Side-mounting 2 different sizes (ex: 80cu & 40cu).

[sabbe]

I recently started looking into a redundant air-source, and may suggested side-mounting. Then the idea of side-mounting both my main (80cu) and redundant (19cu or 40cu) came up. This seems like it would be great for the type of diving I do (boat with small ladder). My only question is, does anyone have advice for running this configuration? For the most part, I'd want to leave my small air-supply untouched.

For example:

• Should I mount the 80cu on the left, so I can easily plug in the inflator hose? I'm relatively ambidextrous, and don't mind the main being on the left.
• Does this configuration feel noticeably unbalanced in terms of drag or bouyancy?
• I have 4x weight pockets, what's the best place to attach them on a backplate setup & would I likely want more weight on one side?
• Is there anything important, I'm probably missing about running in this configuration?

Having slung an AL40 for solo I can understand the desire.

It doesn't sound crazy. The hardest part I expect would be trimming sidemount with a backplate. Multipurpose BCDs are not as good at sidemount as a SM dedicated BCD.

I'd mount the small tank on left, the right tank is designed to be removed. Assuming you're not doing too much up & down the power inflator use should be small. You could potentially remove large right tank before getting in boat and keep left tank / regulator. That's safer than removing both tanks while still wearing your weight climbing into a boat.

Sam

 

[raftingtigger]

I only SM anymore (strictly recreational OW) and am pretty casual on mixing tanks. My primary boat config. is L and R valved steel LP 72s. My primary shore config is L and R valved Alum 40s. I was concerned about paying double for fills when using the 40's, but all the local shops (at my request) agreed the pair are a 'single tank'.

Sometimes I'll dive warm water with a single SM Al 80. Sometimes I'll dive a single SM steel 72 (rarely, I want the redundancy). Steel 72 on one side and Al 40 on another. All depends on what gas I need and what I want to carry to the water. I'm all about what FUNCTIONS best for my dive, not what I look like.

Trim is important. Al (anything from 30 - 80 cuft) needs an extra Kg of ballast on that side vs the steel LP 72. HP steels just are too heavy for my SM diving and are gathering dust in my garage. I can shift my harness to trim underwater, but balancing with an extra Kg lead weight on the aluminum side is cleaner.

The only time I wear my tanks up a ladder is on a commercial dive boat. They prefer I get my own tanks up - please note I am a California diver and we are expected to be self-sufficient. This is a great place for a pair of 40s.

When diving on a warm water boat they don't like me SMing (they think I will stay down too long). This is where one Al 80 and a 15 - 40cf are helpful. The operator thinks of them as pony bottles and doesn't object. I get my redundancy this way.

Again, it all comes down to trim. Easy to correct if you pay attention ahead of time. Just shift some lead to the proper side is all.

Lastly, get some training. Online, in person, mentor, ...

I started my SM journey to dive with my doubles buddies. BM with a HP steel 100 and SM (not slung) an Al 80. It was all 'downhill' from there

 

[SlugLife]

I only SM anymore (strictly recreational OW) and am pretty casual on mixing tanks. My primary boat config. is L and R valved steel LP 72s. My primary shore config is L and R valved Alum 40s. I was concerned about paying double for fills when using the 40's, but all the local shops (at my request) agreed the pair are a 'single tank'.

Sometimes I'll dive warm water with a single SM Al 80. Sometimes I'll dive a single SM steel 72 (rarely, I want the redundancy). Steel 72 on one side and Al 40 on another. All depends on what gas I need and what I want to carry to the water. I'm all about what FUNCTIONS best for my dive, not what I look like.

Trim is important. Al (anything from 30 - 80 cuft) needs an extra Kg of ballast on that side vs the steel LP 72. HP steels just are too heavy for my SM diving and are gathering dust in my garage. I can shift my harness to trim underwater, but balancing with an extra Kg lead weight on the aluminum side is cleaner.

The only time I wear my tanks up a ladder is on a commercial dive boat. They prefer I get my own tanks up - please note I am a California diver and we are expected to be self-sufficient. This is a great place for a pair of 40s.

When diving on a warm water boat they don't like me SMing (they think I will stay down too long). This is where one Al 80 and a 15 - 40cf are helpful. The operator thinks of them as pony bottles and doesn't object. I get my redundancy this way.

Again, it all comes down to trim. Easy to correct if you pay attention ahead of time. Just shift some lead to the proper side is all.

Lastly, get some training. Online, in person, mentor, ...

I started my SM journey to dive with my doubles buddies. BM with a HP steel 100 and SM (not slung) an Al 80. It was all 'downhill' from there

I'll ask local dive-shops, if they're willing to fill 2x pony's for the price of an 80. Theoretically, they make about the same amount of money.

I'm always hauling my own tanks into the boat, since it's my friend's boat. I can generally do whatever I want, although they also generally want me back up around 1-hr for their own sanity & worrying about me.

I didn't realize there's a difference between slinging and side-mount.

In terms of training, I can't find any side-mount training at any of the 3 dive-centers I checked so far. I'm generally fairly good at doing my own research, so instead I've been looking at youtube videos, discussions here, and asking questions as needed. I have a MUCH more experienced dive-buddy, I'll also ask him if he has SM or sling experience.

Building a DIY sling seems super-easy, and I already have a bunch of webbing, sewing equipment, clamps, elastic, etc.

edit: Side-mount looks slightly more refined and secure than just slinging. Adding the bungies and moving around the d-rings is no problem. If running a backplate setup, is a butt-plate usually recommended for side-mount? I see it mentioned in a few guides, but not in others.

 

[napDiver]

Building a DIY sling seems super-easy, and I already have a bunch of webbing, sewing equipment, clamps, elastic, etc.

edit: Side-mount looks slightly more refined and secure than just slinging. Adding the bungies and moving around the d-rings is no problem. If running a backplate setup, is a butt-plate usually recommended for side-mount? I see it mentioned in a few guides, but not in others.

DGX has sling/sm kits. If you have qs you can pm me.

Yeah Sling its just hanging out. SM strictly is its perfectly parallel to your body and trim out to one or each side.

Butt plates are usually used for heavy steel tanks due to how they trim out. In reality, I think most people can get away without using a butt plate unless they use massive steel tanks and/or get them cavefilled.

 

[happy-diver]

Both are rigged the same, albeit that the bottom boltsnap location in terms of how far around the cylinder it is away from the meridian of the modular stub is different to account for the cylinder diameter and buoyancy differences.

This is great, do you mind if I use it

Lastly, get some training. Online, in person, mentor, ...

Love this

manual, ...



DIR-diver.com - Stagebottle rigging

 

[SlugLife]

Speaking of online training, does anyone have suggestions? I did find sidemount.com, which I'm considering. I found a few more videos scattered on YouTube from other instructors, but most of it's rather limited. I think I've picked up the basics enough to try it safely, but obviously don't want to stop there. My primary goals are to (1) side-mount with a backplate setup and (2) have a redundant air-supply.

P.S. There are some other classes I plan to take locally this year, but as mentioned earlier, I cannot find side-mount locally.

 

[happy-diver]

Did you open the stagebottlerigging link

Technical Diving Articles | Techniques | Knowledgebase

 

[SlugLife]

DGX has sling/sm kits. If you have qs you can pm me.

Yeah Sling its just hanging out. SM strictly is its perfectly parallel to your body and trim out to one or each side.

Butt plates are usually used for heavy steel tanks due to how they trim out. In reality, I think most people can get away without using a butt plate unless they use massive steel tanks and/or get them cavefilled.

The cheapest kits are $45, which is not bad. However, I want some semi-permaent rigs for each of my tanks, and then 2x more I can use on rentals. I also want to customize the setups slightly, including a carrying handle, and I have all the supplies and then some including a bunch of nylon webbing, elastic, bungee, bolt snaps, sewing equipment, etc.

This is great, do you mind if I use it Love this manual, ...

DIR-diver.com - Stagebottle rigging

That's one of the guides I bookmarked as a starting point.

 

[SlugLife]

Did you open the stagebottlerigging link

There's a magnificent sidemount site with more information than you can read
but I just can't think of the name

edit: I didn't see the Technical Diving Articles | Techniques | Knowledgebase link. I'll dig through that. Sorry, I misread.

edit2: There's a lot of info there, I think that will keep me busy for a short while!

 

[JonG1]

This is great, do you mind if I use it




Love this

manual, ...



DIR-diver.com - Stagebottle rigging

No worries