Bungee attachment - single piece or a loop?

[roydude]

I'm pretty new to sidemount and I've always used a loop of bungee for the top of each cylinder (from backplate, through a d-ring and back to the backplate). But I've just seen pictures of a single length of bungee from the backplate and just tied to the d-ring.

Compare, for example:
http://scubatechphilippines.com/scuba_blog/wp-content/uploads/2012/05/sidemount-bungee-1.jpg
vs
http://www.deepdivegear.com/WebRoot...40/436E/stealth_harness_only_adjust_CWP_m.jpg

A single length seems like a better option (less fuss), but are there advantages to having the bungee in a loop instead of a single piece?

 

[mddolson]

There are two schools here, not sure which is better, preference seems to be the deciding factor. I'm a newb & still trying to work out what works best for me. With the loop there would be more material and perhaps less stretching of the bungie, so maybe it lasts longer. You might use lighter cord to get the same tension. Not sure.

 

[tbone1004]

i'm not a fan of either of the options you have listed as it puts the valves much lower than I like them. With the attachment down at the d-ring, there is no way for the bungee to hold the tank "up" towards your spine. That's a choice.

Valve position like what is shown below is only possible with a loop bungee that has a sufficient length of line to let the bottom of the loop settle where the valve knob is. This is a relatively extreme tank position compared to most sidemount divers because it is optimized for sidemount only cave diving. No part of the tank will touch the cave before my body does. The downside is the razor style SPG's are incredibly difficult to work with, even on 9" hoses, and feathering the valves is quite difficult. If I had to feather a valve, I would remove it from the bungee and let it hang from the neck leash

The picture below shows Steve Boegarts and the tank positioning that the single bungee a la razor, the loop bungee that you linked to, as well as the stock bungees for the SMS100 and old Nomads. You can't move the valves farther back towards your hips, or closer to your spine with this configuration because of the attachment points. Pros and cons. The pros are much easier access to the valve for feathering and shut down, and easier access to the SPG's. Downside is the crown of the tanks will hit the floor before you will and it is a little less streamlined.

 

[roydude]

Wow - that's crazy streamlined! I like it, you're a diver after my own heart in that respect, but I doubt I could reach that in a drysuit without dislocating a shoulder

 

[tbone1004]

Wow - that's crazy streamlined! I like it, you're a diver after my own heart in that respect, but I doubt I could reach that in a drysuit without dislocating a shoulder

they live in the same spot when I dive dry, just don't have any pictures in a drysuit

 

[Subcooled]

There is no one truth.

If the only bungee supporting a tank fails, then you have to carry that cylinder in your hand, which is not a major crisis, but annoying still.
If both cylinders are supported by the same bungee, and it fails, then life *ucks.

If you have two double bungees (and the right type of knots) then a failure of one bungee (half a loop) is not so annoying. (This risk is related to some metal clamps used to make bungee loops. A better alternative is to use knots instead. They are big, cumbersome, and dependable.)

The above mentioned risks can easily be avoided once you acknowledge their existence.

A double bungee is best used knotted. If thick enough (and one per tank) I cannot see a major fault in one bungee either...

Hence, it is a matter of preference.

Use whatever feels good and minimises trouble!

 

[Subcooled]

Bungees are like socks. You own many pairs and you throw them away when they are worn out. You could even own bungees of different thicknesses.

 

[DevonDiver]

I find that looped bungee (making use of double strands of 4 or 6mm) provides more support to the tank, but is easier to manipulate.

In contrast, you might need thicker diameter bungee (maybe 8mm) with a single strand on continuous or independent bungees. More strain on the fingers...less elasticity on the tanks.

Using loop bungees isn't hard. I find that students master it just as quick as single bungee (and much quicker than if bolt-snaps are used on bungees).

With a properly trimmed tank, it looks hard to access the value or spg... BUT... there's a lot of elasticity in a loop bungee... so you can manipulate/move the tank easily to gain clear access.

 

[tbone1004]

@Subcooled do you not believe in neck leashes?

 

[roydude]

I find that looped bungee (making use of double strands of 4 or 6mm) provides more support to the tank, but is easier to manipulate.

In contrast, you might need thicker diameter bungee (maybe 8mm) with a single strand on continuous or independent bungees. More strain on the fingers...less elasticity on the tanks.

Yeah I'm noticing that in the pictures - a single bungee is thicker. I'm very comfortable with a looped bungee so I'll stick with that for now and experiment in a pool at some point with a few options and see what the pro's and cons are for me.