Breaking in a new BC

[Crush]

I am not advocating the rubber pad, Tobin, but you are very much incorrect in your vector analysis. If you were right, dragsters would have very thin rear tires. I can go through the math if you wish, but I prefer not to do so since I see no need to defend a rubber pad that: (1) isn't necessary; and (2) IMHO just gets tangled up when I slip in my tank. Give me two straps and I am happy.

 

[fdarden]

My brand new Aqualung Dimension BC's strap came with one of these pads. It works perfectly. I actually have been thinking about a way of replacing this belt with a band, more like what you would find on a Dive-Rite BC, mainly because I feel that strap and buckle system is much easier to deal with.

 

[cool_hardware52]

I am not advocating the rubber pad, Tobin, but you are very much incorrect in your vector analysis. If you were right, dragsters would have very thin rear tires. I can go through the math if you wish, but I prefer not to do so since I see no need to defend a rubber pad that: (1) isn't necessary; and (2) IMHO just gets tangled up when I slip in my tank. Give me two straps and I am happy.

Humm,

Really? Love to see the math, not sure how you get forces normal to a surface from forces purely parallel to it.

Dragster tires? I have no idea what you point is here but....

Comparing the dynamics of a vulcanized rubber tire that achieves a friction coefficient of greater than one (due to adhesive traction compounds) to a slick, water lubricated, piece of vinyl seems quite a stretch. The starting line at a Top Fuel Race is sticky enough to pull your shoes off BTW.

What I know works, from actual quantitative testing, are short, comparatively tall very soft elastomeric "blocks" that function much like the 6 x 6 on the steel plate example I already referenced.

Tobin

 

[Jim Lapenta]

I was taught to wet the tank band before every dive. When they dry out they shrink. When they get wet they expand. None of my BC's have rubber pads on the tank bands. Some of them came with them and I took em off. They got in the way. The rubber tension blocks on the DSS plate and wing set ups work the best and they never contact the tank itself. I've been toying with the idea or waterjetting some similar blocks that could slide on to cam bands for the same purpose. Just need to get rid of my boss for a few hours. I've never seen a properly set up tank slip unless the bands are just worn out or broken in some way. Wet the bands, tighten, let set for a minute and retighten. Should have been covered in your OW class. Rubber pads, fancy buckles, etc are no substitute for proper technique.

 

[cool_hardware52]

My brand new Aqualung Dimension BC's strap came with one of these pads. It works perfectly. I actually have been thinking about a way of replacing this belt with a band, more like what you would find on a Dive-Rite BC, mainly because I feel that strap and buckle system is much easier to deal with.

Have you tried it without the pad?

The key to getting Cambands to work are:

1) Lace the buckle correctly

2) Make sure the cambands pass *straight* around the cylinder, forming a true circle. Often the band is lower or higher on the cylinder than on the BC. That results in sort of an ellipse, not a circle, i.e. a longer path. When the tank shifts a bit the tension is lost.

3) Proper methods for tightening the buckle. Cambuckles don't really offer much mechanical advantage, but there is enough if the technique is proper.

Better "systems" will have some form of "compliance" in them, i.e. something compressible. Many jacket BC's will have a soft rubber pad when the tank contacts the BC. This pad will compress when the cambands are closed. This reduces the closing forces, and provides a degree of preload as the cambands stretch and the tank diameter reduces as the pressure drops. Luggage strap pads are simply to wide and thin to compress.

Tobin

 

[Aqua-Andy]

3) Proper methods for tightening the buckle. Cambuckles don't really offer much mechanical advantage, but there is enough if the technique is proper.

Maybe you should produce a video of the proper tightening procedure, I would think that around 99% of tank slippage is due to improper tightening methods. And I don't buy the wet the tank band thing, maby if you let it soak for a half hour or so but a quick dip and putting on the tank? I believe it takes nylon more than a quick dip and maybe 5 minutes of water drying off it to absorb enough water to do anything.

 

[Slamfire]

Many jacket BC's will have a soft rubber pad when the tank contacts the BC. This pad will compress when the cambands are closed. This reduces the closing forces, and provides a degree of preload as the cambands stretch and the tank diameter reduces as the pressure drops. Luggage strap pads are simply to wide and thin to compress.

Tobin

This is the pad I was referring to that came with the BC. I took it out because I felt it was getting on the way. One day the tank slipped a bit. So I put it back in and the tank hasn't slipped since. The picture I originally posted may well be that of a pvc luggage pad, but as I said, I just googled it for illustrative purposes.

 

[Slamfire]

This is still not exactly the way my pad looks, but it is closer than the first pic I posted. This one has two additional slits in the center that mine doesn't have.

 

[Shftrdog]

Yeah make sure you get the strap wet before you put it on the tank

 

[Jim Lapenta]

Maybe you should produce a video of the proper tightening procedure, I would think that around 99% of tank slippage is due to improper tightening methods. And I don't buy the wet the tank band thing, maby if you let it soak for a half hour or so but a quick dip and putting on the tank? I believe it takes nylon more than a quick dip and maybe 5 minutes of water drying off it to absorb enough water to do anything.

No one ever said a quick dip. Look at the strap. It is made up of hundreds of individual threads that act like a big wick. I let mine soak for a minute or so. I do not let it dry. Put the BC on the tank, tighten the cam and let it sit and stretch for minute, The retighten. I can sometimes get another 1/8 -1/4 inch of slack taken up. Hundreds of pool sessions and nearly 400 dives and I have never had a tank slip. I watched two divers set up their gear on a boat in Puerto Rico. They did not want to lean over the rail and wet the tank straps while we were still at the dock. I watched them crank down on the straps. Less than 5 minutes into the 1st dive I was grabbing them and telling them to stay still so I could put their tanks back in. Not one of my students has had a tank slip nor have any that I have heard of trained by my own OW instructor who has certed many hundreds of divers. When they don't do it- then the tank is likely to slip.