steel vs. alum.: where's the logic?

[ Follow Ups ] [ Post Followup ] [ California Scuba Diving BBS ] [ FAQ ]

Posted by JRM on November 13, 2000 at 12:06:07:

In Reply to: Re: DIR question posted by MHK on November 13, 2000 at 10:54:31:

MHK wrote:
You mistate the drysuit position.. Thermal protection, of course, is addressed but the idea behind drysuits in warmer climates is to provide an additional inflation sourse if you are using
steel tanks.. Under DIR philosphies if you use AL tank[s], which become positively bouyant when empty the drysuit is not required.. If you are using steel tank[s], which remain negatively
bouyant when empty than we recommend drysuits so in case you have a bladder failure you will still have an inflation source to get you to the surface...

Ok, I can see why a drysuit would be good in this situation. But what's the difference between diving a steel tank, or an AL80 with a 6lb keel weight. They both pretty much end up neutral (depending on the steel, some are even a few pounds positive, according to the OMS catalog). The DIR philosphy seems to defy logic here, in that steel in a wetsuit is wrong, but AL and keel weight in a wetsuit is right. What's the difference?

It also seems that this would only make a difference if I suffered an inflator failure (which happened to me this weekend when some gravel jammed my exhaust valve open) at the end of the dive? If it wonks at the beginning, the tank is still negative. So steel or AL it's still negative, just one more slightly so than the other.

As a side note, I use a 5' primary hose. Actually, I have been ever since I got my own rig, since I'm using a Poseiden second stage that my was using as an octo, so it came with the longer hose. And it does make it really nice to share (when practicing). The other thing that is cool is the Poseiden doesn't really have a "right side up". When doing OOA drills in class, it was a pain to rotate the renter Sherwood regs on the short hose.

Oh, and as far as the plastic breaking argument, I've seen those plastic snaps shear off lots of times. And usually at the most in-oportune times. I've had them shear off of backpacks a couple of times. Usually it's the outer tabs on the male end. Give 'em a couple of good tugs and they pop. And plastic fatigues like crazy. Of course, I still have them on my BC :-) Because of the discussions on this list I've split my weight three ditchable ways. Integrated weight pockets (independent) and a belt. I actually really like adding the belt, because I know if I do lose the BC I won't go rocketing to the surface.


--learning fast. Someday I'd like see one of those DIR demos. When's the next one?

Follow Ups:

Post a Followup




[ Follow Ups ] [ Post Followup ] [ California Scuba Diving BBS ] [ FAQ ]