BC bands: To wet or not to wet

[DebT]

I'm a relatively new scuba instructor. Recently at a training dive, another more experienced instructor made a comment about me wetting my BC bands. She laughed and said "you still wet your bands?". Am I missing something? Is there new research out there that says not to wet your bands before gear assembly? I've seen more than one tank slip out of a band that hadn't been wetted first, but maybe wetting had nothing to do with it. Thoughts?

 

[decompression]

As long as they are tight when dry the odds of slipping are slim. Especially if there are 2 bands. If you are teaching them to adjust the bands underwater as well, that's when they will be wet. No worries.


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[Jim Lapenta]

No you are not missing anything. If a BC has two cam bands there is less likelihood of the tank slipping. But even at that I still wet mine and teach students to wet them. Some bands also do hold better than others. These may have a rubber pad on them or be similar to the ScubaPro style or Highland style bands and allow the diver to tighten them better than your old standard ones.
Even at that they are still nylon and nylon stretches. So if she says anything again say "Yes I do still wet them, will keep wetting them, and will teach students to do the same." And walk away. You and your students will not have to encounter the situations like I did in Puerto Rico where on a descent I had to help the DM with a group of divers who did not wet their bands and stretch and then readjust. I put two tanks back in before we hit the target depth.
And you can tell her it's pretty ignorant of her to laugh about you doing it.

 

[Damselfish]

I think some bands are more affected by wetting than others. I suspect water lubes the fibers of some webbing so they slide past each other more easily. If you know it helps to wet yours before tightening it, do it and ignore someone who thinks their way is the only way. It would be silly not to reach people something so simple that can prevent a problem UW.

 

[dumpsterDiver]

If the bands are old and broken in, then they don't need it too much. Also if you are a strong person, you can more easily tighten the cam band sufficiently to get it to snap shut securely. Women and children do not have the hand strength to easily close the buckle with a lot of force (comfortably anyway).

I myself don't wet the bands, but if I was teaching divers, I would definitely teach them to wet the cam band. It is an extra step, but it also serves to remind them that there is a very real potential for the cam band to become loose on a dive.

This extra step, should emphasize that they need to make sure they get it right. Plus, nylon does stretch when wet and this allows them to tighten the cam more easily..Still a smart thing to teach.

Also, the biggest issue I see, even from somewhat experienced divers is that they do not understand how the CAM action works, they don't understand how to have the buckle not threaded in the last slot, to tighten past the leverage point provided by the cam and THEN to thread the strap through the last slot. The failure to understand the mechanical advantage of the cam itself and the proper sequential procedure is the PRIMARY cause of problems with tanks coming loose.

 

[AdivingBel]

they don't understand how to have the buckle not threaded in the last slot, to tighten past the leverage point provided by the cam and THEN to thread the strap through the last slot.

I see this a lot on vacation dive boats. It gets a nice "ooo ahh" when you see someone struggling with it between dives and you nicely offer to help them out. Many times it gets you a round at the tiki bar afterward.

 

[drbill]

What? You take your BC off your tank? I think mine is glued on. Actually I leave my BC attached to my tank unless I have to switch tanks if the one I primarily use isn't full. I have dual tank bands and the only time my tank has slipped out was the other night when I did a solo night dive and totally forgot to cinch the bands down when I changed tanks. I wondered why my reg kept tugging to get out of my mouth on the dive. The tank didn't slip out until I ended the dive and was walking up the dive park stairs (even then the two bands held it from falling to the ground. Of course I tend to dive a lot so my bands rarely get totally dry unless the humidity is really low (like during a Socal Santa Ana).

 

[Wookie]

I think some bands are more affected by wetting than others. I suspect water lubes the fibers of some webbing so they slide past each other more easily. If you know it helps to wet yours before tightening it, do it and ignore someone who thinks their way is the only way. It would be silly not to reach people something so simple that can prevent a problem UW.

^^^This. I've never had to wet my bands, but then, I have gorilla strength and have actually broken one before while tightening it. If wetting your bands works for you, do it.

Y'know, I would never question another scuba instructor or boat captain's methods unless they are putting their students (or passengers) in danger. It seems a bit asinine to even bring up the issue, at the lake, maybe with students overhearing. Now that you know that you are dealing with a A$$, you don't have to worry about what he (she) thinks any more.

 

[RJP]

I teach "straps tend to stretch/loosen when wet, so to ensure a good tight connection you should wet the bands" rather than trying to explain a series of conditional exceptions "if there are two bands... or if it's a good band because some are better than others... or if it's tight enough when dry" etc. Most students will end up renting gear somewhere, or just plain not pay attention to the gear, or maybe they have a different idea of what "tight enough" means. Why leave it to the vagaries of the student's judgement... there's zero downside to wetting the bands. As DD points out above, if nothing else it sends the message "... and for crissakes make sure your cam straps are tight!"

PS - if that instructor laughed and made a comment to you in front of students she needs a metaphoric slap upside the head. A.) you just don't do that, and B.) I'm sure if a bunch of us watched her class we could find 1/2 dozen things to laugh at or comment on.

 

[Akimbo]

We did some experiments when writing http://www.scubaboard.com/forums/bu.../391300-cam-buckle-assembly-instructions.html that lead us to think the Nylon band isn’t stretching significantly, but the compression of material between the band and cylinder was considerable. Another area that showed observable loosening of the bands was deflection on metal backplates and STAs.

There is a paragraph that suggests storing new BCs and bands on a cylinder and progressively tightening bands over days. Resilient materials relax and metal slowly bends. The most important thing we observed was how effective two bands are. There is a binding effect that prevented significant tank slippage even when tests were run with ridiculously loose bands.