Doubles questions

[TkdDiver]

I've searched for a while and haven't found the answers that I'm looking for. I'm about to purchase 2 HP 120 tanks for backmount in preparation for tech diving in the future. In pictures I've seen how the two first stage regs are always at that slight angle, why is this?

Also, I've seen varied methods of routing hoses between the two first stages, what is the "best" method of routing hoses. I know one second stage on each but other than that I'm sure there are good reasons for putting this hose there instead of there. Any and all help appreciated!

 

[DA Aquamaster]

First, what regulators do you own?

With an L shaped regulator like the Scubapro Mk 5, Mk 10, Mk 15, Mk 20, Mk 25, or a Mk 21 with the optional end port, the right hand regulator is positioned so that the long hose comes out the end port pointed down toward your can light on the right hip, keeping it tucked in close to the body without forming any loop. That also lets the DS inflator hose on the turret point in toward the diver and over the shoulder which again avoids any loop in the hose.

On the left hand regulator angling the end port of the first stage outward in the opposite direction (pointing at the left hip d-ring), allows the HP hose on the side of the first stage to point downward where it stays streamlined. And in the same fashion it allows the back up regulator hose to route directly around the neck and allows theBC inflator hose to route cleanly over the shoulder.

Given that this first stage layout is common, this hose configuration is common as well.

However, it's not the only configuration you'll see.

For a balanced diaphragm first stage with 1 HP and 2 LP ports on each side of the regulator, you position the first stages on their sides so that the HP hose on the left reg points down for clean routing, while the back up reg and BC inflator hose route down and then bend back up and over shoulder or around the neck. On the right side the long hose and DS inflator hose also route down, with the inflator hose coming back up over the shoulder.

This approach is a little cleaner overall, but it puts a little more bend in a couple of the hoses.

In that regard, you tailor the hose routing to the type of first stage you have to avoid any loops in the hoses that stick out away from the body, and to avoid any sharp bends in the hoses that may lead to failure.

Some divers will use a 90 degree swivel or elbow for the inflator and/or back up second stage hose(s) to avoid any bend in the hose(s) at all. It's a mixed bag however, as with a swivel you're adding a dymamic o-ring and a static o-ring to the system, as well as a swivel joint that is help together by a screw that can fail. At a minimum, you don't want to use cheap swivel and you'll need to pay close attention to it's health over the dive season.

 

[divad]

In pictures I've seen how the two first stage regs are always at that slight angle, why is this?
View attachment 220490

I do it so I can get my head (up) in there. I need to start doing stretches that will allow me to lower the doubles.

 

[decompression]

Simple reasons for stages on doubles;

Hose routing (reduce stress)
Access to valves
Redundancy (if a tank is shut down your complete system will still function)


Sent from my iPhone using Tapatalk

 

[CptTightPants21]

It is usually cheaper to buy a used set of doubles online than to make your own. Remember you need to buy the bands, manifold, and then pay someone to set them up. Used set of doubles routinely go for $400-$550 depending on tank size, age, and condiditon. Setting up those doubles yourself with new tanks will easily cost between $850-$1000.

To answer you question, the angle of the first stages depends on the exact first stage and personal preference. First stages are positioned part for hose routing (minimal bends/kinks in the hoses), part so it doesn't obstruct the valve, part so the first stage is "streamlined".

Regulator on your right (Right Post) will have your 7ft hose and lp inflator to the BC. The 7ft hose is always on the right because if you hit the tank valve in an overhead environment it will only be able to roll "on" and not in the off position.

Regulator on the the Left Post has SPG (24-26 inch hose), drysuit inflator, and backup regulator on a 22 inch hose.

You need 1 regulator and 1 inflation hose on each post. GUE standards and most people set up with the BC inflation on the right and drysuit on the left, but I have seen others with those positions reversed--just as long as there is one on each post.

Google the PDF for Jablonski's DIR book.

Are you going to travel to do your tech training or stay local?

 

[tbone1004]

also keep in mind with the HP120's that if they are the true HP tanks with the skinny necks, manifolds for them are as rare as hens teeth. Your hose routing will depend on what style first stage you have as mentioned

https://www.globalunderwaterexplorers.org/equipment/config
about 1/3 of the way down you can see the two basic ways of setting up doubles. With an end port a la Apeks DST, Hog D1/D3, Dive Rite, Hollis, Scubapro MK25, yadda yadda yadda, you get a lot cleaner hose routing. Without an end port, you have to run them like the DS4's show in the picture which puts a bit of kink on the hoses, mainly the primary second stage and the HP hose. Unfortunate fact of life with that style first stage is there really is no "good" way to use them unless you have the cocked back valves that Sherwood used to make which relieves the hose strain but you still have the secondary second stage and the inflator hose turning 90* from where they end up.

 

[TkdDiver]

CptTightPants21 I'm getting the two tanks, tank band and manifold from diverightinscuba
XS Scuba HP100 Steel Doubles Package | Dive Right In Scuba - Plainfield, IL - Dive Right in Scuba
I have a Mk25 and s600 for the right post and long hose and genesis gs200 for left post and short hose. I think(without having all my gear in front of me at the moment) that i can do all this, and understand now that they'll probably be at slight angles. But thanks for the DIR book recomendation!

 

[tbone1004]

oh my expensive.... You know doubles regularly go for half that right? Nothing against DRiS, I just can't believe the price of new tanks these days. Also, make sure you are tall enough for the 120's. You really have to be 6'3"+ to dive them comfortably and be able to sit. Unfortunately nothing in your area for doubles right now, but quite a few in mine for $500 ish.

Also, I would recommend jumping on ebay and getting a matching first stage. MK25/S600's usually go for a couple hundred bucks and are for sale all the time. If you aren't going in a cave or taking GUE courses you can move the hoses around. If you want the sp/genesis to stay together, i would put the genesis flat on the left post like the Apeks in the pictures from GUE, then cock the mk25 where the inflator comes out the bottom port and the primary is on the turret. That will look funny since they are mismatched but give you the best hose routing. If you are OK with splitting and having non-DIR hose routing, I would put the GS2000 first stage on the right with your S600 as primary, have that and the drysuit hose coming down from there, then move the MK25 to the left post with the secondary coming out the bottom, and inflator coming out of the turret. This is the best for hose routing given your circumstance but is non-DIR

 

[halocline]

On the left hand regulator angling the end port of the first stage outward in the opposite direction (pointing at the left hip d-ring), allows the HP hose on the side of the first stage to point downward where it stays streamlined. And in the same fashion it allows the back up regulator hose to route directly around the neck and allows theBC inflator hose to route cleanly over the shoulder.

I think you mean the end port is pointed inward towards the center, so the alternate 2nd stage hose points in the direction of the right shoulder. This puts one of the HP ports pointing down as well.

 

[tbone1004]

I've seen it done both ways. With the MK25's it's not that bad because the DIN screw is mounted so high on the body, the Hog D3's can work like this as well. With DST style regs the diaphragm and enviro seal sticks way up which is not ideal, especially in a cave as that will be first point of impact if you are any bit head up.
The disadvantage to this is that in an air sharing situation the primary hose is more prone to kinking and damage at the crimp, and if you're tall you lose easily 6" of hose length with the 180* bend it has to make. Putting the primary on the turret allows it to swivel forward when deployed which reduces hose strain and gives you the full length of the hose.
It also causes the HP hose to turn 90* to go down to the hip or shoulder d-ring which is less than ideal and can increase your profile.