v]

Many thanks for all of the opinions and suggestions. I think that I shall follow the suggestion of sticking with the harness that I have and the Zeagle Wing does indeed look like a clean answer to my B.C. need. I aso think I'll keep an eye on my 3-piece manifold and as long as it doesn't give me any trouble in the water I'll not worry over it.

Jim- that was a cool video. Do you have any more?

[Bryan]

http://www.vintagedoublehose.com/index. ... id=9500234

[al249v]

Hmm- I'd never really looked at Bryan's smaller BC, I was always focused on the full jacket B.C. It looks like this one works sort of like the "U" shape of the Zeagle, but with a sheet of fabric closing in the middle of the U. Has anyone used this one with twin tanks? I can readily see that it would be quite compatible with a single tank.

[Bryan]

Its the plate that makes the difference.....Read the posts above or go back and read
This thread
The BCD is really secondary as most divers weight themselves correctly and put very little air in the BCD anyway. The VDH plate will work with 99% of the wings on the market...I'm just trying to keep the $$$ here by offer and complete package. In the end all that matters is you are comfortable in the setup you choose no matter who makes it.