How to tighten tank strap

[Dredgy]

This an extremely basic question, but I feel I'm doing something wrong.

I just bought a new backplate/wing setup and loving the dives. When I went diving yesterday, first dives went great. Loved it. Tank straps were nice and tight, no problem.

Loosened them during the tank change, and during the second dive the tank fell off. I was able to hold it in place until I found a sandy spot to kneel down, take my BC off and reattach the tanks. While it was a relatively minor inconvenience, I don't want it to happen again.

The straps were only a fraction as tight as they were on the first dive, but nothing I'm doing seems to be able to get them tight again so I have to be missing something extremely basic. I've tried pulling them tight both dry and wet (and literally underwater) to no avail.

Am I missing something? I think the threading is right, but I took a video of me trying to tighten to demonstrate the problem:
I think I need to thread another 6 inches or so to get it properly tight, and I can barely budge it a millimetre.

What am I doing wrong?

 

[Zef]

I don't think you have it threaded properly. Take a look at this guide:


Skip to the 13:00min mark for the part relevant to how the buckle is threaded.

If there are double slots on your back plate (2 sets side by side) then only use the slots closer to the center line of the plate.

There is also a tendency for straps to stretch when they are wet, especially when they are new...but that does not seem to be the problem you are having. Ensure yours are threaded through one pair of slots on your plate and threaded through the buckle properly.

-Z

 

[Zef]

Here are a couple more that are shorter and perhaps clearer:



-Z

 

[Mike1967]

I don't think you have it threaded properly.

He's got it threaded right.

 

[Dredgy]

I now have them tightened, by taking the tank off, tightening it all the way, and just loosening bit by bit to get it on the tank.

Now it's a pain in the ass to get the cylinder on, but once its on it's not moving. Hopefully it'll just become easier with time.
But I'm not worried about the straps anymore as I have a dive in the morning and my first stage is violently leaking.

 

[Mike1967]

But I'm not worried about the straps anymore as I have a dive in the morning and my first stage is violently leaking.

It's not just the o-ring between the first stage and valve is it?

 

[Dredgy]

It's not just the o-ring between the first stage and valve is it?

I'm hoping that's what it is. It's something to do with that area. I replaced the O-ring, but new O-ring was wrong size and I may have damaged the original O-Ring getting it out. Then I realised the DIN connector (I had the regulator converted from Yoke to DIN) was a bit loose so I tightened that up, and then when I turned the tank back on it held pressure for about 10 seconds before blowing again.

If it's an o-ring, it'll be super easy to fix at the dive shop tomorrow.

Other option is when I had the tank filled, some damage was done to the inside thread. DIN regulators aren't common here so I usually put the yoke-insert in when it gets filled, but I forgot this time and the instructor said it had been a while since he'd done a DIN one. I think this is extremely unlikely though.

 

[Mike1967]

Yeah there's not much that can go wrong other than an O-ring, you'll get it sorted tomorrow. Enjoy your dive!

 

[johndiver999]

The videos are missing the important part! You do not thread it through the last slot!

You skip the last slot and tighten the cam band on the tank and full it tight, PAST the point where the cam action of the buckle really tugs on the belt. It sorta pops as you bring it past this point. Then the band is tight, but the buckle is NOT closed (but nearly closed).. THEN when the tension is off the tail of the strap, you run the tail of the strap through the last notch.

 

[Dredgy]

The videos are missing the important part! You do not thread it through the last slot!

Yes I do, at 0:28 or so in the video, but my hand obstructs it from view.

I can definitely feel the "pop" when doing it, but when the strap is properly tight, the "pop" has enough resistance that it is actually difficult to close.