First SM dive. Questions/Comments

[GreyDyvr]

I dove sidemount for the first time yesterday. I set up my gear after much reading and experimenting. I feel pretty good about it but definitely need to tweak some things.

I am using the SMS75, Faber HP100 steel tanks, and Hollis DCX first stages. I ended up not needing any additional lead and I still felt like I was heavy. I was putting quite a lot of air in the bladder to stay neutral at depth. Is this normal for diving doubles?

In these pictures both tank were around 1500psi and set up the same. One is staying horizontal and one is a little floaty at the bottom.

Critique and comments are welcome.

Thanks.

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[RVBldr]

Getting access errors on the links.

 

[RainPilot]

Hard to tell over pics, the left tank looks excellent, I would check to make sure the right tank is identically setup, if it is then it's probably your bungee length. A tighter bungee will cause a tank to pivot around the lower attachment point.

As far as weight goes, two steel tanks in a wetsuit will probably be overweight for most people. Not a massive issue but consider redundant buoyancy issues when deciding how to dive these. In the meanwhile, check with 500psi in each tank how heavy you really are.

 

[Bierstadt]

Can't see the links. I will note that my semi-dry requires about 25 lbs to sink, and of course provides a fraction of that at depth. It's just the nature of the beast when diving a thick wetsuit. Your steels are going to be 18-20 pounds negative, plus reg weight. That is why you take redundant bouyancy - drysuit, double bladder, or 50 lbs lift bag. Balanced rigs are all well and good, but we dive with the gear we have.

 

[GreyDyvr]

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Sidemount left

• GreyDyvr
• Sep 29, 2018

 

[decompression]

Looks quite good for first dive SM. As Brandon says, ensure both tanks rigging is identical, bungee is same, d rings are the same. Dive the tanks at 500 psi, check, then you make corrections. Common issue is bungee to loose, especially with steels. The Fabers are probably neutral to a couple lbs neg, so if you arent wearing any lead and still adding considerable air then I’d consider a switch to Al tanks.

 

[ChuckP]

What's causing the difference with that right tank in the middle pic? I'm about to try this adventure too and just trying to learn...

It almost looks back some too.......

 

[GreyDyvr]

Just looked at my tank rigging and the right side tank cam and was a little lower than the left. Not by much though. Less than an inch. I didn’t think that would have made such a difference but it’s possible I guess.

 

[RainPilot]

Just looked at my tank rigging and the right side tank cam and was a little lower than the left. Not by much though. Less than an inch. I didn’t think that would have made such a difference but it’s possible I guess.

Joys of sidemount. Death of a thousand micro adjustments.

The angle between the bottom boltsnap and the tank valve is an often overlooked variable as well. With the torque difference from a different bungee tension and a different valve-to-lower attachment point length there can be a remarkable difference in how the tank hangs.

Luckily your left tank is perfect so you have a template to sort the right one out.

 

[ScubaJCBS]

I've never thought of this but your long line is probably on your right side would that give that tank a slightly different buoyancy characteristic?